Emerging therapeutic approaches for multipotent mesenchymal stromal cells

Promising role for mesenchymal stromal cells in coronavirus infectious disease-19 (COVID-19)-related severe acute respiratory syndrome?

Mesenchymal stromal cells (MSC) have immune regulatory and tissue regenerative properties. MSCs are being studied as a therapy option for many inflammatory and immune disorders and are approved to treat acute graft-versus-host disease (GvHD). The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic and associated coronavirus infectious disease-19 (COVID-19) has claimed many lives. Innovative therapies are needed. Preliminary data using MSCs in the setting of acute respiratory distress syndrome (ARDS) in COVID-19 are emerging. We review mechanisms of action of MSCs in inflammatory and immune conditions and discuss a potential role in persons with COVID-19.

Preclinical translation of exosomes derived from mesenchymal stem/stromal cells

Exosomes are nanovesicles secreted by virtually all cells. Exosomes mediate the horizontal transfer of various macromolecules previously believed to be cell-autonomous in nature, including nonsecretory proteins, various classes of RNA, metabolites, and lipid membrane-associated factors. Exosomes derived from mesenchymal stem/stromal cells (MSCs) appear to be particularly beneficial for enhancing recovery in various models of disease. To date, there have been more than 200 preclinical studies of exosome-based therapies in a number of different animal models. Despite a growing number of studies reporting the therapeutic properties of MSC-derived exosomes, their underlying mechanism of action, pharmacokinetics, and scalable manufacturing remain largely outstanding questions. Here, we review the global trends associated with preclinical development of MSC-derived exosome-based therapies, including immunogenicity, source of exosomes, isolation methods, biodistribution, and disease categories tested to date. Although the in vivo data assessing the therapeutic properties of MSC-exosomes published to date are promising, several outstanding questions remain to be answered that warrant further preclinical investigation.

Stem cells therapy: a review on approaches that can be used for treatment of respiratory failures in sulfur mustard-injured patients

Sulfur mustard (SM) is a toxic agent which causes severe abnormalities in an airway system such as necrosis and inflammation, oxidative stress, chronic bronchitis, shortness of breath, and chronic obstructive pulmonary disease. Although possible mechanisms of SM toxicity have been extensively considered, there is still need to find an appropriate clinical treatment to decrease chronic lung injuries caused by SM. Due to extensive progresses and achievement in tissue repairing through stem cells therapy, the importance of cell therapy for the treatment of lung injuries has been increased. However, several factors such as types of stem cells, necessary conditions for growth and proliferation of stem cells, and their homing into the target tissues are considered as the most important problems in this issue. Mesenchymal stem cells (MSCs) are a class of multipotent stem cells with proliferative and self-renewal capacity which are able to differentiate into different cell lines such as lung epithelial cells. They have a potential repairing and immune modulatory properties which make them as a good candidate for the regeneration of bronchioles tract in SM-exposed patients. Unlike chemical drugs, the differentiation and high-level safety properties of MSCs can be considered as a new strategy for the treatment of SM-injured patients with pulmonary complications. This review aims to consider the therapeutic effects of MSCs in the treatment of SM-induced pulmonary injuries in both animals and humans.

Concise Review: Multifaceted Characterization of Human Mesenchymal Stem Cells for Use in Regenerative Medicine

Mesenchymal stem cells (MSC) hold great potential for regenerative medicine because of their ability for self-renewal and differentiation into tissue-specific cells such as osteoblasts, chondrocytes, and adipocytes. MSCs orchestrate tissue development, maintenance and repair, and are useful for musculoskeletal regenerative therapies to treat age-related orthopedic degenerative diseases and other clinical conditions. Importantly, MSCs produce secretory factors that play critical roles in tissue repair that support both engraftment and trophic functions (autocrine and paracrine). The development of uniform protocols for both preparation and characterization of MSCs, including standardized functional assays for evaluation of their biological potential, are critical factors contributing to their clinical utility. Quality control and release criteria for MSCs should include cell surface markers, differentiation potential, and other essential cell parameters. For example, cell surface marker profiles (surfactome), bone-forming capacities in ectopic and orthotopic models, as well as cell size and granularity, telomere length, senescence status, trophic factor secretion (secretome), and immunomodulation, should be thoroughly assessed to predict MSC utility for regenerative medicine. We propose that these and other functionalities of MSCs should be characterized prior to use in clinical applications as part of comprehensive and uniform guidelines and release criteria for their clinical-grade production to achieve predictably favorable treatment outcomes for stem cell therapy. Stem Cells Translational Medicine 2017;6:2173-2185.

