Hindawi Publishing Corporation
Journal of Biomedicine and Biotechnology
Volume 2012, Article ID 362473, 8pages
Human Umbilical Cord Blood-Derived Mesenchymal
Stem Cell Therapy Promotes Functional Recovery of Contused
Rat Spinal Cord through Enhancement of
Endogenous Cell Proliferation and Oligogenesis
Sang In Park,1, 2 Jung Yeon Lim,2Chang Hyun Jeong,2Seong Muk Kim,2
Jin Ae Jun,2Sin-Soo Jeun,2and Won Il Oh3
1Institute of Catholic Integrative Medicine (ICIM), Incheon St. Mary’s Hospital, The Catholic University of Korea,
Incheon, Republic of Korea
2Department of Neurosurgery, The Catholic University of Korea, Seoul, Republic of Korea
3Medipost Biomedical Research Institute, Medipost Co., Ltd., Seoul, Republic of Korea
Correspondence should be addressed to Sin-Soo Jeun, email@example.com
Received 23 June 2011; Accepted 29 September 2011
Academic Editor: Ken-ichi Isobe
Copyright © 2012 Sang In Park et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Numerous studies have shown the beneﬁts of mesenchymal stem cells (MSCs) on the repair of spinal cord injury (SCI) model
and on behavioral improvement, but the underlying mechanisms remain unclear. In this study, to investigate possible mechanisms
by which MSCs contribute to the alleviation of neurologic deﬁcits, we examined the potential eﬀect of human umbilical cord
blood-derived MSCs (hUCB-MSCs) on the endogenous cell proliferation and oligogenesis after SCI. SCI was injured by contusion
using a weight-drop impactor and hUCB-MSCs were transplanted into the boundary zone of the injured site. Animals received
a daily injection of bromodeoxyuridine (BrdU) for 7 days after treatment to identity newly synthesized cells of ependymal
and periependymal cells that immunohistochemically resembled stem/progenitor cells was evident. Behavior analysis revealed
that locomotor functions of hUCB-MSCs group were restored signiﬁcantly and the cavity volume was smaller in the MSCs-
transplanted rats compared to the control group. In MSCs-transplanted group, TUNEL-positive cells were decreased and BrdU-
positive cells were signiﬁcantly increased rats compared with control group. In addition, more of BrdU-positive cells expressed
neural stem/progenitor cell nestin and oligo-lineage cell such as NG2, CNPase, MBP and glial ﬁbrillary acidic protein typical
of astrocytes in the MSC-transplanted rats. Thus, endogenous cell proliferation and oligogenesis contribute to MSC-promoted
functional recovery following SCI.
Recovery following spinal cord injury (SCI) is limited
because of axonal damage , demyelination, and scar
formation . In addition to the formation of a central
hemorrhagic lesion devoid of normal neurons and glia,
oligodendrocytes and astrocytes in the white matter near the
impact site are reduced by about 50% by 24h after injury .
Recently, the use of stem cell for neurodegenerative
disease has been widely investigated as a therapeutic strategy
[4–6]. Neural stem cells have been used for the treatment
of neurological diseases such as SCI orstroke.
Numerous studies have reported that the survival and differ-
entiation of grafted cells into neural cells correlate with
behavior improvement. However, these cells are limited for
clinical application because of insuﬃcient cell supply, risk of
immune rejection, and ethical problems. Since mesenchymal
stem cells (MSCs) can be readily isolated and their numbers
increased in vitro and diﬀerentiated into several types of
mature cells including neurons, adipocytes, cartilage, and
skeletal hepatocytes under appropriate conditions ,anew
therapeutic strategy has been a valuable source for central
nervous stem (CNS) disease [10,11]. Human umbilical
cord blood-derived MSCs (hUCB-MSCs) have therapeutic
2Journal of Biomedicine and Biotechnology
potential and are attractive because these cells are readily
available and are less immunogenic as compared to other
sources of stem cells, such as bone marrow or adipose .
An alternative strategy of stem cell therapy is protection
of injured cells and promotion of endogenous cell regen-
eration. Several studies have reported that stem cells might
provide a better environment for damaged tissue and save
remaining neurons by neurotrophic factors or cytokines [13,
14]. However, the speciﬁc mechanism of the MSCs for these
assertions remains controversial and ill-explored. Neverthe-
less, MSC treatment of SCI has been reported as a candi-
date that supplies angiogenic, antiapoptotic, and mitogenic
factors as well as migration toward damaged tissue .
