The cell culture expansion of bone marrow stromal cells from humans with spinal cord injury: implications for future cell transplantation therapy

An In Vitro Comparison of the Neurotrophic and Angiogenic Activity of Human and Canine Adipose-Derived Mesenchymal Stem Cells (MSCs): Translating MSC-Based Therapies for Spinal Cord Injury

The majority of research into the effects of mesenchymal stem cell (MSC) transplants on spinal cord injury (SCI) is performed in rodent models, which may help inform on mechanisms of action, but does not represent the scale and wound heterogeneity seen in human SCI. In contrast, SCI in dogs occurs naturally, is more akin to human SCI, and can be used to help address important aspects of the development of human MSC-based therapies. To enable translation to the clinic and comparison across species, we have examined the paracrine, regenerative capacity of human and canine adipose-derived MSCs in vitro. MSCs were initially phenotyped according to tissue culture plastic adherence, cluster of differentiation (CD) immunoprofiling and tri-lineage differentiation potential. Conditioned medium (CM) from MSC cultures was then assessed for its neurotrophic and angiogenic activity using established cell-based assays. MSC CM significantly increased neuronal cell proliferation, neurite outgrowth, and βIII tubulin immunopositivity. In addition, MSC CM significantly increased endothelial cell migration, cell proliferation and the formation of tubule-like structures in Matrigel assays. There were no marked or significant differences in the capacity of human or canine MSC CM to stimulate neuronal cell or endothelial cell activity. Hence, this study supports the use of MSC transplants for canine SCI; furthermore, it increases understanding of how this may subsequently provide useful information and translate to MSC transplants for human SCI.

Spinal cord injury causes chronic bone marrow failure

Spinal cord injury (SCI) causes immune dysfunction, increasing the risk of infectious morbidity and mortality. Since bone marrow hematopoiesis is essential for proper immune function, we hypothesize that SCI disrupts bone marrow hematopoiesis. Indeed, SCI causes excessive proliferation of bone marrow hematopoietic stem and progenitor cells (HSPC), but these cells cannot leave the bone marrow, even after challenging the host with a potent inflammatory stimulus. Sequestration of HSPCs in bone marrow after SCI is linked to aberrant chemotactic signaling that can be reversed by post-injury injections of Plerixafor (AMD3100), a small molecule inhibitor of CXCR4. Even though Plerixafor liberates HSPCs and mature immune cells from bone marrow, competitive repopulation assays show that the intrinsic long-term functional capacity of HSPCs is still impaired in SCI mice. Together, our data suggest that SCI causes an acquired bone marrow failure syndrome that may contribute to chronic immune dysfunction.

Predictors of fracture healing in patients with recalcitrant nonunions treated with autologous culture expanded bone marrow-derived mesenchymal stromal cells

The study reports the prospective outcome of treating severe recalcitrant fracture nonunion in patients with autologous bone marrow-derived mesenchymal stromal cells (BMSC) from 2003 to 2010 and analyze predictors of union. Autologous BMSC were culture expanded and inserted at nonunion site with or without carriers in addition to surgical stabilization of the fracture. Radiological union was ascertained by musculoskeletal radiologists on plain radiographs and/or CT scans. A logistic regression analysis was performed with cell-expansion parameters (cell numbers, cell doubling time) and known clinical factors (e.g., smoking and diabetes) as independent variables and fracture union as the dependent variable to identify the factors that influence bony healing. An Eq5D index score assessed the effect of treatment on general quality of health. A total of 35 patients (mean age 51+/-13 years) with established nonunion (median 2.9 years, 1-33) and, at least one failed nonunion surgery (median 4,1-14) received treatment. Fracture union was achieved in 21 patients (60%; 95%CI 44-75) at 2.6 years. Multiple penalized logistic regression revealed faster cell doubling time (p = 0.07), absence of diabetes (p = 0.003), less previous surgeries (p = 0.008), and lower age at cell implantation (p = 0.02) were significant predictors for fracture union. A significant increase in Eq5D index (p = 0.01) was noted with a mean rise of the score by 0.34 units (95%CI 0.11-0.58) at 1 year following the study. In summary, the study revealed cell doubling time as a novel in vitro parameter in conjunction with age, multiple surgeries, and diabetes as being significant predictors of the fracture union. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 37:1303-1309, 2019.