Mesenchymal Stem Cell Soluble Mediators and Cystic Fibrosis

Human Mesenchymal stem cells (hMSCs) secrete products (supernatants) that are anti-inflammatory and antimicrobial. We have previously shown that hMSCs decrease inflammation and Pseudomonas aeruginosa infection in the in vivo murine model of Cystic Fibrosis (CF). Cystic Fibrosis (CF) is a genetic disease in which pulmonary infection and inflammation becomes the major cause of morbidity and mortality. Our studies focus on determining how MSCs contribute to improved outcomes in the CF mouse model centering on how the MSCs impact the inflammatory response to pathogenic organisms. We hypothesize that MSCs secrete products that are anti-inflammatory in scenarios of chronic pulmonary infections using the murine model of infection and inflammation with a specific interest in Pseudomonas aeruginosa (gram negative). Further, our studies will identify whether the MSCs are impacting this inflammatory response through the regulation of peroxisome proliferator activator receptor gamma (PPARγ) which aides in decreasing inflammation.

Characterization of the Tumor Microenvironment and Tumor-Stroma Interaction by Non-invasive Preclinical Imaging

Tumors are often characterized by hypoxia, vascular abnormalities, low extracellular pH, increased interstitial fluid pressure, altered choline-phospholipid metabolism, and aerobic glycolysis (Warburg effect). The impact of these tumor characteristics has been investigated extensively in the context of tumor development, progression, and treatment response, resulting in a number of non-invasive imaging biomarkers. More recent evidence suggests that cancer cells undergo metabolic reprograming, beyond aerobic glycolysis, in the course of tumor development and progression. The resulting altered metabolic content in tumors has the ability to affect cell signaling and block cellular differentiation. Additional emerging evidence reveals that the interaction between tumor and stroma cells can alter tumor metabolism (leading to metabolic reprograming) as well as tumor growth and vascular features. This review will summarize previous and current preclinical, non-invasive, multimodal imaging efforts to characterize the tumor microenvironment, including its stromal components and understand tumor-stroma interaction in cancer development, progression, and treatment response.

Comparative Clinical Observation of Arthroscopic Microfracture in the Presence and Absence of a Stromal Vascular Fraction Injection for Osteoarthritis

Osteoarthritis (OA) is a degenerative cartilage disease that is characterized by a local inflammatory reaction. Consequently, many studies have been performed to identify suitable prevention and treatment interventions. In recent years, both arthroscopic microfracture (AM) and stem cell therapy have been used clinically to treat OA. This study aimed to evaluate the clinical effects of AM in the presence and absence of a stromal vascular fraction (SVF) injection in the management of patients with OA. Thirty patients with grade 2 or 3 (Lawrence scale) OA of the knee participated in this study. Placebo group patients (n = 15) received AM alone; treatment group patients (n = 15) received AM and an adipose tissue‐derived SVF injection. The SVF was suspended in platelet‐rich plasma (PRP) before injection into the joint. Patient groups were monitored and scored with the Western Ontario and McMaster Universities Arthritis Index (WOMAC), Lysholm, Visual Analog Pain Scale (VAS), and modified Outerbridge classifications before treatment and at 6, 12, and 18 months post‐treatment. Bone marrow edema was also assessed at these time points. Patients were evaluated for knee activity (joint motion amplitude) and adverse effects relating to surgery and stem cell injection. Treatment efficacy was significantly different between placebo and treatment groups. All treatment group patients had significantly reduced pain and WOMAC scores, and increased Lysholm and VAS scores compared with the placebo group. These findings suggest that the SVF/PRP injection efficiently improved OA for 18 months after treatment. This study will be continuously monitored for additional 24 months. Stem Cells Translational Medicine2017;6:187–195

