[Show abstract][Hide abstract] ABSTRACT: The understanding of structure-function relationships in normal and pathologic mammalian tissues is at the basis of a tissue engineering (TE) approach for the development of biological substitutes to restore or improve tissue function. In this framework, it is interesting to investigate engineered bone tissue, formed when porous ceramic constructs are loaded with bone marrow stromal cells (BMSC) and implanted in vivo. To monitor the relation between bone formation and vascularization, it is important to achieve a detailed imaging and a quantitative description of the complete three-dimensional vascular network in such constructs. Here, we used synchrotron X-ray phase-contrast micro-tomography to visualize and analyze the three-dimensional micro-vascular networks in bone-engineered constructs, in an ectopic bone formation mouse-model. We compared samples seeded and not seeded with BMSC, as well as samples differently stained or unstained. Thanks to the high quality of the images, we investigated the 3D distribution of both vessels and collagen matrix and we obtained quantitative information for all different samples. We propose our approach as a tool for quantitative studies of angiogenesis in TE and for any pre-clinical investigation where a quantitative analysis of the vascular network is required.
Frontiers in Bioengineering and Biotechnology 10/2015; 3(133). DOI:10.3389/fbioe.2015.00133
[Show abstract][Hide abstract] ABSTRACT: A deeper comprehension of the biomineralization (BM) process is at the basis of tissue engineering and regenerative medicine developments. Several in-vivo and in-vitro studies were dedicated to this purpose via the application of 2D and 3D diagnostic techniques. Here, we develop a new methodology, based on different complementary experimental techniques (X-ray phase contrast tomography, micro-X-ray diffraction and micro-X-ray fluorescence scanning technique) coupled to new analytical tools. A qualitative and quantitative structural investigation, from the atomic to the micrometric length scale, is obtained for engineered bone tissues. The high spatial resolution achieved by X-ray scanning techniques allows us to monitor the bone formation at the first-formed mineral deposit at the organic–mineral interface within a porous scaffold. This work aims at providing a full comprehension of the morphology and functionality of the biomineralization process, which is of key importance for developing new drugs for preventing and healing bone diseases and for the development of bio-inspired materials.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 07/2015; DOI:10.1016/j.nimb.2015.06.023 · 1.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Mice Drawer System (MDS) Tissue Sharing program was the longest rodent space mission ever performed. It provided 20 research teams with organs and tissues collected from mice having spent 3 months on the International Space Station (ISS). Our participation to this experiment aimed at investigating the impact of such prolonged exposure to extreme space conditions on mouse skin physiology.Methods:Mice were maintained in the MDS for 91 days aboard ISS (space group (S)). Skin specimens were collected shortly after landing for morphometric, biochemical, and transcriptomic analyses. An exact replicate of the experiment in the MDS was performed on ground (ground group (G)).Results:A significant reduction of dermal thickness (−15%, P=0.05) was observed in S mice accompanied by an increased newly synthetized procollagen (+42%, P=0.03), likely reflecting an increased collagen turnover. Transcriptomic data suggested that the dermal atrophy might be related to an early degradation of defective newly formed procollagen molecules. Interestingly, numerous hair follicles in growing anagen phase were observed in the three S mice, validated by a high expression of specific hair follicles genes, while only one mouse in the G controls showed growing hairs. By microarray analysis of whole thickness skin, we observed a significant modulation of 434 genes in S versus G mice. A large proportion of the upregulated transcripts encoded proteins related to striated muscle homeostasis.Conclusions:These data suggest that a prolonged exposure to space conditions may induce skin atrophy, deregulate hair follicle cycle, and markedly affect the transcriptomic repertoire of the cutaneous striated muscle panniculus carnosus.
[Show abstract][Hide abstract] ABSTRACT: Umbilical Cord Mesenchymal Stem Cells (UC-MSC) show properties similar to Bone Marrow Mesenchymal Stem Cells (BM-MSC), though controversial data exists regarding their osteogenic potential. We prepared clinical-grade UC-MSC from Wharton's Jelly and we investigated if UC-MSC could be used as substitutes for BM-MSC in muscoloskeletal regeneration as a more readily available and functional source of MSCs. UC-MSC were loaded onto scaffolds and implanted subcutaneously (ectopically) and in critical-size calvarial defects (orthotopically) in mice. For live cell-tracking experiments, UC-MSC were first transduced with the luciferase gene. Angiogenic properties of UC-MSC were tested using the mouse metatarsal angiogenesis assay. Cell secretomes were screened for the presence of various cytokines using an array assay. Analysis of implanted scaffolds showed that UC-MSC, contrary to BM-MSC, remained detectable in the implants for 3 weeks at most and did not induce bone formation in an ectopic location. Instead, they induced a significant increase of blood vessel ingrowth. In agreement with these observations, UC-MSC conditioned medium presented a distinct and stronger pro-inflammatory/chemotactic cytokine profile than BM-MSC and a significantly enhanced angiogenic activity. When UC-MSC were orthotopically transplanted in a calvarial defect, they promoted increased bone formation as well as BM-MSC. However, at variance with BM-MSC, the new bone was deposited through the activity of stimulated host cells highlighting the importance of the microenvironment on determining cell commitment and response. Therefore, we propose, as therapy for bone lesions, the use of allogeneic UC-MSC not depositing directly bone matrix, but acting through the activation of endogenous repair mechanisms.
