Allogeneic clonal mesenchymal stem cell therapy for refractory graft-versus-host disease to standard treatment: a phase I study

Mesenchymal stem cell-based therapy for autoimmune-related fibrotic skin diseases-systemic sclerosis and sclerodermatous graft-versus-host disease

BACKGROUND

Systemic sclerosis (SSc) and sclerodermatous graft-versus-host disease (Scl-GVHD)-characterized by similar developmental fibrosis, vascular abnormalities, and innate and adaptive immune response, resulting in severe skin fibrosis at the late stage-are chronic autoimmune diseases of connective tissue. The significant immune system dysfunction, distinguishing autoimmune-related fibrosis from mere skin fibrosis, should be a particular focus of treating autoimmune-related fibrosis. Recent research shows that innovative mesenchymal stem cell (MSC)-based therapy, with the capacities of immune regulation, inflammation suppression, oxidation inhibition, and fibrosis restraint, shows great promise in overcoming the disease.

MAIN BODY

This review of recent studies aims to summarize the therapeutic effect and theoretical mechanisms of MSC-based therapy in treating autoimmune-related fibrotic skin diseases, SSc and Scl-GVHD, providing novel insights and references for further clinical applications. It is noteworthy that the efficacy of MSCs is not reliant on their migration into the skin. Working on the immune system, MSCs can inhibit the chemotaxis and infiltration of immune cells to the skin by down-regulating the expression of skin chemokines and chemokine receptors and reducing the inflammatory and pro-fibrotic mediators. ​Furthermore, to reduce levels of oxidative stress, MSCs may improve vascular abnormalities, and enhance the antioxidant defenses through inducible nitric oxide synthase, thioredoxin 1, as well as other mediators. The oxidative stress environment does not weaken MSCs and may even strengthen certain functions. Regarding fibrosis, MSCs primarily target the transforming growth factor-β signaling pathway to inhibit fibroblast activation. Here, miRNAs may play a critical role in ECM remodeling. Clinical studies have demonstrated the safety of these approaches, though outcomes have varied, possibly owing to the heterogeneity of MSCs, the disorders themselves, and other factors. Nevertheless, the research clearly reveals the immense potential of MSCs in treating autoimmune-related fibrotic skin diseases.

CONCLUSION

The application of MSCs presents a promising approach for treating autoimmune-related fibrotic skin diseases: SSc and Scl-GVHD. Therapies involving MSCs and MSC extracellular vesicles have been found to operate through three primary mechanisms: rebalancing the immune and inflammatory disorders, resisting oxidant stress, and inhibiting overactivated fibrosis (including fibroblast activation and ECM remodeling). However, the effectiveness of these interventions requires further validation through extensive clinical investigations, particularly randomized control trials and phase III/IV clinical trials. Additionally, the hypothetical mechanism underlying these therapies could be elucidated through further research.

Immunomodulatory potential of human clonal mesenchymal stem cells and their extracellular vesicle subpopulations in an inflammatory-mediated diabetic Rhesus monkey model

AIMS

This study aimed to investigate the therapeutic potential of a homogenous clonal population of mesenchymal stem cells (cMSC) and their extracellular vesicles (cMSC-EV) subpopulations on isolated rat islets in vitro and in inflammatory-mediated type 1 diabetes (T1D) non-human primate models.

MAIN METHODS

EV subpopulations were isolated from human bone marrow-derived cMSC supernatant by low- and high-speed ultracentrifuge (EV-20K and EV-U110K) and sucrose density gradient (EV-S110K). The EVs were characterized generally and for the level of albumin, acetylcholinesterase (AChE) activity, co-isolate apoptotic markers, and expression of CD63+/annexin V+. Rat islet-derived single cells (iSCs) proliferation was measured using a Ki-67 proliferation assay. Diabetes was induced by multiple low-dose administrations of streptozotocin in rhesus monkeys. The diabetic monkeys were divided into three groups: the cMSC group, received two injections of 1.5 × 106 cMSC/kg body weight; the EV group received two injections of EVs isolated from 1.5 × 106 cMSC/kg, and the vehicle group received phosphate-buffered saline.

