Mesenchymal Stem Cell-based Therapy: A New Paradigm in
Neeraj Kumar Satija1, Vimal Kishor Singh1, Yogesh Kumar Verma1, Pallavi Gupta1, Shilpa
Sharma1, Farhat Afrin2, Menka Sharma1, Pratibha Sharma1, R.P. Tripathi1 and G.U.
1Stem Cell & Gene Therapy Research Group, Institute of Nuclear Medicine & Allied
Sciences, Lucknow Road, Timarpur, Delhi-110054, India.
2Department of Biotechnology, Hamdard University, Hamdard Nagar, New Delhi-110062,
Received date: 12-Aug-08, Revised date: 27-Mar-09, Accepted date: 7-Jul-09
*Corresponding author: Dr. G. U. Gurudutta
Stem Cell & Gene Therapy Research Group,
Institute of Nuclear Medicine & Allied Sciences,
Lucknow Road, Timarpur,
Please cite this article as a “Postprint”;10.1111/j.1582-4934.2009.00857.x
has yet to undergo copy-editing and proof correction. See
http://www.blackwell-synergy.com/loi/jcmm for details.
approved for publication in the Journal of Cellular and Molecular Medicine, but
This is an Accepted Work that has been peer-reviewed and
Mesenchymal stem cells (MSCs), adherent fibroblastoid cells, present in bone marrow and
many other tissues can be easily isolated and expanded in vitro. They are capable of
differentiating into different cell types such as osteoblasts, chondrocytes, adipocytes,
cardiomyocytes, hepatocytes, endothelial cells and neuronal cells. Such immense plasticity
coupled with their ability to modulate the activity of immune cells makes them attractive for
stem cell-based therapy aimed at treating previously incurable disorders. Preclinical studies
have reported successful use of MSCs for delivering therapeutic proteins and repairing
defects in a variety of disease models. These studies highlighted the in vivo potential of
MSCs and their ability to home to injury sites and modify the microenvironment by secreting
paracrine factors to augment tissue repair. Their therapeutic applicability has been widened
by genetic modification to enhance differentiation and tissue targeting, and use in tissue
engineering. Clinical trials for diseases like osteogenesis imperfecta, graft-versus-host disease
and myocardial infarction have shown some promise demonstrating the safe use of both
allogeneic and autologous cells. However, lack of knowledge of MSC behaviour and
responses in vitro and in vivo forces the need for basic and animal studies before heading to
the clinic. Contrasting reports on immunomodulatory functions and tumorigenicity along
with issues like mode of cell delivery, lack of specific marker, low survival and engraftment
require urgent attention to harness the potential of MSC-based therapy in the near future.
Keywords: mesenchymal stem cells, stem cell therapy, genetic modification, protein therapy,
List of main topics:
• Mesenchymal stem cells and its characteristics
• Experimental/Preclinical MSC-based studies
o MSC transplantation
o Genetically modified-MSC-based therapy
o MSC-based protein therapy
o Tissue engineering using MSCs
• Clinical studies
• Challenges and future prospects
Bone marrow harbours cells of hematopoietic and non-hematopoietic lineages and their
precursors, known as stem/progenitor cells. The non-hematopoietic stem/progenitor cell
compartment contains mesenchymal stem cells (MSCs), which are involved in remodeling of
the mesenchymal tissues throughout adult life. These multipotent cells are easily isolated
from bone marrow and are capable of expansion and differentiation into mesodermal lineage
cells including osteoblasts, chondrocytes and adipocytes, under appropriate conditions, in
culture [1, 2]. This led to the evaluation of their potential for treating diseases, and the birth
of MSC-based therapy.
Recent clinical trials with MSCs for treating debilitating disorders like osteogenesis
imperfecta, myocardial infarction, stroke and graft-versus-host disease have shown some
promise [3-6]. Numerous preclinical studies have established the therapeutic potential of
MSCs in tissue engineering and as cellular protein factory for delivery of cytokines and
anticancer agents [7-9]. Genetically modified-MSCs have also been successfully evaluated in
animal models for diabetes, skeletal defects and myocardial infarction [10-14].
Cotransplantation of MSCs with hematopoietic stem cells (HSCs) has been documented to
improve HSC engraftment in mice [15, 16]. Though there has been a surge in preclinical and
clinical trials using MSCs, caution must be taken in planning such studies since MSC biology
is only beginning to be understood. However, the question arises: what makes MSCs unique
and preferable for cell-based therapies?
In this review, we focus on the suitability of MSCs in the field of regenerative medicine. We
provide an overview of the current status of research on MSC-based therapies in
experimental animals and humans. Different therapeutic designs along with preclinical cases
which also address the mechanisms of MSC action are discussed. Clinical trials with MSCs
are critically evaluated followed by a discussion on the controversies surrounding the use of
MSCs and the challenges that need to be overcome for translation of the therapy from the
bench to the clinic.
Mesenchymal stem cells and its characteristics
MSCs were first identified about 30 years ago by Friedenstein and colleagues as an adherent
fibroblast-like population in the bone marrow capable of differentiating into bone . Since
then MSCs have been isolated from the human bone marrow based on their ability to adhere
to tissue culture plastic . Though occurring at a very low frequency of 1 in 10,000 to
100,000 bone marrow mononuclear cells, these cells are capable of proliferating in vitro
without significant loss of differentiation potential during early passages [1, 2, 18].
Originally isolated from the bone marrow, similar populations have also been isolated from
peripheral blood , periosteum , umbilical cord blood , synovial membrane ,
trabecular bone , adipose tissue , limbal stroma , amniotic fluid , lung ,
dermis and muscle . These populations have been functionally characterized based on
their ability to differentiate into osteoblasts, chondrocytes and adipocytes in culture upon
induction due to lack of specific markers for MSCs . However, phenotypically they are
defined as positive for CD105, CD73 and CD90, and negative for hematopoietic markers
(CD34, CD45, CD11b and CD19) and HLA-DR . Since these surface markers are used
for characterizing cultured MSCs, immense efforts are underway to identify markers for their
direct isolation from tissue. Positive selection approaches using antibodies against low-
affinity nerve growth factor receptor , stage-specific embryonic antigen (SSEA)-1 
and SSEA-4  have been used for isolation of primitive MSCs. Transplantation of a single
cell-derived population of SSEA-1+ mesenchymal cells in mice is the first in vivo study
demonstrating their capability of differentiating into different mesenchymal cell types, thus
showing their true stem cell properties. However, these cell populations were similar
phenotypically but heterogeneous in their functionality since all clones did not demonstrate
same differentiation potential suggesting only enrichment of MSCs using these markers.
Antibodies have also been raised against MSCs for their prospective isolation such as STRO-
1, SH-2, SH-3 and SH-4, but none of them recognize an epitope exclusively present on MSCs
. Though the use of non-homogenous MSCs in preclinical and clinical studies has proved
safe and effective (as will be discussed ahead), the search for surface markers exclusive to
MSCs for their isolation and characterization is extremely important.
Playing a role in the homeostasis of mesenchymal lineages, these cells differentiate into
osteoblasts, adipocytes, chondrocytes, tenocytes, myoblasts and stromal fibroblasts [1, 35,
36]. Recent identification of various MSC populations such as mesodermal progenitor cells
(MPCs) , marrow-isolated adult multilineage inducible (MIAMI) cells , very small
embryonic-like stem cells (VSELs)  and SSEA-1+ mesenchymal cells  have
demonstrated their differentiation into mesodermal, endodermal and neuroectodermal
lineages, such as cardiomyocytes, hepatocytes, neural cells and endothelial cells [32, 35, 39-
41]. Hematopoietic differentiation has also been observed upon transplantation of SSEA-1+
cells in mice, signifying their primitiveness compared to all other populations . However,
the transdifferentiation potential of MSCs has been questioned due to differences in the MSC
populations, culture conditions, experimental models and evaluation methods . Many of
the observed morphological changes could be a culture artifact or a result of fusion with
somatic cell [43, 44]. Therefore, a thorough evaluation of the plasticity of MSCs in vivo is
essential since in vitro conditions might not represent the true in vivo milieu.
Another distinguishing feature of MSCs is their ability to expand in vitro under normal
culture conditions . We have observed 88- to 560-fold expansion in a single passage (15-
20 days) upon culturing early passage MSCs at a density of 50-500 cells/cm2 [our
unpublished data]. Colter et al have reported extensive expansion of a subpopulation of
MSCs, designated recycling stem (RS) cells, to the order of 109-fold in 6 weeks by culturing
cells at low density of 1.5 or 3 cells/cm2 . Clinical feasibility of culture expanded MSCs
has been validated by a number of studies [4, 46-49]. Thus, a small amount of bone marrow
aspirate is sufficient for generation of large number of cells needed for transplantation
following in vitro expansion.
Immunological characterization of human MSCs revealed intermediate expression levels of
human leukocyte antigen major histocompatibility complex (MHC) class I, and no expression
of MHC class II antigen and costimulatory molecules CD40, CD80 and CD86 [50-52]. The
expression of MHC class I prevents them from the action of natural killer cells while absence
of costimulatory molecules leaves T cells anergic [reviewed in 53, 54]. In addition, MSCs
have been demonstrated to suppress T lymphocyte proliferation and activation [50, 51]. As a
consequence, MSCs are able to modulate the immune response making them immune
privileged and suitable for allogeneic transplantation, as has been reported in numerous
clinical studies [3, 55, 56]. Further, MSCs have been reported to home to sites of injury and
disease following intravenous infusion and contribute to the repair process [5, 48, 57]. The
expression of chemokine receptors on MSCs might be responsible for their ability to sense
and respond to signals like chemokines expressed by injured tissues , causing them to
extravasate from the blood vessels, like immune cells , via a coordinated rolling and
adhesion behaviour on endothelial cells in a P-selectin- and VCAM1-dependent manner .
Their contribution to tissue repair is also mediated by secretion of paracrine factors having
angiogenic and anti-apoptotic properties [61-63]. These paracrine factors not only attract
endothelial cells and macrophages but are also likely to stimulate the resident stem/progenitor
cells to aid in the process of tissue repair .
MSCs can be easily isolated from readily accessible blood and bone marrow compared to
other stem cells from tissues like brain, heart and liver [65, 66]. Additionally, ex vivo
expansion potential enables generation of a sufficient number of cells for transplantation .
Immunomodulatory functions, homing ability to injured sites and capability to modify the
microenvironment by paracrine factors makes intravenous delivery feasible in comparison to
site-specific delivery of neural , cardiac  and muscle stem cells . Thus, making
MSCs a promising candidate for stem cell-based therapy (Figure 1).
Experimental/Preclinical MSC-based studies
Capitalizing the extraordinary properties of MSCs, several studies have been undertaken to
evaluate their potential for tissue repair in animal models. Depending on the type of
disease/injury, different strategies involving site-specific delivery, genetic modification and
use of scaffolds have been designed. Basic studies to identify the mode of action of MSCs
and their responses to damages have also been addressed highlighting the therapeutic
potential as well as safety and efficacy of using MSCs. However, certain issues remain to be
resolved before translation of MSC-based therapy to the clinic (Figure 2).
To begin with, numerous studies using systemic administration of MSCs have been
performed at preclinical level to assess their in vivo behaviour and suitability for the
treatment of a number of injuries and diseases (Table 1). Ortiz and colleagues evaluated the
ability of intravenously infused MSCs in bleomycin exposed mice, which represents a lung
injury model, to engraft in the lung tissue . Bleomycin treatment resulted in 23-fold
increase in engraftment levels of MSCs compared to mice not exposed to bleomycin. Further,
the engrafted cells adopted an epithelium-like morphology and reduced bleomycin-induced
inflammation and collagen deposition in the lung [70, 71]. Whether MSCs actually
underwent transdifferentiation into alveolar epithelial type II cells or fused with epithelial
cells was not evaluated. However, transplanted mice exhibited increased level of G-CSF and
GM-CSF which might have mobilized endogenous stem cells aiding in repair . The anti-
inflammatory action of MSCs was mediated by secretion of IL-1 receptor antagonist (IL1RN)
which suppressed expression of pro-inflammatory cytokines TNF-α and IL-1α . In vitro
migration assays demonstrated the release of, as yet unknown, chemotactic factors from
damaged lung cells which attracted MSCs to the injury site .
Shimizu’s group standardized transdifferentiation of MSCs into keratinocytes in culture and
investigated whether MSCs could migrate and engraft into wounded skin in murine model.
They found that intravenously injected MSCs transdifferentiated into keratinocytes,
endothelial cells and pericytes at the wound site, thereby accelerating the repair process .