Recently, MSCs have been used in clinical treatment and were
shown to be eﬀective in the treatment of various pathologies
although evidence for distinct therapeutic mechanism was
The normal spinal cord contains endogenous neural
progenitor cells (NPC) and oligodendrocyte precursor cells
(OPCs) . Nevertheless, production of new neurons and
oligodendrocytes by endogenous cells into the spinal cord
may be very restricted after injury . Furthermore, cell
transplantation studies have demonstrated that exogenous
stem cells diﬀerentiate only very poorly when grafted into the
spinal cord. Thus, the environment of the spinal cord appears
to be highly restrictive for the diﬀerentiation of OPCs.
If this environmental restriction can be changed by hUCB-
MSC in SCI, OPCs may be able to supply new neurons
and oligodendrocytes. However, it is not known whether
survival and diﬀerentiation generated from endogenous cells
are inﬂuenced by transplanted hUCB-MSCs.
In the present study, we show that the transplantation
of hUCB-MSCs confers therapeutic eﬀects in a rat experi-
mental SCI model. We investigated whether transplantation
of hUCB-MSCs improved the functional recovery and im-
proved the proliferation and genesis of resident endogenous
cells within the spinal cord by hUCB-MSCs.
2. Materials and Methods
2.1. Human UCB-Derived MSCs. Human UCBs were ob-
tained from normal full-term pregnant woman. The protocol
for human subjects adhered to the guidelines outlined by the
institutional review IRB board of the Catholic University of
Korea (Seoul, Republic of Korea). hUCB-MSCs were isolated
and expanded using a previously described protocol .
2.2. Animal Model. All animal protocols were approved by
the Institutional Animal Care and Use Committee of Catho-
lic University Medical School. Forty-ﬁve adult male Sprague-
Dawley rats weighting between 270 and 300 g were employed
in our experiments. Surgical techniques were similar to
those described previously . Brieﬂy, rats were deeply
anesthetized with ketamine-xylazine cocktail (80 mg/kg of
ketamine, 10 mg/kg of xylazine). Under a dissecting micro-
scope, the skin and muscles overlying the thoracic cord were
separated and retracted, the T9 vertebral level was removed
by laminectomy, and the underlying spinal cord segment
was exposed by slitting the dural sheath. The impact rod
of the NYU impactor was centered above T9 and dropped
from a height of 25 mm to induce an incomplete partial SCI.
Following lesion, the dorsal back musculature was sutured
and the skin closed with surgical clips. After surgery, the
animals were kept on a thermostatically regulated heating
pad until completely awake. The urinary bladder of all rats
was emptied manually two times per day until recovery of
2.3. Cell Transplantation. Rats were assigned randomly to
one of the following two major groups: one group of rats
were treated with 5 µL phosphate-buﬀered saline (PBS) as the
control group. The second group of rats received transplant-
ed with hUCB-MSCs (3 ×105cells/5 µL). In experiment 1,
the hUCB-MSCs was designed to test the therapeutic
eﬀectiveness (n=26), and, in experiment 2, these cells were
designed to evaluate the proliferation of endogenous cells
after transplantation (n=12).
Initial locomotor scores were equalized between groups.
The weight-drop injury level was based on our experience
with the model to produce spontaneous recovery at a Basso-
Beatti-Bresnahan (BBB) score of 4. Once the 46 rats were
subjected to contusion SCI, they were divided randomly into
the two groups. Using a 25-gauge syringe (Hamilton, Reno,
NV) ﬁxed in a stoelting stereotaxic frame (Dae Jong) at 7
days after injury, hUCB-MSCs were transplanted into the
spinal cord (0.5 mm from the midline, 1.5 mm down from
the dura, and 5 mm rostral from the contusion epicenter).
Each rat received a 5µL injection in the contusion site over
a 10 min period each time. The cannula of the Hamilton
syringe was left in place after injection for an additional
5 min. All animal received antibiotics (Gentamicin sulfate,
30 mg/kg/day) during the ﬁrst week after transplantation.
2.4. 5-Bromo-2-Deoxyuridine (BrdU) Administration. Spra-
gue-Dawley rats (n=12) were injected with 50 mg/kg BrdU
(Sigma-Aldrich, St. Louis, MO, USA) intraperitoneally each
day for 7 days to label the newly generating cells after trans-
plantation. The examined proliferative response focused on
cell genesis occurring within 7 days after transplantation.