KEY FINDINGS

EV-S110K showed higher AChE activity, lower expression of CD63+/annexin V+, and lower apoptotic co-isolates. EV-S110K induced β-cell proliferation in vitro in a dose-dependent manner. The administration of EV-S110K and/or cMSC in diabetic monkeys demonstrated no significant changes in general diabetic indices and β-cell mass in the pancreas of the monkeys. Both treatments demonstrated a lowering trend in blood glucose levels and reduced pro-inflammatory cytokines. In contrast, regulatory T cells and anti-inflammatory cytokines were increased.

SIGNIFICANCE

cMSC and cMSC-EV provided initial evidence to attenuate clinical symptoms in inflammatory-mediated T1D non-human primates through immunomodulation.

Breaking the graft-versus-host-disease barrier: Mesenchymal stromal/stem cells as precision healers

Mesenchymal Stromal/Stem Cells (MSCs) are multipotent, non-hematopoietic progenitor cells with a wide range of immune modulation and regenerative potential which qualify them as a potential component of cell-based therapy for various autoimmune/chronic inflammatory ailments. Their immunomodulatory properties include the secretion of immunosuppressive cytokines, the ability to suppress T-cell activation and differentiation, and the induction of regulatory T-cells. Considering this and our interest, we here discuss the significance of MSC for the management of Graft-versus-Host-Disease (GvHD), one of the autoimmune manifestations in human. In pre-clinical models, MSCs have been shown to reduce the severity of GvHD symptoms, including skin and gut damage, which are the most common and debilitating manifestations of this disease. While initial clinical studies of MSCs in GvHD cases were promising, the results were variable in randomized studies. So, further studies are warranted to fully understand their potential benefits, safety profile, and optimal dosing regimens. Owing to these inevitable issues, here we discuss various mechanisms, and how MSCs can be employed in managing GvHD, as a cellular therapeutic approach for this disease.

Homogenous subpopulation of human mesenchymal stem cells and their extracellular vesicles restore function of endometrium in an experimental rat model of Asherman syndrome

BACKGROUND

Asherman syndrome (AS), or intrauterine adhesions, is a main cause of infertility in reproductive age women after endometrial injury. Mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) are promising candidates for therapies that repair damaged endometria. However, concerns about their efficacy are attributed to heterogeneity of the cell populations and EVs. A homogenous population of MSCs and effective EV subpopulation are needed to develop potentially promising therapeutic options in regenerative medicine.

METHODS

AS model was induced by mechanical injury in adult rat uteri. Then, the animals were treated immediately with homogeneous population of human bone marrow-derived clonal MSCs (cMSCs), heterogenous parental MSCs (hMSCs), or cMSCs-derived EV subpopulations (EV20K and EV110K). The animals were sacrificed two weeks post-treatment and uterine horns were collected. The sections were taken, and hematoxylin-eosin was used to examine the repair of endometrial structure. Fibrosis was measured by Masson's trichrome staining and α-SMA and cell proliferation by Ki67 immunostaining. The function of the uteri was explored by the result of mating trial test. Expression changes of TNFα, IL-10, VEGF, and LIF were assayed by ELISA.

RESULTS

Histological analysis indicated fewer glands, thinner endometria, increased fibrotic areas, and decreased proliferation of epithelial and stroma of the uteri in the treated compared with intact and sham-operated animals. However, these parameters improved after transplantation of both types of cMSCs and hMSCs and/or both cryopreserved EVs subpopulations. The cMSCs demonstrated more successful implantation of the embryos in comparison with hMSCs. The tracing of the transplanted cMSCs and EVs showed that they migrated and localized in the uteri. Protein expression analysis results demonstrated downregulation of proinflammatory factor TNFα and upregulation of anti-inflammatory cytokine IL-10, and endometrial receptivity cytokines VEGF and LIF in cMSC- and EV20K-treated animals.

CONCLUSION

Transplantation of MSCs and EVs contributed to endometrial repair and restoration of reproductive function, likely by inhibition of excessive fibrosis and inflammation, enhancement of endometrial cell proliferation, and regulation of molecular markers related to endometrial receptivity. Compared to classical hMSCs, cMSCs were more efficient than hMSCs in restoration of reproductive function. Moreover, EV20K is more cost-effective and feasible for prevention of AS in comparison with conventional EVs (EV110K).