A robust potency assay highlights significant donor variation of human mesenchymal stem/progenitor cell immune modulatory capacity and extended radio-resistance

The inherent immunomodulatory capacity of mesenchymal stem/progenitor cells (MSPCs) encouraged initiation of multiple clinical trials. Release criteria for therapeutic MSPCs cover identity, purity and safety but appropriate potency assessment is often missing. Reports on functional heterogeneity of MSPCs created additional uncertainty regarding donor and organ/source selection. We established a robust immunomodulation potency assay based on pooling responder leukocytes to minimize individual immune response variability. Comparing various MSPCs revealed significant potency inconsistency and generally diminished allo-immunosuppression compared to dose-dependent inhibition of mitogenesis. Gamma-irradiation to block unintended MSPC proliferation did not prohibit chondrogenesis and osteogenesis in vivo, indicating the need for alternative safety strategies.

MicroRNA-181a, a potential diagnosis marker, alleviates acute graft versus host disease by regulating IFN-γ production

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a valuable therapeutic strategy for a wide variety of diseases. Acute graft-versus-host disease (aGVHD) is a major complication in up to 75% of allo-HSCT. The absence of a reliable predicative marker for aGVHD onset prevents preemptive treatment and impedes widespread and successful application of this therapy. In this study we found that after allo-HSCT, the levels of miR-181a were reduced significantly prior to the onset of aGVHD. More importantly, the degree of its reduction correlated with the severity of aGVHD. Mechanistically, miR-181a affects the function of T lymphocytes by down-regulating IFN-γ in a dose-dependent manner. Meanwhile, we confirmed that miR-181a can effectively preserve the anti-leukemic effect in vitro. Using a murine allo-HSCT model, we demonstrated that murine miR-181b, the human miR-181a homolog, served as an effective predictor of aGVHD. Moreover, expression of this microRNA ameliorated the severity of aGVHD. Collectively, these results show that the level of miR-181a may serve as a reliable marker for the diagnosis and prognosis the onset of aGVHD. Am. J. Hematol. 90:998-1007, 2015. © 2015 Wiley Periodicals, Inc.

Extensive Characterization of Platelet Gel Releasate From Cord Blood in Regenerative Medicine

Platelet gel derived from peripheral blood is widely applied in many clinical fields of surgery as biomaterial containing growth factors with high proliferative properties. In 2010, we studied and patented a platelet gel derived from cord blood. In this study, due to the crucial role of the factors released by the platelet gel, we first extended the characterization of its releasate. Using a wide proteomic array and splitting the two components of the releasate, that is, platelets and plasma, we have been able to study their growth factor content. Interestingly, we discovered high levels of hormones and molecules able to support tissue growth in the cord blood platelet gel releasate and, in addition, higher concentrations of several angiogenic factors if compared with the peripheral blood counterpart. On the contrary, the latter was much richer in inflammatory factors. The second aim of our work was to study the effects on cell culture, immunophenotype, and function of mesenchymal stem cells exposed to these two platelet gel releasates as substitute for the animal serum. Since our findings nicely show that the use of the peripheral versus the cord blood platelet gel releasate can differently influence the mesenchymal stem cell commitment, we can suggest that in addition to its peculiar angiogenic properties cord blood platelet gel releasate shows excellent proliferative properties as cell culture supplement.

Single cell-derived clones from human adipose stem cells present different immunomodulatory properties