2.5. Behavioral Testing. The motor function restoration after
spinal cord contusion was observed by open-ﬁeld BBB
locomotor ratio scale . The scale used for measuring
hind-limb function with these procedures ranges from a
score of 0, indicating no spontaneous movement, to a
maximum score of 21, with an increasing score indicating
the use of individual joints, coordinated joint movement,
coordinated limb movement, weight-bearing, and other
functions. Behavioral testing was performed weekly on
each hindlimb from the postoperative day to 7 weeks after
SCI. Spinal cord contusion and cell transplantation were
separately performed in double-blinded experiments by
2.6. Tissue of Harvest. To study functional recovery and dif-
ferentiation of transplanted hUCB-MSCs, rats from each
group were sacriﬁced at 1 and 2 weeks (PBS, n=3; Trans-
plantation, n=3) after transplantation and the others were
Journal of Biomedicine and Biotechnology 3
examined by the BBB locomotor test 6 weeks after transplan-
tation (PBS, n=7; transplantation, n=7). Also, to study
endogenous cell proliferation after transplantation, rats from
each group were sacriﬁced at 2 h and 1 week after the last
BrdU injection (n=5). All the rats were deeply anesthetized
with a ketamine-xylazine cocktail (80 mg/kg of ketamine,
10 mg/kg of xylazine) and then perfused transcardially with
0.01 M PBS (pH 7.4), followed by 4% paraformaldehyde
(PFA) in 0.01M PBS. The spinal cord was removed from
each rat and postﬁxed in 4% PFA for 4 hours. Postﬁxed
tissue was cryoprotected in 0.1 M phosphate buﬀer (pH 7.4)
containing 15% and 30% sucrose solution at 4◦C. The spinal
−70◦C. To examine the cavity volume, 14 µm thick serial
transverse sections were prepared from 20 mm long spinal
cord stumps (1 mm each for rostral and caudal to the lesion
epicenter). Also, to compare the coexpression of various cell-
type-speciﬁc markers and BrdU+cells, 10 µm thick serial
coronal sections were prepared as described above. Coronal
sections were collected from cell transplantation site to the
injury epicenter sites and mounted on gelatin-coated slides.
2.7. Histology and Immunohistoﬂuorescence. Single and dou-
ble ﬂuorescent staining was used. Single staining was used
to identify newly generated cells after transplantation. For
BrdU immunohistochemistry, the sections were warmed for
20 min and washed with 0.01 M PBS for 10 min. Sections
were incubated in 50% formamide-2X standard saline citrate
at 60◦C for 2 h, subsequently treated with 2 N HCL at 37◦C
for 30 min to denature deoxyribonucleic acid, and then
incubated in 0.1 mol/L boric acid at room temperature for
10 min to neutralize residual acid. The sections were incu-
bated with rat anti-BrdU (1 : 100; Abcam, Cambridge, UK)
or mouse anti-BrdU (1 : 100; DakoCytomation, Glostrup,
Denmark). Subsequently, sections were incubated for 1 h at
room temperature with ﬂuorescence-conjugated secondary
antibody or biotinylated antibody; the latter was reacted
with avidin peroxidase for 30 min (ABC-kit; Vectastain
Elite; Vector Laboratories, Burlingame, CA) followed by
detection solution (0.25 mg/mL diaminobenzidine, 0.03%
H2O2, 0.04% NiCl).
