Increasing donor age adversely impacts beneficial effects of bone marrow but not smooth muscle myocardial cell therapy

Fetal adnexa-derived allogeneic mesenchymal stem cells for cardiac regeneration: the future trend of cell-based therapy for age-related adverse conditions

Heart failure is known as the leading cause of mortality and morbidity in adults, not only in USA but worldwide. Since the world's population is aging, the burden of cardiovascular disorders is increasing. Mesenchymal stem/stromal cells (MSCs) from a patient's bone marrow or other tissues have been widely used as the primary source of stem cells for cellular cardiomyoplasty. The incongruencies that exist between various cell-therapy approaches for cardiac diseases could be attributed to variations in cell processing methods, quality of the process, and cell donors. Off-the-shelf preparations of MSCs, enabled by batch processing of the cells and controlled cell processing factories in regulated facilities, may offer opportunities to overcome these problems. In this study, for the first time, we focused on the fetal membranes and childbirth byproducts as a promising source of cells for regenerative medicine. While many studies have described the advantages of cells derived from these organs, their advantage as a source of younger cells has not been sufficiently covered by the literature. Thus, herein, we highlight challenges that may arise from the impairment of the regenerative capacity of MSCs due to donor age and how allograft cells from fetal adnexa can be a promising substitute for the aged patients' stem cells for myocardial regeneration. Moreover, obstacles to the use of off-the-shelf cell-therapy preparations in regenerative medicine are briefly summarized here.

The other side of the coin: mesenchymal stromal cell immortalization beyond evasion of senescence

Mesenchymal stromal cells (MSC) are promising options to cellular therapy to several clinical disorders, mainly because of its ability to immunomodulate and differentiate into different cell types. Even though MSC can be isolated from different sources, a major challenge to understanding the biological effects is that the primary cells undergo replicative senescence after a limited number of cell divisions in culture, requiring time-consuming and technically challenging approaches to get a sufficient cell number for clinical applications. Therefore, a new isolation, characterization, and expansion is necessary every time, which increases the variability and is time-consuming. Immortalization is a strategy that can overcome these challenges. Therefore, here, we review the different methodologies available to cellular immortalization, and discuss the literature regarding MSC immortalization and the broader biological consequences that extend beyond the mere increase in proliferation potential.

Intelligent Hydrogels in Myocardial Regeneration and Engineering

Myocardial infarction (MI) causes impaired cardiac function due to the loss of cardiomyocytes following an ischemic attack. Intelligent hydrogels offer promising solutions for post-MI cardiac tissue therapy to aid in structural support, contractility, and targeted drug therapy. Hydrogels are porous hydrophilic matrices used for biological scaffolding, and upon the careful alteration of ideal functional groups, the hydrogels respond to the chemistry of the surrounding microenvironment, resulting in intelligent hydrogels. This review delves into the perspectives of various intelligent hydrogels and evidence from successful models of hydrogel-assisted treatment strategies.

Effects of rhBMP-2 on Bone Formation Capacity of Rat Dental Stem/Progenitor Cells from Dental Follicle and Alveolar Bone Marrow

Dental stem/progenitor cells are a promising cell sources for alveolar bone (AB) regeneration because of their same embryonic origin and superior osteogenic potential. However, their molecular processes during osteogenic differentiation remain unclear. The objective of this study was to identify the responsiveness of dental follicle cells (DFCs) and AB marrow-derived mesenchymal stem cells (ABM-MSCs) to recombinant human bone morphogenetic protein-2 (rhBMP-2). These cells expressed vimentin and MSC markers and did not express cytokeratin and hematopoietic stem cell markers and showed multilineage differentiation potential under specific culture conditions. DFCs exhibited higher proliferation and colony-forming unit-fibroblast efficiency than ABM-MSCs; rhBMP-2 induced DFCs to differentiate toward a cementoblast/osteoblast phenotype and ABM-MSCs to differentiate only toward a osteoblast phenotype; and rhBMP-2-induced DFCs exhibited higher osteogenic differentiation potential than ABM-MSCs. These cells adhered, grew, and produced extracellular matrix on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA). During a 14-day culture on nHAC/PLA, the extracellular alkaline phosphatase (ALP) activity of DFCs decreased gradually and that of ABM-MSCs increased gradually; rhBMP-2 enhanced their extracellular ALP activity, intracellular osteocalcin (OCN), and osteopontin (OPN) protein expression; and DFCs exhibited higher extracellular ALP activity and intracellular OCN protein expression than ABM-MSCs. When implanted subcutaneously in severe combined immunodeficient mice for 3 months, DFCs+nHAC/PLA+rhBMP-2 obtained higher percentage of bone formation area, OCN, and cementum attachment protein expression and lower OPN expression than ABM-MSCs+nHAC/PLA+rhBMP-2. These results showed that DFCs possessed superior proliferation and osteogenic differentiation potential in vitro, and formed higher quantity and quality bones in vivo. It suggested that DFCs might exhibit a more sensitive responsiveness to rhBMP-2, so that DFCs enter a relatively mature stage of osteogenic differentiation earlier than ABM-MSCs after rhBMP-2 induction. The findings imply that these dental stem/progenitor cells are alternative sources for AB engineering in regenerative medicine, and developing dental tissue may provide better source for stem/progenitor cells.

A Phase I Study to Evaluate Two Doses of Wharton's Jelly-Derived Mesenchymal Stromal Cells for the Treatment of De Novo High-Risk or Steroid-Refractory Acute Graft Versus Host Disease

BACKGROUND

Because of their well-described immunosuppressive properties, allogeneic adult human mesenchymal stromal cells (MSC) derived from bone marrow have demonstrated safety and efficacy in steroid refractory acute graft versus host disease (SR aGVHD). Clinical trials have resulted in variable success and an optimal source of MSC has yet to be defined. Based on the importance of maternal-fetal interface immune tolerance, extraembryonic fetal tissues, such as the umbilical cord, may provide an superior tissue source of MSC to mediate immunomodulation in aGVHD.

METHODS

A two-dose cohort trial allogeneic Wharton's Jelly-derived mesenchymal stromal cells (WJMSC, referred to as MSCTC-0010, here) were tested in 10 patients with de novo high risk (HR) or SR aGVHD post allogeneic hematopoietic stem cell transplantation (allo-HCT). Following Good Manufacturing Practices isolation, expansion and cryostorage, WJMSC were thawed and administered via intravenous infusions on days 0 and 7 at one of two doses (low dose cohort, 2 × 106/kg, n = 5; high dose cohort, 10 × 106/kg, n = 5). To evaluate safety, patients were monitored for infusion related toxicity, Treatment Related Adverse Events (TRAE) til day 42, or ectopic tissue formation at day 90. Clinical responses were monitored at time points up to 180 days post infusion. Serum biomarkers ST2 and REG3α were acquired 1 day prior to first MSCTC-0010 infusion and on day 14.

RESULTS

Safety was indicated, e.g., no infusion-related toxicity, no development of TRAE, nor ectopic tissue formation in either low or high dose cohort was observed. Clinical response was suggested at day 28: the overall response rate (ORR) was 70%, 4 of 10 patients had a complete response (CR) and 3 had a partial response (PR). By study day 90, the addition of escalated immunosuppressive therapy was necessary in 2 of 9 surviving patients. Day 100 and 180 post infusion survival was 90% and 60%, respectively. Serum biomarker REG3α decreased, particularly in the high dose cohort, and with REG3α decrease correlated with clinical response.

CONCLUSIONS

Treatment of patients with de novo HR or SR aGVHD with low or high dose MSCTC-0010 was safe: the infusion was well-tolerated, and no TRAEs or ectopic tissue formation was observed. A clinical improvement was seen in about 70% patients, with 4 of 10 showing a complete response that may have been attributable to MSCTC-0010 infusions. These observations indicate safety of two different doses of MSCTC-0010, and suggest that the 10 × 106 cells/ kg dose be tested in an expanded randomized, controlled Phase 2 trial. Graphical abstract.

The therapeutic impact of human neonatal BMSC in a right ventricular pressure overload model in mice

Objective

To determine the impact of donor age on the therapeutic effect of bone marrow-derived mesenchymal stem cells (BMSCs) in treating adverse remodeling as the result of right ventricle (RV) pressure overload.