Evaluating the migratory mechanism using in vitro and in vivo migration assays, they
identified chemokine receptor CCR7 to play a major role since its ligand SLC/CCL21
induced MSC migration . Expression of keratin by transplanted MSCs and formation of
glandular structures was reported by Wu and colleagues upon injection of MSCs around
wound in an excisional wound splinting model in diabetic mice . They observed
reduction in the number of donor-derived cells in the wound during the 4 week follow-up
suggesting that MSC effects are transient and do not provide long-term self-renewal stem
cells for keratinocytes. Since MSCs have also been observed to return to the bone marrow
after wound healing , the local concentration of the chemokine signals or the expression
of a particular chemokine in response to injury at the site might have a significant role in
retaining MSCs , which needs further evaluation. Apart from undergoing
transdifferentiation, MSCs are also likely to contribute to the repair process by secreting
paracrine factors including VEGF-α, EGF, keratinocyte growth factor, SDF-1, IGF-1 and
Angiopoietin-1 (Ang-1), which facilitate the recruitment of macrophages, keratinocytes and
endothelial cells to the wound site and enhance angiogenesis and wound healing [63, 74].
Thus, reduction in inflammatory responses and accelerated angiogenesis contribute to the
ongoing reparative process but functionality of MSC-generated tissue like sebaceous and
sweat glands, if any, is not known. Therefore, complete regeneration of the tissue is debatable
Similarly, transplantation of human MSCs in hyperglycemic NOD/SCID mice resulted in
homing to islets associated with an increase in pancreatic islets and mouse insulin production
. No human insulin was detected in blood and the reduction in blood glucose levels was
mainly a result of stimulation of islets and β-cell [78-80], similar to that observed for neural
stem cells in mice , as well as inhibition of T cell responses against the new β-cells 
These studies bring to light the potential of MSCs to migrate to injury site and modify the
microenvironment, thereby modulating the immune response and facilitating tissue repair by
stimulating endogenous stem/progenitor cells. It is, therefore, necessary that studies
suggesting transdifferentiaion clearly define the experimental conditions and thoroughly
evaluate the true nature of the differentiated cells by expression profiling and functional
assays. Genetic marking approach may be useful in assessing the differentiation potential of
putative MSCs upon transplantation in animal model systems . Further, these animal
models represent excellent systems to elucidate the mechanism of action of MSCs in
mediating various therapeutic effects, in order to improve the present treatment regimens and
facilitate the development of new approaches.
Recently, MSCs have also been shown to improve hematopoietic transplantation [15, 16, 47,
84, 85]. Transplantation of HSCs is used for the treatment of oncohematological disorders,
but marrow ablative therapy (involving high dose chemotherapy and radiotherapy) destroys
not only hematopoietic cells but also damages the stroma [86, 87]. This is likely to cause
reduction in the engraftment of HSCs in the hostile environment as has been demonstrated in
mice , thereby, decreasing the success of transplant. Koc et al reported rapid
hematopoietic recovery in 28 breast cancer patients undergone high-dose chemotherapy
following coinfusion of HSCs and MSCs . Enhanced hematopoietic engraftment was also
reported upon infusion of limiting number of umbilical cord blood stem cells with unrelated
MSCs in mice . Co-transplanting MSCs with HSCs (CD34+ cells) has been shown to
improve engraftment in the bone marrow in mice, though the underlying mechanism needs to
be elucidated [15, 16]. This will not only help in improving the present regimens to enhance
HSC engraftment, but represents a useful strategy that can be employed to enhance success of
transplantation of other adult stem cells, as documented by increased survival of MHC-
mismatched skin grafts in immunocompetent baboons .
Migration of MSCs to the sites of injury and disease has also been well documented in animal
models for myocardial infarction and cerebral ischemia [90, 91]. Also, culture expanded
human MSCs have been shown to home to radiation-injured tissues in NOD/SCID mouse
model . This portrays their ability to sense and respond to damage signals, thereby
avoiding the need for targeted delivery (such as intramyocardial, intrahepatic) to damaged
tissues. However, intravenous infusion would cause distribution of cells throughout the body
reducing the fraction of cells homing to the damaged site [93, 94]. Another issue is
entrapment of a large fraction of cells in the lung  resulting in very low engraftment
levels of the order of 0.1% to 2.7% in the tissues [3, 93]. In vitro expansion of MSCs is also
likely to result in low homing as demonstrated in murine study , but whether human
MSCs also exhibit similar effect remains to be determined. Another contributing factor is low
cell survival rate after transplantation [96, 97]. Thus, preconditioning of MSCs prior to
transplant by culturing in presence of SDF-1  or under hypoxic conditions [99, 100] are
useful strategies which enhance cell survival in the hostile environment in vivo. Such
preconditioning leads to the activation of Akt survival pathway as well as increased
expression of pro-survival and pro-angiogenic factors like hypoxia-inducible factor 1, VEGF,
erythropoietin, Ang-1 and Bcl-2. Also increased expression of c-met leads to higher
migration rates to ischemic tissue in response to secreted hepatocyte growth factor as
demonstrated in rat hind limb ischemia model .
Further studies using disease models need to be carried out to elucidate the molecular
mechanism involved in MSC homing for the improvement of current therapies. For instance,
studies have revealed the involvement of integrin β1 in MSC migration and engraftment in
ischemic myocardium in mice , whereas CD44 has been implicated in migration and
localization of MSCs to kidneys in mouse model of acute renal failure . Cytokine-
mediated up-regulation of CXCR4 expression in Flk1+ MSCs improved their engraftment in
bone marrow of sublethally irradiated NOD/SCID mice  while ectopic expression of α4
integrin on mouse MSCs resulted in significant increase in bone specific retention of
transplanted MSCs in mouse . These studies offer molecular targets for genetic
engineering of MSCs to enhance their homing and engraftment to injury sites and accelerate
recovery. Alternatively, cytokine treatment of MSCs to enhance expression of tissue-specific
adhesion molecule or tissue-specific administration of chemotactic factor like SDF-1α ,
CCL12  and MCP-3  is likely to facilitate targeting to a particular tissue.
Genetically modified-MSC-based therapy
Integrating the strengths of genetic engineering and stem cell biology holds tremendous
potential for designing treatments for critical injuries and diseases by inducing differentiation
into a specific lineage and improving adhesion potential. Following transplantation, the fate
of MSCs would be determined stochastically in vivo depending on the niches they home and
therefore, not all transplanted cells might contribute to the repair of the damage. As recently
demonstrated in mice, transplanted MSCs differentiated into osteoblasts in the heart .
Thus, site-specific transplantation of functional, differentiated cells would be advantageous
under certain conditions. Though differentiated cells can be generated by chemical stimulants
or differentiation factors in vitro, the differentiation state might not be stable upon
transplantation. Such reversal of differentiation (i.e. dedifferentiation) has been shown in
vitro for MSCs upon the withdrawal of stimulants . Therefore, genetically modifying
stem cell by a key differentiation factor would help to achieve directed and complete
differentiation into the desired lineage.
Studies on the therapeutic applicability of genetically modified - MSCs (GM-MSCs) have
been carried out in animal models (Table 2). MSCs transduced with BMP2 and BMP4 have
been shown to successfully repair a variety of musculoskeletal defects in animal models as
BMPs are potent inducers of osteogenic differentiation [11, 12, 108]. The cells not only
themselves undergo differentiation but also stimulate the neighbouring cells to participate in
the repair process. It has also been reported that short-term expression (for 6 days) of BMP-2
in MSCs was sufficient to irreversibly induce osteochondral bone formation upon
implantation into tibialis anterior muscle or joints of SCID mice .
Differentiation being a process coordinately regulated by number of factors, expression of
combination of genes has proved more fruitful for orthopedic gene therapy. BMP-2/7 and
BMP-4/7 heterodimers exhibit higher activity than homodimers, therefore, simultaneous
transduction with BMP-2 and BMP-4 or BMP-7 in mesenchymal cells resulted in 2- to 3-fold
more bone formation in mice [110, 111]. However, BMPs are secreted factors and their
constitutive overexpression is likely to cause abnormal bone formation in vivo. Therefore,
regulated overexpression of osteogenic transcription factor Runx2 (using tetracycline-
regulated Tet-Off expression system) has been demonstrated to offer control over osteoblast
differentiation of engineered MSCs in mice . These engineered cells provide a novel
approach for treatment of osteochondral disorders and use of regulateable expression systems
to prevent undesirable effects, but studies aimed at mapping the fate of GM-MSCs following
repair of the defect are required before leaping at the prospect of using them for human
Use of GM-MSCs has been investigated in culture as a choice for the treatment of genetic
disorders. Genetic modification of MSCs with dominant-negative collagen type I protein
successfully repaired bones derived from osteogenesis imperfecta patients , whereas
dystrophin-transfected MSCs participated in myogenesis through cellular fusion and
complemented the genetic defect of muscular dystrophy myotubes in vitro .
Generation of cells of different tissues for the purpose of transplantation can also be achieved
by genetic modification. Pancreatic transplantation is the only cure for type 1 diabetes
patients. However, shortage of pancreas donors calls for the development of alternative cell-
replacement therapy. Transdifferentiation of human bone marrow-MSCs into insulin-
producing cells by overexpression of pancreatic duodenal factor 1 (PDX1) has been achieved
in vitro [10, 115]. Only 50% of the cells expressed insulin and secreted it in response to
glucose in culture while other islet hormones were expressed by all cells. Since these cells did
not differentiate completely in vitro, as determined by microarray, transplantation under the
renal capsule in streptozotocin-diabetic immunodeficient mice induced further differentiation
and resulted in the reduction of hyperglycemia and stabilization of blood glucose levels
during the 5 week follow-up . None of the transplanted cells were observed to migrate to
the pancreas, signifying the advantage of site-specific transplantation and avoidance of
unwanted effects due to homing to undamaged organs following systemic infusion. However,
to assess the maintenance of differentiated state, the cells can be transfected with vector
containing GFP or YFP cloned under the control of cell type-specific transcription factor
prior to transplantation to evaluate their fate in vivo, specifically when they are transplanted
in another tissue/organ since the microenvironment can alter their fate.
The cells must also be labeled properly (dyes like PHK26 or genetically like GFP) to track
them following transplantation in animal models. For instance, using GFP-labeled Akt-
overexpressing murine MSCs, Noiseux et al tracked MSC fate following intramyocardial
injection in mouse model of myocardial infarction . They observed transient
engraftment of MSCs in the infarct zone and fusion of MSCs with recipient cardiomyocytes
as early as 3 days post-injection, raising concern regarding safety and long-term outcome of
the fusion events. Though a very small fraction of cells likely differentiated into
cardiomyocytes, the reduction in infarct size and improvement in cardiac function was
possibly mediated by secreted paracrine factors . Enhanced expression (100-fold) of
secreted frizzled-related protein 2 (SFRP2) by Akt-overexpressing MSCs was determined to
exert a prosurvival effect on myocardium by increasing nuclear β-catenin, which activated
antiapoptotic gene transcription in ischemic cardiomyocytes .
Cell replacement is also an attractive opportunity for treating a number of neurological
disorders. Kim et al demonstrated that Neurogenin1 (Ngn1) overexpression was capable of
inducing neuronal differentiation of MSCs in vitro . The differentiated cells expressed
voltage-gated L-type Ca2+ channels and TTX-sensitive voltage-gated Na+ channels, which are
critical for initiation and propagation of action potential in neurons . These cells on
intracranial transplantation in rat stroke model engrafted in the ischemic brain, formed
connections with host neurons and improved motor functions compared to control
transplanted with normal MSCs. MSCs modified with Ngn1 were detected even after 8 weeks
following transplant compared to normal MSCs which disappear within 4 weeks. Both
animal groups receiving normal and GM-MSCs documented proliferation of neural
progenitors and protected delayed cell death, as shown in earlier studies, as a result of
paracrine effects of MSCs [121, 122]. Taken together, these studies clearly demonstrate the
significance of GM-MSCs exhibiting enhanced functional capabilities as a suitable system
for the generation of transplantable cells in vitro as well as their efficacy in vivo.