Mesenchymal stromal cells derived from whole human umbilical cord exhibit similar properties to those derived from Wharton's jelly and bone marrow

Mesenchymal stromal cells (MSC) can be isolated from several regions of human umbilical cords, including Wharton's jelly (WJ), artery, vein or cord lining. These MSC appear to be immune privileged and are promising candidates for cell therapy. However, isolating MSC from WJ, artery, vein or cord lining requires time-consuming tissue dissection. MSC can be obtained easily via briefly digesting complete segments of the umbilical cord, likely containing heterogenous or mixed populations of MSC (MC-MSC). MC-MSC are generally less well characterized than WJ-MSC, but nevertheless represent a potentially valuable population of MSC. This study aimed to further characterize MC-MSC in comparison to WJ-MSC and also the better-characterized bone marrow-derived MSC (BM-MSC). MC-MSC proliferated faster, with significantly faster doubling times reaching passage one 8.8 days sooner and surviving longer in culture than WJ-MSC. All MSC retained the safety aspect of reducing telomere length with increasing passage number. MSC were also assessed for their ability to suppress T-cell proliferation and for the production of key markers of pluripotency, embryonic stem cells, tolerogenicity (CD40, CD80, CD86 and HLA-DR) and immunomodulation (indoleamine 2,3-dioxygenase [IDO] and HLA-G). The MC-MSC population displayed all of the positive attributes of WJ-MSC and BM-MSC, but they were more efficient to obtain and underwent more population doublings than from WJ, suggesting that MC-MSC are promising candidates for allogeneic cell therapy in regenerative medicine.

Periodontal Wound Healing by Transplantation of Jaw Bone Marrow-Derived Mesenchymal Stem Cells in Chitosan/Anorganic Bovine Bone Carrier Into One-Wall Infrabony Defects in Beagles

BACKGROUND

This study aims to evaluate the performance of chitosan/anorganic bovine bone (C/ABB) scaffold seeded with human jaw bone marrow-derived mesenchymal stem cells (hJBMMSCs) in supporting the healing/repair of 1-wall critical-size periodontal defects.

METHODS

Physical properties of the C/ABB scaffold were compared with those of the chitosan scaffold. hJBMMSCs were obtained from healthy human alveolar bone during the extraction of third molar impacted teeth. One-wall (7 × 4 mm) infrabony defects were surgically created at the bilateral mandibular third premolars and first molars in six beagles. The defects were randomly assigned to six groups and implanted with different scaffolds: 1) chitosan (C) scaffold; 2) C scaffold with hJBMMSCs (C + cell); 3) C/ABB scaffold (C/ABB); 4) C/ABB scaffold with hJBMMSCs (C/ABB + cell); 5) ABB scaffold (ABB); and 6) open flap debridement (control). The animals were euthanized 8 weeks after surgery for histologic analysis.

RESULTS

The C/ABB scaffold had a porous structure and increased compressive strength. Both C/ABB and C/ABB + cell exhibited the newly formed cellular mixed-fiber cementum, woven/lamellar bone, and periodontal ligament. Cementum formation was significantly greater in group C/ABB + cell than in group C/ABB (2.64 ± 0.50 mm versus 0.91 ± 0.55 mm, P <0.05). For new bone (NB) height, group C/ABB + cell and C/ABB showed mean ± SD values of 2.83 ± 0.29 mm and 2.65 ± 0.52 mm and for NB area 8.89 ± 1.65 mm and 8.73 ± 1.94 mm(2), respectively. For NB (height and area), there was no significant difference between the two groups.

CONCLUSIONS

The combination of hJBMMSCs and C/ABB scaffolds could promote periodontal repair. Future studies are expected to further optimize the combination and lead to an ideal periodontal regeneration.