Methods

BMSCs were isolated from neonatal (< 1 month), infant (1 month to 1 year), and young children (1 year to 5 years) and were compared in their migration potential, surface marker expression, VEGF secretion, and matrix metalloprotein (MMP) 9 expression. Four-week-old male C57 mice underwent pulmonary artery banding and randomized to treatment and untreated control groups. During the surgery, BMSCs were administered to the mice by intramyocardial injection into the RV free wall. Four weeks later, RV function and tissue were analyzed by echocardiography, histology, and quantitative real-time polymerase chain reaction.

Results

Human neonatal BMSCs demonstrated the greatest migration capacity and secretion of vascular endothelial growth factor but no difference in expression of surface markers. Neonate BMSCs administration resulted in increasing expression of VEGF, a significant reduction in RV wall thickness, and internal diameter in mice after PA banding. These beneficial effects were probably associated with paracrine secretion as no cardiomyocyte transdifferentiation was observed.

Conclusions

Human BMSCs from different age groups have different characteristics, and the youngest BMSCs may favorably impact the application of stem cell-based therapy to alleviate adverse RV remodeling induced by pressure overload.

Enzyme-injected method of enzymatic dispersion at low temperature is effective for isolation of smooth muscle cells from human esophagogastric junction

The present study was conducted to examine the feasibility of in vitro isolation and primary culture of smooth muscle cells (SMCs) from the esophagogastric junction (EGJ). Smooth muscles of EGJ were harvested from 23 patients with esophageal cancer during esophagostomy from January 2015 to December 2017. Enzymatic dispersion (ED) was performed for isolation. Collagenase II and Trypsin/EDTA were applied by enzyme injection (EI) into tissue fragments or immersion of tissue fragments into enzyme solution. Growth characteristics and proliferation [Cell Counting Kit-8 (CCK-8)] of cells were recorded for both smooth muscle cell medium (SMCM) and DMEM/F12 containing 10% newborn bovine serum (10%-F12). All ED methods could isolate primary cells; EI was the most effective method with low collagenase II concentration (0.5 mg/ml) at 4˚C for 14-24 h. Primary cells demonstrated mainly spindle- and long-spindle-shaped with ‘hills and valleys’ morphology. The CCK-8 assay in SMCM showed better proliferation results than in 10%-F12. After passaging for 4-8 generations in SMCM or 2-4 generations in 10%-F12, cells enlarged gradually with passages and lost spindle structures. mRNA and proteins of α-smooth muscle actin (α-SMA), smooth muscle 22 α (SM22α), vimentin, desmin, CD90 and proliferating cell nuclear antigen were detected in tissues and cells with different levels of expression. SMCs of esophageal circular muscle, esophageal longitudinal muscle, gastric circular muscle near sling in gastric bottom and gastric circular muscle near clasp in lesser gastric curvature, all cultured in 10%-F12, exhibited superior smooth muscle phenotypes compared with SMCs cultured in SMCM in terms of α-SMA, SM22α and vimentin expression. The EI method of ED at low temperature appears effective for isolation and primary culture of SMCs from human EGJ in vitro.

Relationship between senescence in macaques and bone marrow mesenchymal stem cells and the molecular mechanism

The relationship between bone marrow mesenchymal stem cells (BMSCs) and aging, as well as the antiaging effects of BMSCs, was observed. An aging macaque BMSC model was established. We isolated BMSCs from young and aged macaques and used RT-PCR and Western blot to confirm the aging-related mRNAs and their expression, revealing that TERT, SIRT1 and SIRT6 expression was decreased in the aged BMSCs. The morphology, immunophenotype, differentiation potential, proliferation potential, and antiaging effects of aged and young BMSCs on 293T cells were compared. The expression of aging-related genes and the difference between the secreted cytokines in natural aging and induced aging BMSCs were observed. The transcriptome of peripheral blood mononuclear cells from macaques was analyzed by high-throughput sequencing. Finally, the transcriptional characteristics and regulatory mechanisms of gene transcription in aging macaques were investigated.

Age-Related Impaired Efficacy of Bone Marrow Cell Therapy for Myocardial Infarction Reflects a Decrease in B Lymphocytes

Treatment of myocardial infarction (MI) with bone marrow cells (BMCs) improves post-MI cardiac function in rodents. However, clinical trials of BMC therapy have been less effective. While most rodent experiments use young healthy donors, patients undergoing autologous cell therapy are older and post-MI. We previously demonstrated that BMCs from aged and post-MI donor mice are therapeutically impaired, and that donor MI induces inflammatory changes in BMC composition including reduced levels of B lymphocytes. Here, we hypothesized that B cell alterations in bone marrow account for the reduced therapeutic potential of post-MI and aged donor BMCs. Injection of BMCs from increasingly aged donor mice resulted in progressively poorer cardiac function and larger infarct size. Flow cytometry revealed fewer B cells in aged donor bone marrow. Therapeutic efficacy of young healthy donor BMCs was reduced by depletion of B cells. Implantation of intact or lysed B cells improved cardiac function, whereas intact or lysed T cells provided only minor benefit. We conclude that B cells play an important paracrine role in effective BMC therapy for MI. Reduction of bone marrow B cells because of age or MI may partially explain why clinical autologous cell therapy has not matched the success of rodent experiments.

Combination of MSC spheroids wrapped within autologous composite sheet dually protects against immune rejection and enhances stem cell transplantation efficacy

Mesenchymal stem cells (MSCs) are widely used in transplantation therapy due to their multilineage differentiation potential, abundance, and immuno-modulating ability. However, the risk of allograft rejection limits their application. Here, we proposed a novel method to facilitate MSC transplantation with enhanced applicability and efficacy. We cultured human adipose-derived MSCs in a 3D culture under in vitro expansion conditions and under conventional 2D adherent culture conditions. MSC spheroids promoted extracellular matrix molecules that stimulate MSC proliferation, and produced more angiogenic cytokines such as vascular endothelial growth factor, hepatocyte growth factor, and fibroblast growth factor than 2D-cultured MSCs. Further, MSC spheroids showed increased IDO expression, increased proportion of M2 macrophages, and decreased macrophage proliferation, compared to 2D-cultured MSCs. Next, we proposed the wrapping of autologous cell sheets from the recipient around in-vitro-grown MSC spheroids to prevent allogenic immune rejection during transplantation. Myoblasts from C57BL/6 mice were used to prepare a stem cell composite sheet containing human-derived MSC spheres. The transplantation of MSC spheroids increased the survival rate and decreased the inflammatory response of the immunocompetent C57BL/6 ischemic mice. Thus, combining 3D-cultured MSC spheroid technology with immune evasion stem cell composite sheet improved the outcome and strengthened the protection against allogenic immune rejection.

Emerging roles of extracellular vesicles in cardiac repair and rejuvenation

Cell therapy has received significant attention as a therapeutic approach to restore cardiac function after myocardial infarction. Accumulating evidence supports that beneficial effects observed with cell therapy are due to paracrine secretion of multiple factors from transplanted cells, which alter the tissue microenvironment and orchestrate cardiac repair processes. Of these paracrine factors, extracellular vesicles (EVs) have emerged as a key effector of cell therapy. EVs regulate cellular function through the transfer of cargo, such as microRNAs and proteins, which act on multiple biological pathways within recipient cells. These discoveries have led to the development of cell-free therapies using EVs to improve cardiac repair after a myocardial infarction. Here, we present an overview of the current use of EVs to enhance cardiac repair after myocardial infarction. We also discuss the emerging use of EVs for rejuvenation-based therapies. Finally, future directions for the use of EVs as therapeutic agents for cardiac regenerative medicine are also discussed.

Differentiation of umbilical cord mesenchymal stem cells into hepatocytes in comparison with bone marrow mesenchymal stem cells

Mesenchymal stem cells (MSCs) are considered to be an ideal source for the cell therapy of end-stage liver diseases. Umbilical cord (UC)-MSCs can be obtained via a non-invasive procedure and can be easily cultured, making them potentially superior candidates for cell transplantation when compared with MSCs from other sources. In the present study, UC-MSCs were induced to differentiate into hepatocytes and were compared with bone marrow (BM)-MSCs for their hepatic differentiation potential. UC-MSCs showed significantly higher proliferation than BM-MSCs. Under hepatic induction, UC-MSCs and BM-MSCs could differentiate into hepatocytes. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis revealed that a higher expression of the hepatocyte-specific genes albumin, cytochrome P450 3A4 (CYP3A4), tyrosine-aminotransferase, glucose-6phosphate, α1 antitrypsin and α-fetoprotein was detected in differentiated UC-MSCs when compared with differentiated BM-MSCs. The results of ELISA and western blotting were in accordance with those of RT-qPCR. Theses results indicated that UC-MSCs had higher hepatic differentiation potential than BM-MSCs. Therefore, UC-MSCs may be advantageous over BM-MSCs for the treatment of end-stage liver disease.