Apart from modifying the differentiation potential of MSCs, they can also be engineered for
targeting to specific tissues. For instance, MSCs transduced with CXCR4 exhibited enhanced
homing to infarcted myocardium in rats following intravenous delivery [123, 124]. CXCR4
overexpression in MSCs facilitated their mobilization and engraftment in the collagenous
tissue of the infarcted area, perhaps via upregulation of matrix metalloproteinases, and led to
significant neoangiogenesis compared to normal MSCs . Such strategies will help in the
development of non-invasive cell therapy. Route of delivery of GM-MSCs and tissue
targeting is also important in order to avoid formation of heterotopic tissue, especially in case
of cells modified to favour differentiation into a particular lineage. Low cell survival
following transplantation is a hurdle in MSC-based therapy as mentioned earlier. Genetic
modification of MSCs with hypoxia-regulated heme oxygenase-1 , Bcl-2  and
Akt1  resulted in enhanced cell survival upon transplant in animal models by inhibition
of apoptosis and represents a potential opportunity. Another important issue is the mode of
gene transfer. The use of viral vectors due to their high transduction efficiency is likely to be
associated with activation of immune responses and problem of insertional mutagenesis
despite the development of different generations of viral vectors . Thus, the use of non-
viral approaches is an alternative which has been documented to repair critical size bone
defect in mice even though their transfection efficiencies are very low .
MSC-based protein therapy
MSCs can also serve as ‘protein factory/production unit’ for the treatment of disorders
caused as a result of attenuated production of cytokine/growth factor or synthesis of a
mutated inactive protein (Table 3). They are genetically modified to synthesize the desired
factor and then transplanted either intravenously or at the required site depending on the
situation. This therapeutic approach has the advantage of continuous supply of the protein (or
can be controlled by use of inducible expression systems), delivery of potentially more
physiological levels compared to conventional protein therapy and comfortable for the
patient. It might be possible to design treatments for blood disorders like hemophilia and
anemia, autoimmune disease and tumors using engineered MSCs in the near future.
Transplantation of erythropoietin (EPO)-transduced MSCs in baboons showed the presence
of EPO in serum for upto 137 days and displayed increase in hematocrit . Further
improvements are required since such short-term expression can only be useful in conditions
like myocardial infarction and is not suitable for treating genetic disorders. However, the
feasibility of the system for allogeneic transplantation is skeptical with recent observation
that allogeneic murine EPO expressing MSCs resulted in the development of severe anemia
in mice due to induction of neutralizing anti-EPO antibodies . Intravenous injection of
INFβ-transfected MSCs into SCID mice with established tumors resulted in incorporation of
MSCs in tumor architecture and inhibition of tumor growth . Mice injected with INFβ-
overexpressing MSCs survived for longer time period compared to those receiving INFβ
injection only, suggesting involvement of other secreted factors as well. With their ability to
home to damaged sites, MSCs can be used as vehicles for targeted delivery of therapeutic
proteins eliminating effects on other tissues. This strategy can also be applied under certain
situations to stimulate the resident stem cell population via paracrine action of cytokines,
thereby inducing natural repair systems or accelerating the ongoing regeneration process. The
problems associated with genetic modification are already mentioned earlier. Another
important concern is the level of transgene expression and sustenance of expression in vivo.
Use of inducible expression system is likely to prevent undesirable effects due to high level
of expression as well as offer control on timing of expression of the transgene .
Tissue engineering using MSCs
Another out-branch of stem cell therapy involves the generation of graftable tissues in vitro-
combining cells (normal or engineered) or parts thereof and scaffolds to generate three
dimensional implants. It involves trying to recapitulate the in vivo environment to favor the
development of the desired tissue for transplantation. Various approaches such as protein
impregnated scaffolds , gene vector incorporated matrices , and combinations of
cells and scaffold have been designed (Table 4). Scaffolds alone have been useful in repairing
certain kinds of damages by incorporating into them differentiation signals such as BMP2,
which stimulates the endogenous cells at the defect site . However, seeding scaffolds
with MSCs has greater regeneration ability since it augments the in situ repair process by
supplying progenitors as well as stimulatory factors. To further enhance the therapeutic
potential of tissue engineered implants, GM-MSCs can be seeded onto scaffolds. It offers the
advantage of directed and irreversible differentiation and greater responsiveness to
extracellular signals .
The choice of biomaterial used for making the scaffold is important since its physical and
chemical properties affect MSC differentiation. For instance, the elasticity of the agarose
matrix seeded with MSCs determines their differentiation into neuronal, muscle or bone
lineages depending on the crosslinking density . Presence of carboxyl or hydroxyl
groups on scaffold surface favour chondrogenic differentiation whereas amino and sulfhydryl
groups promote osteogenic differentiation of MSCs . MSCs have been exploited in bone
and cartilage tissue engineering using a variety of polymer materials such as hydroxyapaptite
and tricalcium phosphate ceramics, alumina and titanium metal alloys, synthetic polymers
made of polyglycolic and polylactic acids and natural polymers such as collagen-I, cellulose,
agarose and demineralised bone composites [reviewed in 136]. Arinzeh and colleagues
transplanted allogeneic MSCs loaded onto a hollow ceramic cylinder made of
hydroxyapatite-tricalcium phosphate, into critical-sized bone defect in the femoral diaphysis
in dogs without the use of immunosuppressive therapy . A critical size bone defect
cannot be healed by the body’s own regenerative potential. The ‘test’ group receiving the
implant exhibited no adverse host response as documented by absence of lymphocyte
infiltration and antibodies against allogeneic cells. Radiological and histological evaluation
post-implantation demonstrated new bone formation after 16 weeks throughout the implant
with significantly greater amount of bone within the pore space of implants loaded with
MSCs than cell-free implants . This study highlights the immunomodulatory functions
of MSCs which prevented any immune rejection against transplanted cells as well as ability
of MSCs to differentiate into osteoblasts and repair the bone defect.
Generation of complex 3D tissue grafts is confronted by problem of supply of nutrients to the
cells deep inside the graft. Vascularisation of the graft is essential for the survival of cells and
sustenance of the implant. Though host blood vessels invade the implant in response to
signals secreted by implanted cells due to oxygen deficiency, it occurs at very slow pace and
would require weeks to vasculate an implant of few millimeters  leading to death of
cells inside the implant. Endothelial precursor cells (EPCs) and pro-angiogenic factors like
VEGF have been used for the generation of vascularised grafts . They can be used either
by mixing EPCs and MSCs or transfecting MSCs with VEGF gene to promote angiogenesis
in vivo upon transplant . Human MSCs coupled with human umbilical vein endothelial
cells were used to generate vascularised bone in vitro, but no perfusion was observed upon
implantation . No vascularisation strategy is available at present which can support large
constructs after implantation. Current approaches like in vivo prevascularisation, in vitro
prevascularisation, use of scaffold and angiogenic factor delivery [reviewed in 142] are only
likely to increase the chances of vascularisation of the implant, since each has certain
limitations. In vivo evaluation of proper integration of the implant at the injury site and its
long-term persistence using imaging techniques is required to ensure safety and facilitate
further improvements since neovascularisation mediated by VEGF alone may produce non-
functional vessel with defective cellular differentiation .
Encouraging results of tissue repair and immunomodulation in animal studies have led to
limited clinical studies with MSCs for some debilitating disorders (Table 5). Metachromatic
leukodystrophy (MLD) and Hurler syndrome are autosomal recessive disorders due to
deficiency of enzymes arylsulfatase A and α-L-iduronidase, respectively. These patients
develop neurological and musculoskeletal defects that limit their survival . HSC
transplantation significantly improves survival of patients but abnormalities still persist. Koc
and colleagues postulated that infusion of MSCs might correct the defects since they are
capable of differentiating into mesenchymal and neuronal cells . Patients undergone HSC
transplant were infused with MSCs from the same donor and demonstrated no infusion-
related toxicity. Donor derived-MSCs constituted only 0.4 and 2% of MSCs from 2 of 11
patients enrolled in the study. Though MLD patients showed significant improvement in
nerve conduction velocity, no change in overall health of the patients was apparent. The study
demonstrated the safety of allogeneic MSC transplantation and highlights the low
engraftment efficiency of culture expanded MSCs which could be either due to poor survival
following transplant, proliferative defect or low homing ability of cultured MSCs .
However more studies are required to investigate any role of MSC in the treatment of MLD
and Hurler syndrome.
Myocardial infarction (MI) caused by an imbalance between the oxygen supply and the
demand of the myocardium results in the development of myocardial necrosis. Thus, the
restoration of functional cardiomyocytes in the infarcted myocardium is the only solution.
Since, MSCs have been demonstrated to differentiate into cardiomyocytes in vitro as well as
in animal model of MI [144, 145], Chen and colleagues planned a randomized study to
investigate the effectiveness of intracoronary injection of autologous culture expanded MSCs
in patients with MI . During the 6 month follow-up study, the percentage of hypokinetic,
akinetic and dyskinetic segments decreased whereas wall movement velocity and left
ventricular ejection fraction increased significantly in transplant recipients compared with
control group. Most of the improvement was observed after 3 months of transplant, without
much improvement thereafter, implicating only short-term benefit . Thus, it is not
justifiable to judge the clinical potential for MI based on few small-scale studies [4, 146].
Moreover, low efficiency of engraftment, transient effects and insufficient evidence
supporting the presence of MSC-derived cells at the infarct site as documented in animal
studies emphasizes the need to determine the optimal cell dose , number of infusions,
route of delivery and timing of transplant.
Osteogenesis imperfecta (OI), a genetic disorder of mesenchymal cells caused due to
mutation in collagen type I gene, results in osteopenia, multiple fractures, bone deformities
and short stature. Allogeneic bone marrow transplantation (BMT) in children with OI
demonstrated 1.5% – 2.0% donor derived osteoblasts with an increase in total bone mineral
content as well as improvement in body growth and reduced fracture incidence in all
children. This study highlights the ability of MSCs and their progenitors to engraftment in the
bone, and subsequently differentiate into functional osteoblasts . Follow-up over 18-36
months showed increase in total bone mineral content with decreasing growth rates. Hence, it
was hypothesized that additional MSC transplantation without marrow ablative treatment
would safely boost responses in these patients undergone BMT. After two rounds of
infusions, 5 of 6 children showed engraftment of MSCs and their differentiation into
osteoblast as well as skin fibroblast . Thus, a small fraction of allogeneic MSCs engrafted
in the bone and underwent osteogenic differentiation without causing any immune problems
signifying the feasibility of allogeneic MSC transplantation in humans. However, the benefit
from a single transplant was short-lived and subsequent transplants were performed
highlighting the need to modify transplant strategies to improve MSC homing and
engraftment in vivo for potential long-term gains.
Use of MSCs for the treatment of steroid-resistant, severe, acute graft-versus-host disease
(GVHD) has also been initiated following demonstration of the safety of allogeneic MSC
infusion and immune suppression by MSCs (mentioned earlier). In an earlier study on 8
patients with steroid refractory grades III-IV acute GVHD, MSC infusion resulted in
disappearance of GVHD in 6 of 8 patients . Henceforth, the study was extended to
phase II trial involving 55 patients. Out of 55 patients treated during the 5 year study, 39
patients responded with 30 showing complete response. The response was independent of the
HLA-match and resulted in higher overall survival 2 year after HSC transplantation, 53%
among complete responders compared to 16% among partial or non-responders . No
side-effects were observed after HLA-identical or mismatched MSc infusions , and the
response rate was not related to donor HLA-match . On the other hand, in a multicentric
study by Lazarus et al, MSC coinfusion with HLA-identical HSCs in patients undergoing
allogeneic transplant for GVHD did not produce any effect such as prevention of graft
rejection or accelerated hematopoietic recovery . Cotransplantation of MSCs and MHC-
identical allogeneic HSCs in patients suffering from hematopoietic malignancies was
reported to have lower rate of GVHD but higher relapse rate than patients receiving HSC
transplant alone . Hence, evaluation of their mechanism of action is extremely essential
before using them in clinical settings.
Limited not only to simple transplantation, MSCs and scaffold have been combined and used
in clinic. In a classical study of bone tissue engineering, Quarto and colleagues used culture
expanded autologous MSCs to treat large bone defects in 3 patients . The patients had
loss of 4-7 cm bone segments and bone grafting is the only approach for treating such large
defects. Each patient was implanted at the lesion site with expanded MSCs seeded on
hydroxyapatite scaffolds of appropriate size and shape. None of the patients demonstrated
any complications over more than 15 months follow-up and all of them recovered limb
function , but as no biopsies were taken, it remains unclear whether the callus was
induced by implanted MSCs or by endogenous bone forming cells. Non-cultured enriched
bone marrow-derived MSCs combined with porous β-tricalcium phosphate (β-TCP) have
been used for posterior spinal fusion . The enriched MSCs were mixed with β-TCP
granules and incubated for 2 hrs for cells to adhere, and thereafter implanted in patients with
spondylolysis or thoracolumbar fracture. None of the patients had neurological deterioration
after operation and there was no deep vein thrombosis or pulmonary embolism. After about 3
years, 95% cases had good spinal fusion signifying the potential of the approach over
conventional bone grafting which is associated with problems like donor site morbidity .