Co-transplantation of autologous OM-MSCs and OM-OECs: a novel approach for spinal cord injury

Spinal cord injury (SCI) is a disastrous injury that leads to motor and sensory dysfunctions in patients. In recent years, co-transplantation has become an increasingly used therapeutic treatment for patients with SCI. Both mesenchymal stem cells (MSCs) and olfactory-ensheathing cells (OECs) have been adopted to ameliorate SCI, with promising outcomes. Remarkable effects on the rehabilitation of patients with SCI have been achieved using MSCs. Olfactory mucosa (OM) MSCs from human OM are one of the most ideal cell resources for auto-transplantation in clinical application owing to their a high proliferation rate and multipotent capability. In addition, OECs derived from OM have been used to improve functional recovery of SCI and resulted in promising functional recovery in years. Accordingly, co-transplantation of OM-MSCs coupled with OM-OECs has been adopted to improve the recovery of SCI. Here we reviewed the reported applications of OM-MSCs and OM-OECs for SCI treatment and proposed that a novel combined strategy using both autologous OM-MSCs and OM-OECs would achieve a better approach for the treatment of SCI.

Human mesenchymal stem cells stimulate EaHy926 endothelial cell migration: combined proteomic and in vitro analysis of the influence of donor-donor variability

Mesenchymal stem cells (MSCs) stimulate angiogenesis within a wound environment and this effect is mediated through paracrine interactions with the endothelial cells present. Here we report that human MSC-conditioned medium (n=3 donors) significantly increased EaHy-926 endothelial cell adhesion and cell migration, but that this stimulatory effect was markedly donor-dependent. MALDI-TOF/TOF mass spectrometry demonstrated that whilst collagen type I and fibronectin were secreted by all of the MSC cultures, the small leucine rich proteoglycan, decorin was secreted only by the MSC culture that was least effective upon EaHy-926 cells. These individual extracellular matrix components were then tested as culture substrata. EaHy-926 cell adherence was greatest on fibronectin-coated surfaces with least adherence on decorin-coated surfaces. Scratch wound assays were used to examine cell migration. EaHy-926 cell scratch wound closure was quickest on substrates of fibronectin and slowest on decorin. However, EaHy-926 cell migration was stimulated by the addition of MSC-conditioned medium irrespective of the types of culture substrates. These data suggest that whilst the MSC secretome may generally be considered angiogenic, the composition of the secretome is variable and this variation probably contributes to donor-donor differences in activity. Hence, screening and optimizing MSC secretomes will improve the clinical effectiveness of pro-angiogenic MSC-based therapies.

Viability, growth kinetics and stem cell markers of single and clustered cells in human intervertebral discs: implications for regenerative therapies

PURPOSE

There is much interest in the development of a cellular therapy for the repair or regeneration of degenerate intervertebral discs (IVDs) utilising autologous cells, with some trials already underway. Clusters of cells are commonly found in degenerate IVDs and are formed via cell proliferation, possibly as a repair response. We investigated whether these clusters may be more suitable as a source of cells for biological repair than the single cells in the IVD.

METHODS

Discs were obtained at surgery from 95 patients and used to assess the cell viability, growth kinetics and stem or progenitor cell markers in both the single and clustered cell populations.

RESULTS

Sixty-nine percent (±15) of cells in disc tissue were viable. The clustered cell population consistently proliferated more slowly in monolayer than single cells, although this difference was only significant at P0-1 and P3-4. Both populations exhibited progenitor or notochordal cell markers [chondroitin sulphate epitopes (3B3(-), 7D4, 4C3 and 6C3), Notch-1, cytokeratin 8 and 19] via immunohistochemical examination; stem cell markers assessed with flow cytometry (CD73, 90 and 105 positivity) were similar to those seen on bone marrow-derived mesenchymal stem cells.

CONCLUSIONS

These results confirm those of previous studies indicating that progenitor or stem cells reside in adult human intervertebral discs. However, although the cell clusters have arisen via proliferation, there appear to be no greater incidence of these progenitor cells within clusters compared to single cells. Rather, since they proliferate more slowly in vitro than the single cell population, it may be beneficial to avoid the use of clustered cells when sourcing autologous cells for regenerative therapies.

Bridging defects in chronic spinal cord injury using peripheral nerve grafts combined with a chitosan-laminin scaffold and enhancing regeneration through them by co-transplantation with bone-marrow-derived mesenchymal stem cells: case series of 14 patients

OBJECTIVE

To investigate the effect of bridging defects in chronic spinal cord injury using peripheral nerve grafts combined with a chitosan-laminin scaffold and enhancing regeneration through them by co-transplantation with bone-marrow-derived mesenchymal stem cells.