Aged Human Multipotent Mesenchymal Stromal Cells Can Be Rejuvenated by Neuron-Derived Neurotrophic Factor and Improve Heart Function After Injury

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The benefits of cell transplantation for cardiac repair are diminished in older individuals and effective methods to rejuvenate aged stem cells are needed to treat the increasing number of older patients with heart failure.

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Over-expressing NDNF in old hBM-MSCs rejuvenated the cells, increasing their proliferative capacity and reducing cellular apoptosis.

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In vivo engraftment of NDNF-overexpressing old hBM-MSCs into the ischemic area of mouse hearts improved cardiac function after myocardial infarction, while promoting engrafted stem cell survival and proliferation and decreasing cell senescence.

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NDNF rejuvenated aged human stem cells, improving their capability to repair the aged heart after ischemic injury through Activation of Akt singling.

Reduced regenerative capacity of aged stem cells hampers the benefits of autologous cell therapy for cardiac regeneration. This study investigated whether neuron-derived neurotrophic factor (NDNF) could rejuvenate aged human bone marrow (hBM)- multipotent mesenchymal stromal cells (MSCs) and whether the rejuvenated hBM-MSCs could improve cardiac repair after ischemic injury. Over-expression of NDNF in old hBM-MSCs decreased cell senescence and apoptosis. Engraftment of NDNF over-expressing old hBM-MSCs into the ischemic area of mouse hearts resulted in improved cardiac function after myocardial infarction, while promoting implanted stem cell survival. Our findings suggest NDNF could be a new factor to rejuvenate aged stem cells and improve their capability to repair the aged heart after injury.

Angiogenic potency evaluation of cell therapy candidates by a novel application of the in vitro aortic ring assay

Background

Due to limitations of current angiogenesis assays, we aimed to develop a novel application of the rat aortic ring assay to assess the angiogenic potential of mesenchymal stromal cells (MSCs). First-trimester human umbilical cord-derived perivascular cells (FTM HUCPVCs) have multipotent characteristics and previously demonstrated angiogenic potential. We compared the effect of this young source of MSCs and adult bone marrow stromal cells (BMSCs) on ex vivo aortic endothelial network formation.

Methods

Thoracic segments of adult rat aortas were isolated, sectioned and embedded into Matrigel™. Fluorophore-labeled FTM HUCPVC lines and BMSCs (N = 3) were cocultured with developing endothelial networks (day 0). MSC integration, tube formation and endothelial network growth were monitored daily using phase-contrast and fluorescence microscopy. Quantification of endothelial networks was performed using ImageJ network analysis software on day 5 of coculture.

Results

FTM HUCPVCs from two umbilical cord samples migrated toward and integrated with developing aortic ring tubular networks while displaying elongated morphologies (day 1). In contrast, BMSCs did not show targeted migration and maintained spherical morphologies with limited physical interactions. Within 1 week of coculture, FTM HUCPVC lines contributed to significantly greater radial network growth and network loop formation when compared to BMSCs and untreated networks.

Conclusions

We have developed a novel potency assay to assess the angiogenic potential of cell therapy candidates. Favorable properties of FTM HUCPVCs over BMSCs that we observed with this assay and which merit further study include chemotaxis, affinity for developing vasculature, and physical supportive interactions contributing to the development of endothelial networks.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0631-1) contains supplementary material, which is available to authorized users.

PIM1-minicircle as a therapeutic treatment for myocardial infarction

PIM1, a pro-survival gene encoding a serine/ threonine kinase, influences cell proliferation and survival. Modification of cardiac progenitor cells (CPCs) or cardiomyocytes with PIM1 using a lentivirus-based delivery method showed long-term improved cardiac function after myocardial infarction (MI). However, lentivirus based delivery methods have stringent FDA regulation with respect to clinical trials. To provide an alternative and low risk PIM1 delivery method, this study examined the use of a non-viral modified plasmid-minicircle (MC) as a vehicle to deliver PIM1 into mouse CPCs (mCPCs) in vitro and the myocardium in vivo. MC containing a turbo gfp reporter gene (gfp-MC) was used as a transfection and injection control. PIM1 was subcloned into gfp-MC (PIM1-MC) and then transfected into mCPCs at an efficiency of 29.4±3.7%. PIM1-MC engineered mCPCs (PIM1-mCPCs) exhibit significantly (P<0.05) better survival rate under oxidative treatment. PIM1-mCPCs also exhibit 1.9±0.1 and 2.2±0.2 fold higher cell proliferation at 3 and 5 days post plating, respectively, as compared to gfp-MC transfected mCPCs control. PIM1-MC was injected directly into ten-week old adult FVB female mice hearts in the border zone immediately after MI. Delivery of PIM1 into myocardium was confirmed by GFP⁺ cardiomyocytes. Mice with PIM1-MC injection showed increased protection compared to gfp-MC injection groups measured by ejection fraction at 3 and 7 days post injury (P = 0.0379 and P = 0.0262 by t-test, respectively). Success of PIM1 delivery and integration into mCPCs in vitro and cardiomyocytes in vivo by MC highlights the possibility of a non-cell based therapeutic approach for treatment of ischemic heart disease and MI.

Young Bone-Marrow Sca-1+ Stem Cells Rejuvenate the Aged Heart and Improve Function after Injury through PDGFRβ-Akt pathway

Bone marrow (BM) reconstitution with young BM cells in aged recipients restores the functionality of cardiac resident BM-derived progenitors. This study investigated the cell type primarily responsible for this effect. We reconstituted old mice with BM cells from young or old mice and found that the number of stem cell antigen 1 (Sca-1) cells homing to the heart was significantly greater in young than old chimeras. We then reconstituted old mice with young BM Sca-1⁺ or Sca-1⁻ cells. We found that Sca-1 cells repopulated the recipient BM and homed to the heart. The number of BM-derived cells in the aged myocardium co-expressing PDGFRβ was 3 times greater in Sca-1⁺ than Sca-1⁻ chimeric mice. Sca-1⁺ chimeras had more active cell proliferation in the infarcted heart and improved ventricular function after MI. The improved regeneration involved activation of the PDGFRβ/Akt/p27^Kip1 pathway. Sca-1⁺ stem cells rejuvenated cardiac tissue in aged mice. Restoration of the Sca-1⁺ subset of stem cells by BM reconstitution improved cardiac tissue regeneration after injury in aged mice.

Optimizing stem cells for cardiac repair: Current status and new frontiers in regenerative cardiology

Cell therapy has the potential to improve healing of ischemic heart, repopulate injured myocardium and restore cardiac function. The tremendous hope and potential of stem cell therapy is well understood, yet recent trials involving cell therapy for cardiovascular diseases have yielded mixed results with inconsistent data thereby readdressing controversies and unresolved questions regarding stem cell efficacy for ischemic cardiac disease treatment. These controversies are believed to arise by the lack of uniformity of the clinical trial methodologies, uncertainty regarding the underlying reparative mechanisms of stem cells, questions concerning the most appropriate cell population to use, the proper delivery method and timing in relation to the moment of infarction, as well as the poor stem cell survival and engraftment especially in a diseased microenvironment which is collectively acknowledged as a major hindrance to any form of cell therapy. Indeed, the microenvironment of the failing heart exhibits pathological hypoxic, oxidative and inflammatory stressors impairing the survival of transplanted cells. Therefore, in order to observe any significant therapeutic benefit there is a need to increase resilience of stem cells to death in the transplant microenvironment while preserving or better yet improving their reparative functionality. Although stem cell differentiation into cardiomyocytes has been observed in some instance, the prevailing reparative benefits are afforded through paracrine mechanisms that promote angiogenesis, cell survival, transdifferentiate host cells and modulate immune responses. Therefore, to maximize their reparative functionality, ex vivo manipulation of stem cells through physical, genetic and pharmacological means have shown promise to enable cells to thrive in the post-ischemic transplant microenvironment. In the present work, we will overview the current status of stem cell therapy for ischemic heart disease, discuss the most recurring cell populations employed, the mechanisms by which stem cells deliver a therapeutic benefit and strategies that have been used to optimize and increase survival and functionality of stem cells including ex vivo preconditioning with drugs and a novel “pharmaco-optimizer” as well as genetic modifications.