Human adipose mesenchymal stem cells are a heterogeneous population, where cell cultures derived from single-cell-expanded clones present varying degrees of differential plasticity. This work focuses on the immunomodulatory/anti-inflammatory properties of these cells. To this end, five single-cell clones were isolated (generally called 1.X and 3.X) from two volunteers. Regarding the expression level of the lineage-characteristic surface antigens, clones 1·10 and 1·22 expressed the lowest amounts, while clones 3·10 and 3·5 expressed more CD105 than the rest and clone 1·7 expressed higher amounts of CD73 and CD44. Regarding cytokine secretion, all clones were capable of spontaneously releasing high levels of interleukin (IL)-6 and low to moderate levels of IL-8. These differences can be explained in part by the distinct methylation profile exhibited by the clones. Furthermore, and after lipopolysaccharide stimulation, clone 3.X produced the highest amounts of proinflammatory cytokines such as IL-1β, while clones 1·10 and 1·22 highly expressed IL-4 and IL-5. In co-culture experiments, clones 1.X are, together, more potent inhibitors than clones 3.X for proliferation of total, CD3(+) T, CD4(+) T and CD8(+) T lymphocytes and natural killer (NK) cells. The results of this work indicate that the adipose stem cell population is heterogeneous in cytokine production profile, and that isolation, characterization and selection of the appropriate cell clone is a more exact method for the possible treatment of different patients or pathologies.

Isolation, expansion and characterization of bone marrow-derived mesenchymal stromal cells in serum-free conditions

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) heralded a new beginning for regenerative medicine and generated tremendous interest as the most promising source for therapeutic application. Most cell therapies require stringent regulatory compliance and prefer the use of serum-free media (SFM) or xeno-free media (XFM) for the MSC production process, starting from the isolation onwards. Here, we report on serum-free isolation and expansion of MSCs and compare them with cells grown in conventional fetal bovine serum (FBS)-containing media as a control. The isolation, proliferation and morphology analysis demonstrated significant differences between MSCs cultured in various SFM/XFM in addition to their difference with FBS controls. BD Mosaic™ Mesenchymal Stem Cell Serum-Free media (BD-SFM) and Mesencult-XF (MSX) supported the isolation, sequential passaging, tri-lineage differentiation potential and acceptable surface marker expression profile of BM-MSCs. Further, MSCs cultured in SFM showed higher immune suppression and hypo-immunogenicity properties, making them an ideal candidate for allogeneic cell therapy. Although cells cultured in control media have a significantly higher proliferation rate, BM-MSCs cultured in BD-SFM or MSX media are the preferred choice to meet regulatory requirements as they do not contain bovine serum. While BM-MSCs cultured in BD-SFM and MSX media adhered to all MSC characteristics, in the case of few parameters, the performance of cells cultured in BD-SFM was superior to that of MSX media. Pre-clinical safety and efficiency studies are required before qualifying SFM or XFM media-derived MSCs for therapeutic applications.

Immunomodulatory nature and site specific affinity of mesenchymal stem cells: a hope in cell therapy

Immunosuppressive ability of mesenchymal stem cells (MSCs), their differentiation properties to various specialized tissue types, ease of in vitro and in vivo expansion and specific migration capacity, make them to be tested in different clinical trials for the treatment of various diseases. The immunomodulatory effects of MSCs are less identified which probably has high clinically significance. The clinical trials based on primary research will cause better understanding the ability of MSCs in immunomodulatory applications and site specific migration in the optimization of therapy. So, this review focus on MSCs functional role in modulating immune responses, their ability in homing to tumor, their potency as delivery vehicle and their medical importance.

Safety and immunomodulatory effects of allogeneic canine adipose-derived mesenchymal stromal cells transplanted into the region of the lacrimal gland, the gland of the third eyelid and the knee joint

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have been extensively studied as a cellular therapeutic for various pathologic conditions. However, there remains a paucity of data regarding regional and systemic safety of MSC transplantations, particularly with multiple deliveries of allogeneic cells. The purpose of this study was to investigate the safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs into the region of the lacrimal gland, the gland of the third eyelid and the knee joint in dogs.

METHODS

Allogeneic adipose tissue-derived canine MSCs were delivered to the regions of the lacrimal gland and the third eyelid gland as well as in the knee joints of six healthy laboratory beagles as follows: six times with 1-week intervals for delivery to the lacrimal gland and the third eyelid gland regions and three to four times with 1- to 2-week intervals for intra-articular transplantations. Dogs were sequentially evaluated by clinical examination. At the conclusion of the study, dogs were humanely euthanized, and a complete gross and histopathologic examination of all organ systems was performed. Mixed leukocyte reactions were also performed before the first transplantation and after the final transplantation.