The use of MSC enrichment technique would likely be of great advantage since it diminishes
the effects of culture conditions on MSC behaviour and might result in higher level of
engraftment, which must be evaluated in subsequent studies. Thus, all these studies are
suggestive of the clinical potential of MSCs and document their safe use in humans. Hence,
the likelihood of establishing MSC banks, which expand and cryopreserve an individuals
MSCs, can be of great therapeutic significance. However, since these early studies have been
done on small set of patients without complete knowledge of MSC biology, it emphasizes the
need to examine certain critical issues to harness complete potential of MSCs.
Challenges and future prospects
Numerous animal model studies have documented the therapeutic potential of MSCs and
their safety and efficacy in vivo. But the regenerative capacity of MSCs in humans is
controversial due to limited human studies performed on very small set of patients. Large
scale multicentric clinical trials designed with great caution need to be performed for
complete validation of MSC-based therapy . However, before planning and initiating
such trials, certain issues related to MSC biology need to be addressed at basic and preclinical
levels (Figure 2).
Since the true identity of MSCs in vivo remains elusive, current approaches used for their
isolation have resulted in heterogeneous sub-populations exhibiting MSC-like characteristics.
Therefore, identification of MSC specific marker for isolation of a homogenous population of
cells directly from tissue is necessary. Such homogenous population would help in
determining the true potential of MSCs as well as deciphering their exact anatomical location.
Since they are believed to play role in regulation of hematopoiesis, their true identification
will aid in delineating the underlying signaling events and possible cell-cell interactions with
HSCs. In addition, it will accelerate the pace of research on MSCs as comparison of results
among laboratories would then be feasible. Hence, concerted efforts employing high-end
techniques like 2D gel electrophoresis and mass spectrometry (MS and combination with
chromatography LC-MS) are required for identification of a novel surface molecule
expressed exclusively on the putative MSC.
A potential block in the applicability of these therapies is the requirement of large number of
cells for direct transplant or for the generation of an implant. For example, BMT requires on
average 5 x 106 cells per kg body weight. Though MSCs are easy to isolate and undergo in
vitro proliferation, extended expansion was observed to alter their properties [18, 155-157].
Although stem cells must exhibit indefinite self-renewal as per definition, human MSCs have
been shown to undergo senescence and exhibit reduced differentiation potential 6th passage
onwards , which is in agreement with other studies showing that around 13 to 25
population doublings result in complete senescence . Senescence associated changes in
cellular morphology, expression of surface markers and global gene profile have been
observed with increasing number of passages beginning from the first passage itself .
Increase in expression of cell cycle inhibitor p16INK4A  and decrease in telomere length
during culture contribute to the process of senescence . However, variation in culture
conditions such as passing at low density , use of cytokines like FGF2 [159, 160] and
overexpression of hTERT  are likely to delay the progress of senescence, thereby
helping in achieving greater number of doublings.
Continuous passaging has also been observed to lead to the transformation of murine bone
marrow-derived MSCs which formed fibrosarcoma upon transplantation in mice . These
cells lost their osteogenic capacity after 13 passages and became malignant after 29 passages
. Human bone marrow-derived MSCs appear to be resistant to transformation compared
to murine MSCs as revealed by genetic characterization using comparative genomic
hybridization, karyotyping and subtelomeric fluorescent in situ hybridization analysis at
different passages during long-term culture . However, Rubio and colleagues
demonstrated that long-term culture (4-5months) of adipose tissue-derived human MSCs led
to spontaneous transformation. The transformed cells exhibited chromosomal abnormalities,
increased c-myc levels and telomerase activity, and formed tumors on transplantation .
Therefore, great caution needs to be taken in clinical studies since transplantation of MSCs is
likely to be associated with potential risk of tumor generation and ability to enhance the
growth of previously undetected tumor (discussed ahead). Genetic characterization and
expression profiling of expanded MSCs might be a way to screen for changes in the cells
before using them for transplant.
Immunomodulatory effects of MSCs also require due consideration since studies have
demonstrated the ability of MSCs to home to sites of tumor and suppress or stimulate tumor
growth in animal models . For instance, inhibition of primary tumor growth was
observed upon coinjection of MSCs with tumor cells in models of Lewis lung carcinoma and
B16 melanoma , whereas coculture of MSCs with breast cancer cells enhanced tumor
cell proliferation . Molecular studies beginning to elucidate the underlying mechanism
suggest the role of IL-6 secreted by MSCs in promoting multiple myeloma proliferation
. Karnoub et al also recently demonstrated integration of MSCs into breast cancer
stroma and enhancement of cancer cell metastasis by MSC secreted chemokine CCL5-
dependent signaling . Thus, understanding the interrelationship between MSCs and
cancer is essential for clinical utilization of MSCs and the development of suitable anticancer
therapies. Further, the interaction between the immune cells and MSCs need to be studied in
vivo since MSC transplant proved beneficial in animal models for autoimmune diseases like
type I diabetes , experimental autoimmune encephalomyelitis , but had no effect on
collagen-induced arthritis in murine model of rheumatoid arthritis .
Thus, the future research on MSCs needs to focus on: (i) identification of exclusive marker
on MSCs, (ii) assessment of differentiation potential, (iii) standardization of culture
conditions, (iv) state of cells to be transplanted-MSCs, progenitors or differentiated cells, (v)
survival and long-term engraftment on transplant, (vi) in vivo behaviour of MSCs, (vii)
immunomodulatory functions, and (viii) paracrine effects. Addressing these issues would
require time and patience as well as thorough studies at basic, pre-clinical and clinical levels.
Hence, with the continued efforts of hundreds of scientists and clinicians around the world,
and step-by-step progress in the field and related areas, all kinds of diseases and damages
would be repairable in the near future.
We are thankful to Dr R.P.Tripathi, Institute of Nuclear Medicine and Allied Sciences,
DRDO, Lucknow Road, Delhi-110054 for providing us necessary facilities and support. Mr.
Neeraj Kumar Satija in particular thanks CSIR (India) for the award of Senior Research
1. Pittenger MF, Mackay AM, Beck SC, Jaiswal RK, Douglas R, Mosca JD,
Moorman MA, Simonetti DW, Craig S, Marshak DR. Multilineage potential of
adult human mesenchymal stem cells. Science. 1999; 284: 143-7.
2. Bruder SP, Jaiswal N, Haynesworth SE. Growth kinetics, self-renewal and the
osteogenic potential of purified human mesenchymal stem cells during extensive
subcultivation and following cryipreservation. J Cell Biochem. 1997; 64: 278-94.
3. Horwitz ED, Prockop DJ, Fitzpatrick LA, Koo WWK, Gordon PL, Neel M,
Sussman M, Orchard P, Marx JC, Pyeritz RE, Brenner MK. Transplantability
and therapeutic effects of bone marrow-derived mesenchymal cells in children with
osteogenesis imperfecta. Nat Med. 1999; 5: 309-13.
4. Chen SL, Fang WW, Ye F, Liu YH, Qian J, Shan SJ, Zhang JJ, Chunhua RZ,
Liao LM, Lin S, Sun JP. Effect on left ventricular function of intracoronary
transplantation of autologous bone marrow mesenchymal stem cell in patients with
acute myocardial infarction. Am J Cardiol. 2004; 94: 92-5.
5. Bang OY, Lee JS, Lee PH, Lee G. Autologous mesenchymal stem cell
transplantation in stroke patients. Ann Neurol. 2005; 57: 874-82.
6. Ringden O, Uzunel M, Rasmusson I, Remberger M, Sundberg B, Lonnies H,
Marschall H-U, Dlugosz A, Szakos A, Hassan Z, Omazic B, Aschan J, Barkholt
L, Le Blanc K. Mesenchymal stem cells for treatment of therapy-resistant graft-
versus-host disease. Transplant. 2006; 81: 1390-7.
7. Nakamura K, Ito Y, Kawano Y, Kurozumi K, Kobune M, Tsuda H, Bizen A,
Honmou O, Niitsu Y, Hamada H. Antitumor effect of genetically engineered
mesenchymal stem cells in a rat glioma model. Gene Ther. 2004; 11: 1155-64.
8. Studeny M, Marini FC, Dembinski JL, Zompetta C, Cabreira-Hansen M, Bekele
BN, Champlin RE, Andreeff M. Mesenchymal stem cells: potential precursors for
tumor stroma and targeted-delivery vehicles for anticancer agents. J Natl Cancer Inst.
2004; 96: 1593-603.
9. Eliopoulos N, Gagnon RF, Francois M, Galipeau J. Erythropoietin delivery by
genetically engineered bone marrow stromal cells for correction of anemia in mice
with chronic renal failure. J Am Soc Nephrol. 2006; 17: 1576-84.
10. Karnieli O, Izhar-Prato Y, Bulvik S, Efrat S. Generation of insulin-producing cells
from human bone marrow mesenchymal stem cells by genetic modification. Stem
Cells. 2007; 25: 2837-44.
11. Gugala Z, Olmsted-Davis EA, Gannon FH, Lindsey RW, Davis AR.
Osteoinduction by ex vivo adenovirus-mediated BMP2 delivery is independent of cell
type. Gene Ther. 2003; 10: 1289-96.
12. Zhang XS, Linkhart TA, Chen ST, Peng H, Wergedal JE, Guttierez GG, Sheng
MH, Lau KH, Baylink DJ. Local ex vivo gene therapy with bone marrow stromal
cells expressing human BMP4 promotes endosteal bone formation in mice. J Gene
Med. 2004; 6: 4–15.
13. Gersbach CA, Le Doux JM, Guldberg RE, Garcia AJ. Inducible regulation of
Runx2–stimulated osteogenesis. Gene Ther. 2006; 13: 873-82.
14. Sun L, Cui M, Wang Z, Feng X, Mao J, Chen P, Kangtao M, Chen F, Zhou C.
Mesenchymal stem cells modified with angiopoietin-1 improve remodeling in a rat
model of acute myocardial infarction. Biochem Biophys Res Commun. 2007; 357:
15. Noort WA, Kruisselbrink AB, in't Anker PS, Kruger M, van Bezooijen RL, de
Paus RA, Heemskerk MH, Löwik CW, Falkenburg JH, Willemze R, Fibbe WE.
Mesenchymal stem cells promote engraftment of human umbilical cord blood-derived
CD34(+) cells in NOD/SCID mice. Exp Hematol. 2002; 30: 870-8.
16. Park SK, Won JH, Kim HJ, Bae SB, Kim CK, Lee KT, Lee NS, Lee YK, Jeong
DC, Chung NG, Kim HS, Hong DS, Park HS. Co-transplantation of human
mesenchymal stem cells promotes human cd34+ cells engraftment in a dose-
dependent fashion in NOD/SCID mice. J Korean Med Sci. 2007; 22: 412-9.
17. Friedenstein AJ, Gorskaja JF, Kulagina NN. Fibroblast precursors in normal and
irradiated mouse hematopoietic organs. Exp Hematol. 1976; 4: 267-74.
18. Mohyeddin-Bonab M, Alimoghaddam K, Talebian F, Ghaffari SH,
Ghavamzadeh A, Nikbin B. Aging of mesenchymal stem cells in vitro. BMC Cell
Biol. 2006; 7: 14.
19. Zvaifler NJ, Marinova-Mutafchieva L, Adams G, Edwards CJ, Moss J, Burger
JA, Maini RN. Mesenchymal precursor cells in the blood of normal individuals.
Arthritis Res. 2000; 2: 477-88.
20. de Bari C, Dell’Accio F, Luyten FP. Human periosteum-derived cells maintain
phenotypic stability and chondrogenic potential throughout expansion regardless of
donor age. Arthritis Rheum. 2001; 44: 85-95.
21. Lee OK, Kuo TK, Chen WM, Lee KD, Hsieh SL, Chen TH. Isolation of
multipotent mesenchymal stem cells from umbilical cord blood. Blood. 2004; 103:
22. de Bari C, Dell’Accio F, Tylzanowski P, Luyten FP. Multipotent mesenchymal
stem cells from adult human synovial membrane. Arthritis Rheum. 2001; 44: 1928-42.
23. Tuli R, Tuli S, Nandi S, Wang ML, Alexander PG, Haleem-Smith H, Hozack
WJ, Manner PA, Danielson KG, Tuan RS. Characterisation of multipotential
mesenchymal progenitor cells derived from human trabecular bone. Stem Cells. 2003;
24. Boquest AC, Shahdadfar A, Fronsdal K, Sigurjonsson O, Tunheim SH, Collas P,
Brinchmann JE. Isolation and transcription profiling of purified uncultured human
stromal stem cells: Alternation of gene expression after in vitro cell culture. Mol Biol
Cell. 2005; 16: 1131-41.