Class II transactivator knockdown limits major histocompatibility complex II expression, diminishes immune rejection, and improves survival of allogeneic bone marrow stem cells in the infarcted heart

This study was performed to investigate how to overcome immunorejection associated with allogeneic stem cell therapy in the infarcted heart. Allogeneic bone marrow mesenchymal stem cell (MSC) differentiation increases major histocompatibility complex II (MHC II) expression, inducing transition from immunoprivileged to immunogenic phenotype. MHC II expression is regulated by the class II transactivator (CIITA). We isolated and characterized mouse and human MSCs and knocked down CIITA expression. Wild-type (WT) or CIITA-knockout (CIITA(-)) mouse MSCs were implanted into infarcted mouse myocardia, and recipient allo-antibody formation, cell survival, and cardiac function were measured. WT mouse and human MSCs that were myogenically differentiated showed increased MHC II and CIITA expression. Differentiated CIITA(-) MSCs lacked MHC II induction and showed reduced cytotoxicity in allogeneic leukocyte coculture. Differentiation of human MSCs increased MHC II expression, which resulted in cytotoxicity in allogeneic leukocyte coculture and was prevented by CIITA small interfering RNA. In contrast to WT MSCs, CIITA(-) MSCs did not initiate recipient allo-antibody formation and instead survived in the injured myocardium and significantly improved ventricular function. Decreasing CIITA expression in allogeneic MSCs abolished MHC II induction during myogenic differentiation and prevented immunorejection of these cells from the infarcted myocardium, which enhanced beneficial functional effects of MSC implantation on myocardial repair.-Huang, X.-P., Ludke, A., Dhingra, S., Guo, J., Sun, Z., Zhang, L., Weisel, R. D., Li, R.-K. Class II transactivator knockdown limits major histocompatibility complex II expression, diminishes immune rejection, and improves survival of allogeneic bone marrow stem cells in the infarcted heart.

Knockdown of SIRT6 Enables Human Bone Marrow Mesenchymal Stem Cell Senescence

Autologous bone marrow mesenchymal stem cell (BM-MSC) transplantation is a novel strategy for treating ischemic heart disease. However, limited benefits have been reported in aging patients. Rejuvenation of aged human BM-MSCs (hBM-MSCs) could be a means to improve the efficacy of stem cell transplantation in older patients. While it has been shown that sirtuin 6 (SIRT6) is an important antiaging factor in various cells, the role of SIRT6 in hBM-MSCs remains unknown. The hBM-MSCs from different ages were cultured for quantifying SIRT6 expression by mRNA and Western blotting. The cell proliferative and migration abilities were evaluated by BrdU staining, cell growth curves, and scratch assay. Senescence-associated β-galactosidase (SA-β-Gal) activity and aging-associated p16 (cyclin-dependent kinase inhibitor 2A) expression were also quantified. The knockdown of SIRT6 in hBM-MSCs was used to investigate its impact on aging. SIRT6 expression increased with age, while the proliferative and migration abilities of aged hBM-MSCs were decreased compared with young cells. Knockdown of SIRT6 impaired the proliferative, migration, and oxidative stress resistance potentials of BM-MSCs. SA-β-Gal activity and p16 expression were increased in aged cells compared with young ones and in siRNA SIRT6 knockdown cells compared with their controls. Aging results in compensatory overexpression of SIRT6 in hBM-MSCs. Downregulation of SIRT6 in these cells resulted in less cell proliferation and migration but increased SA-β-Gal activity and p16 expression. These results suggest that SIRT6 regulates the aging process in hBM-MSCs and could serve as a target for their rejuvenation.

Standardizing Umbilical Cord Mesenchymal Stromal Cells for Translation to Clinical Use: Selection of GMP-Compliant Medium and a Simplified Isolation Method

Umbilical cord derived mesenchymal stromal cells (UC-MSCs) are a focus for clinical translation but standardized methods for isolation and expansion are lacking. Previously we published isolation and expansion methods for UC-MSCs which presented challenges when considering good manufacturing practices (GMP) for clinical translation. Here, a new and more standardized method for isolation and expansion of UC-MSCs is described. The new method eliminates dissection of blood vessels and uses a closed-vessel dissociation following enzymatic digestion which reduces contamination risk and manipulation time. The new method produced >10 times more cells per cm of UC than our previous method. When biographical variables were compared, more UC-MSCs per gram were isolated after vaginal birth compared to Caesarian-section births, an unexpected result. UC-MSCs were expanded in medium enriched with 2%, 5%, or 10% pooled human platelet lysate (HPL) eliminating the xenogeneic serum components. When the HPL concentrations were compared, media supplemented with 10% HPL had the highest growth rate, smallest cells, and the most viable cells at passage. UC-MSCs grown in 10% HPL had surface marker expression typical of MSCs, high colony forming efficiency, and could undergo trilineage differentiation. The new protocol standardizes manufacturing of UC-MSCs and enables clinical translation.

Patient-Specific Age: The Other Side of the Coin in Advanced Mesenchymal Stem Cell Therapy

Multipotential mesenchymal stromal cells (MSC) are present as a rare subpopulation within any type of stroma in the body of higher animals. Prominently, MSC have been recognized to reside in perivascular locations, supposedly maintaining blood vessel integrity. During tissue damage and injury, MSC/pericytes become activated, evade from their perivascular niche and are thus assumed to support wound healing and tissue regeneration. In vitro MSC exhibit demonstrated capabilities to differentiate into a wide variety of tissue cell types. Hence, many MSC-based therapeutic approaches have been performed to address bone, cartilage, or heart regeneration. Furthermore, prominent studies showed efficacy of ex vivo expanded MSC to countervail graft-vs.-host-disease. Therefore, additional fields of application are presently conceived, in which MSC-based therapies potentially unfold beneficial effects, such as amelioration of non-healing conditions after tendon or spinal cord injury, as well as neuropathies. Working along these lines, MSC-based scientific research has been forged ahead to prominently occupy the clinical stage. Aging is to a great deal stochastic by nature bringing forth changes in an individual fashion. Yet, is aging of stem cells or/and their corresponding niche considered a determining factor for outcome and success of clinical therapies?

Inhibition of Akt/mTOR attenuates age-related changes in mesenchymal stem cells

The decline in mesenchymal stem cell (MSC) self-renewal and function with aging contributes to diseases associated with impaired osteogenesis. MSC donor age in prolonged culture also limits the therapeutic potential of these cells for tissue engineering and regenerative medicine. Here, we demonstrate an intervention to preserve the immature state MSC and consequently maintain self-renewal and differentiation capacity during in vitro aging. We showed that blocking of phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (mTOR) prevents the development of an age-related phenotype and maintains MSC morphology of early passage cells with high clonogenic frequency and enhanced proliferative capacity. MSC cultured in the presence of inhibitors of Akt or mTOR also robustly maintain their osteogenic potential, that is otherwise lost during in vitro aging. We further report that these effects may be mediated by induction of expression of pluripotency genes Nanog and Oct-4 and by the reduction in the production of cytoplasmic reactive oxygen species (ROS). Additionally, loss of Akt/mTOR and ROS was accompanied with lower levels of DNA damage. These results provide an insight into mechanisms involved in MSC aging and suggest possible interventions to maintain quiescence and function of MSC prior to in vivo transplantation or as pharmacological agents in diseases associated with loss of MSC function.

Use of mesenchymal stem cells for therapy of cardiac disease

Despite substantial clinical advances over the past 65 years, cardiovascular disease remains the leading cause of death in America. The past 15 years has witnessed major basic and translational interest in the use of stem and precursor cells as a therapeutic agent for chronically injured organs. Among the cell types under investigation, adult mesenchymal stem cells are widely studied, and in early stage, clinical studies show promise for repair and regeneration of cardiac tissues. The ability of mesenchymal stem cells to differentiate into mesoderm- and nonmesoderm-derived tissues, their immunomodulatory effects, their availability, and their key role in maintaining and replenishing endogenous stem cell niches have rendered them one of the most heavily investigated and clinically tested type of stem cell. Accumulating data from preclinical and early phase clinical trials document their safety when delivered as either autologous or allogeneic forms in a range of cardiovascular diseases, but also importantly define parameters of clinical efficacy that justify further investigation in larger clinical trials. Here, we review the biology of mesenchymal stem cells, their interaction with endogenous molecular and cellular pathways, and their modulation of immune responses. Additionally, we discuss factors that enhance their proliferative and regenerative ability and factors that may hinder their effectiveness in the clinical setting.