To determine the fate of newly generated cells after trans-
plantation, double-ﬂuorescent immunolabeling was per-
formed, combining BrdU labeling with one of cell-speciﬁc
phenotypic markers listed below. We used mouse anti-Nestin
(1 : 100; Millipore, Billerica, MA) to identify neural stem
progenitor; mouse anti-NG-2 chondroitin sulfate proteo-
glycan (anti-NG-2; 1 : 100; Millipore) to identify oligoden-
drocyte progenitor; mouse anti-2,3-cyclic nucleotide 3-
phosphodiesterase (anti-CNPase; 1 : 100; Millipore), mouse
antimyelin basic protein (anti-MBP, 1 : 100; Millipore), rab-
bit anti-glial ﬁbrillar y acidic protein (anti-GFAP; 1 : 500;
Millipore) to identify astrocytes. After washing, samples
were incubated in Alexa 488-conjugated goat anti-rat IgG
(1 : 200; Vector Laboratories), Alexa 546-conjugated goat
anti-mouse IgG (1 : 200; Vector Laboratories), or Alexa 546-
conjugated goat anti-rabbit IgG (1 : 200; Vector Laboratories)
for 1 h. Fluorescently stained slides were stored at −20◦C
and observed using a ﬂuorescence microscope equipped
with a spot digital camera or a model LSM 510 confocal
scanning laser microscope (Zeiss, Jena, Gemany). Apoptosis
was detected by the terminal deoxynucleotidyl-transferase-
mediated d-UTP-biotin nick end (TUNEL) assay using the
in situ cell death detection kit (Roche, Indianapolis, IN)
developed using the Cy2-conjugated streptavidin (Jackson
Laboratories, West Grove, PA). The slides were observed
using the aforementioned confocal scanning laser micro-
2.8. Cell Counts. The counting of BrdU+cells was done by
previously described . BrdU+cells were counted within
a reticule of a speciﬁed area (0.0682 mm2) positioned in
the ependymal and parenchymal region (dorsal (above the
corticospinal tract), lateral, and ventromedial region of the
residual white matter) in sections. White matter regions were
counted in six randomly chosen sections per 1 mm2length of
spinal cord, and the numbers were averaged.
2.9. Measurement of the Cavity Volume. For measurement of
the cavity volume, rats at 6 weeks after transplantation were
used. The transverse sections were stained with hematoxylin-
eosin (HE). The area of the cavity in the damaged spinal
cord was measured in images of the sections using ImageJ
version 1.38 image analyzer software (National Institutes of
Health, Bethesda, MD) on consecutive sections at an interval
of 70 µm. The volume of the cavity was then calculated by
multiplying the average area by the depth of the spinal cord.
2.10. Statistical Analysis. The BBB score and cell counts
were subjected to the paired t-test or one-way ANOVA for
transplantation and PBS-treated groups of rats. Data are
presented as mean ±SE. Value of P<0.05 was considered
3.1. Behavioral Assessment and Measurement of the Cavity
Volume. We assessed the recovery of hindlimb function with
the BBB locomotor scale from 1 day to 6 weeks after SCI. In
the case of SCI rats, BBB scores were low (<9). The motor
function scores of MSCs-injected rats (11.07 ±0.3) were
signiﬁcantly higher than the PBS-injected rats (9.25 ±0.3)
at 7 weeks after SCI. The behavioral data from the BBB
locomotor scores demonstrated that MSCs-treated rats were
dramatically improved in neurological function (P<0.005,
Figure 1). In addition, the spinal cords of MSCs-injected rats
had cavities much smaller than those of the PBS-injected rats.
The cavity volume of MSCs-treated rat was 0.82 ±0.14 mm3
on average, whereas the PBS-treated rats showed a volume
of 2.12 ±0.28 mm3. These results for cavity volume were
signiﬁcantly diﬀerent between the MSCs-treated and PBS-
treated rats. Thus, MSC transplantation led to a signiﬁcant
improvement of behavior as well as reduction of cavity
volume after SCI.
3.2. Proliferation of Endogenous Generated Cells. MSCs pro-
moted the functional recovery and reduced the cavity volume
following transplantation in SCI (Figure 1). Since an eﬀect
4Journal of Biomedicine and Biotechnology
Days after trauma
Cavity volume (mm3)
1 7 14 21 28 35 42 49 56
Figure 1: BBB scores of rats with SCI before and after hUCB-MSCs transplantation at 7 days after SCI. (a) hUCB-MSC transplantation group
displayed signiﬁcantly improved scores compared with control at 6 weeks after transplantation. (b) Cavity volume between the hUCB-MSC
and control groups at 6 weeks after transplantation. The values of the cavity volume of the hUCB-MSC group were lower than those of the
control group. (c) and (d) HE-stained sections of transplantation group and control group, P<0.05.
Ependymal region Parenchymal region
Number of BrdU +cells/0.0682 mm2
Number of BrdU +cells/0.0682 mm2
Figure 2: Quantitative analysis of BrdU-labeled cells in the ependymal and parenchymal regions. (a) Result of immunohistochemistry using
anti-BrdU antibody. (b) Enlargement of the boxed region in (a), showing BrdU-labeled cells in the parenchymal region. (c) Average number
of BrdU-labeled cells per white matter area from all ﬁve white matter areas in the parenchymal region. (d) Average number of BrdU-labeled
cells per ependymal region in grey matter. At 14 days after transplantation, proliferation of endogenous cells was signiﬁcantly increased from
injury site to cell transplantation site in hUCB-MSCs-transplanted group compared with control group, ∗P<0.05.
of hUCB-MSCs was evident, we investigated whether newly
generated cells were enhanced by the transplanted cells .