Stem Cells and Development 02/2015; 24(13). DOI:10.1089/scd.2014.0490 · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Metformin is a widely used oral hypoglycemizing agent recently proposed as potential anti-cancer drug. In this study we report the antiproliferative effect of metformin treatment in a high risk neuroblastoma cell model, focusing on possible effects associated to different levels of differentiation and/or tumor initiating potential.
Antiproliferative and cytotoxic effects of metformin were tested in human SKNBE2 and SH-SY5Y neuroblastoma cell lines and in SKNBE2 cells in which differentiation is induced by retinoic acid treatment or stable overexpression of NDM29 non-coding RNA, both conditions characterized by a neuron-like differentiated phenotype.
We found that metformin significantly inhibits the proliferation of NB cells, an effect that correlates with the inhibition of Akt, while AMPK activity resulted unchanged. Notably, metformin effects were modulated in a different ways by differentiating stimuli, being abolished after retinoic acid treatment but potentiated by overexpression of NDM29.
These data suggest the efficacy of metformin as neuroblastoma anticancer agent, and support the requirement of further studies on the possible role of the differentiation status on the antiproliferative effects of this drug.
Cancer Cell International 07/2014; 14:59. DOI:10.1186/1475-2867-14-59 · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The therapeutic use of stem cells is a very promising strategy in the area of regenerative medicine. The stem cell regenerative paradigm has been mostly based on the assumption that progenitor cells play a critical role in tissue repair by their plasticity and differentiation potential. However, recent works suggest that the mechanism underlying the benefits of stem cell transplantation might relate to a paracrine modulatory effect rather than the replacement of affected cells at the site of injury. Preclinical and clinical skeletal studies, conducted in animal and adult series, support the use of mesenchymal stem cells (MSCs) for bone healing in critical clinical situations. These results have led to an increasing number of papers reporting the use of MSCs in adult clinical trials, whereas only few papers reported the use of these cells in pediatric skeletal disorders, probably because of unknown long-term results and long-life consequences of cellular therapy. The exponential growth of knowledge in adult MSCs could be translated and applied to pediatric disorders. Pediatric osteoarticular diseases have an enormous potential to be treated by MSCs, as severe congenital bone or local cartilage defects, not responding to conventional surgery treatment, might be successfully treated by cellular therapy. Translating basic stem cell research into routine therapies is a complex multistep process which entails the managing of the expected therapeutic benefits with the potential risks in correlation within the existing regulations. Here, we reported the state of art on the use of MSC in skeletal pediatric disorders.
European Journal of Pediatric Surgery 06/2014; 24(03). DOI:10.1055/s-0034-1382777 · 0.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Wound healing is achieved through distinct programmed phases: hemostasis, inflammation, mesenchymal cell proliferation and migration, and tissue remodeling. At the injury site, clot formation and platelet degranulation release cytokines, growth factors and actively participating in the healing process and regulating the migration of inflammatory cells, such as neutrophils, macrophages, and lymphocytes. We previously demonstrated that, in an inflammatory environment, PGE2 secreted by mesenchymal stem cells (MSCs) promoted the macrophage switch from a pro-inflammatory to a pro-resolving phenotype. Using an in vitro model, we here evaluated the role carried out by the two main players of the wound healing process, the platelet degranulation content mimicked by the platelet lysate (PL) and the inflammatory stimulus, on the modulation of mouse bone marrow-derived MSC paracrine activity. We demonstrated that, in MSCs, PL induced NF-kB activation, expression of COX-2, mPGE synthase and PGE2 production; in an inflammatory microenvironment, PL increased the inflammatory response and promoted the secretion of the pro-inflammatory cytokine IL-6. We assayed on mouse primary macrophages the paracrine activity of MSCs exposed to the different microenvironments and we observed that PL-treated MSC conditioned medium maintained macrophages in a pro-inflammatory state. The involved factors were GM-CSF induced by PL in MSCs and TNF-α induced by PL-MSC conditioned medium in macrophages. Our findings indicate that PL triggers an inflammatory response in MSCs and induces the secretion of factors maintaining macrophages in a pro-inflammatory state thus enhancing the initial inflammatory response to the injury, a key element in the activation of wound healing.