The Effect of Umbilical Cord Blood Derived Mesenchymal Stem Cells in Monocrotaline-induced Pulmonary Artery Hypertension Rats

Pulmonary arterial hypertension (PAH) causes right ventricular failure due to a gradual increase in pulmonary vascular resistance. The purposes of this study were to confirm the engraftment of human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) placed in the correct place in the lung and research on changes of hemodynamics, pulmonary pathology, immunomodulation and several gene expressions in monocrotaline (MCT)-induced PAH rat models after hUCB-MSCs transfusion. The rats were grouped as follows: the control (C) group; the M group (MCT 60 mg/kg); the U group (hUCB-MSCs transfusion). They received transfusions via the external jugular vein a week after MCT injection. The mean right ventricular pressure (RVP) was significantly reduced in the U group after the 2 week. The indicators of RV hypertrophy were significantly reduced in the U group at week 4. Reduced medial wall thickness in the pulmonary arteriole was noted in the U group at week 4. Reduced number of intra-acinar muscular pulmonary arteries was observed in the U group after 2 week. Protein expressions such as endothelin (ET)-1, endothelin receptor A (ERA), endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 significantly decreased at week 4. The decreased levels of ERA, eNOS and MMP-2 immunoreactivity were noted by immnohistochemical staining. After hUCB-MSCs were administered, there were the improvement of RVH and mean RVP. Reductions in several protein expressions and immunomodulation were also detected. It is suggested that hUCB-MSCs may be a promising therapeutic option for PAH.

Uterine-derived progenitor cells are immunoprivileged and effectively improve cardiac regeneration when used for cell therapy

Cell therapy to prevent cardiac dysfunction after myocardial infarction (MI) is less effective in aged patients because aged cells have decreased regenerative capacity. Allogeneic transplanted stem cells (SCs) from young donors are usually rejected. Maintaining transplanted SC immunoprivilege may dramatically improve regenerative outcomes. The uterus has distinct immune characteristics, and we showed that reparative uterine SCs home to the myocardium post-MI. Here, we identify immunoprivileged uterine SCs and assess their effects on cardiac regeneration after allogeneic transplantation. We found more than 20% of cells in the mouse uterus have undetectable MHC I expression by flow cytometry. Uterine MHC I((neg)) and MHC I((pos)) cells were separated by magnetic cell sorting. The MHC I((neg)) population expressed the SC markers CD34, Sca-1 and CD90, but did not express MHC II or c-kit. In vitro, MHC I((neg)) and ((pos)) SCs show colony formation and endothelial differentiation capacity. In mixed leukocyte co-culture, MHC I((neg)) cells showed reduced cell death and leukocyte proliferation compared to MHC I((pos)) cells. MHC I((neg)) and ((pos)) cells had significantly greater angiogenic capacity than mesenchymal stem cells. The benefits of intramyocardial injection of allogeneic MHC I((neg)) cells after MI were comparable to syngeneic bone marrow cell transplantation, with engraftment in cardiac tissue and limited recruitment of CD4 and CD8 cells up to 21 days post-MI. MHC I((neg)) cells preserved cardiac function, decreased infarct size and improved regeneration post-MI. This new source of immunoprivileged cells can induce neovascularization and could be used as allogeneic cell therapy for regenerative medicine.

Wharton's Jelly-Derived Mesenchymal Stromal Cells as a Promising Cellular Therapeutic Strategy for the Management of Graft-versus-Host Disease

Allogeneic hematopoietic cell transplantation (allo-HCT), a treatment option in hematologic malignancies and bone marrow failure syndromes, is frequently complicated by Graft-versus-host disease (GVHD). The primary treatment for GVHD involves immune suppression by glucocorticoids. However, patients are often refractory to the steroid therapy, and this results in a poor prognosis. Therefore alternative therapies are needed to treat GVHD. Here, we review data supporting the clinical investigation of a novel cellular therapy using Wharton’s jelly (WJ)-derived mesenchymal stromal cells (MSCs) as a potentially safe and effective therapeutic strategy in the management of GVHD. Adult-derived sources of MSCs have demonstrated signals of efficacy in the management of GVHD. However, there are limitations, including: limited proliferation capacity; heterogeneity of cell sources; lengthy expansion time to clinical dose; expansion failure in vitro; and a painful, invasive, isolation procedure for the donor. Therefore, alternative MSC sources for cellular therapy are sought. The reviewed data suggests MSCs derived from WJ may be a safe and effective cellular therapy for GVHD. Laboratories investigated and defined the immune properties of WJ-MSCs for potential use in cellular therapy. These cells represent a more uniform cell population than bone marrow-derived MSCs, displaying robust immunosuppressive properties and lacking significant immunogenicity. They can be collected safely and painlessly from individuals at birth, rapidly expanded and stored cryogenically for later clinical use. Additionally, data we reviewed suggested licensing MSCs (activating MSCs by exposure to cytokines) to enhance effectiveness in treating GVHD. Therefore, WJCs should be tested as a second generation, relatively homogeneous allogeneic cell therapy for the treatment of GVHD.

Effect of mild heat stress on the proliferative and differentiative ability of human mesenchymal stromal cells

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are an attractive candidate for autologous cell therapy, but regenerative potential can be compromised with extensive in vitro cell passaging. Development of viable cell therapies must address the effect of in vitro passaging to maintain overall functionality of expanded MSCs.

METHODS

We examined the effect of repeated mild heat shock on the proliferation and differentiation capability of human adipose-derived MSCs. Adipose tissue MSCs were characterized by means of fluorescence activated cell sorting analysis for expression of CD3, CD14, CD19, CD34, CD44, CD45, CD73, CD90 and CD105. Similarly, the expression of SIRT-1, p16(INK4a) and p21 was determined by means of polymerase chain reaction. Measurements of population doubling, doubling time and superoxide dismutase activity were also determined. Differentiation of expanded MSCs into bone and adipose were analyzed qualitatively and quantitatively.

RESULTS

The strategy led to an increase in expression of SIRT-1 concomitant with enhanced viability, proliferation and delayed senescence. The stressed MSCs showed better differentiation into osteoblasts and adipocytes.

CONCLUSIONS

The results indicate that mild heat shock could be used to maintain MSC proliferative and differentiation potential.

Aberrant gene expression profiles, during in vitro osteoblast differentiation, of telomerase deficient mouse bone marrow stromal stem cells (mBMSCs)

Background

Telomerase deficiency has been associated with inadequate differentiation of mesenchymal stem cells. However, the effect of telomerase deficiency on differential regulation of osteoblast specific genes, based on functional gene grouping, during in vitro osteoblast differentiation has not been reported before.

Results

To examine these effects, Terc^-/- BMSCs (bone marrow stromal stem cells) were employed which exhibited reduced proliferation during in vitro osteogenesis along with increased population doubling time and level compared to wild type (WT) BMSCs during the normal culture. Osteogenic super array at day 10 of osteoblast differentiation revealed that telomerase deficiency strongly affected the osteoblast commitment by down-regulating Runx2, Twist and Vdr – known transcription regulators of osteogenesis. Similarly, in Terc^-/- BMSCs a marked reduction in other genes engaged in various phases of osteoblast differentiation were observed, such as Fgfr2 involved in bone mineralization, Phex and Dmp1 engaged in ossification, and Col11a1 and Col2a1 involved in cartilage condensation. A similar trend was observed for genes involved in osteoblast proliferation (Tgfb1, Fgfr2 and Pdgfa) and bone mineral metabolism (Col1a1, Col2a1, Col1a2 and Col11a1). More profound changes were observed in genes engaged in extracellular matrix production: Col1a1, Col1a2, Mmp10, Serpinh1 and Col4a1.