Rapid and effective preparation of clonal bone marrow-derived mesenchymal stem/stromal cell sheets to reduce renal fibrosis

Allogeneic "off-the-shelf" mesenchymal stem/stromal cell (MSC) therapy requires scalable, quality-controlled cell manufacturing and distribution systems to provide clinical-grade products using cryogenic cell banking. However, previous studies report impaired cell function associated with administering freeze-thawed MSCs as single cell suspensions, potentially compromising reliable therapeutic efficacy. Using long-term culture-adapted clinical-grade clonal human bone marrow MSCs (cBMSCs) in this study, we engineered cBMSC sheets in 24 h to provide rapid preparation. We then sought to determine the influence of cBMSC freeze-thawing on both in vitro production of pro-regenerative factors and in vivo ability to reduce renal fibrosis in a rat model compared to freshly harvested cBMSCs. Sheets from freeze-thawed cBMSCs sheets exhibited comparable in vitro protein production and gene expression of pro-regenerative factors [e.g., hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and interleukin 10 (IL-10)] to freshly harvested cBMSC sheets. Additionally, freeze-thawed cBMSC sheets successfully suppressed renal fibrosis in vivo in an established rat ischemia-reperfusion injury model. Despite previous studies reporting that freeze-thawed MSCs exhibit impaired cell functions compared to fresh MSC single cell suspensions, cell sheets engineered from freeze-thawed cBMSCs do not exhibit impaired cell functions, supporting critical steps toward future clinical translation of cBMSC-based kidney disease treatment.

Regenerative potential of different extracellular vesicle subpopulations derived from clonal mesenchymal stem cells in a mouse model of chemotherapy-induced premature ovarian failure

AIMS

Some studies have shown that mesenchymal stem cells (MSCs) and their derived extracellular vesicles (MSC-EVs) can restore ovarian function in premature ovarian failure (POF), however, concerns about their efficacy are attributed to the heterogeneity of the cell populations and EVs. Here, we assessed the therapeutic potential of a homogeneous population of clonal MSCs (cMSCs) and their EVs subpopulations in a mouse model of POF.

MAIN METHODS

Granulosa cells were treated with cyclophosphamide (Cy) in the absence or presence of cMSCs, or cMSCs-derived EV subpopulations (EV20K and EV110K, isolated by high-speed centrifugation and differential ultracentrifugation, respectively). In addition, POF mice were treated with cMSCs, EV20K and/or EV110K.

KEY FINDINGS

cMSC and both EV types protected granulosa cells from Cy-induced damage. Calcein-EVs were detected in the ovaries. Moreover, cMSC and both EV subpopulations significantly increased body weight, ovary weight, and the number of follicles, restored FSH, E2, and AMH levels, increased the granulosa cell numbers and restored the fertility of POF mice. cMSC, EV20K, and EV110K alleviated inflammatory-related genes expression (Tnf-α and IL8), and improved angiogenesis via upregulation expression of Vegf and Igf1 at the mRNA level and VEGF and αSMA at the protein level. They also inhibited apoptosis through the PI3K/AKT signaling pathway.

SIGNIFICANCE

The administration of cMSCs and two cMSC-EVs subpopulations improved ovarian function and restored fertility in a POF model. EV20K is more cost-effective and feasible in terms of isolation, particularly in good manufacturing practice (GMP) facilities for treatment of POF patients in comparison with conventional EVs (EV110K).

Interferon-Gamma Primed Human Clonal Mesenchymal Stromal Cell Sheets Exhibit Enhanced Immunosuppressive Function