It has been suggested that oligogenesis byendogenous
OPCs and survival of these cells can contribute to self-repair
after myelin loss . With the thought that these processes
might be stimulated recovery to CNS injury, an experiment
was done to investigate the proliferation endogenous gen-
erated cells by daily injection of BrdU during the 7 days
after transplantation. BrdU-positive cells were counted in the
ependymal and parenchymal regions (Figures 2(a) and 2(b))
as previously described [23,25]. Proliferation of the newly
generated cells increased greatly in hUCB-MSCs-treated rats
Journal of Biomedicine and Biotechnology 5
Nestin+/ BrdU+cells/0.0682 mm2
GFAP+/ BrdU+cells/0.0682 mm 2
Ependymal region Parenchymal region
PBS hUCB-MSCs PBS hUCB-MSCs
(i) (j) (k)
NG2+/ BrdU +cells/0.0682 mm2
Figure 3: Endogenous neurogenesis induced by transplantation. Endogenous stem cells were assessed quantitatively by double staining of
BrdU with nestin, GFAP, and NG2 at 1 and 2 weeks after transplantation in both the ependymal and parenchymal regions. (a)–(d) At 1
and 2 weeks following transplantation, BrdU/nestin-labeled cells as well as BrdU/GFAP-labeled astrocytes were present in ependyma. (e)
and (h) BrdU-labeled NG2 cells were coexpressed at 1 and 2 weeks in the parenchyma. (i) and (j) The numbers of BrdU-labeled ependyma
coexpressing GFAP/nestin were quantiﬁed at 1 and 2 weeks after transplantation. (k) The numbers of BrdU-labeled parenchyma coexpressing
NG2 were quantiﬁed at 1 and 2 weeks after transplantation. ∗P<0.05, scale bars =10 µmin(a)–(d);20µmin(e)–(h).
as compared with PBS-treated rats (Figure 2(c)). This data
demonstrated that hUCB-MSCs could enhance proliferation
of endogenous cells within the spinal cord.
3.3. Characterization of Endogenous Stem Cells. Functional
recovery in response to therapeutic grafting of stem cells
after SCI is related to the diﬀerentiation of grafted cells
into glial cells, including astrocytes or oligodendrocytes .
Appropriately, an experiment was done to examine if the
transplantation of MSCs could enhance the diﬀerentiation
of endogenous OPCs into astrocytes or oligodendrocytes
by performing immunostaining for BrdU and several phe-
notype markers including diﬀerentiating oligodencrocyte
markers NG2, CNPase, the mature oligodendrocyte marker
6Journal of Biomedicine and Biotechnology
CNPase/BrdU MBP/BrdU GFAP/BrdU
Number of BrdU+cells/0.0682 mm2
Figure 4: Quantitative analysis of endogenous oligogenesis by hUCB-MSCs. At 2 weeks after cell transplantation, BrdU and cell-speciﬁc
markers were observed up to the edge of the SCI region. (a) and (b) BrdU/CNPase-labeled cells were present. (c) and (d) BrdU/MBP-labeled
cells. (e) and (f) BrdU/GFAP-labeled cells. (g) Quantity of BrdU/CNPase, MBP, and GFAP-labeled cells. ∗P<0.05. Scale bars: 10 µm.
MBP, GFAP typical of astrocytes, and the neural stem cell
marker nestin. Cells in the ependymal and parenchymal
region were counted in sections from the injury epicenter
to cell transplantation site. One and 2 weeks after cell
transplantation, the numbers of BrdU positive cells were sig-
niﬁcantly increased compared with the PBS group (Figure 3).
In the ependymal region, BrdU-labeled nestin and GFAP
cells were increased compared with the PBS group at 1
and 2 weeks (Figure 3). The numbers of BrdU-labeled NG2
positive cells were also signiﬁcantly increased compared with
the PBS group in the parenchymal region (Figure 3). Also,
BrdU-labeled cells displaying strong immunoreactivities for
CNPase, MBP, or GFAP in the cell transplantation group
were evident. But these immunoreactivities were weak for
those rats treated with PBS (Figure 4). These data sug-
gest that hUCB-MSCs are an inﬂuential microenvironment
within the spinal cord.