RESULTS

Clinical and pathologic examinations found no severe consequences after repeated MSC transplantations. Results of mixed leukocyte reactions demonstrated suppression of T-cell proliferation after MSC transplantations.

CONCLUSIONS

This is the first study to demonstrate regional and systemic safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs in vivo.

Heterogeneity of the biological properties and gene expression profiles of murine bone marrow stromal cells

Although mesenchymal stromal cells (MSCs) have demonstrated great therapeutic potential, the heterogeneity of MSCs may be responsible for the incongruent data obtained in MSC-based preclinical studies and clinical trials. Here, four mouse clonal MSC lines, termed MSC1, MSC2, MSC3, and MSC4, were isolated and extensively characterized. MSC4 cells grew most rapidly and formed colonies of the largest size, whereas MSC3 cells exhibited the slowest growth and formed only a few tiny clusters. MSC4 cells could differentiate into adipocytes, osteoblasts, and chondrocytes in vitro, and more importantly, establish hematopoietic microenvironment in vivo; whereas the other lines displayed uni-adipogenic, osteo-chondrogenic, or non-differentiation potential. All lines were positive for Sca-1, CD106, and CD44; MSC4 was also positive for CD90.2. In terms of immunosuppressive capacity, MSC2, MSC3, and MSC4 cells exerted clear inhibitory effects on lymphocyte proliferation, whereas MSC1 did not. Further investigation revealed that the NO and not the PGE2 pathway may play a role in the different immunomodulatory effects of the cell lines. To clarify the molecular basis of this heterogeneity, we employed RNA sequencing to compare the gene expression profiles of the four subtypes, revealing a relationship between gene expression and variability in subtype function. This study provides novel information about the heterogeneity of MSCs and insight into the selection of optimal cell sources for therapeutic applications.

Transplantation of Nonexpanded Adipose Stromal Vascular Fraction and Platelet-Rich Plasma for Articular Cartilage Injury Treatment in Mice Model

Stromal vascular fraction (SVF) combined with platelet-rich plasma (PRP) is commonly used in preclinical and clinical osteoarthritis as well as articular cartilage injury treatment. However, this therapy has not carefully evaluated the safety and the efficacy. This research aims to assess the safety and the efficacy of SVF combined with PRP transplantation. Ten samples of SVFs and PRPs from donors were used in this research. About safety, we evaluate the expression of some genes related to tumor formation such as Oct-4, Nanog, SSEA3, and SSEA4 by RT-PCR, flow cytometry, and tumor formation when injected in NOD/SCID mice. About efficacy, SVF was injected with PRP into murine joint that caused joint failure. The results showed that SVFs are negative with Oct-4, Nanog, SSEA-3, and SSEA-4, as well as they cannot cause tumors in mice. SVFs combined with PRP can improve the joint regeneration in mice. These results proved that SVFs combined with PRP transplantation is a promising therapy for articular cartilage injury treatment.

Enhanced healing of diabetic wounds by subcutaneous administration of human umbilical cord derived stem cells and their conditioned media

Objective. Mesenchymal stem cells (MSCs) isolated from the umbilical cord and their conditioned media (CM) can be easily obtained and refined compared with stem cells from other sources. Here, we explore the possibility of the benefits of these cells in healing diabetic wounds. Methodology and Results. Delayed wound healing animal models were established by making a standard wound on the dorsum of eighteen db/db mice, which were divided into three groups with six mice in each: groups I, II, and III received PBS, UC-MSC, and CM, respectively. UC-MSC and their CM significantly accelerated wound closure compared to PBS-treated wounds, and it was most rapid in CM-injected wounds. In day-14 wounds, significant difference in capillary densities among the three groups was noted (n = 6; P < 0.05), and higher levels of VEGF, PDGF, and KGF expression in the CM- and UC-MSC-injected wounds compared to the PBS-treated wounds were seen. The expression levels of PDGF- β and KGF were higher in CM-treated wounds than those in UC-MSC-treated wounds. Conclusion. Both the transplantation of UC-MSC and their CM are beneficial to diabetic wound healing, and CM has been shown to be therapeutically better than UC-MSC, at least in the context of diabetic wound healing.