METHODS

In 14 patients with chronic paraplegia caused by spinal cord injury, cord defects were grafted and stem cells injected into the whole construct and contained using a chitosan-laminin paste. Patients were evaluated using the International Standards for Classification of Spinal Cord Injuries.

RESULTS

Chitosan disintegration leading to post-operative seroma formation was a complication. Motor level improved four levels in 2 cases and two levels in 12 cases. Sensory-level improved six levels in two cases, five levels in five cases, four levels in three cases, and three levels in four cases. A four-level neurological improvement was recorded in 2 cases and a two-level neurological improvement occurred in 12 cases. The American Spinal Impairment Association (ASIA) impairment scale improved from A to C in 12 cases and from A to B in 2 cases. Although motor power improvement was recorded in the abdominal muscles (2 grades), hip flexors (3 grades), hip adductors (3 grades), knee extensors (2-3 grades), ankle dorsiflexors (1-2 grades), long toe extensors (1-2 grades), and plantar flexors (0-2 grades), this improvement was too low to enable them to stand erect and hold their knees extended while walking unaided.

CONCLUSION

Mesenchymal stem cell-derived neural stem cell-like cell transplantation enhances recovery in chronic spinal cord injuries with defects bridged by sural nerve grafts combined with a chitosan-laminin scaffold.

Cell sources for nucleus pulposus regeneration

PURPOSE

There is increasing interest in the development of cell therapy as a possible approach for the treatment of degenerative disc disease. To regenerate nucleus pulposus tissue, the cells must produce an appropriate proteoglycan-rich matrix, as this is essential for the functioning of the intervertebral disc. The natural environment within the disc is very challenging to implanted cells, particularly if they have been subcultured in normal laboratory conditions. The purpose of this work is to discuss parameters relevant to translating different proposed cell therapies of IVD into clinical use.

RESULTS

Several sources of cells have been proposed, including nucleus pulposus cells, chondrocytes and mesenchymal stem cells derived from bone marrow or adipose tissue. There are some clinical trials and reports of attempts to regenerate nucleus pulposus utilising either autologous or allogenic cells. While the published results of clinical applications of these cell therapies do not indicate any safety issues, additional evidence will be needed to prove their long-term efficacy.

CONCLUSION

This article discusses parameters relevant for successful translation of research on different cell sources into clinically applicable cell therapies: the influence of the intervertebral disc microenvironment on the cell phenotype, issues associated with cell culture and technical preparation of cell products, as well as discussing current regulatory requirements. There are advantages and disadvantages of each proposed cell type, but no strong evidence to favour any one particular cell source at the moment.

Mesenchymal autologous stem cells

The use of cell-based therapies for spinal cord injuries has recently gained prominence as a potential therapy or component of a combination strategy. Experimental and clinical studies have been performed using mesenchymal stem cell therapy to treat spinal cord injuries with encouraging results. However, there have been reports on the adverse effects of these stem cell-based therapies, especially in the context of tumor modulation. This article surveys the literature relevant to the potential of mesenchymal autologous stem cells for spinal cord injuries and their clinical implications.

Human mesenchymal stem cells isolated from olfactory biopsies but not bone enhance CNS myelination in vitro

Spinal cord injury (SCI) is a devastating condition with limited capacity for repair. Cell transplantation is a potential strategy to promote SCI repair with cells from the olfactory system being promising candidates. Although transplants of human olfactory mucosa (OM) are already ongoing in clinical trials, the repair potential of this tissue remains unclear. Previously, we identified mesenchymal-like stem cells that reside in the lamina propria (LP-MSCs) of rat and human OM. Little is known about these cells or their interactions with glia such as olfactory ensheathing cells (OECs), which would be co-transplanted with MSCs from the OM, or endogenous CNS glia such as oligodendrocytes. We have characterized, purified, and assessed the repair potential of human LP-MSCs by investigating their effect on glial cell biology with specific emphasis on CNS myelination in vitro. Purified LP-MSCs expressed typical bone marrow MSC (BM-MSC) markers, formed spheres, were clonogenic and differentiated into bone and fat. LP-MSC conditioned medium (CM) promoted oligodendrocyte precursor cell (OPC) and OEC proliferation and induced a highly branched morphology. LP-MSC-CM treatment caused OEC process extension. Both LP and BM-MSCs promoted OPC proliferation and differentiation, but only myelinating cultures treated with CM from LP and not BM-MSCs had a significant increase in myelination. Comparison with fibroblasts and contaminating OM fibroblast like-cells showed the promyelination effect was LP-MSC specific. Thus LP-MSCs harvested from human OM biopsies may be an important candidate for cell transplantation by contributing to the repair of SCI.