Conclusion

Taken together, these data suggest that telomerase deficiency causes impairment of BMSCs differentiation into osteoblasts affecting commitment, proliferation, matrix mineralization and maturation. Thus, modulating telomerase in BMSCs with advanced aging could improve BMSCs responsiveness towards osteoblast differentiation signals, optimal for osteoblast commitment, proliferation and maturation processes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-015-0116-4) contains supplementary material, which is available to authorized users.

Characterization of bone marrow-derived mesenchymal stem cells in aging

Adult mesenchymal stem cells are a resource for autologous and allogeneic cell therapies for immune-modulation and regenerative medicine. However, patients most in need of such therapies are often of advanced age. Therefore, the effects of the aged milieu on these cells and their intrinsic aging in vivo are important considerations. Furthermore, these cells may require expansion in vitro before use as well as for future research. Their aging in vitro is thus also an important consideration. Here, we focus on bone marrow mesenchymal stem cells (BMSCs), which are unique compared to other stem cells due to their support of hematopoietic cells in addition to contributing to bone formation. BMSCs may be sensitive to age-related diseases and could perpetuate degenerative diseases in which bone remodeling is a contributory factor. Here, we review (1) the characterization of BMSCs, (2) the characterization of in vivo-aged BMSCs, (3) the characterization of in vitro-aged BMSCs, and (4) potential approaches to optimize the performance of aged BMSCs. This article is part of a Special Issue entitled "Stem Cells and Bone".

p16(INK4A) mediates age-related changes in mesenchymal stem cells derived from human dental pulp through the DNA damage and stress response

Mesenchymal stem cells derived from human dental pulp (DP-MSCs) are characterized by self-renewal and multi-lineage differentiation, which play important roles in regenerative medicine. Autologous transfers, as non-immunogenic, constitute the safest approach in cellular transplantations. However, their use may be limited by age-related changes. In the study, we compared DP-MSCs isolated from human in five age groups: 5-12 y, 12-20 y, 20-35 y, 35-50 y, and >50 y. We tested the effect of age on proliferation, differentiation, senescence-associated β-galactosidase (SA-β-gal), cell cycle and programmed cell death. DP-MSCs showed characteristics of senescence as a function of age. Meanwhile, the expression of p16(INK4A) and γ-H2A.X significantly increased with age, whereas heat shock protein 60 (HSP60) was decreased in the senescent DP-MSCs. Reactive oxygen species (ROS) staining showed the number of ROS-stained cells and the DCFH fluorescent level were higher in the aged group. Further we examined the senescence of DP-MSCs after modulating p16(INK4A) signaling. The results indicated the dysfunction of DP-MSCs was reversed by p16(INK4A) siRNA. In summary, our study indicated p16(INK4A) pathway may play a critical role in DP-MSCs age-related changes and the DNA damage response (DDR) and stress response may be the main mediators of DP-MSCs senescence induced by excessive activation of p16(INK4A) signaling.

Immunogenicity of allogeneic mesenchymal stem cells transplanted via different routes in diabetic rats

Due to their hypoimmunogenicity and unique immunosuppressive properties, mesenchymal stem cells (MSCs) are considered one of the most promising adult stem cell types for cell therapy. Although many studies have shown that MSCs exert therapeutic effects on several acute and subacute conditions, their long-term effects are not confirmed in chronic diseases. Immunogenicity is a major limitation for cell replacement therapy, and it is not well understood in vivo. We evaluated the immunogenicity of allogeneic MSCs in vivo by transplanting MSCs into normal and diabetic rats via the tail vein or pancreas and found that MSCs exhibited low immunogenicity in normal recipients and even exerted some immunosuppressive effects in diabetic rats during the initial phase. However, during the later stage in the pancreas group, MSCs expressed insulin and MHC II, eliciting a strong immune response in the pancreas. Simultaneously, the peripheral blood mononuclear cells in the recipients in the pancreas group were activated, and alloantibodies developed in vivo. Conversely, in the tail vein group, MSCs remained immunoprivileged and displayed immunosuppressive effects in vivo. These data indicate that different transplanting routes and microenvironments can lead to divergent immunogenicity of MSCs.

Decreased SIRT3 in aged human mesenchymal stromal/stem cells increases cellular susceptibility to oxidative stress

Sirtuin3 (SIRT3) is an important member of the sirtuin family of protein deacetylases that is localized to mitochondria and linked to lifespan extension in organisms ranging from yeast to humans. As aged cells have less regenerative capacity and are more susceptible to oxidative stress, we investigated the effect of ageing on SIRT3 levels and its correlation with antioxidant enzyme activities. Here, we show that severe oxidative stress reduces SIRT3 levels in young human mesenchymal stromal/stem cells (hMSCs). Overexpression of SIRT3 improved hMSCs resistance to the detrimental effects of oxidative stress. By activating manganese superoxide dismutase (MnSOD) and catalase (CAT), SIRT3 protects hMSCs from apoptosis under stress. SIRT3 expression, levels of MnSOD and CAT, as well as cell survival showed little difference in old versus young hMSCs under normal growth conditions, whereas older cells had a significantly reduced capacity to withstand oxidative stress compared to their younger counterparts. Expression of the short 28 kD SIRT3 isoform was higher, while the long 44 kD isoform expression was lower in young myocardial tissues compared with older ones. These results suggest that the active short isoform of SIRT3 protects hMSCs from oxidative injury by increasing the expression and activity of antioxidant enzymes. The expression of this short isoform decreases in cardiac tissue during ageing, leading to a reduced capacity for the heart to withstand oxidative stress.

Loss of Sirt3 limits bone marrow cell-mediated angiogenesis and cardiac repair in post-myocardial infarction

Sirtuin-3 (Sirt3) has a critical role in the regulation of human aging and reactive oxygen species (ROS) formation. A recent study has identified Sirt3 as an essential regulator of stem cell aging. This study investigated whether Sirt3 is necessary for bone marrow cell (BMC)-mediated cardiac repair in post-myocardial infarction (MI). In vitro, BMC-derived endothelial progenitor cells (EPCs) from wild type (WT) and Sirt3KO mice were cultured. EPC angiogenesis, ROS formation and apoptosis were assessed. In vivo, WT and Sirt3 KO mice were subjected to MI and BMCs from WT and Sirt3 KO mice were injected into ischemic area immediately. The expression of VEGF and VEGFR2 was reduced in Sirt3KO-EPCs. Angiogenic capacities and colony formation were significantly impaired in Sirt3KO-EPCs compared to WT-EPCs. Loss of Sirt3 further enhanced ROS formation and apoptosis in EPCs. Overexpression of Sirt3 or treatment with NADPH oxidase inhibitor apocynin (Apo, 200 and 400 microM) rescued these abnormalities. In post-MI mice, BMC treatment increased number of Sca1⁺/c-kit⁺ cells; enhanced VEGF expression and angiogenesis whereas Sirt3KO-BMC treatment had little effects. BMC treatment also attenuated NADPH oxidase subunits p47^phox and gp91^phox expression, and significantly reduced ROS formation, apoptosis, fibrosis and hypertrophy in post-MI mice. Sirt3KO-BMC treatment did not display these beneficial effects. In contrast, Sirt3KO mice treated with BMCs from WT mice attenuated myocardial apoptosis, fibrosis and improved cardiac function. Our data demonstrate that Sirt3 is essential for BMC therapy; and loss of Sirt3 limits BMC-mediated angiogenesis and cardiac repair in post-MI.

The effect of age and medical comorbidities on in vitro myoblast expansion in women with and without pelvic organ prolapse

INTRODUCTION

This is an observational study is designed to assess the influence of age, prolapse and medical co-morbidities on myogenic stem cells growth in-vitro.

METHODS

A biopsy of the rectus abdominus muscle was obtained during surgery in patients with and without pelvic organ prolapse (POP). Nuclei number and fiber count were correlated with patient's age, presence of POP, and medical comorbidities. Efficiency of expansion of myogenic stem cells in vitro was calculated. The percentage of Pax7-, MyoD-, and desmin-positive cells was correlated with age, POP status, and medical comorbidities.

RESULTS

A total of 17 specimens were obtained; 13 specimens were available for histologic analysis. There was no correlation between patient's age, POP status or medical comorbidities and nuclei or fiber count, growth rate, or the percentage of Pax7- and MyoD-positive cells. Patients with 2 to 4 medical comorbidities were noted to have a significantly lower percentage of desmin-positive cells. Specimens with a higher nuclear count had significantly better cellular expansion. Data were analyzed using Kruskal-Wallis or Wilcoxon rank sum statistics.