Mesenchymal stromal cells (MSCs) represent a promising treatment for immune-related diseases due to their diverse immunomodulatory paracrine functions. However, progress of culture-expanded MSCs is hindered by inconsistent cell function, poor localization, and insufficient retention when administered as suspended cell injections, thus placing spatiotemporal dosing constraints on therapeutic functions. To address these limitations, we introduce the combination of in vitro interferon-gamma (IFN-γ) priming, a key stimulator of MSC immunosuppressive potency, and thermoresponsive cultureware to harvest cultured MSCs as directly transplantable scaffold-free immunosuppressive cell sheets. Here, we demonstrate that MSC sheets produced with IFN-γ priming upregulate expression of immunosuppressive factors indoleamine 2,3-dioxygenase (IDO-1), interleukin-10 (IL-10), programmed death ligand-1 (PD-L1), and prostaglandin E2 (PGE2) in both dose- and duration-dependent manners. In addition, IFN-γ primed MSC sheets showed increased ability to inhibit T-cell proliferation via indirect and direct contact, specifically related to increased IDO-1 and PGE2 concentrations. Furthermore, this study's use of human clinical-grade single-cell-derived clonal bone marrow-derived MSCs, contributes to the future translatability and clinical relevancy of the produced sheets. Ultimately, these results present the combination of IFN-γ priming and MSC sheets as a new strategy to improve MSC-mediated treatment of localized inflammatory diseases.

Standard toxicity study of clinical-grade allogeneic human bone marrow-derived clonal mesenchymal stromal cells

INTRODUCTION

Mesenchymal stromal cells (MSCs) have opened a new window to treat inflammatory and non-inflammatory diseases. Nonetheless, their clinical applications require rigorous control and monitoring procedures to ensure full compliance with the principles of good manufacturing practice (GMP). Various evaluations should be passed in conjunction with the development of these newly emerging therapeutic products from bench-to-bedside. These evaluations include in vitro characterization, preclinical studies, and clinical trials to ensure product safety and efficacy. Therefore, a robust and well-designed preclinical study is critical to confirm product safety. This study aims to determine the probable toxicity effects of local and systemic injections of cryopreserved human bone marrow-derived clonal MSCs (BM-cMSCs) during subacute and subchronic periods of time.

METHODS

BM-cMSCs were characterized according to the International Society for Cell and Gene Therapy (ISCT) criteria for MSCs. Both safety and toxicity of the BM-cMSCs population produced under GMP-compatible conditions were assessed in both sexes of Sprague Dawley (SD) rats via systemic intravenous (IV) administration and local injection in intervertebral disc (IVD). Behavioral changes, clinical signs of toxicity, and changes in body weight, water and food consumption were the important variables for product toxicity testing over 14 consecutive days during the subacute period and 90 consecutive days during the subchronic period. At the end of the assessment periods, the rats were killed for histopathology analysis of the target tissues. The BM-cMSCs potential for tumorigenicity was checked in nude mice.

RESULTS

Single IV and IVD injections of BM-cMSCs did not cause significant signs of clinical toxicity, or changes in laboratory and histopathology data during the subacute (14 day) and subchronic (90 day) periods. Ex vivo-expanded and cryopreserved BM-cMSCs did not induce tumor formation in nude mice.

CONCLUSION

The results suggest that local and systemic administrations of xenogeneic BM-cMSCs in both sexes of SD rats do not cause toxicity during the subacute and subchronic periods of time. Also, BM-cMSCs were non-tumorigenic in nude mice.

Current status of clinical trials assessing mesenchymal stem cell therapy for graft versus host disease: a systematic review

Background

Graft-versus-host disease (GVHD) is a common fatal complication of hematopoietic stem cell transplantation (HSCT), where steroids are used as a treatment option. However, there are currently no second-line treatments for patients that develop steroid-resistance (SR). Mesenchymal stem cells (MSCs) have immunomodulatory functions and can exert immunosuppressive effects on the inflammatory microenvironment. A large number of in vitro experiments have confirmed that MSCs can significantly inhibit the proliferation or activation of innate and adaptive immune cells. In a mouse model of GVHD, MSCs improved weight loss and increased survival rate. Therefore, there is great promise for the clinical translation of MSCs for the prevention or treatment of GVHD, and several clinical trials have already been conducted to date.

Main body

In this study, we searched multiple databases and found 79 clinical trials involving the use of MSCs to prevent or treat GVHD and summarized the characteristics of these clinical trials, including study design, phase, status, and locations. We analyzed the results of these clinical trials, including the response and survival rates, to enable researchers to obtain a comprehensive understanding of the field’s progress, challenges, limitations, and future development trends. Additionally, factors that might result in inconsistencies in clinical trial results were discussed.