Index of CD34+ Cells and Mononuclear Cells in the Bone Marrow of Spinal Cord Injury Patients of Different Age Groups: A Comparative Analysis

Introduction. Recent evidence of safety and efficacy of Bone Marrow Mononuclear Cells (BMMNC) in spinal cord injury makes the Bone Marrow (BM) CD34+ percentage and the BMMNC count gain significance. The indices of BM that change with body mass index and aging in general population have been reported but seldom in Spinal Cord Injury (SCI) victims, whose parameters of relevance differ from general population. Herein, we report the indices of BMMNC in SCI victims. Materials and Methods. BMMNCs of 332 SCI patients were isolated under GMP protocols. Cell count by Trypan blue method and CD34+ cells by flow cytometry were documented and analysed across ages and gender. Results. The average BMMNC per ml in the age groups 0–20, 21–40, 41–60, and 61–80 years were 4.71, 4.03, 3.67, and 3.02 million and the CD34+ were 1.05%, 1.04%, 0.94%, and 0.93% respectively. The decline in CD34+ was sharp between 20–40 and 40–60 age groups. Females of reproductive age group had lesser CD34+. Conclusion. The BMMNC and CD34+ percentages decline with aging in SCI victims. Their lower values in females during reproductive age should be analysed for relevance to hormonal influence. This study offers reference values of BMMNC and CD34+ of SCI victims for successful clinical application.

Tissue engineered regeneration of completely transected spinal cord using human mesenchymal stem cells

The present study employed a combinatorial strategy using poly(D,L-lactide-co-glycolide) (PLGA) scaffolds seeded with human mesenchymal stem cells (hMSCs) to promote cell survival, differentiation, and neurological function in a completely transected spinal cord injury (SCI) model. The SCI model was prepared by complete removal of a 2-mm length of spinal cord in the eighth-to-ninth spinal vertebra, a procedure that resulted in bilateral hindlimb paralysis. PLGA scaffolds 2 mm in length without hMSCs (control) or with different numbers of hMSCs (1 × 10(5), 2 × 10(4), and 4 × 10(3)) were fitted into the completely transected spinal cord. Rats implanted with hMSCs received Basso-Beattie-Bresnahan scores for hindlimb locomotion of about 5, compared with ~2 for animals in the control group. The amplitude of motor-evoked potentials (MEPs) averaged 200-300 μV in all hMSC-implanted SCR model rats. In contrast, the amplitude of MEPs in control group animals averaged 135 μV at 4 weeks and then declined to 100 μV at 8 weeks. These results demonstrate functional recovery in a completely transected SCI model under conditions that exclude self-recovery. hMSCs were detected at the implanted site 4 and 8 weeks after transplantation, indicating in vivo survival of implanted hMSCs. Immunohistochemical staining revealed differentiation of implanted hMSCs into nerve cells, and immunostained images showed clear evidence for axonal regeneration only in hMSC-seeded PLGA scaffolds. Collectively, our results indicate that hMSC-seeded PLGA scaffolds induced nerve regeneration in a completely transected SCI model, a finding that should have significant implications for the feasibility of therapeutic and clinical hMSC-delivery using three-dimensional scaffolds, especially in the context of complete spinal cord transection.