CONCLUSIONS

Multiple medical comorbidities but not patient's age or POP status influenced in vitro myogenic stem cell growth. These data suggest that patients with advancing age or POP may be acceptable autologous donors if treatment of urinary or anal incontinence requires myoblast transplantation.

The promise and challenges of cardiac stem cell therapy

After an extensive myocardial infarction, restoration of heart function depends on the ability of the heart to promote regeneration and prevent adverse ventricular remodeling. Preclinical research demonstrated that the transplantation of healthy stem cells restored heart function, but the stem cells obtained from older animals or patients were not as efficacious as those from younger individuals. In this paper, we review the successes and limitations discovered in preclinical studies and clinical trials examining cell therapy for damaged hearts. After the modest successes of the early clinical trials, research is now exploring the benefits of enhanced stem cell therapy. Cell based gene therapy markedly improves the angiogenesis achieved. Rejuvenating aged stems cells prior to transplantation restores the functional benefits attained. Transplanting healthy allogeneic stem cells from young donors into aged individuals can restore function if rejection can be prevented. Finally, modulating the cellular environment in aged individuals permits the full functional benefits of stem cell therapy to be realized. Significant challenges remain, but these approaches show promise that cell therapy may become routine therapy to improve functional recovery of older patients after an extensive myocardial infarction.

The rejuvenation of aged stem cells for cardiac repair

Rejuvenation is one of the greatest challenges of modern science. Aging affects every tissue and organ in the body, leading to a deterioration of normal function and inhibition of repair mechanisms. Cell therapy has received much attention for its potential to regenerate organs, but in the context of cardiac repair, the initial clinical trials in aged patients did not replicate the dramatic benefits recorded in preclinical studies with young animals. The benefits of autologous cell therapy are reduced in the elderly, the largest target group for regenerative medicine. Adult stem cell functionality decreases with age which impairs tissue regeneration. In this review we discuss the age-related changes in stem cell function, with particular attention to stem cell therapy in heart disease. We also focus on possible mechanisms of adult stem cell aging and targets for rejuvenation strategies to reverse the aging process. We provide useful insights on how to apply this knowledge to advance cellular therapies for heart disease.

Stem Cell Banking for Regenerative and Personalized Medicine

Regenerative medicine, tissue engineering and gene therapy offer the opportunity to treat and cure many of today’s intractable afflictions. These approaches to personalized medicine often utilize stem cells to accomplish these goals. However, stem cells can be negatively affected by donor variables such as age and health status at the time of collection, compromising their efficacy. Stem cell banking offers the opportunity to cryogenically preserve stem cells at their most potent state for later use in these applications. Practical stem cell sources include bone marrow, umbilical cord blood and tissue, and adipose tissue. Each of these sources contains stem cells that can be obtained from most individuals, without too much difficulty and in an economical fashion. This review will discuss the advantages and disadvantages of each stem cell source, factors to be considered when contemplating banking each stem cell source, the methodology required to bank each stem cell source, and finally, current and future clinical uses of each stem cell source.

Optimization of the cardiovascular therapeutic properties of mesenchymal stromal/stem cells-taking the next step

Despite current treatment options, cardiac failure is associated with significant morbidity and mortality highlighting a compelling clinical need for novel therapeutic approaches. Based on promising pre-clinical data, stem cell therapy has been suggested as a possible therapeutic strategy. Of the candidate cell types evaluated, mesenchymal stromal/stem cells (MSCs) have been widely evaluated due to their ease of isolation and ex vivo expansion, potential allogeneic utility and capacity to promote neo-angiogenesis and endogenous cardiac repair. However, the clinical application of MSCs for mainstream cardiovascular use is currently hindered by several important limitations, including suboptimal retention and engraftment and restricted capacity for bona fide cardiomyocyte regeneration. Consequently, this has prompted intense efforts to advance the therapeutic properties of MSCs for cardiovascular disease. In this review, we consider the scope of benefit from traditional plastic adherence-isolated MSCs and the lessons learned from their conventional use in preclinical and clinical studies. Focus is then given to the evolving strategies aimed at optimizing MSC therapy, including discussion of cell-targeted techniques that encompass the preparation, pre-conditioning and manipulation of these cells ex vivo, methods to improve their delivery to the heart and innovative substrate-directed strategies to support their interaction with the host myocardium.

Restoration of angiogenic capacity of diabetes-insulted mesenchymal stem cells by oxytocin

Background

Angiogenesis is the main therapeutic mechanism of cell therapy for cardiovascular diseases, but diabetes is reported to reduce the function and number of progenitor cells. Therefore, we studied the effect of streptozotocin-induced diabetes on the bone marrow-mesenchymal stem cell (MSC) function, and examined whether diabetes-impaired MSC could be rescued by pretreatment with oxytocin.

Results

MSCs were isolated and cultured from diabetic (DM) or non-diabetic (non-DM) rat, and proliferation rate was compared. DM-MSC was pretreated with oxytocin and compared with non-DM-MSC. Angiogenic capacity was estimated by tube formation and Matrigel plug assay, and therapeutic efficacy was studied in rat myocardial infarction (MI) model.

The proliferation and angiogenic activity of DM-MSC were severely impaired but significantly improved by pretreatment with oxytocin. Krüppel-like factor 2 (KLF2), a critical angiogenic factor, was dramatically reduced in DM-MSC and significantly restored by oxytocin. In the Matrigel plug assay, vessel formation of DM-BMSCs was attenuated but was recovered by oxytocin. In rat MI model, DM-MSC injection did not ameliorate cardiac injury, whereas oxytocin-pretreated DM-MSC improved cardiac function and reduced fibrosis.

Conclusions

Our results show that diabetes influenced MSC by reducing angiogenic capacity and therapeutic potential. We demonstrate the striking effect of oxytocin on stem cell dysfunction and suggest the use of oxytocin as a priming reagent in autologous stem cell therapy.

A critical challenge: dosage-related efficacy and acute complication intracoronary injection of autologous bone marrow mesenchymal stem cells in acute myocardial infarction

BACKGROUND

Previous studies showed improvement in heart function by injecting bone marrow mesenchymal stem cells (BMSCs) after AMI. Emerging evidence suggested that both the number and function of BMSCs decline with ageing. We designed a randomized, controlled trial to further investigate the safety and efficacy of this treatment.

METHODS

Patients with ST-elevation AMI undergoing successful reperfusion treatment within 12 hours were randomly assigned to receive an intracoronary infusion of BMSCs (n=21) or standard medical treatment (n=22) (the numbers of patients were limited because of the complication of coronary artery obstruction).

RESULTS

There is a closely positive correlation of the number and function of BMSCs vs. the cardiac function reflected by LVEF at baseline (r=0.679, P=0.001) and at 12-month follow-up (r=0.477, P=0.039). Six months after cell administration, myocardial viability within the infarct area by 18-FDG SPECT was improved in both groups compared with baseline, but no significant difference in the BMSCs compared with control groups (4.0±0.4% 95%CI 3.1-4.9 vs. 3.2±0.5% 95%CI 2.1-4.3, P=0.237). 99mTc-sestamibi SPECT demonstrated that myocardial perfusion within the infarct area in the BMSCs did not differ from the control group (4.4±0.5% 95%CI 3.2-5.5 vs. 3.9±0.6% 95%CI 2.6-5.2, P=0.594). Similarly, LVEF after 12 and 24 months follow-up did not show any difference between the two groups. In the BMSCs group, one patient suffered a serious complication of coronary artery occlusion during the BMSCs injection procedure.

CONCLUSIONS

The clinical benefits of intracoronary injection of autologous BMSCs in acute STEMI patients need further investigation and reevaluation.

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.