3.4. Apoptotic Phenomena of Endogenous Cells. To investigate
whether transplantation of MSCs have a protected injured
spinal cord cells from apoptosis, a TUNEL assay was per-
formed on sections obtained from the injury site on 2 weeks
after transplantation. Numerous TUNEL-positive (green)
cells were observed at the injury site in PBS-treated rats.
The number of TUNEL positive cells was signiﬁcantly lower
in MSC-treated rats than in PBS-treated rats (Figure 5(b)).
Taken together, these results indicate that hUCB-MSCs
not only promote oligogenesis in the spinal cord but also
have a neuroprotective eﬀect relative with cavity volume
In this study, hUCB-MSCs that were transplanted after SCI
survived in and around the injured site and were able to
ameliorate some of the behavior eﬀects of SCI, as measured
by spontaneous limb movement in an open-ﬁeld test, hind
limb extension, and toe spread. In addition, the cavities
of MSC-treated rats were much smaller than PBS-injected
rats. Cavity formation is a characteristic of progressive tissue
necrosis, which follows the initial primary cell destruction in
SCI. Therefore, reduction of the cavity volume means that
transplanted MSCs after SCI have a neuroprotective eﬀect.
The presently indicated therapeutic eﬀect of hUCB-MSCs in
SCIagreeswithpreviousdata, but the exact mechanisms
to improve the functional deﬁcits remain to be elucidated.
A prior study showed that transplanted cells ameliorated
the functional recovery through the integration into spinal
cord tissue and establishment of some connections within
the injured area of the spinal cord . However, the
transplantation of hUCB-MSCs could not solely account
for functional recovery after SCI. Other possibility may
be various beneﬁcial actions of endogenous neurogenesis
or oligogenesis within the adult spinal cord which is
largely mediated via trophic inﬂuences. Previous studies
have indicated that MSCs could produce trophic factors,
cytokines, and other neuroprotective factors in stroke or
traumatic brain injury [28,29]. These factors and cytokines
can then promote the regrowth of interrupted nerve ﬁber
tract. BMS cells secrete more than 20 cytokines in vitro,
and hUCB-MSCs can secrete a number of cytokines and
Journal of Biomedicine and Biotechnology 7
TUNEL positive cell
(c) (d) (e)
Figure 5: Protection of apoptosis by hUCB-MSCs as revealed by TUNEL assay in the injury site at 2 weeks after transplantation. (a)–(d)
TUNEL staining (green) and staining with 4,6-diamidino-2-phenylindole (blue) indicate undergoing apoptotic cell death. (e) Quantity of
TUNEL positive cells. The number of TUNEL positive cells was signiﬁcantly reduced in cell transplantation group than in control group.
∗P<0.05, scale bars denote: 10 µm.
chemokines . Therefore, these factors and some of the
other cytokines secreted by hUCB-MSCs may function as
survival and diﬀerentiation factors for neural progenitor cells
and then play an important role in the proliferation and
diﬀerentiation of neural tissue and in the increase of central
nerve system plasticity [31,32].
To understand whether the transplanted hUCB-MSCs
are capable of restoring the production of endogenous cells,
we studied the mechanisms that contributed to functional
recovery by determining the endogenous cell proliferation
and diﬀerentiation into glial cells following transplantation.
Compared to the control group, transplanted cells increased
endogenous cell division within the SCI area and a subpop-
ulation of newly dividing cells. Also, in the received, the
transplanted cells, immature and mature oligodendrocytes,
and astrocytes were stimulated. These observations support
the possibility that factors produced by hUCB-MSCs activate
nearby oligogenesis, and that activation of the astrocytes
increases in oligogenesis, since astrocytes are located in close
proximity to neural stem cells and express several factors that
independently increase oligogenesis. In addition, some of
transplanted cells were BrdU-positive cell. It has been shown
that transplanted cells might proliferate in the spinal cord.
But, these cells are not diﬀerentiated neural lineage markers.
In agreement with the present ﬁndings, a previous study
reported not only extensive oligogenesis of newly born cells
after SCI but also that MSCs promote oligogenesis in neural
stem cells in vitro [24,33].
Presently, the majority of hUCB-MSCs progressed to
apoptotic cell death. However, MSC-treated rats displayed
markedly reduced apoptotic cell death in the injured site.
These results suggest that functional recovery might result in
endogenous oligogenesis and neuroprotection stimulated by
trophic factors secreted into transplanted cells.