25. Polisetty N, Fatima A, Madhira SL, Sangwan VS, Vemuganti GK. Mesenchymal
cells from limbal stroma of human eye. Mol Vis. 2008; 14: 431-42.
26. In’t Anker PS, Scherion SA, Kleijburg-van der Keur C, Noort WA, Claas FH,
Willemze R, Fibbe WE, Kanhai HH. Amniotic fluid as a novel source of
mesenchymal stem cells for therapeutic transplantation. Blood. 2003; 102: 1548-9.
27. Martin J, Helm K, Ruegg P, Varella-Garcia M, Burnham E, Majka S. Adult lung
side population cells have mesenchymal stem cell potential. Cytotherapy. 2008; 10:
28. Young HE, Steele TA, Bray RA, Hudson J, Floyd JA, Hawkins K, Thomas K,
Austin T, Edwards C, Cuzzourt J, Duenzl M, Lucas PA, Black AC. Human
reserve pluripotent mesenchymal stem cells are present in the connective tissues of
skeletal muscle and dermis derived from fetal, adult, and geriatric donors. Anat Rec.
2001; 264: 51–62.
29. da Silva Meirelles L, Caplan AI, Nardi NB. In search of the in vivo identity of
mesenchymal stem cells. Stem Cells. 2008; 26: 2287-99.
30. Dominici M, Le Blanc K, Mueller I, Slaper-Cortenbach I, Marini F, Krause D,
Deans R, Keating A, Prockop Dj, Horwitz E. Minimal criteria for defining
multipotent mesenchymal stromal cells. The International Society for Cellular
Therapy position statement. Cytotherapy. 2006; 8: 315-7.
31. Quirici N, Soligo D, Bossolasco P, Servida F, Lumini C, Deliliers GL. Isolation of
bone marrow mesenchymal stem cells by anti-nerve growth factor receptor
antibodies. Exp Hematol. 2002; 30: 783-91.
32. Anjos-Afonso F, Bonnet D. Nonhematopoietic/endothelial SSEA-1+ cells define the
most primitive progenitors in the adult murine bone marrow mesenchymal
compartment. Blood. 2007; 109: 1298-306.
33. Gang EJ, Bosnakovski D, Figueiredo CA, Visser JW, Perlingeiro RCR. SSEA-4
identifies mesenchymal stem cells from bone marrow. Blood. 2007; 109: 1743-51.
34. Satija NK, Gurudutta GU, Sharma S, Afrin F, Gupta P, Verma YK, Singh YK,
Tripathi RP. Mesenchymal stem cells: Molecular targets for tissue engineering. Stem
Cells Dev. 2007; 16: 7-23.
35. Reyes M, Lund T, Lenvik T, Aguiar D, Koodie L, Verfailllie CM. Purification and
ex vivo expansion of postnatal human marrow mesodermal progenitor cells. Blood.
2001; 98: 2615-25.
36. Pittenger MF, Marshak DR. Mesenchymal stem cells of human adult bone marrow
In: Marshak DR, Gardner RL, Gottlieb D, editors. Stem Cell Biology. New York:
Cold Spring Harbor Laboratory Press; 2001. p. 349-73.
37. D’lppolito G, Diabira S, Howard GA, Menei P, Roos BA, Schiller PC. Marrow-
isolated adult multilineage inducible (MIAMI) cells, a unique population of postnatal
young and old human cells with extensive expansion and differentiation potential. J
Cell Sci. 2004; 117: 2971-81.
38. Kucia M, Reca R, Campbell FR, Zuba-Suma E, Majka M, Ratajczak J,
Ratajczak MZ. A population of very small embryonic-like (VSEL) CXCR4+ SSEA-
1+ Oct-4+ stem cells identified in adult bone marrow. Leukemia. 2006; 20: 857-69.
39. Kadivar M, Khatami S, Mortazavi Y, Shokrgozar MA, Taghikhani M, Soleimani
M. In vitro cardiomyogenic potential of human umbilical vein-derived mesenchymal
stem cells. Biochem Biophys Res Commun. 2006; 340: 639-47.
40. Kang XQ, Zang WJ, Bao LJ, Li DL, Song TS, Xu XL, Yu XJ. Fibroblast growth
factor-4 and hepatocyte growth factor induce differentiation of human umbilical cord
blood-derived mesenchymal stem cells into hepatocytes. World J Gastroenterol.
2005; 11: 7461-5.
41. Hung SC, Chen H, Pan CY, Tsai MJ, Kao LS, Ma HL. In vitro differentiation of
size-sieved stem cells into electrically active neural cells. Stem Cells. 2002; 20: 522-9.
42. Phinney DG, Prockop DJ. Concise Review: Mesenchymal stem/multi-potent stromal
cells (MSCs): The state of transdifferentiation and modes of tissue repair-Current
views. Stem Cells. 2007; 25: 2896-902.
43. Terada N, Hamazaki T, Oka M, Hoki M, Mastalerz DM, Nakano Y, Meyer EM,
Laurence M, Petersen BE, Scott EW. Bone marrow cells adopt the phenotype of
other cells by spontaneous cell fusion. Nature. 2002; 416: 542-5.
44. Spees JL, Olson SD, Ylostalo J, Lynch PJ, Smith J, Perry A, Peister A, Wang
MY, Prockop DJ. Differentiation, cell fusion, and nuclear fusion during ex vivo
repair of epithelium by human adult stem cells from bone marrow stroma. Proc Natl
Acad Sci USA. 2003; 100: 2397-402.
45. Colter DC, Class R, DiGirolamo CM, Prockop DJ. Rapid expansion of recycling
stem cells in cultures of plastic adherent cells from human bone marrow. Proc Natl
Acad Sci USA. 2000; 97: 3213-8.
46. Lazarus HM, Haynesworth SE, Gerson SL, Rosenthal NS, Caplan AI. Ex vivo
expansion and subsequent infusion of human bone marrow-derived stromal progenitor
cells (mesenchymal progenitor cells): implications for therapeutic use. Bone Marrow
Transplant. 1995; 16: 557-64.
47. Koc ON, Gerson SL, Cooper BW, Dyhouse SM, Haynesworth SE, Caplan AI,
Lazarus HM. Rapid hematopoietic recovery after coinfusion of autologous-blood
stem cells and culture-expanded marrow mesenchymal stem cells in advanced breast
cancer patients receiving high-dose chemotherapy. J Clin Oncol. 2000; 18: 307-16.
48. Horwitz EW, Gordon PL, Koo WKK, Marx JC, Neel MD, McNall RY, Muul L,
Hofmann T. Isolated allogeneic bone marrow-derived mesenchymal stem cells
engraft and stimulate growth in children with osteogenesis imperfecta: implications
for cell therapy of bone. Proc Natl Acad Sci USA. 2002; 99: 8932-7.
49. Lataillade JJ, Doucet C, Bey E, Carsin H, Huet C, Clairand I, Bottollier-Depois
JF, Chapel A, Ernou I, Gourven M, Boutin L, Hayden A, Carcamo C, Buglova
E, Joussemet M, de Revel T, Gourmelon P. New approach to radiation burn
treatment by dosimetry-guided surgery combined with autologous mesenchymal stem
cell therapy. Regen Med. 2007; 2: 785-94.
50. Le Blanc K, Tammik C, Rosendahl K, Zetterberg E, Ringdén O. HLA expression
and immunologic properties of differentiated and undifferentiated mesenchymal stem
cells. Exp Hematol. 2003; 31: 890-6.
51. Di Nicola M, Carlo-Stella C, Magni M, Milanesi M, Longoni PD, Matteucci P,
Grisanti S, Gianni AM. Human bone marrow stromal cells suppress T-lymphocyte
proliferation induced by cellular or nonspecific mitogenic stimuli. Blood. 2002; 99:
52. Majumdar MK, Keane-Moore M, Buyaner D, Hardy WB, Moorman MA,
McIntosh KR, Mosca JD. Characterization and functionality of cell surface
molecules on human mesenchymal stem cells. J Biomed Sci. 2003; 10: 228-41.
53. Ryan JM, Barry FP, Murphy JM, Mahon BP. Mesenchymal stem cells avoid
allogeneic rejection. J Inflamm. 2005; 2: 8.
54. Nauta AJ, Fibbe WE. Immunomodulatory properties of mesenchymal stem cells.
Blood. 2007; 110: 3499-506.
55. Le Blanc K, Rasmusson I, Sundberg B, Götherström C, Hassan M, Uzunel M,
Ringdén O. Treatment of severe acute graft-versus-host disease with third party
haploidentical mesenchymal stem cells. Lancet. 2004; 363: 1439-41.
56. Koc ON, Day J, Nieder M, Gerson SL, Lazarus HM, Krivit W. Allogeneic
mesenchymal stem cell infusion for treatment of metachromatic leukodystrophy
(MLD) and Hurler syndrome (MPS-IH). Bone Marrow Transplant. 2002; 30: 215-22.
57. Herrera MB, Bussolati B, Bruno S, Fonsato V, Romanazzi GM, Camussi G.
Mesenchymal stem cells contribute to the renal repair of acute tubular epithelial
injury. Int J Mol Med. 2004; 14: 1035-41.
58. Chamberlain G, Fox J, Ashton B, Middleton J. Concise review: Mesenchymal
stem cells: Their phenotype, differentiation capacity, immunological features, and
potential for homing. Stem Cells. 2007; 25: 2739-49.
59. Stein JV, Nombela-Arrieta C. Chemokine control of lymphocyte trafficking: a
general overview. Immunol. 2005; 116: 1-12.
60. Ruster B, Gottig S, Ludwig RJ, Bistrian R, Muller S, Seifried E, Gille J,
Henschler R. Mesenchymal stem cells display coordinated rolling and adhesion
behavior on endothelial cells. Blood. 2006; 108: 3938-44.
61. Kinnaird T, Stabile E, Burnett MS, Shou M, Lee CW, Barr S, Fuchs S, Epstein
SE. Local delivery of marrow-derived stromal cells augments collateral perfusion
through paracrine mechanisms. Circulation. 2004; 109: 1543-9.
62. Kinnaird T, Stabile E, Burnett MS, Lee CW, Barr S, Fuchs S, Epstein SE.
Marrow-derived stromal cells express genes encoding a broad spectrum of
arteriogenic cytokines and promote in vitro and in vivo arteriogenesis through
paracrine mechanisms. Circ Res. 2004; 94: 678-85.
63. Chen L, Tredget EE, Wu PY, Wu Y. Paracrine factors of mesenchymal stem cells
recruit macrophages and endothelial lineage cells and enhance wound healing. PLoS
ONE. 2008; 3: e1886.
64. Nakanishi C, Yamagishi M, Yamahara K, Hagino I, Mori H, Sawa Y, Yagihara
T, Kitamura S, Nagaya N. Activation of cardiac progenitor cells through paracrine
effects of mesenchymal stem cells. Biochem Biophys Res Commun. 2008; 374: 11-6.
65. Oettgen P. Cardiac stem cell therapy. Need for optimization of efficiency and safety
monitoring. Circulation. 2006; 114: 353-8.
66. Choumerianou DM, Dimitriou H, Kalmanti M. Stem cells: promises versus
limitations. Tissue Eng Part B Rev. 2008; 14: 53-60.
67. Hess DC, Borlongan CV. Stem cells and neurological diseases. Cell Prolif. 2008; 41
Suppl 1: 94-114.
68. Segers VFM, Lee RT. Stem-cell therapy for cardiac disease. Nature. 2008; 451: 937-
69. Kuang S, Rudnicki MA. The emerging biology of satellite cells and their therapeutic
potential. Trends Mol Med. 2008; 14: 82-91.
70. Ortiz LA, Gambelli F, McBride C, Gaupp D, Baddoo M, Kaminski N, Phinney
DG. Mesenchymal stem cell engraftment in lung is enhanced in response to
bleomycin exposure and ameliorates its fibrotic effects. Proc Natl Acad Sci USA.
2003; 100: 8407–11.
71. Rojas M, Xu J, Woods CR, MoraAL, Spears W, Roman J, Brigham KL. Bone
marrow-derived mesenchymal stem cells in the repair of the injured lung. Am J Respir
Cell Mol Biol. 2005; 33: 145-52.
72. Ortiz LA, DuTreil M, Fattman C, Pandey AC, Torres G, Go K, Phinney DG.
Interleukin 1 receptor antagonist mediates the antiinflammatory and antifibrotic effect
of mesenchymal stem cells during lung injury. Proc Natl Acad Sci USA. 2007; 104:
73. Sasaki M, Abe R, Fujita Y, Ando S, Inokuma D, Shimizu H. Mesenchymal stem
cells are recruited into wounded skin and contribute to wound repair by
transdifferentiation into multiple skin cell type. J Immunol. 2008; 180: 2581-7.