The immunosuppressive effect of mesenchymal stromal cells on B lymphocytes is mediated by membrane vesicles

The immunomodulatory properties of mesenchymal stromal cells are the subject of increasing interest and of widening clinical applications, but the reproducibility of their effects is controversial and the underlying mechanisms have not been fully clarified. We investigated the transfer of membrane vesicles, a recently recognized pathway of intercellular communication, as possible mediator of the interaction between mesenchymal stromal cells and B lymphocytes. Mesenchymal stromal cells exhibited a strong dose-dependent inhibition of B-cell proliferation and differentiation in a CpG-stimulated peripheral blood mononuclear cell coculture system. We observed that these effects could be fully reproduced by membrane vesicles isolated from mesenchymal stromal cell culture supernatants in a dose-dependent fashion. Next, we evaluated the localization of fluorescently labeled membrane vesicles within specific cell subtypes both by flow cytometry and by confocal microscopy analysis. Membrane vesicles were found to be associated with stimulated B lymphocytes, but not with other cell phenotypes (T lymphocytes, dendritic cells, natural killer cells), in peripheral blood mononuclear cell culture. These results suggest that membrane vesicles derived from mesenchymal stromal cells are the conveyors of the immunosuppressive effect on B lymphocytes. These particles should be further evaluated as immunosuppressive agents in place of the parent cells, with possible advantages in term of standardization, safety, and feasibility.

Mesenchymal stem cells in mammary adipose tissue stimulate progression of breast cancer resembling the basal-type

Data are accumulating to support a role for adipose-derived mesenchymal stem cells (MSCs) in breast cancer progression; however, to date most studies have relied on adipose MSCs from non-breast sources. There is a particular need to investigate the role of adipose MSCs in the pathogenesis of basal-like breast cancer, which develops at a disproportionate rate in pre-menopausal African-American women with a gain in adiposity. The aim of this study was to better understand how breast adipose MSCs (bMSCs) contribute to the progression of basal-like breast cancers by relying on isogenic HMT-3255 S3 (pre-invasive) and T4-2 (invasive) human cells that upon transplantation into nude mice resemble this tumor subtype. In vitro results suggested that bMSCs may contribute to breast cancer progression in multiple ways. bMSCs readily penetrate extracellular matrix components in part through their expression of matrix metalloproteinases 1 and 3, promote the invasion of T4-2 cells and efficiently chemoattract endothelial cells via a bFGF-independent, VEGF-A-dependent manner. As mixed xenografts, bMSCs stimulated the growth, invasion and desmoplasia of T4-2 tumors, yet these resident stem cells showed no observable effect on the progression of pre-invasive S3 cells. While bMSCs form vessel-like structures within Matrigel both in vitro and in vivo and chemoattract endothelial cells, there appeared to be no difference between T4-2/bMSC mixed xenografts and T4-2 xenografts with regard to intra- or peri-tumoral vascularity. Collectively, our data suggest that bMSCs may contribute to the progression of basal-like breast cancers by stimulating growth and invasion but not vasculogenesis or angiogenesis.

The potential of mesenchymal stromal cells as a novel cellular therapy for multiple sclerosis

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease of the CNS for which only partially effective therapies exist. Intense research defining the underlying immune pathophysiology is advancing both the understanding of MS as well as revealing potential targets for disease intervention. Mesenchymal stromal cell (MSC) therapy has the potential to modulate aberrant immune responses causing demyelination and axonal injury associated with MS, as well as to repair and restore damaged CNS tissue and cells. This article reviews the pathophysiology underlying MS, as well as providing a cutting-edge perspective into the field of MSC therapy based upon the experience of authors intrinsically involved in MS and MSC basic and translational science research.