Implanted electro-acupuncture electric stimulation improves outcome of stem cells' transplantation in spinal cord injury

Spinal cord injury (SCI) is one of the most serious disorders in clinics, and the high disability rate and functional deficits are common issues in patients. Transplantation of bone-marrow-derived mesenchymal stromal cells (BMSCs) into the injured spinal cord is emerging as a novel method in the therapeutics of SCI; however, its application is limited by the poor survival rate of the transplanted cells and low differentiation rate into neurons. Our laboratory recently reported that electrical stimulation (ES) dramatically improves the survival rate of transplanted BMSCs and increases spinal cord functions in animals with spinal cord injury. In this paper, we asked whether implanted electro-acupuncture (iEA) can advance the beneficial effects from the ES treatment in animals with spinal cord injury. We showed that BMSCs transplantation alone resulted in significant functional recovery in animals. Interestingly, iEA with BMSCs treatment induced a significantly higher functional improvement in locomotor functions and SSEP compared to the BMSCs treatment alone. Additionally, we used molecular biology techniques and showed that BMSCs transplantation with iEA treatment significantly increased the number of surviving BMSCs compared to the BMSCs alone group. In conclusion, our experiment showed that the approach of coupling iEA electric stimulation and BMSCs transplantation remarkably promotes functional improvements in animals with spinal cord injury and holds promising potential to treat spinal cord injury in humans.

Concise review: Bone marrow for the treatment of spinal cord injury: mechanisms and clinical applications

Transplantation of bone marrow stem cells into spinal cord lesions enhances axonal regeneration and promotes functional recovery in animal studies. There are two types of adult bone marrow stem cell; hematopoietic stem cells (HSCs), and mesenchymal stem cells (MSCs). The mechanisms by which HSCs and MSCs might promote spinal cord repair following transplantation have been extensively investigated. The objective of this review is to discuss these mechanisms; we briefly consider the controversial topic of HSC and MSC transdifferentiation into central nervous system cells but focus on the neurotrophic, tissue sparing, and reparative action of MSC grafts in the context of the spinal cord injury (SCI) milieu. We then discuss some of the specific issues related to the translation of HSC and MSC therapies for patients with SCI and present a comprehensive critique of the current bone marrow cell clinical trials for the treatment of SCI to date.

Development of a brain metastatic canine prostate cancer cell line

BACKGROUND

Prostate cancer in men has a high mortality and morbidity due to metastatic disease. The pathobiology of prostate cancer metastasis is not well understood and cell lines and animal models that recapitulate the complex nature of the disease are needed. Therefore, the goal of the study was to establish and characterize a new prostate cancer line derived from a dog with spontaneous prostate cancer.

METHODS

A new cell line (Leo) was derived from a dog with spontaneous prostate cancer. Immunohistochemistry and PCR were used to characterize the primary prostate cancer and xenografts in nude mice. Subcutaneous tumor growth and metastases in nude mice were evaluated by bioluminescent imaging, radiography and histopathology. In vitro chemosensitivity of Leo cells to therapeutic agents was measured.

RESULTS

Leo cells expressed the secretory epithelial cytokeratins (CK)8, 18, and ductal cell marker, CK7. The cell line grew in vitro (over 75 passages) and was tumorigenic in the subcutis of nude mice. Following intracardiac injection, Leo cells metastasized to the brain, spinal cord, bone, and adrenal gland. The incidence of metastases was greatest to the central nervous system (80%) with a lower incidence to bone (20%) and the adrenal glands (16%). In vitro chemosensitivity assays demonstrated that Leo cells were sensitive to Velcade and an HDAC-42 inhibitor with IC(50) concentrations of 1.9 nm and 0.95 µm, respectively.

CONCLUSION

The new prostate cancer cell line (Leo) will be a valuable model to investigate the mechanisms of the brain and bone metastases.

Implanted spike wave electric stimulation promotes survival of the bone marrow mesenchymal stem cells and functional recovery in the spinal cord injured rats

Transplantation of bone marrow-derived mesenchymal stromal cells (BMSCs) into the injured spinal cord may provide therapeutic benefit, but its application is limited by their poor survival and low differentiation rate into neurons. Electrical stimulation (ES) has been reported to promote survival and differentiation of the BMSCs. Therefore we investigated whether implanted spike wave ES could improve survival of BMSCs after transplantation and result in functional improvement in animals with spinal cord injury. Our results showed that the number and ratio of survived BMSCs near the lesion site were significantly increased in the BMSCs+ES-treated group as compared to BMSCs transplantation or ES treatment alone group. Furthermore, results from BBB scales, SSEP and DTI demonstrated a significant improved functional recovery in the BMSCs+ES group. This indicated that implanted spike wave ES could promote the bioactivity of BMSCs and their survival. This represents a new therapeutic potential of the combination of BMSCs transplantation with implanted spike wave ES to treat spinal cord injury.