74. Wu Y, Chen L, Scott PG, Tredget EE. Mesenchymal stem cells enhance wound
healing through differentiation and angiogenesis. Stem Cells. 2007; 25: 2648-59.
75. Li HH, Fu XB, Ouyang YS, Cai CL, Wang J, Sun TZ. Adult bone-marrow-derived
mesenchymal stem cells contribute to wound healing of skin appendages. Cell Tissue
Res. 2006; 14: 325-35.
76. Schenk S, Mal N, Finan A, Zhang M, Kiedrowski M, Popovic Z, McCarthy PM,
Penn MS. Monocyte chemotactic protein-3 is a myocardial mesenchymal stem cell
homing factor. Stem Cells. 2007; 25: 245-51.
77. Fu XB, Fang LJ, Li XK, Cheng B, Sheng ZY. Enhanced wound-healing quality
with bone marrow mesenchymal stem cells autografting after skin injury. Wound Rep
Reg. 2006; 14: 325-35.
78. Lee RH, Seo MJ, Reger RL, Spees JL, Pulin AA, Olson SD, Prockop DJ.
Multipotent stromal cells from human marrow home to and promote repair of
pancreatic islets and renal glomeruli in diabetic NOD/SCID mice. Proc Natl Acad Sci
USA. 2006; 103: 17438-43.
79. Gao X, Song L, Shen K, Wang H, Niu W, Qin X. Transplantation of bone marrow
derived cells promotes pancreatic islet repair in diabetic mice. Biochem Biophys Res
Commun. 2008; 371; 132-7.
80. Boumaza I, Srinivasan S, Witt WT, Feghali-Bostwick C, Dai Y, Garcia-Ocana A,
Feili-Hariri M. Autologous bone marrow-derived rat mesenchymal stem cells
promote PDX-1 and insulin expression in the islets, alter T cell cytokine pattern and
preserve regulatory T cells in the periphery and induce sustained normoglycemia. J
Autoimmun. 2009; 32: 33-42.
81. Munoz JR, Stoutenger BR, Robinson AP, Spees JL, Prockop DJ. Human
stem/progenitor cells from bone marrow promote neurogenesis of endogenous neural
stem cells in the hippocampus of mice. Proc Natl Acad Sci USA. 2005; 102: 18171-6.
82. Urbán VS, Kiss J, Kovács J, Gócza E, Vas V, Monostori E, Uher F. Mesenchymal
stem cells cooperate with bone marrow cells in therapy of diabetes. Stem Cells. 2008;
83. Shi PA, Hematti P, von Kalle C, Dunbar CE. Genetic marking as an approach to
study in vivo hematopoiesis: progress in the non-human primate model. Oncogene.
2002: 21: 3274-83.
84. Maitra B, Szekely E, Gjini K, Laughlin MJ, Dennis J, Haynesworth SE, Koc ON.
Human mesenchymal stem cells support unrelated donor hematopoietic stem cells and
suppress T-cell activation. Bone Marrow Transplant. 2004; 33: 597-604.
85. Le Blanc K, Ringden O. Immunobiology of human mesenchymal stem cells and
future use in hematopoietic stem cell transplantation. Biol Blood Marrow Transplant.
2005; 11: 321-34.
86. Fliedner TM, Nothdirft W, Calvo W. The development of radiation late effects to
the bone marrow after single and chronic exposure. Int J Radiat Biol Stud Phys Chem
Med. 1986; 49: 35-46.
87. Galotto M, Berisso G, Delfino L, Podesta M, Ottaggio L, Dallorso S, Dufour C,
Ferrara GB, Abbondandolo A, Dini G, Bacigalupo A, Cancedda R, Quarto R.
Stromal damage as consequence of high-dose chemo/radiotherapy in bone marrow
transplant recipients. Exp Hematol. 1999; 27:1460-6.
88. Madhusudhan T, Majumdar SS, Mukhopadhyay A. Degeneration of stroma
reduces retention of homed cells in bone marrow of lethally irradiated mice. Stem Cell
Dev. 2004; 13: 173-82.
89. Bartholomew A, Sturgeon C, Siatskas M, Ferrer K, McIntosh K, Patil S, Hardy
W, Devine S, Ucker D, Deans R, Moseley A, Hoffman R. Mesenchymal stem cells
suppress lymphocyte proliferation in vitro and prolong skin graft survival in vivo. Exp
Hematol. 2002; 30: 42-8.
90. Barbash IM, Chouraqui P, Baron J, Feinberg MS, Etzion S, Tessone A, Miller
L,Guetta E, Zipori D, Kedes LH, Kloner RA, Leor J. Systemic delivery of bone
marrow-derived mesenchymal stem cells to the infarcted myocardium: Feasibility,
cell migration, and body distribution. Circulation. 2003; 108: 863–8.
91. Mahmood A, Lu D, Lu M, Chopp M. Treatment of traumatic brain injury in adult
rats with intravenous administration of human bone marrow stromal cells.
Neurosurgery. 2003; 53: 697–702.
92. Mouiseddine M, François S, Semont A, Sache A, Allenet B, Mathieu N, Frick J,
Thierry D, Chapel A. Human mesenchymal stem cells home specifically to
radiation-injured tissues in a non-obese diabetes/severe combined immunodeficiency
mouse model. Br J Radiol. 2007; 80 Spec No 1: S49-55.
93. Devine SM, Cobbs C, Jennings M, Bartholomew A, Hoffman R. Mesenchymal
stem cells distribute to a wide range of tissues following systemic infusion into
nonhuman primates. Blood. 2003; 101: 2999-3001.
94. Hofmann M, Wollert KC, Meyer GP, Menke A, Arseniev L, Hertenstein B,
Gasner A, Knapp WH, Drexler H. Monitoring of bone marrow cell homing into the
infarcted human myocardium. Circulation. 2005; 111: 2198-202.
95. Rombouts WJ, Ploemacher RE. Primary murine MSC show highly efficient homing
to the bone marrow but lose homing ability following culture. Leukemia. 2003; 17:
96. Zhang M, Methot D, Poppa V, Fujio Y, Walsh K, Murry CE. Cardiomyocyte
grafting for cardiac repair: graft cell death and anti-death strategies. J Mol Cell
Cardiol. 2001; 33: 907-21.
97. Toma C, Pittenger MF, Cahill KS, Byrne BJ, Kessler PD. Human mesenchymal
stem cell differentiate to a cardiomyocyte phenotype in the adult murine heart.
Circulation. 2002; 105: 93-8.
98. Pasha Z, Wang Y, Sheikh R, Zhang D, Zhao T, Ashraf M. Preconditioning
enhances cell survival and differentiation of stem cells during transplantation in
infarcted myocardium. Cardiovasc Res. 2008; 77: 134-42.
99. Hu X, Yu SP, Fraser JL, Lu Z, Ogle ME, Wang JA, Wei L. Transplantation of
hypoxia-preconditioned mesenchymal stem cells improves infarcted heart function via
enhanced survival of implanted cells and angiogenesis. J Thorac Cardiovasc Surg.
2008; 135: 799-808.
Rosova I, Dao M, Capoccia B, Link D, Nolta JA. Hypoxic preconditioning
results in increased motility and improved therapeutic potential of human
mesenchymal stem cells. Stem Cells. 2008; 26: 2173-82.
Ip JE, Wu Y, Huang J, Zhang L, Pratt RE, Dzau VJ. Mesenchymal stem
cells use integrinβ1 not CXC chemokine receptor 4 for myocardial migration and
engraftment. Mol Biol Cell. 2007; 18: 2873-82.
Herrera MB, Bussolati B, Bruno S, Morando L, Mauriello-Romanazzi G,
Sanavio F, Stamenkovic I, Biancone L, Camussi G. Exogenous mesenchymal stem
cells localize to the kidney by means of CD44 following acute tubular injury. Kidney
Int. 2007; 72: 430-44.
Shi M, Li J, Liao L, Chen B, Li B, Chen L, Jia H, Zhao RC. Regulation of
CXCR4 expression in human mesenchymal stem cells by cytokine treatment: role in
homing efficiency in NOD/SCID mice. Haematologica. 2007; 92: 897-904.
Kumar S, Ponnazhagan S. Bone homing of mesenchymal stem cells by
ectopic alpha 4 integrin expression. FASEB J. 2007; 21: 3917-27.
Ji JF, He BP, Dheen ST, Tay SSW. Interactions of chemokines and
chemokine receptors mediate the migration of mesenchymal stem cells to the
impaired site in the brain after hypoglossal nerve injury. Stem Cells. 2004; 22: 415-27.
Breitbach M, Bostani T, Roell W, Xia Y, Dewald O, Nygren JM, Fries
JWU, Tiemann K, Bohlen H, Hescheler J, Welz A, Bloch W, Jacobsen SEW,
Fleischmann BK. Potential risks of bone marrow cell transplantation into infarcted
hearts. Blood. 2007; 110: 1362-9.
Song L, Webb NE, Song Y, Tuan RS. Identification and functional analysis
of candidate genes regulating mesenchymal stem cell self-renewal and multipotency.
Stem Cells. 2006; 24: 1707–18.
Chang SC, Chuang HL, Chen YR, Chen JK, Chung HY, Lu YL, Lin HY,
Tai CL, Lou J. Ex vivo gene therapy in autologous bone marrow stromal stem cells
for tissue-engineered maxillofacial bone regeneration. Gene Ther. 2003; 10: 2013–9.
Noel D, Gazit D, Bouquet C, Apparailly F, Bony C, Plence P, Millet V,
Turgeman G, Perricaudet M, Sany J, Jorgensen C. Short-term BMP-2 expression
is sufficient for in vivo osteochondral differentiation of mesenchymal stem cells. Stem
Cells. 2004; 22: 74-85.
Zhao M, Zhao Z, Koh JT, Jin T, Franceschi RT. Combinatorial gene
therapy for bone regeneration: cooperative interactions between adenovirus vectors
expressing bone morphogenetic proteins 2, 4 and 7. J Cell Biochem. 2005; 95: 1-16.
Franceschi RT. Biological approaches to bone regeneration by gene therapy.
J Dent Res. 2005; 84: 1093-103.
Gersbach CA, Le Doux JM, Guldberg RE, Garcia AJ. Inducible regulation
of Runx2–stimulated osteogenesis. Gene Ther. 2006; 13: 873–82.
Chamberlain JR, Schwarze U, Wang PR, Hirata RK, Hankenson KD,
Pace JM, Underwood RA, Song KM, Sussman M, Byers PH, Russell DW. Gene
targeting in stem cells from individuals with osteogenesis imperfecta. Science. 2004;
Goncalves MA, de Vries AA, Holkers M, van de Watering MJ, van der
Velde I, van Nierop GP, Valerio D, Knaän-Shanzer S. Human mesenchymal stem
cells ectopically expressing full-length dystrophin can complement Duchenne
muscular dystrophy myotubes by cell fusion. Human Mol Genet. 2005; 15: 213-21.
Li Y, Zhang R, Qiao H, Zhang H, Wang Y, Yuan H, Liu Q, Liu D, Chen
L, Pei X. Generation of insulin-producing cells from PDX-1 gene-modified human
mesenchymal stem cells. J Cell Physiol. 2007; 211: 36-44.
Noiseux N, Gnecchi M, Lopez-Ilasaca M, Zhang L, Solomon SD, Deb A,
Dazu VJ, Pratt RE. Mesenchymal stem cells overexpressing Akt dramatically repair
infracted myocardium and improve cardiac function despite infrequent cellular fusion
or differentiation. Mol Ther. 2006; 14: 840-50.
Gnecchi M, He H, Liang OD, Melo LG, Morello F, Mu H, Noiseux N,
Zhang L, Pratt RE, Ingwall JS, Dzau VJ. Paracrine action accounts for marked
protection of ischemic heart by Akt-modified mesenchymal stem cells. Nat Med.
2005; 11: 367-8.
Mirotsou M, Zhang Z, Deb A, Zhang L, Gnecchi M, Noiseux N, Mu H,
Pachori A, Dzau V. Secreted frizzled related protein 2 (Sfrp2) is the key Akt-
mesenchymal stem cell-released paracrine factor mediating myocardial survival and
repair. Proc Natl Acad Sci USA. 2007; 104: 1643-8.
Kim SS, Yoo SW, Park TS, Ahn SC, Jeong HS, Kim JW, Chang DY, Cho
KG, Kim SU, Huh Y, Lee JE, Lee SY, Lee YD, Suh-Kim H. Neural Induction with
Neurogenin1 Increases the Therapeutic Effects of Mesenchymal Stem Cells in the
Ischemic Brain. Stem Cells. 2008; 26: 2217-28.