G-CSF-induced myeloid cells stimulated by TLR2 enhance engraftment after allogeneic hematopoietic stem cell transplantation

A high frequency of G-CSF-mobilized myeloid cells (gMCs) in a donor graft accelerates hematopoietic recovery after peripheral blood stem cell transplantation (PBSCT). However, because of the limited functional efficacy of gMCs, repeated transfusions of gMCs are frequently required. In this study, we investigated a strategy to improve the functional capacity of gMCs during hematopoietic engraftment after allogeneic transplantation. We found that toll-like receptor 2 (TLR2) is constitutively expressed on gMCs. Treating gMCs with the synthetic TLR2 ligand Pam(3)CSK(4) (PAM) dramatically enhanced IL-10 and TNF-α production. However, PAM treatment does not induce substantial cellular maturation. Moreover, PAM treatment significantly improved gMC survival. PAM treated gMCs significantly promoted myeloid differentiation of donor hematopoietic stem cells (HSCs), resulting in accelerated engraftment after allogeneic transplantation. Our data suggest that TLR2-stimulated gMCs may be a novel cellular therapeutic for increasing the efficiency of allogeneic hematopoietic stem cell transplantation (HSCT) by reducing infectious complications associated with delayed engraftment.

Autologous stromal vascular fraction therapy for rheumatoid arthritis: rationale and clinical safety

Advancements in rheumatoid arthritis (RA) treatment protocols and introduction of targeted biological therapies have markedly improved patient outcomes, despite this, up to 50% of patients still fail to achieve a significant clinical response. In veterinary medicine, stem cell therapy in the form of autologous stromal vascular fraction (SVF) is an accepted therapeutic modality for degenerative conditions with 80% improvement and no serious treatment associated adverse events reported. Clinical translation of SVF therapy relies on confirmation of veterinary findings in targeted patient populations. Here we describe the rationale and preclinical data supporting the use of autologous SVF in treatment of RA, as well as provide 1, 3, 6, and 13 month safety outcomes in 13 RA patients treated with this approach.

The immunomodulatory capacity of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are currently being tested in clinical trials for the treatment of various diseases owing to the ease of generating and expanding these cells, the ability to differentiate them into various specialized mesenchymal tissue types and their immunosuppressive properties. However, their immunomodulatory potential remains controversial. This review describes the constitutive and regulated expression of molecules of the major histocompatibility complex (MHC) class I antigen processing machinery (APM), co-stimulatory B7 molecules and HLA-G. Furthermore, this review focuses on the secretion of factors, such as cytokines, in mesenchymal stem cells, their functional role in mounting and controlling immune responses mediated by different immune cell subpopulations, their medical significance, and the obstacles that limit their clinical application.

Novel transplant strategies in adults with acute leukemia

Autologous and allogeneic hematopoietic cell transplantation (HCT) is regularly used as a curative treatment option for patients with various disorders, including acute leukemia in adults. The past decade has witnessed dramatic improvements in the reduction of treatment-related mortality (TRM), in part attributable to improved supportive care but also due to better graft selection and donor-to-recipient matching regimens, and the emergence of reduced-intensity conditioning in place of myeloablative conditioning. Despite these advances, HCT remains plagued by the risk of relapse or failure due to graft-versus-host disease, infectious complications, and TRM. This article reviews new approaches that may improve overall patient outcome.

Cell therapy for multiple sclerosis

The spontaneous recovery observed in the early stages of multiple sclerosis (MS) is substituted with a later progressive course and failure of endogenous processes of repair and remyelination. Although this is the basic rationale for cell therapy, it is not clear yet to what degree the MS brain is amenable for repair and whether cell therapy has an advantage in comparison to other strategies to enhance endogenous remyelination. Central to the promise of stem cell therapy is the therapeutic plasticity, by which neural precursors can replace damaged oligodendrocytes and myelin, and also effectively attenuate the autoimmune process in a local, nonsystemic manner to protect brain cells from further injury, as well as facilitate the intrinsic capacity of the brain for recovery. These fundamental immunomodulatory and neurotrophic properties are shared by stem cells of different sources. By using different routes of delivery, cells may target both affected white matter tracts and the perivascular niche where the trafficking of immune cells occur. It is unclear yet whether the therapeutic properties of transplanted cells are maintained with the duration of time. The application of neural stem cell therapy (derived from fetal brain or from human embryonic stem cells) will be realized once their purification, mass generation, and safety are guaranteed. However, previous clinical experience with bone marrow stromal (mesenchymal) stem cells and the relative easy expansion of autologous cells have opened the way to their experimental application in MS. An initial clinical trial has established the probable safety of their intravenous and intrathecal delivery. Short-term follow-up observed immunomodulatory effects and clinical benefit justifying further clinical trials.