Conclusion

In this study, we attempted to analyze the clinical trials for MSCs in GVHD, identify the most suitable group of patients for MSC therapy, and provide a new perspective for the design of such trials in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02751-0.

Strategies to address mesenchymal stem/stromal cell heterogeneity in immunomodulatory profiles to improve cell-based therapies

Mesenchymal stromal cells (MSCs) have gained immense attention over the past two decades due to their multipotent differentiation potential and pro-regenerative and immunomodulatory cytokine secretory profiles. Their ability to modulate the host immune system and promote tolerance has prompted several allogeneic and autologous hMSC-based clinical trials for the treatment of graft-versus-host disease and several other immune-induced disorders. However, clinical success beyond safety is still controversial and highly variable, with inconclusive therapeutic benefits and little mechanistic explanation. This clinical variability has been broadly attributed to inconsistent MSC sourcing, phenotypic characterization, variable potency, and non-standard isolation protocols, leading to functional heterogeneity among administered MSCs. Homogeneous MSC populations are proposed to yield more predictable, reliable biological responses and clinically meaningful properties relevant to cell-based therapies. Limited comparisons of heterogeneous MSCs with homogenous MSCs are reported. This review addresses this gap in the literature with a critical analysis of strategies aimed at decreasing MSC heterogeneity concerning their reported immunomodulatory profiles. STATEMENT OF SIGNIFICANCE: This review collates, summarizes, and critically analyzes published strategies that seek to improve homogeneity in immunomodulatory functioning MSC populations intended as cell therapies to treat immune-based disorders, such as graft-vs-host-disease. No such review for MSC therapies, immunomodulatory profiles and cell heterogeneity analysis is published. Since MSCs represent the most clinically studied experimental cell therapy platform globally for which there remains no US domestic marketing approval, insights into MSC challenges in therapeutic product development are imperative to providing solutions for immunomodulatory variabilities.

Infusion of Mesenchymal Stem Cells to Treat Graft Versus Host Disease: the Role of HLA-G and the Impact of its Polymorphisms

Hematopoietic stem-cell transplantation is widely performed for the treatment of hematologic diseases and is increasingly being used for the experimental treatment of various autoimmune diseases. Despite the rapid evolution of this therapy, the mortality rate of patients undergoing this procedure is still high, mainly due to the development of graft versus host disease (GvHD). Even with the administration of immunosuppressive therapy, some patients manifest the chronic form of the disease. For these cases, infusion of mesenchymal stem cells (MSCs) was proposed as a therapeutic strategy, considering the immunosuppressive potential of these cells. This review describes the main results obtained in cell therapy with MSCs for the treatment of GvHD. Despite the encouraging results found, some points differed among the studies. Although the factors that influence the different results are uncertain, some investigators have suggested that variations in immunosuppressive molecules are responsible for these divergences. We highlight the key role of the HLA-G gene in modulating the immune response, and the importance of the polymorphisms and alleles of this gene associated with the outcome of the transplants. We suggest that the HLA-G gene and its polymorphisms be analyzed as a factor in selecting the MSCs to be used in treating GvHD, given its strong immunosuppressive role.

Immunomodulating functions of human leukocyte antigen-G and its role in graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapeutic strategy to treat several hematological malignancies and non-hematological malignancies. However, graft-versus-host disease (GVHD) is a frequent and serious transplant-related complication which dramatically restrains the curative effect of allo-HSCT and a significant cause of morbidity and mortality in allogeneic HCT recipients. Effective prevention of GVHD mainly depends on the induction of peripheral immune tolerance. Human leukocyte antigen-G (HLA-G) is a non-classical MHC class I molecule with a strong immunosuppressive function, which plays a prominent role in immune tolerance. HLA-G triggers different reactions depending on the activation state of the immune cells and system. It also exerts a long-term immune tolerance mechanism by inducing regulatory cells. In this present review, we demonstrate the immunomodulatory properties of human leukocyte antigen-G and highlight the role of HLA-G as an immune regulator of GVHD. Furthermore, HLA-G could also serve as a good predictor of GVHD and represent a new therapeutic target for GVHD.