Westenbroek RE, Merrick DK, Catterall WA. Differential subcellular
localization of the RI and RII Na+ channel subtypes in central neurons. Neuron. 1989;
Li Y, Chen J, Chen XG, Wang L, Gautam SC, Xu YX, Katakowski M,
Zhang LJ, Lu M, Janakiraman N, Chopp M. Human marrow stromal cell therapy
for stroke in rat: neurotrophins and functional recovery. Neurology. 2002; 59: 514-23.
Chen J, Li Y, Katakowski M, Chen X, Wang L, Lu D, Lu M, Gautam SC,
Chopp M. Intravenous bone marrow stromal cell therapy reduces apoptosis and
promotes endogenous cell proliferation after stroke in female rat. J Neurosci Res.
2003; 73: 778-86.
Cheng Z, Ou L, Zhou X, Li F, Jia X, Zhang Y, Liu X, Li Y, Ward CA,
Melo LG, Kong D. Targeted migration of mesenchymal stem cells modified with
CXCR4 gene to infarcted myocardium improves cardiac performance. Mol Ther.
2008; 16: 571-9.
Zhang D, Fan GC, Zhou X, Zhao T, Pasha Z, Xu M, Zhu Y, Ashraf M,
Wang Y. Over-expression of CXCR4 on mesenchymal stem cells augments
myoangiogenesis in the infracted myocardium. J Mol Cell Cardiol. 2008; 44: 281-92.
Tang YL, Tang Y, Zhang YC, Qian K, Shen L, Phillips MI. Improved graft
mesenchymal stem cell survival in ischemic heart with a hypoxia-regulated heme
oxygenase-1 vector. J Am Coll Cardiol. 2005; 46: 1339-50.
Li W, Ma N, Ong LL, Nesselmann C, Klopsch C, Ladilov Y, Furlani D,
Piechaczek C, Moebius JM, Lützow K, Lendlein A, Stamm C, Li RK, Steinhoff
G. Bcl-2 engineered MSCs inhibited apoptosis and improved heart function. Stem
Cells. 2007; 25: 2118-27.
Mangi AA, Noiseux N, Kong D, He H, Rezvani M, Ingwall JS, Dzau VJ.
Mesenchymal stem cells modified with Akt prevent remodeling and restore
performance of infarcted hearts. Nat Med. 2003; 9: 1195-201.
Thomas CE, Ehrhardt A, Kay MA. Progress and problems with the use of
viral vectors for gene therapy. Nat Rev Genet. 2003; 4: 346-58.
Park J, Ries J, Gelse K, Kloss F, von der Mark K, Wiltfang J, Neukam
FW, Schneider H. Bone regeneration in critical size defects by cell-mediated BMP-2
gene transfer: a comparison of adenoviral vectors and liposomes. Gene Ther. 2003;
Bartholomew A, Patil S, Mackay A, Nelson M, Buyaner D, Hardy W,
Mosca J, Sturgeon C, Siatskas M, Mahmud N, Ferrer K, Deans R, Moseley A,
Hoffman R, Devine SM. Baboon mesenchymal stem cells can be genetically
modified to secrete human erythropoietin in vivo. Hum. Gene Ther. 2001; 12: 1527–
Campeau PM, Rafei M, Francois M, Birman E, Forner K-A, Galipeau J.
Mesenchymal stromal cells engineered to express erythropoietin induce anti-
erythropoietin antibodies and anemia in allorecipients. Mol Ther. 2009; 17: 369-72.
Burkus JK, Transfeldt EE, Kitchel SH, Watkins RG, Balderston RA.
Clinical and radiographic outcomes of anterior lumbar interbody fusion using
recombinant human bone morphogenetic protein-2. Spine. 2002; 27: 2396–408.
Fang J, Zhu YY, Smiley E, Bonadio J, Rouleau JP, Goldstein SA,
McCauley LK, Davidson BL, Roessler BJ. Stimulation of new bone formation by
direct transfer of osteogenic plasmid genes. Proc Natl Acad Sci USA. 1996; 93: 5753–
Engler AJ, Sen S, Sweeney HL, Discher DE. Matrix elasticity directs stem
cell lineage specification. Cell. 2006; 126: 677-89.
Curran JM, Chen R, Hunt JA. The guidance of human mesenchymal stem
cell differentiation in vitro by controlled modifications to the cell substrate.
Biomaterials. 2006; 27: 4783-93.
Vilquin JT, Rosset P. Mesenchymal stem cells in bone and cartilage repair:
current status. Regen Med. 2006; 1: 589-604.
Arinzeh TL, Peter SJ, Archambault MP, van den Bos C, Gordon S, Kraus
K, Smith A, Kadiyala S. Allogeneic mesenchymal stem cells regenerate bone in a
critical-sized canine segmental defect. J Bone Joint Surg Am. 2003; 85-A: 1927-35.
Clark ERC. Microscopic observations on the growth of blood capillaries in
the living mammal. Am J Anat. 1939; 64: 251-301.
Cassell OCS, Hofer SOP, Morrison WA, Knight KR. Vascularisation of
tissue-engineered grafts: the regulation of angiogenesis in reconstructive surgery and
in disease states. Br J Plastic Surg. 2002; 55: 603-10.
Yang J, Zhou W, Zheng W, Ma Y, Lin L, Tang T, Liu J, Yu J, Zhou X,
Hu J. Effects of myocardial transplantation of marrow mesenchymal stem cells
transfected with vascular endothelial growth factor for the improvement of heart
function and angiogenesis after myocardial infarction. Cardiology. 2007; 107: 17-29.
Rouwkema J, De Boer J, Van Blitterswijk CA. Endothelial cells assembly
into a 3-dimensional prevascular network in a bone tissue engineering construct.
Tissue Eng. 2006; 12: 2685-93.
Rouwkema J, Rivron NC, Van Blitterswijk CA. Vascularisation in tissue
engineering. Trends Biotechnol. 2008; 26: 434-41.
Ferrara N, Alitalo K. Clinical applications of angiogenic growth factors and
their inhibitors. Nat Med. 1999; 5: 1359-64.
Kadivar M, Khatami S, Mortazavi Y, Shokrgozar MA, Taghikhani M,
Soleimani M. In vitro cardiomyogenic potential of human umbilical vein-derived
mesenchymal stem cells. Biochem Biophys Res Commun. 2006; 340: 639-47.
Amado LC, Saliaris AP, Schuleri KH, St. John M, Xie JS, Cattaneo S,
Durand DJ, Fitton T, Kuang JQ, Stewart G, Lehrke S, Baumgartner WW,
Martin BJ, Heldman AW, Hare JM. Cardiac repair with intramyocardial injection
of allogeneic mesenchymal stem cells after myocardial infarction. Proc Natl Acad Sci
USA. 2005; 102: 11474-9.
Mohyeddin-Bonab M, Mohamad-Hassani MR, Alimoghaddam K,
Sanatkar M, Gasemi M, Mirkhani H, Radmehr H, Salehi M, Eslami M, Farhig-
Parsa A, Emami-Razavi H, Alemohammad MG, Solimani AA, Ghavamzadeh A,
Nikbin B. Autologous in vitro expanded mesenchymal stem cell therapy for human
old myocardial infarction. Arch Iran Med. 2007; 10: 467-73.
Tisato V, Naresh K, Girdlestone J, Navarrete C, Dazzi F. Mesenchymal
stem cells of cord blood origin are effective at preventing but not treating graft-
versus-host disease. Leukemia. 2007; 21: 1992-9.
Ringden O, Uzunel M, Rasmusson I, Remberger M, Sundberg B, Lonnies
H, Marschall H-U, Dlugosz A, Szakos A, Hassan Z, Omazic B, Aschan J,
Barkholt L, Le Blanc K. Mesenchymal stem cells for treatment of therapy-resistant
graft-versus-host disease. Transplant. 2006; 81: 1390-7.
Le Blanc K, Frassoni F, Ball L, Locatelli F, Roelofs H, Lewis I, Lanino E,
Sundberg B, Bernardo ME, Remberger M, Dini G, Egeler RM, Bacigalupo A,
Fibbe W, Ringden O; Developmental Committee of the European Group for
Blood and Marrow Transplantation. Mesenchymal stem cells for treatment of
steroid-resistant, severe, acute graft-versus-host disease: a phase II study. Lancet.
2008; 371: 1579-86.
Lazarus HM, Koc ON, Devine SM, Curtin P, Maziarz RT, Holland HK,
Shpall EJ, McCarthy P, Atkinson K, Cooper BW, Gerson SL, Laughlin MJ,
Loberiza FR Jr, Moseley AB, Bacigalupo A. Cotransplantation of HLA-identical
sibling culture-expanded mesenchymal stem cells and hematopoietic stem cells in
hematologic malignancy patients. Biol Blood Marrow Transplant. 2005; 11: 389-98.
Ning H, Yand F, Jiang M, Hu L, Feng K, Zhang J, Yu Z, Li B, Xu C, Li
Y, Wang J, Hu J, Lou X, Chen H. The correlation between cotransplantation of
MSC and higher recurrence rate in hematologic malignancy patients: outcome of a
pilot clinical trial. Leukemia. 2008; 22: 593-9.
Quarto R, Mastrogiacomo M, Cancedda R, Kutepov SM, Mukhachev V,
Lavroukov A, Kon E, Marcacci M. Repair of large bone defects with the use of
autologous bone marrow stromal cells. N Eng J Med. 2001; 344: 385-6.
Gan Y, Dai K, Zhang P, Tang T, Zhu Z, Lu J. The clinical use of enriched
bone marrow stem cells combined with porous beta-tricalcium phosphate in posterior
spinal fusion. Biomaterials. 2008; 29: 3973-82.
Prockop DJ, Olson SD. Clinical trials with adult stem/progenitor cells for
tissue repair: let’s not overlook some essential precautions. Blood. 2007; 109: 3147-
Miura M, Miura Y, Padilla-Nash HM, Molinolo AA, Fu B, Patel V, Seo B-
M, Sonoyama W, Zheng JJ, Baker CC, Chen W, Ried T, Shi S. Accumulated
chromosomal instability in murine bone marrow mesenchymal stem cells leads to
malignant transformation. Stem Cells. 2006; 24: 1095-103.
Rubio D, Garcia-Castro J, Martin MC, de la Fluente R, Cigudosa JC,
Lloyd AC, Bernad A. Spontaneous human adult stem cell transformation. Cancer
Res. 2005; 65: 3035-9.
Wagner W, Horn P, Castoldi M, Diehlmann A, Bork S, Saffrich R, Benes
V, Blake J, Pfister S, Eckstein V, Ho AD. Replicative senescence of mesenchymal
stem cells: a continuous and organized process. PLoS ONE. 2008; 3: e2213.
Shibata KR, Aoyama T, Shima Y, Fukiage K, Otsuka S, Furu M, Kohno
Y, Ito K, Fujibayashi S, Neo M, Nakayama T, Nakamura T, Toguchida J.
Expression of the p16INK4A gene is associated closely with senescence of human
mesenchymal stem cells and is potentially silenced by DNA methylation during in
vitro expansion. Stem Cells. 2007; 25: 2371-82.
Bianchi G, Banfi A, Mastrogiacomo M, Notaro R, Luzzatto L, Cancedda
R, Quarto R. Ex vivo enrichment of mesenchymal cell progenitors by fibroblast
growth factor 2. Exp Cell Res. 2003; 287: 98-105.
Ito T, Sawada R, Fujiwara Y, Seyama Y, Tsuchiya T. FGF-2 suppresses
cellular senescence of human mesenchymal stem cells by down-regulation of TGF-
β2. Biochem Biophys Res Commun. 2007; 359: 108-14.
Simonsen JL, Rosada C, Serakinci N, Justesen J, Stenderup K, Rattan
SIS, Jensen TG, Kassem M. Telomerase expression extends the proliferative life-
span and maintains the osteogenic potential of human bone marrow stromal cells. Nat
Biotechnol. 2002; 20: 592-6.
Miura M, Miura Y, Padilla-Nash HM, Molinolo AA, Fu B, Patel V, Seo B-
M, Sonoyama W, Zheng JJ, Baker CC, Chen W, Ried T, Shi S. Accumulated
chromosomal instability in murine bone marrow mesenchymal stem cells leads to
malignant transformation. Stem Cells. 2006; 24: 1095-103.