The collective results support the view that hUCB-MSCs
transplantation is beneﬁcial in SCI by virtue of their growth
factor secretion and ability to provide physical support to
growing axons. Further studies are needed to conﬁrm that
the beneﬁt obtained from hUCB-MSCs persists at later time
points and/or to improve the eﬃcacy of the transplanted
hUCB-MCSs. Also, the mechanisms underlying functional
recovery after transplantation of hUCB-MSCs remain to be
We have shown that stem cell therapy of hUCB-MSCs
may provide more of functional recovery in spinal cord
injury such as reduction of cavity volume, increasing of cell
proliferation and endogenous oligogenesis, and decreasing of
apoptosis. Therefore, the author suggests that promotion of
oligogenesis by hUCB-MSCs may provide a scientiﬁc basis
for the potential use of these cells as a therapeutic tool for the
treatment of other disease.
Conﬂict of Interests
The authors declare that there is no conﬂict of interests.
This study was supported by the Basic Science Research
program through the National Research Foundation of Korea
(NRF) funded by the Ministry of Education, Science and
Technology (2010–0022845), Republic of Korea. This study
was supported by a grant of the Korea Healthcare technology
R&D Project, Ministry of Health, Welfare& Family Aﬀairs,
Republic of Korea (A092258).
8Journal of Biomedicine and Biotechnology
 M. P. Kurnellas, A. Nicot, G. E. Shull, and S. Elkabes,
“Plasma membrane calcium ATPase deﬁciency causes neu-
ronal pathology in the spinal cord: a potential mechanism
for neurodegeneration in multiple sclerosis and spinal cord
injury,” FASEB Journal, vol. 19, no. 2, pp. 298–300, 2005.
nation after spinal cord injury,” Journal of Neurotrauma, vol.
23, no. 3-4, pp. 345–359, 2006.
 L. J. Rosenberg and J. R. Wrathall, “Quantitative analysis of
acute axonal pathology in experimental spinal cord contu-
sion,” JournalofNeurotrauma, vol. 14, no. 11, pp. 823–838,
 L. Brundin, H. Brismar, A. I. Danilov, T. Olsson, and C. B.
Johansson, “Neural stem cells: a potential source for remyeli-
nation in neuroinﬂammatory disease,” Brain Pathology, vol.
13, no. 3, pp. 322–328, 2003.
 G. Martino and S. Pluchino, “The therapeutic potential of
neural stem cells,” Nature Reviews Neuroscience, vol. 7, no. 5,
pp. 395–406, 2006.
 O. Lindvall and Z. Kokaia, “Stem cells for the treatment of
neurological disorders,” Nature, vol. 441, no. 7097, pp. 1094–
 S. Kabatas and Y. D. Teng, “Potential roles of the neural stem
cell in the restoration of the injured spinal cord: review of the
literature,” Turkish Neurosurgery, vol. 20, no. 2, pp. 103–110,
 T. L. Ben-Shaanan, T. Ben-Hur, and J. Yanai, “Transplantation
of neural progenitors enhances production of endogenous
cells in the impaired brain,” Molecular Psychiatry, vol. 13, no.
2, pp. 222–231, 2008.
 M. F. Pittenger, A. M. Mackay, S. C. Beck et al., “Multilineage
potential of adult human mesenchymal stem cells,” Science,
vol. 284, no. 5411, pp. 143–147, 1999.
 Y. Ogawa, K. Sawamoto, T. Miyata et al., “Transplantation of
in vitro-expanded fetal neural progenitor cells results in neu-
rogenesis and functional recovery after spinal cord contusion
injury in adult rats,” Journal of Neuroscience Research, vol. 69,
no. 6, pp. 925–933, 2002.
 Y. I. Tarasenko, J. Gao, L. Nie et al., “Human fetal neural stem
cells grafted into contusion-injured rat spinal cords improve
behavior,” Journal of Neuroscience Research, vol. 85, no. 1, pp.
 S. E. Yang, C. W. Ha, M. H. Jung et al., “Mesenchymal
stem/progenitor cells developed in cultures from UC blood,”
Cytotherapy, vol. 6, no. 5, pp. 476–486, 2004.
 P. R. Sanberg, A. E. Willing, S. Garbuzova-Davis et al.,
“Umbilical cord blood-derived stem cells and brain repair,”
Annals of the New York Academy of Sciences, vol. 1049, pp. 67–
 J. R. Pineda, N. Rubio, P. Akerud et al., “Neuroprotection by
GDNF-secreting stem cells in a Huntington’s disease model:
optical neuroimage tracking of brain-grafted cells,” Gene
Therapy, vol. 14, no. 2, pp. 118–128, 2007.