Mesenchymal stem cells and their challenges for bone regeneration and osseointegration

Bone regeneration is an indispensable procedure for implant placement. Original techniques based on mesenchymal stromal cell (MSC) therapy are emerging with the goal of speeding up biology, thereby reducing the osseointegration period. Many products found their way in clinical application, yet their reliability remains uncertain because many in vitro culture-related challenges are facing these cells once they are out of their biologic environment. In this commentary, these limitations are discussed with the emphasis of their impact on the performance of MSCs. Clinicians should be aware of these issues before implementing this cell-based regenerative technique.

Whole-organ tissue engineering: decellularization and recellularization of three-dimensional matrix scaffolds

The definitive treatment for end-stage organ failure is orthotopic transplantation. However, the demand for transplantation far exceeds the number of available donor organs. A promising tissue-engineering/regenerative-medicine approach for functional organ replacement has emerged in recent years. Decellularization of donor organs such as heart, liver, and lung can provide an acellular, naturally occurring three-dimensional biologic scaffold material that can then be seeded with selected cell populations. Preliminary studies in animal models have provided encouraging results for the proof of concept. However, significant challenges for three-dimensional organ engineering approach remain. This manuscript describes the fundamental concepts of whole-organ engineering, including characterization of the extracellular matrix as a scaffold, methods for decellularization of vascular organs, potential cells to reseed such a scaffold, techniques for the recellularization process and important aspects regarding bioreactor design to support this approach. Critical challenges and future directions are also discussed.

Wharton's Jelly stem cells: future clinical applications

This review focuses on the therapeutic potential of stem cells harvested from the Wharton's Jelly of the human umbilical cord. Recently, investigators have found that a potent stem cell population exists within the Wharton's Jelly. In this review, the authors define a new subset of stem cells, termed perinatal stem cells, and compare them to other sources of stem cells. Furthermore, cryopreservation of Wharton's Jelly stem cells is described for potential use in future cell based therapies and/or regenerative medicine applications. Current evidence of the application of mesenchymal stem cells from various sources in both pre-clinical and clinical trials is reviewed in the context of potential indications of use for Wharton's Jelly derived mesenchymal stem cells.

Selecting the optimal cell for kidney regeneration: fetal, adult or reprogrammed stem cells

Chronic kidney disease (CKD) is a progressive loss in renal function over a period of months or years. End-stage renal disease (ESRD) or stage 5 CKD ensues when renal function deteriorates to under 15% of the normal range. ESRD requires either dialysis or, preferentially, a kidney organ allograft, which is severely limited due to organ shortage for transplantation. To combat this situation, one needs to either increase supply of organs or decrease their demand. Two strategies therefore exist: for those that have completely lost their kidney function (ESRD), we will need to supply new kidneys. Taking into account the kidneys' extremely complex structure, this may prove to be impossible in the near future. In contrast, for those patients that are in the slow progression route from CKD to ESRD but still have functional kidneys, we might be able to halt progression by introducing stem cell therapy to diseased kidneys to rejuvenate or regenerate individual cell types. Multiple cell compartments that fall into three categories are likely to be worthy targets for cell repair: vessels, stroma (interstitium) and nephron epithelia. Different stem/progenitor cells can be linked to regeneration of specific cell types; hematopoietic progenitors and hemangioblastic cell types have specific effects on the vascular niche (vasculogenesis and angiogenesis). Multipotent stromal cells (MSC), whether derived from the bone marrow or isolated from the kidney's non-tubular compartment, may, in turn, heal nephron epithelia via paracrine mechanisms. Nevertheless, as we now know that all of the above lack nephrogenic potential, we should continue our quest to derive genuine nephron (epithelial) progenitors from differentiated pluripotent stem cells, from fetal and adult kidneys and from directly reprogrammed somatic cells.