Bernardo ME, Zaffaroni N, Novara F, Cometa AM, Avanzini MA,
Moretta A, Montagna D, Maccario R, Villa R, Daidone MG, Zuffardi O,
Locatelli F. Human bone marrow-derived mesenchymal stem cells do not undergo
transformation after long-term in vitro culture and do not exhibit telomere
maintenance mechanisms. Cancer Res. 2007; 67: 9142-9.
Rubio D, Garcia-Castro J, Martin MC, de la Fluente R, Cigudosa JC,
Lloyd AC, Bernad A. Spontaneous human adult stem cell transformation. Cancer
Res. 2005; 65: 3035-9.
Lazennec G, Jorgensen C. Adult mulipotent stromal cells and cancer: risk or
benefit? Stem Cells. 2008; 26: 1387-94.
Maestroni GJ, Hertens E, Galli P. Factor(s) from nonmacrophage bone
marrow stromal cells inhibit Lewis lung carcinoma and B16 melanoma growth in
mice. Cell Mol Life Sci. 1999; 55: 663-7.
Fierro Fa, Sierralta WD, Epuñan MJ, Minquell JJ. Marrow-derived
mesenchymal stem cells: role in epithelial tumor cell determination. Clin Exp
Metastasis. 2004; 21: 313-9.
Gunn WG, Conley A, Deininger L, Olson SD, Prockop DJ, Gregory CA.
A crosstalk between myeloma cells and marrow stromal cells stimulates production of
Dkk1 and interleukin-6: a potential role in the development of lytic bone disease and
tumor progression in multiple myeloma. Stem Cells. 2006; 24: 986-91.
Karnoub AE, Dash AB, Vo AP, Sullivan A, Brooks MW, Bell GW,
Richardson AL, Polyak K, Tubo R, Weinberg RA. Mesenchymal stem cells within
tumor stroma promote breast cancer metastasis. Nature. 2007; 449: 557-63.
Zappia E, Casazza S, Pedemonte E, Benvenuto F, Bonanni I, Gerdoni E,
Giunti D, Ceravolo A, Cazzanti F, Frassoni F, Mancardi G, Uccelli A.
Mesenchymal stem cells ameliorate experimental autoimmune encephalomyelitis
inducing T-cell anergy. Blood. 2005; 106: 1755-61.
Djouad F, Fritz V, Apparailly F, Louis-Plence P, Bony C, Sany J,
Jorgensen C, Noël D. Reversal of the immunosuppressive properties of mesenchymal
stem cells by tumor necrosis factor alpha in collagen-induced arthritis. Arthritis
Rheum. 2005; 52: 1595-1603.
Chamberlain J, Yamagami T, Colletti E, Theise ND, Desai J, Frias A,
Pixley J, Zanjani ED, Porada CD, Almeida-Porada G. Efficient generation of
human hepatocytes by the intrahepatic delivery of clonal human mesenchymal stem
cells in fetal sheep. Hepatology. 2007; 46: 1935-45.
Sémont A, François S, Mouiseddine M, François A, Saché A, Frick J,
Thierry D, Chapel A. Mesenchymal stem cells increase self-renewal of small
intestinal epithelium and accelerate structural recovery after radiation injury. Adv Exp
Med Biol. 2006; 585: 19-30.
Herrera MB, Bussolati B, Bruno S, Fonsato V, Romanazzi GM, Camussi
G. Mesenchymal stem cells contribute to the renal repair of acute tubular epithelial
injury. Int J Mol Med. 2004; 14: 1035-41.
Deng YB, Liu XG, Liu ZG, Liu XL, Liu Y, Zhou GQ. Implantation of BM
mesenchymal stem cells into injured spinal cord elicits de novo neurogenesis and
functional recovery: evidence from a study in rhesus monkeys. Cytotherapy. 2006; 8:
Arnhold S, Absenger Y, Klein H, Addicks K, Schraermeyer U.
Transplantation of bone marrow-derived mesenchymal stem cells rescue
photoreceptor cells in the dystrophic retina of the rhodopsin knockout mouse. Graefes
Arch Clin Exp Ophthalmol. 2007; 245: 414-22.
Gupta N, Su X, Popov B, Lee JW, Serikov V, Matthay MA.
Intrapulmonary delivery of bone marrow-derived mesenchymal stem cells improves
survival and attenuates endotoxin-induced acute lung injury in mice. J Immunol.
2007; 179: 1855-63.
Ma Y, Xu Y, Xiao Z, Yang W, Zhang C, Song E, Du Y, Li L.
Reconstruction of chemically burned rat corneal surface by bone marrow-derived
human mesenchymal stem cells. Stem Cells. 2006; 24: 315-21.
Xu J, Lu Y, Ding F, Zhan X, Zhu M, Wang Z. Reversal of diabetes in mice
by intrahepatic injection of bone-derived GFP-murine mesenchymal stem cells
infected with the recombinant retrovirus-carrying human insulin gene. World J Surg.
2007; 31: 1872-82.
Sun L, Cui M, Wang Z, Feng X, Mao J, Chen P, Kangtao M, Chen F,
Zhou C. Mesenchymal stem cells modified with angiopoietin-1 improve remodeling
in a rat model of acute myocardial infarction. Biochem Biophys Res Commun. 2007;
Chang W, Kim JY, Lim S, Lee S, Song BW, Kim HJ, Cha MJ, Kwon SY,
Han SM, Min BH, Jang Y, Chung N, Hwang KC. Mesenchymal stem cells with
calreticulin gene modulate cell adhesiveness through an integrin-mediated
mechanism. Tissue Eng Regen Med. 2006; 3: 327-35.
Dumont RJ, Dayoub H, Li JZ, Dumont AS, Kallmes DF, Hankins GR,
Helm GA. Ex Vivo Bone Morphogenetic Protein-9 Gene Therapy Using Human
Mesenchymal Stem Cells Induces Spinal Fusion in Rodents. Neurosurgery. 2002; 51:
Rabin N, Kyriakou C, Coulton L, Gallagher OM, Buckle C, Benjamin R,
Singh N, Glassford J, Otsuki T, Nathwani AC, Croucher PI, Yong KL. A new
xenograft model of myeloma bone disease demonstrating the efficacy of human
mesenchymal stem cells expressing osteoprotegerin by lentiviral gene transfer.
Leukemia. 2007; 21: 2181-91.
Min C-K, Kim B-G, Park G, Cho B, Oh I-H. IL-10-transduced bone
marrow mesenchymal stem cells can attenuate the severity of acute graft-versus-host
disease after experimental allogeneic stem cell transplantation. Bone Marrow
Transplant. 2007; 39: 637-45.
Kurozumi K, Nakamura K, Tamiya T, Kawano Y, Kobune M, Hirai S,
Uchida H, Sasaki K, Ito Y, Kato K, Honmou O, Houkin K, Date I, Hamada H.
BDNF gene-modified mesenchymal stem cells promote functional recovery and
reduce infarct size in the rat middle cerebral artery occlusion model. Mol. Ther. 2004;
Nakamura K, Ito Y, Kawano Y, Kurozumi K, Kobune M, Tsuda H, Bizen
A, Honmou O, Niitsu Y, Hamada H. Antitumor effect of genetically engineered
mesenchymal stem cells in a rat glioma model. Gene Ther. 2004; 11: 1155-64.
Kanehira M, Xin H, Hoshino K, Maemondo M, Mizuguchi H, Hayakawa
T, Matsumoto K, Nakamura T, Nukiwa T, Saijo Y. Targeted delivery of NK4 to
multiple lung tumors by bone marrow-derived mesenchymal stem cells. Cancer Gene
Ther. 2007; 14: 894-903.
Liu Y, Shu XZ, Prestwich GD. Osteochondral defect repair with autologous
bone marrow-derived mesenchymal stem cells in an injectable, in situ, cross-linked
synthetic extracellular matrix. Tissue Eng. 2006; 12: 3404-16.
Syková E, Jendelová P, Urdzíková L, Lesný P, Hejcl A. Bone marrow stem
cells and polymer hydrogels--two strategies for spinal cord injury repair. Cell Mol
Neurobiol. 2006; 26: 1113-29.
Zhang J, Qi H, Wang H, Hu P, Ou L, Guo S, Li J, Che Y, Yu Y, Kong D.
Engineering of vascular grafts with genetically modified bone marrow mesenchymal
stem cells on poly (propylene carbonate) graft. Artif Organs. 2006; 30: 898-905.
Tu Q, Valverde P, Li S, Zhang J, Yang P, Chen J. Osterix overexpression
in mesenchymal stem cells stimulates healing of critical-sized defects in murine
calvarial bone. Tissue Eng. 2007; 13: 2431-40.
Hoffmann A, Pelled G, Turgeman G, Eberle P, Zilberman Y, Shinar H,
Keinan-Adamsky K, Winkel A, Shahab S, Navon G, Gross G, Gazit D.
Neotendon formation induced by manipulation of the Smad8 signalling pathway in
mesenchymal stem cells. J Clin Invest. 2006; 116: 940-52.
Guo CA, Liu XG, Huo JZ, Jiang C, Wen XJ, Chen ZR. Novel Gene-
Modified-Tissue Engineering of Cartilage Using Stable Transforming Growth Factor-
β1-Transfected Mesenchymal Stem Cells Grown on Chitosan Scaffolds. J Biosci
Bioeng. 2007; 103: 547-56.
Mohyeddin-Bonab M, Yazdanbakhsh S, Lotfi J, Alimoghaddom K,
Talebian F, Hooshmand F, Ghavamzadeh A, Nikbin B. Does mesenchymal stem
cell therapy help multiple sclerosis patients? Report of a pilot study. Iran J Immunol.
2007; 4: 50-7.
Garcia-Olmo D, Garcia-Arranz M, Herreros D, Pascual I, Peiro C,
Rodriguez-Montes JA. A phase I clinical trial of the treatment of Crohn’s fistula by
adipose mesenchymal stem cell transplantation. Dis Colon Rectum. 2005; 48: 1416-
Kang KS, Kim SW, Oh YH, Yu JW, Kim K-Y, Park HK, Song C-H, Han
H. A 37-year-old spinal cord-injured female patient, transplanted of multipotent stem
cells from human UC blood, with improved sensory perception and mobility, both
functionally and morphologically: a case study. Cytotherapy. 2005; 7: 368-73.
Table 1: Experimental Mesenchymal Stem Cell-based Therapies
Cells Mode of
Human MSCs Intrahepatic Generation of hepatocyes 172
Human MSCs Intravenous Recovery of small intestine
structure with increase in villus
Kidney engraftment, tubular
recovery from renal failure
De novo neurogenesis and
functional recovery of senses
Mice Murine GFP-
neural cells in
Injected to the
Rescue photoreceptor cells via
Accelerated wound closure with
cellularity and angiogenesis
reduction in scar formation and
Lower blood glucose levels and
increased insulin levels
proinflammatory reponses to
Reconstruction of corneal
surface associated with
inhibition of inflammation and
Pig Allogeneic MSCs Intra-
Human MSCs Intracardiac 78
Murine MSCs Intra-
Rat Human MSCs Injected into
Table 2: Genetically modified-Mesenchymal Stem Cell-based Therapies
Study Cells Mode of
Diabetes Mouse Human insulin
Intrahepatic Diabetes relieved for 6
MSCs differentiate into
cells and restore back
normal glucose levels
modified rat MSCs
Intramyocardial Improved heart function,
enhanced angiogenesis and
reduced cardiac remodeling
injured site migration and survival post-
injection bone formation at injected
Intravenous Reduced osteoclast
activation and trabecular
Intravenous Reduced inflammatory
response and enhanced
Enhanced cell adhesiveness,
Spinal fusions (i.e. ectopic 182
Mouse IL-10 transduced
Table 3: Mesenchymal Stem Cell-based Protein Therapies
Cells Mode of
Anemia Mouse Epo-gene modified
Anemia corrected 9
BDNF production inproved
functional recovery with less
number of cells undergoing
apoptosis in ischemic boundary
Inhibited tumor growth and
prolonged survival of tumor-
Inhibited development of lung
metastasis; Prolonged survival
by inhibiting tumor-associated
angiogenesis & lymphangioge-
nesis & apoptosis of tumor
Glioma Rat Human IL-2
Table 4: Tissue Engineering Therapies using MSCs Download full-text
Disease/injury Cells & scaffold Mode of
Rabbit Autologous MSCs
in an injectable
MSCs seeded onto
seeded in type I
with BMP-2 and
variant seeded onto
Cartilage completely filled
the full-thickness defect
Enhanced ingrowth of axons
in the lesion and
improvement in function
Generation of engineered
None In vitro
Enhanced bone formation 191
Tendon defect Rat
Tendon regeneration 192
Enhanced repair; defect filled
with hyaline cartilage