Recent Patents Pertaining to Immune Modulation and Musculoskeletal Regeneration with Wharton's Jelly Cells

Umbilical cord mesenchymal stromal cells (UCMSCs) are isolated from Wharton's jelly in the umbilical cord at birth, and offer advantages over adult mesenchymal stromal cells (MSCs) such as highly efficient isolation, faster proliferation in vitro, a broader differentiation potential, and non-invasive harvesting procedure. Their expansion and differentiation potential renders them a promising cell source for tissue engineering and clinical applications. This review discusses recent updates on the differentiation strategies for musculoskeletal tissue engineering including cartilage, bone, and muscle. In addition to tissue engineering applications, UCMSCs can be utilized to support hematopoiesis and modulate immune response. We review the patents relevant to the application of MSCs including UCMSCs in hematopoiesis and immune modulation. Finally, the current hurdles in the clinical translation of UCMSCs are discussed. During clinical translation, it is critical to develop large-scale manufacturing of UCMSCs as well as the composition of expansion and differentiation media. Four clinical trials to date have examined the safety and efficacy of UCMSCs. Once public banking of UCMSCs is available to supply matched allogeneic units and once UCMSC manufacturing is standardized, we anticipate that UCMSCs will be more widely used in clinical trials.

Aged human cells rejuvenated by cytokine enhancement of biomaterials for surgical ventricular restoration

OBJECTIVES

This study investigated whether cytokine enhancement of a biodegradable patch could restore cardiac function after surgical ventricular restoration (SVR) even when seeded with cells from old donors.

BACKGROUND

SVR can partially restore heart size and improve function late after an extensive anterior myocardial infarction. However, 2 limitations include the stiff synthetic patch used and the limited healing of the infarct scar in aged patients.

METHODS

We covalently immobilized 2 proangiogenic cytokines (vascular endothelial growth factor and basic fibroblast growth factor) onto porous collagen scaffolds. We seeded human mesenchymal stromal cells from young (50.0 ± 8.0 years, N = 4) or old (74.5 ± 7.4 years, N = 4) donors into the scaffolds, with or without growth factors. The patches were characterized and used for SVR in a rat model of myocardial infarction. Cardiac function was assessed.

RESULTS

In vitro results showed that cells from old donors grew slower in the scaffolds. However, the presence of cytokines modulated the aging-related p16 gene and enhanced cell proliferation, converting the old cell phenotype to a young phenotype. In vivo studies showed that 28 days after SVR, patches seeded with cells from old donors did not induce functional recovery as well as patches seeded with young cells. However, cytokine-enhanced patches seeded with old cells exhibited preserved patch area, prolonged cell survival, and augmented angiogenesis, and rats implanted with these patches had better cardiac function. The patch became an elastic tissue, and the old cells were rejuvenated.

CONCLUSIONS

This sustained-release, cytokine-conjugated system provides a promising platform for engineering myocardial tissue for aged patients with heart failure.

Tissue inhibitor of matrix metalloproteinase-3 or vascular endothelial growth factor transfection of aged human mesenchymal stem cells enhances cell therapy after myocardial infarction

Mesenchymal stem cell (MSC) transplantation has been proposed as a potential therapeutic approach for ischemic heart disease, but the regenerative capacity of these cells decreases with age. In this study, we genetically engineered old human MSCs (O-hMSCs) with tissue inhibitor of matrix metalloproteinase-3 (TIMP3) and vascular endothelial growth factor (VEGF) and evaluated the effects on the efficacy of cell-based gene therapy in a rat myocardial infarction (MI) model. Cultured O-hMSCs were transfected with TIMP3 (O-TIMP3) or VEGF (O-VEGF) and compared with young hMSCs (Y-hMSCs) and non-transfected O-hMSCs for growth, clonogenic capacity, and differentiation potential. In vivo, rats were subjected to left coronary artery ligation with subsequent injection of Y-hMSCs, O-hMSCs, O-TIMP3, O-VEGF, or medium. Echocardiography was performed prior to and at 1, 2, and 4 weeks after MI. Myocardial levels of matrix metalloproteinase-2 (MMP2), MMP9, TIMP3, and VEGF were assessed at 1 week. Hemodynamics, morphology, and histology were measured at 4 weeks. In vitro, genetically modified O-hMSCs showed no changes in growth, colony formation, or multi-differentiation capacity. In vivo, transplantation with O-TIMP3, O-VEGF, or Y-hMSCs increased capillary density, preserved cardiac function, and reduced infarct size compared to O-hMSCs and medium control. O-TIMP3 and O-VEGF transplantation enhanced TIMP3 and VEGF expression, respectively, in the treated animals. O-hMSCs genetically modified with TIMP3 or VEGF can increase angiogenesis, prevent adverse matrix remodeling, and restore cardiac function to a degree similar to Y-hMSCs. This gene-modified cell therapy strategy may be a promising clinical treatment to rejuvenate stem cells in elderly patients.

Bone marrow derived mesenchymal stem cells from aged mice have reduced wound healing, angiogenesis, proliferation and anti-apoptosis capabilities

Decline in the function of stem cells with age, such as other cells of the body, results in an imbalance between loss and renewal. Increasing age of the donor thus diminishes the effectiveness of MSCs (mesenchymal stem cells) transplantation in age-related diseases. The clinical use of stem cell therapies needs autologous stem cell transplantation; it is essential therefore to study the repair ability and survivability of cells before transplantation. Bone marrow derived MSCs possess multi-lineage differentiation potential, but aging adversely affects their therapeutic efficacy. MSCs from young (2-3 months) and aged (23-24 months) GFP (green fluorescent protein)-expressing C57BL/6 mice were isolated and their regenerative potential was assessed in vitro. Real-time RT-PCR (reverse transcriptase-PCR) showed significantly higher expression of Sirt1 in MSCs isolated from young than older animals. Down-regulation of VEGF (vascular endothelial growth factor), SDF-1 (stromal-cell-derived factor 1), AKT (also known as protein kinase B) and up-regulation of p53, p21, Bax and p16 occurred in aged cells. Tube formation, wound healing and proliferative abilities of the young MSCs were better than the aged MSCs. The results suggest that age-related increased expression of apoptotic and senescent genes, with concomitant decrease in Sirt1 gene expression, inhibits to some extent stem cell functioning.

Reconstitution of aged bone marrow with young cells repopulates cardiac-resident bone marrow-derived progenitor cells and prevents cardiac dysfunction after a myocardial infarction

AIMS

The study was designed to evaluate the mechanisms of cardiac regeneration after injury and to determine how to restore that capacity in aged individuals. The adult heart retains a small population of nascent cells that have myeloid, mesenchymal, and mesodermal capabilities, which play an essential role in the recovery of ventricular function after injury. In aged individuals, these cells are diminished and dysfunctional. We evaluated the derivation of some of these cardiac progenitors and a method to restore their number and function.

METHODS AND RESULTS

We first demonstrated that aged mice have fewer progenitors in both the bone marrow (BM) and the myocardium, which correlated with the extent of cardiac dysfunction after injury. Bone marrow chimerism established in aged mice with young BM donors restored both myocardial progenitors and cardiac function, but neither was restored with aged BM donors. Cardiac micro-chimerism in aged mice was established with young BM cells, which restored cardiac function after injury, even with old peripheral BM cells. The young cardiac-resident BM-derived progenitor cells in the aged myocardium persisted for at least a year, and after myocardial infarction they actively proliferated and enhanced cardiac repair through paracrine mechanisms.

CONCLUSION

Bone marrow reconstitution with young BM cells in aged recipients restored progenitors in both the BM and, most importantly, the myocardium. The number and function of cardiac-resident BM-derived progenitor cells in the aged myocardium prior to injury was the major determinant for successful recovery of cardiac function. The aged heart was rejuvenated with young BM cells.

Umbilical cord mesenchymal stem cells suppress B-cell proliferation and differentiation

Mesenchymal stem cells (MSCs) may be obtained from umbilical cord as an abundant and noninvasive source. However, the immunomodulatory properties of umbilical cord-MSCs (UC-MSCs) were poorly studied. In this study, we aimed to investigate the effects of UC-MSCs on B-cell proliferation and differentiation. UC-MSCs were found to suppress the proliferation of B cells isolated from murine spleen. Moreover, UC-MSCs markedly suppressed B-cell differentiation as shown by the decreased number of CD138+cells and reduced levels of IgM and IgG production in coculture. As revealed by transwell experiments, soluble factors produced by UC-MSCs might be involved in mediating B-cell suppression. The Blimp-1 mRNA expression was suppressed whereas the PAX-5 mRNA expression was induced in coculture. Finally, UC-MSCs modified the phosphorylation pattern of Akt and p38 pathways, which were involved in B-cell proliferation and differentiation. These results may further support the potential therapeutic use of UC-MSCs in treating autoimmune disorders.