 J. Chen, Y. Li, M. Katakowski et al., “Intravenous bone
marrow stromal cell therapy reduces apoptosis and promotes
endogenous cell proliferation after stroke in female rat,”
Journal of Neuroscience Research, vol. 73, no. 6, pp. 778–786,
 K. C. Wollert and H. Drexler, “Clinical applications of stem
cells for the heart,” Circulation Research, vol. 96, no. 2, pp. 151–
 P. J. Horner and F. H. Gage, “Regenerating the damaged
central nervous system,” Nature, vol. 407, no. 6807, pp. 963–
 B. H. Dobkin and L. A. Havton, “Basic advances and new
avenues in therapy of spinal cord injury,” Annual Re view of
Medicine, vol. 55, pp. 255–282, 2004.
 D. M. Basso, M. S. Beattie, and J. C. Bresnahan, “Graded
histological and locomotor outcomes after spinal cord contu-
sion using the NYU weight-drop device versus transection,”
Experimental Neurology, vol. 139, no. 2, pp. 244–256, 1996.
 D. M. Basso, M. S. Beattie, and J. C. Bresnahan, “A sensitive
and reliable locomotor rating scale for open ﬁeld testing in
rats,” Journal of Neurotrauma, vol. 12, no. 1, pp. 1–21, 1995.
 L. J. Zai and J. R. Wrathall, “Cell proliferation and replacement
following contusive spinal cord injury,” Glia,vol.50,no.3,pp.
 S. W. Yoo, S. S. Kim, S. Y. Lee et al., “Mesenchymal stem cells
promote proliferation of endogenous neural stem cells and
survival of newborn cells in a rat stroke model,” Experimental
and Molecular Medicine, vol. 40, no. 4, pp. 387–397, 2008.
 L. J. Rosenberg, L. J. Zai, and J. R. Wrathall, “Chronic
alterations in the cellular composition of spinal cord white
matter following contusion injury,” Glia,vol.49,no.1,pp.
 H. Yang, P. Lu, H. M. McKay et al., “Endogenous neurogenesis
replaces oligodendrocytes and astrocytes after primate spinal
cord injury,” Journal of Neuroscience, vol. 26, no. 8, pp. 2157–
 L. J. Zai, S. Yoo, and J. R. Wrathall, “Increased growth factor
expression and cell proliferation after contusive spinal cord
injury,” Brain Research, vol. 1052, no. 2, pp. 147–155, 2005.
 C. P. Hofstetter, E. J. Schwarz, D. Hess et al., “Marrow stromal
cells form guiding strands in the injured spinal cord and
promote recovery,” Proceedings of the National Academy of
Sciences of the United States of America, vol. 99, no. 4, pp. 2199–
 Z. M. Zhao, H. J. Li, H. Y. Liu et al., “Intraspinal transplanta-
tion of CD34+ human umbilical cord blood cells after spinal
cord hemisection injury improves functional recovery in adult
rats,” Cell Transplantation, vol. 13, no. 2, pp. 113–122, 2004.
marrow promote neurogenesis of endogenous neural stem
cells in the hippocampus of mice,” Proceedings of the National
Academy of Sciences of the United States of America, vol. 102,
no. 50, pp. 18171–18176, 2005.
 R. McKay, “Stem cells in the central nervous system,” Science,
vol. 276, no. 5309, pp. 66–71, 1997.
and P. R. Sanberg, “Cytokines produced by cultured human
umbilical cord blood (HUCB) cells: implications for brain
repair,” Experimental Neurology, vol. 199, no. 1, pp. 201–208,
 A. Erices, P. Conget, and J. J. Minguell, “Mesenchymal
progenitor cells in human umbilical cord blood,” British
Journal of Haematology, vol. 109, no. 1, pp. 235–242, 2000.
 Y. Li, J. Chen, X. G. Chen et al., “Human marrow stromal
cell therapy for stroke in rat: neurotrophins and functional
recovery,” Neurology, vol. 59, no. 4, pp. 514–523, 2002.
 Q. M. Li, Y. M. Fu, Z. Y. Shan et al., “MSCs guide neurite
directional extension and promote oligodendrogenesis in
NSCs,” Biochemical and Biophysical Research Communications,
vol. 384, no. 3, pp. 372–377, 2009.