Mesenchymal stem cells and immune disorders: from basic science to clinical transition

As a promising candidate seed cell type in regenerative medicine, mesenchymal stem cells (MSCs) have attracted considerable attention. The unique capacity of MSCs to exert a regulatory effect on immunity in an autologous/allergenic manner makes them an attractive therapeutic cell type for immune disorders. In this review, we discussed the current knowledge of and advances in MSCs, including its basic biological properties, i.e., multilineage differentiation, secretome, and immunomodulation. Specifically, on the basis of our previous work, we proposed three new concepts of MSCs, i.e., "subtotipotent stem cell" hypothesis, MSC system, and "Yin and Yang" balance of MSC regulation, which may bring new insights into our understanding of MSCs. Furthermore, we analyzed data from the Clinical Trials database ( http://clinicaltrials.gov ) on registered clinical trials using MSCs to treat a variety of immune diseases, such as graft-versus-host disease, systemic lupus erythematosus, and multiple sclerosis. In addition, we highlighted MSC clinical trials in China and discussed the challenges and future directions in the field of MSC clinical application.

Human peripheral blood-derived mesenchymal stem cells with NTRK1 over-expression enhance repairing capability in a rat model of Parkinson's disease

The potency of mesenchymal stem cells (MSCs) for tissue repair and regeneration is mainly based on their ability to secret beneficial molecules. Administration of MSCs has been proposed as an innovative approach and is proved by a number of clinical trials to a certain degree for the therapy of many diseases including Parkinson's disease (PD). However, the efficacy of MSCs alone is not significant. We investigated the effect of neurotrophic tyrosine receptor kinase 1 (NTRK1) overexpressed peripheral blood MSCs (PB-MSCs) on PD rat model. NTRK1 was overexpressed in PB-MSCs, which were then injected into PD rat model, Dopaminergic (DA) neuron regeneration and rotational performance was assessed. We found that DA neuron repair was increased in lesion site, rotational performance was also improved in MSC transplanted PD rat, with most potent effect in NTRK1 overexpressed PB-MSC transplanted PD rat. Our results indicate that overexpression of NTRK1 in MSCs could be an optimized therapeutic way via MSCs for PD treatment.

Effects of over-expression of SOD2 in bone marrow-derived mesenchymal stem cells on traumatic brain injury

Intravenous administration of bone marrow-derived mesenchymal stem cells (BM-MSCs) has been shown to promote nerve cell regeneration following traumatic brain injury (TBI). As the anti-oxidant defense systems in neuronal tissue including superoxide dismutase 2 (SOD2) are crucial to defend cell against oxidative stress. We proposed a new stratege to increase the therapeutic effect of MSCs by preventing cells death from oxidative stress. We overexpressed SOD2 in BM-MSCs, transplanted these MSCs into TBI model mice, assessed the protective effect of SOD2 against oxidation-induced apoptosis in BM-MSCs both in vitro and in vivo, evaluated brain functional recovery by the rotarod behavioral test, and tested the oxidation status of TBI mice brain after BM-MSCs transplantation by monitoring the superoxide dismutase, glutathione and malonaldehyde level. We found over-expression of SOD2 protected BM-MSCs from H₂O₂-induced cell apoptosis. Injection of SOD2 over-expressed BM-MSCs attenuated neuro-inflammation in the ipsilateral cortex of TBI mice, and protected TBI mice against loss of blood-brain barrier integrity. Furthermore, the rotarod behavioral test showed functional recovery of TBI mice after MSC treatment. Our experiments indicated that SOD2-over-expressed BM-MSCs have an improved therapeutic effect on brain injury treatment in TBI mice.

Immunomodulatory mechanisms of mesenchymal stem cells and their therapeutic applications

In the recent years, many studies have shown that MSCs must be stimulated by pro-inflammatory cytokines or other immune mediators before they can modulate immune cells in inflamed and damaged tissues. MSCs appear to be involved in inducing several regulatory immune cells, such as Tregs, Bregs, and regulatory NK cells. This new immune milieu created by MSCs may establish a tolerogenic environment that leads to an optimal condition for the treatment of immune diseases. The mechanisms of MSC action to treat immune disorders need to be further investigated in more detail. Since there have been some contradictory outcomes of clinical trials, it is necessary to perform large-scale and randomized clinical studies, such as a phase 3 placebo-controlled double-blind study of a third party MSCs to optimize MSC administration and to prove safety and efficacy of MSC treatment. MSCs offer great therapeutic promise, especially for the treatment of difficult-to-treat immune diseases.