Stem cells and development 04/2014; 23(16). DOI:10.1089/scd.2013.0567 · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effects of 3 months of spaceflight (SF), hindlimb suspension, or exposure to 2G on the characteristics of neck muscle in mice were studied. Three 8-week-old male C57BL/10J wild-type mice were exposed to microgravity on the International Space Station in mouse drawer system (MDS) project, although only one mouse returned to the Earth alive. Housing of mice in a small MDS cage (11.6 × 9.8-cm and 8.4-cm height) and/or in a regular vivarium cage was also performed as the ground controls. Furthermore, ground-based hindlimb suspension and 2G exposure by using animal centrifuge (n = 5 each group) were performed. SF-related shift of fiber phenotype from type I to II and atrophy of type I fibers were noted. Shift of fiber phenotype was related to downregulation of mitochondrial proteins and upregulation of glycolytic proteins, suggesting a shift from oxidative to glycolytic metabolism. The responses of proteins related to calcium handling, myofibrillar structure, and heat stress were also closely related to the shift of muscular properties toward fast-twitch type. Surprisingly, responses of proteins to 2G exposure and hindlimb suspension were similar to SF, although the shift of fiber types and atrophy were not statistically significant. These phenomena may be related to the behavior of mice that the relaxed posture without lifting their head up was maintained after about 2 weeks. It was suggested that inhibition of normal muscular activities associated with gravitational unloading causes significant changes in the protein expression related to metabolic and/or morphological properties in mouse neck muscle.
[Show abstract][Hide abstract] ABSTRACT: Computed x-ray phase contrast micro-tomography is the most valuable tool for a three dimensional (3D) and non destructive analysis of the tissue engineered bone morphology. We used a Talbot interferometer installed at SYRMEP beamline of the ELETTRA synchrotron (Trieste, Italy) for a precise 3D reconstruction of both bone and soft connective tissue, regenerated in vivo within a porous scaffold. For the first time the x-ray tomographic reconstructions have been combined with x-ray scanning micro-diffraction measurement on the same sample, in order to give an exhaustive identification of the different tissues participating to the biomineralization process. As a result, we were able to investigate in detail the different densities in the tissues, distinguishing the 3D organization of the amorphous calcium phosphate from the collagen matrix. Our experimental approach allows for a deeper understanding of the role of collagen matrix in the organic-mineral transition, which is a crucial issue for the development of new bio-inspired composites.
Physics in Medicine and Biology 01/2014; 59(1):189-201. DOI:10.1088/0031-9155/59/1/189 · 2.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX(®)) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12-16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX(®)) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.
Frontiers in Bioengineering and Biotechnology 01/2014; 2:80. DOI:10.3389/fbioe.2014.00080
Scaffolds for Tissue Engineering Biological Design, Materials, and Fabrication, Edited by Claudio Migliaresi and Antonella Motta, 01/2014: chapter Chapter 4. Principles and Biological Pathways to Tissue Regeneration: The Tissue Regenerative Niche: pages Pages 79–114; Pan Stanford Publishing., ISBN: 978-981-4463-21-8
[Show abstract][Hide abstract] ABSTRACT: We monitored bone regeneration in a tissue engineering approach. To visualize and understand the structural evolution, the samples have been measured by X-ray micro-diffraction. We find that bone tissue regeneration proceeds through a multi-step mechanism, each step providing a specific diffraction signal. The large amount of data have been classified according to their structure and associated to the process they came from combining Neural Networks algorithms with least square pattern analysis. In this way, we obtain spatial maps of the different components of the tissues visualizing the complex kinetic at the base of the bone regeneration.
[Show abstract][Hide abstract] ABSTRACT: For a long time, the stem cell regenerative paradigm has been based on the assumption that progenitor cells play a critical role in tissue repair by means of their plasticity and differentiation potential. However, recent works suggest that the mechanism underlying the benefits of stem cell transplantation might relate to a paracrine modulatory effect rather than the replacement of affected cells at the site of injury. Therefore, mounting evidence that stem cells may act as a reservoir of trophic signals released to modulate the surrounding tissue has led to a paradigm shift in regenerative medicine. Attention has been shifted from analysis of the stem cell genome to understanding the stem cell "secretome", which is represented by the growth factors, cytokines and chemokines produced through paracrine secretion. Insights into paracrine-mediated repair support a new approach in regenerative medicine and the isolation and administration of specific stem cell-derived paracrine factors may represent an extremely promising strategy, introducing paracrine-based therapy as a novel and feasible clinical application. In this review, we will discuss the regenerative potential of fetal and adult stem cells, with particular attention to their secretome.
Journal of Clinical Medicine 12/2013; 2(4):302-327. DOI:10.3390/jcm2040302