Stem cells for spinal cord regeneration: Current status

Background:

Nearly 11,000 cases of spinal cord injury (SCI) are reported in the United States annually. Current management options give a median survival time of 38 years; however, no rehabilitative measures are available. Stem cells have been under constant research given their ability to differentiate into neural cell lines replacing non functional tissue. Efforts have been made to establish new synapses and provide a conducive environment, by grafting cells from autologous and fetal sources; including embryonic or adult stem cells, Schwann cells, genetically modified fibroblasts, bone stromal cells, and olfactory ensheathing cells and combinations/ variants thereof.

Methods:

In order to discuss the underlying mechanism of SCI along with the previously mentioned sources of stem cells in context to SCI, a simple review of literature was conducted. An extensive literature search was conducted using the PubMed data base and online search engines and articles published in the last 15 years were considered along with some historical articles where a background was required.

Results:

Stem cell transplantation for SCI is at the forefront with animal and in vitro studies providing a solid platform to enable well-designed human studies. Olfactory ensheathing cells seem to be the most promising; whilst bone marrow stromal cells appear as strong candidates for an adjunctive role.

Conclusion:

The key strategy in developing the therapeutic basis of stem cell transplantation for spinal cord regeneration is to weed out the pseudo-science and opportunism. All the trials should be based on stringent scientific criteria and effort to bypass that should be strongly discouraged at the international level.

A Comparison of High-Content Screening versus Manual Analysis to Assay the Effects of Mesenchymal Stem Cell–Conditioned Medium on Neurite Outgrowth In Vitro

Bone marrow mesenchymal stem cells (MSCs) promote nerve growth and functional recovery in animal models of spinal cord injury (SCI) to varying levels. The authors have tested high-content screening to examine the effects of MSC-conditioned medium (MSC-CM) on neurite outgrowth from the human neuroblastoma cell line SH-SY5Y and from explants of chick dorsal root ganglia (DRG). These analyses were compared to previously published methods that involved hand-tracing individual neurites. Both methods demonstrated that MSC-CM promoted neurite outgrowth. Each showed the proportion of SH-SY5Y cells with neurites increased by ~200% in MSC-CM within 48 h, and the number of neurites/SH-SY5Y cells was significantly increased in MSC-CM compared with control medium. For high-content screening, the analysis was performed within minutes, testing multiple samples of MSC-CM and in each case measuring >15,000 SH-SY5Y cells. In contrast, the manual measurement of neurite outgrowth from >200 SH-SY5Y cells in a single sample of MSC-CM took at least 1 h. High-content analysis provided additional measures of increased neurite branching in MSC-CM compared with control medium. MSC-CM was also found to stimulate neurite outgrowth in DRG explants using either method. The application of the high-content analysis was less well optimized for measuring neurite outgrowth from DRG explants than from SH-SY5Y cells.

Bone marrow stromal cell transplantation for treatment of sub-acute spinal cord injury in the rat

Bone marrow stromal cells (BMSCs) have been studied as effective transplants for the treatment of spinal cord injury (SCI). Our previous study showed that BMSCs infused into the cerebrospinal fluid (CSF) exhibited distinct effects on the recovery of acute SCI. The present study examined the effects of BMSCs in sub-acute SCI (2weeks post-injury) by transplanting them directly into the lesion. The spinal cord was crush-injured at the Th8-9 level in rats, and 2weeks later, cultured BMSCs (5x10(5)) derived from GFP-transgenic rats of the same strain were transplanted into the lesion. Tissue repair and nerve regeneration were examined by immunohistochemistry and electron microscopy. GFP-labeled BMSCs survived as cell assemblies in the spinal cord for 1-2weeks after transplantation. The dorsal side of BMSC assemblies in the spinal cord usually showed an expanded GFAP-negative, astrocyte-devoid area, in which extracellular matrices including collagen fibrils were deposited. Numerous regenerating axons associated with Schwann cells grew out through such astrocyte-devoid extracellular matrices. Ascending (CGRP-containing) and descending (5HT- and TH-containing) axons were included in these regenerating axons. Regenerated axons were myelinated by Schwann cells beyond 2weeks post-transplantation. Cavity formation was reduced in the cell transplantation group. Locomotory behavior assessed by the BBB scale improved to 9.8 points in the cell transplantation group, while it was to 5.5-5.7 in the control. BMSC transplantation into lesions of advanced SCI has markedly beneficial effects on tissue repair and axonal outgrowth, leading to improved locomotion in rats.