Transplantation of human bone marrow-derived clonal mesenchymal stem cells reduces fibrotic scar formation in a rat spinal cord injury model

This study aimed to evaluate the therapeutic effect on tissue repair and scar formation of human bone marrow-derived clonal mesenchymal stem cells (hcMSCs) homogeneously isolated by using a subfractionation culturing method, in comparison with the non-clonal MSCs (hMSCs), in a rat spinal cord injury (SCI) model. The SCI was made using a vascular clip at the T9 level. Cells were transplanted into the lesion site 3 days after injury. A functional test was performed over 4 weeks employing a BBB score. Rats were killed for histological analysis at 3 days, 1 week and 4 weeks after injury. The transplantation of hMSCs and hcMSCs significantly reduced lesion size and the fluid-filled cavity at 4 weeks in comparison with the control group injected with phosphate buffered saline (PBS) (p < 0.01). Transplantation of hcMSCs showed more axons reserved than that of hMSCs in the lesion epicentre filled with non-neuronal tissues. In addition, hMSCs and hcMSCs clearly reduced the inflammatory reaction and intraparenchymal hemorrhaging, compared with the PBS group. Interestingly, hcMSCs largely decreased Col IV expression, one of the markers of fibrotic scars. hcMSCs yielded therapeutic effects more than equal to those of hMSCs on the SCI. Both hMSCs and hcMSCs created an increase in axon regeneration and reduced scar formation around the SCI lesion. Copyright © 2017 John Wiley & Sons, Ltd.

Recipient bone marrow-derived stromal cells prolong graft survival in a rat hind limb allotransplantation model

BACKGROUND

Recent studies have indicated that bone marrow-derived stromal cells (BMSCs) have immunomodulatory properties that suppress the T cell responses that cause graft rejection. The purpose of this study is to evaluate the effect of recipient BMSCs intravenous infusion for immunomodulation in a rat vascularized composite allotransplantation model.

METHODS

A total of nine Wistar (WIS) rats and thirty Lewis (LEW) rats were used. BMSCs were harvested from three LEW rats. Twenty-four LEW rats were used as recipients and divided randomly into four groups: BMSC group, FK group, UT group, and Iso group. In the BMSC group, orthotopic rat hind limb transplantation was performed between WIS donor and LEW recipient rats. Recipient rats were injected intravenously with 2 × 10⁶ recipient BMSCs on day 6, and with 0.2 mg/kg/day tacrolimus administered over 7 days (n = 6). In the FK group, recipient rats were treated with tacrolimus alone (n = 6). Rats in the UT group received no immunosuppressive treatment (n = 6). In the Iso group, transplantation was performed from three LEW donor rats to six LEW recipient rats without any immunosuppressive treatment (n = 6). Graft survival was assessed by daily inspection and histology. The immunological reactions of recipients were also evaluated.

RESULTS

The graft survival of recipient rats in the BMSC group (24.5 days) was significantly prolonged in comparison with that of the FK group (18 days) (P < .01). Cytokine expression analysis of the skin of grafted limbs showed that BMSCs treatment significantly decreased IFN-γ mRNA expression of the BMSC group (0.138 ± 0.045) in comparison with that of the FK group (1.049 ± 0.167) (P = .0001). Recipient rats in the BMSC group had significantly reduced serum IFN-γ cytokine levels (1.571 ± 0.779 pg/ml) in comparison with that of the FK group (7.059 ± 1.522 pg/ml) (P = .001). In in vitro study, BMSCs induce T cell hyporesponsiveness in a mixed lymphocyte reaction.

CONCLUSION

BMSCs induce T cell hyporesponsiveness and prolong graft survival in the rat vascularized composite allotransplantation model. BMSCs exhibit immunomodulatory properties against acute rejection that can be realized without the need for significant recipient immunosuppression.