Decreased osteogenesis, increased cell senescence and elevated Dickkopf-1 secretion in human fracture non union stromal cells

The delicately orchestrated process of bone fracture healing is not always successful and long term non union of fractured bone occurs in 5-20% of all cases. Atrophic fracture non unions have been described as the most difficult to treat and this is thought to arise through a cellular and local failure of osteogenesis. However, little is known about the presence and osteogenic proficiency of cells in the local area of non union tissue. We have examined the growth and differentiation potential of cells isolated from human non union tissues compared with normal human bone marrow mesenchymal stromal cells (BMSC). We report the isolation and culture expansion of a population of non union stromal cells (NUSC) which have a CD profile similar to that of BMSC, i.e. CD34-ve, CD45-ve and CD105+ve. The NUSC demonstrated multipotentiality and differentiated to some extent along chondrogenic, adipogenic and osteogenic lineages. However, and importantly, the NUSC showed significantly reduced osteogenic differentiation and mineralization in vitro compared to BMSC. We also found increased levels of cell senescence in NUSC compared to BMSC based on culture growth kinetics and cell positivity for senescence associated beta galactosidase (SA-beta-Gal) activity. The reduced capacity of NUSC to form osteoblasts was associated with significantly elevated secretion of Dickkopf-1 (Dkk-1) which is an important inhibitor of Wnt signalling during osteogenesis, compared to BMSC. Conversely, treating BMSC with levels of rhDkk-1 that were equivalent to those levels secreted by NUSC inhibited the capacity of BMSC to undergo osteogenesis. Treating BMSC with NUSC conditioned medium also inhibited the capacity of the BMSC to undergo osteogenic differentiation when compared to their treatment with BMSC conditioned medium. Our results suggest that the development of fracture non union is linked with a localised reduced capacity of cells to undergo osteogenesis, which in turn is associated with increased cell senescence and Dkk-1 secretion.

Synergistic actions of hematopoietic and mesenchymal stem/progenitor cells in vascularizing bioengineered tissues

Poor angiogenesis is a major road block for tissue repair. The regeneration of virtually all tissues is limited by angiogenesis, given the diffusion of nutrients, oxygen, and waste products is limited to a few hundred micrometers. We postulated that co-transplantation of hematopoietic and mesenchymal stem/progenitor cells improves angiogenesis of tissue repair and hence the outcome of regeneration. In this study, we tested this hypothesis by using bone as a model whose regeneration is impaired unless it is vascularized. Hematopoietic stem/progenitor cells (HSCs) and mesenchymal stem/progenitor cells (MSCs) were isolated from each of three healthy human bone marrow samples and reconstituted in a porous scaffold. MSCs were seeded in micropores of 3D calcium phosphate (CP) scaffolds, followed by infusion of gel-suspended CD34(+) hematopoietic cells. Co-transplantation of CD34(+) HSCs and CD34(-) MSCs in microporous CP scaffolds subcutaneously in the dorsum of immunocompromised mice yielded vascularized tissue. The average vascular number of co-transplanted CD34(+) and MSC scaffolds was substantially greater than MSC transplantation alone. Human osteocalcin was expressed in the micropores of CP scaffolds and was significantly increased upon co-transplantation of MSCs and CD34(+) cells. Human nuclear staining revealed the engraftment of transplanted human cells in vascular endothelium upon co-transplantation of MSCs and CD34(+) cells. Based on additional in vitro results of endothelial differentiation of CD34(+) cells by vascular endothelial growth factor (VEGF), we adsorbed VEGF with co-transplanted CD34(+) and MSCs in the microporous CP scaffolds in vivo, and discovered that vascular number and diameter further increased, likely owing to the promotion of endothelial differentiation of CD34(+) cells by VEGF. Together, co-transplantation of hematopoietic and mesenchymal stem/progenitor cells may improve the regeneration of vascular dependent tissues such as bone, adipose, muscle and dermal grafts, and may have implications in the regeneration of internal organs.