Therapeutic potential of mesenchymal stem cells in regenerative medicine

Senescence of mesenchymal stem cells (Review)

Mesenchymal stem cells (MSCs) have been used in cell-based therapy for various diseases, due to their immunomodulatory and inflammatory effects. However, the function of MSCs is known to decline with age, a process that is called senescence. To date, the process of MSC senescence remains unknown as in-depth understanding of the mechanisms involved in cellular senescence is lacking. First, senescent MSCs are so heterogeneous that not all of them express the same phenotypic markers. In addition, the genes and signaling pathways which regulate this process in MSCs are still unknown. Thus, an understanding of the molecular processes controlling MSC senescence is crucial to determining the drivers and effectors of age-associated MSC dysfunction. Moreover, the proper use of MSCs for clinical application requires a general understanding of the MSC aging process. Furthermore, such knowledge is essential for the development of therapeutic interventions that can slow or reverse age-related degenerative changes to enhance repair processes and maintain healthy function in aging tissues. To further clarify the properties of senescent cells, as well as to present significant findings from studies on the mechanisms of cellular aging, we summarize these biological features in the senescence of MSCs in this scenario. This review summarizes recent advances in our understanding of the markers and differentiation potential indicating MSC senescence, as well as factors affecting MSC senescence with particular emphasis on the roles of oxidative stress, intrinsic changes in telomere shortening, histone deacetylase and DNA methyltransferase, genes and signaling pathways and immunological properties.

Erythropoietin facilitates the recruitment of bone marrow mesenchymal stem cells to sites of spinal cord injury

Despite the successes of bone marrow mesenchymal stem cell (BMSC) transplantation for the treatment of spinal cord injuries, only a small fraction of grafted cells migrate to the target areas. Therefore, there remains a need for more efficient strategies of BMSC delivery. The present study was designed to explore this. Rat models of spinal cord injury (SCI) were established and exposed to phosphate buffered saline (control), BMSCs or BMSCs + erythropoietin (EPO). Basso, Beattie and Bresnahan (BBB) locomotor scale and grid walk tests were then utilized to estimate neurological rehabilitation. Additionally, the following assays were performed: Immunofluorescence localization of BMSCs to the site of SCI; the transwell migration assay to detect in vitro cellular migration; the terminal deoxynucleotidyl transferase dUTP nick end labeling assay to determine the apoptotic index of the lesion; and western blotting analysis to evaluate the expression of vascular endothelial growth factor (VEGF) and brain derived neurotrophic factor (BDNF) at the site of SCI. The BBB scores of the BMSC + EPO treated group were significantly increased compared with the BMSC treatment group (P<0.05). For example, BMSC + EPO treated rats had a significantly decreased number of hind limb slips compared with the BMSC treatment group (P<0.05). Furthermore, EPO significantly increased the migration capacity of BMSCs compared with the control group (P<0.001). In addition, the apoptotic index of the BMSC + EPO group was significantly decreased compared with the BMSC group (P<0.05). Green fluorescent protein-labeled BMSCs were detected at the site of SCI in the BMSC and BMSCs + EPO groups, with the signal being notably stronger in the latter. Moreover, the expression of VEGF and BDNF in the BMSCs + EPO group was significantly increased compared with the BMSC group (P<0.05). In conclusion, the results of the present study indicate that EPO can facilitate the recruitment of BMSCs to sites of SCI, increase expression of BDNF and VEGF, and accelerate recovery of neurological function following SCI.

CD61 promotes the differentiation of canine ADMSCs into PGC-like cells through modulation of TGF-β signaling

Previous studies have shown that CD61 (integrin-β3) promotes the differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) into germ-like cells. However, the mechanism remains unclear. In this study, we showed that overexpression of CD61 in canine adipose-derived mesenchymal stem cells (cADMSCs) promotes their differentiation into primordial germ cell (PGC)-like cells. Quantitative real-time PCR, immunocytochemistry and western blot detected higher levels of PGC-specific markers in CD61-overexpressed cADMSCs compared with those in control cells. Moreover, phosphorylation of Smad2, a downstream mediator of transforming growth factor beta (TGF-β), was increased in CD61-overexpressed cADMSCs than that in control cells. However, the expression of PGC-specific markers was downregulated in cADMSCs treated with a TGF-β inhibitor. These results suggested that CD61 could induce cADMSCs to differentiate into PGC-like cells by relying on the activation of TGF-β pathway. ADMSCs possess a considerable potential in treating the infertility of rare animal species.

Promising Therapeutic Strategies for Mesenchymal Stem Cell-Based Cardiovascular Regeneration: From Cell Priming to Tissue Engineering

The primary cause of death among chronic diseases worldwide is ischemic cardiovascular diseases, such as stroke and myocardial infarction. Recent evidence indicates that adult stem cell therapies involving cardiovascular regeneration represent promising strategies to treat cardiovascular diseases. Owing to their immunomodulatory properties and vascular repair capabilities, mesenchymal stem cells (MSCs) are strong candidate therapeutic stem cells for use in cardiovascular regeneration. However, major limitations must be overcome, including their very low survival rate in ischemic lesion. Various attempts have been made to improve the poor survival and longevity of engrafted MSCs. In order to develop novel therapeutic strategies, it is necessary to first identify stem cell modulators for intracellular signal triggering or niche activation. One promising therapeutic strategy is the priming of therapeutic MSCs with stem cell modulators before transplantation. Another is a tissue engineering-based therapeutic strategy involving a cell scaffold, a cell-protein-scaffold architecture made of biomaterials such as ECM or hydrogel, and cell patch- and 3D printing-based tissue engineering. This review focuses on the current clinical applications of MSCs for treating cardiovascular diseases and highlights several therapeutic strategies for promoting the therapeutic efficacy of MSCs in vitro or in vivo from cell priming to tissue engineering strategies, for use in cardiovascular regeneration.

Guiding osteogenesis of mesenchymal stem cells using carbon-based nanomaterials

In the field of regenerative medicine, stem cells are highly promising due to their innate ability to generate multiple types of cells that could replace/repair damaged parts of human organs and tissues. It has been reported that both in vitro and in vivo function/survival of stem cells could significantly be improved by utilizing functional materials such as biodegradable polymers, metal composites, nanopatterns and nanohybrid particles. Of various biocompatible materials available for use in stem cell-based therapy and research, carbon-based materials-including fullerenes graphene/graphene oxide and carbon nanotubes-have been found to possess unique physicochemical characteristics that contribute to the effective guidance of stem cell differentiation into specific lineages. In this review, we discuss a number of previous reports that investigated the use of carbon-based materials to control stem cell behavior, with a particular focus on their immense potential to guide the osteogenesis of mesenchymal stem cells (MSCs). We hope that this review will provide information on the full potential of using various carbon-based materials in stem cell-mediated regenerative therapy, particularly for bone regeneration and repair.

The effects of the DNA methyltranfserases inhibitor 5-Azacitidine on ageing, oxidative stress and DNA methylation of adipose derived stem cells

Human adipose tissue is a great source of adult mesenchymal stem cells (MSCs) which are recognized from their ability to self‐renew and differentiation into multiple lineages. MSCs have promised a vast therapeutic potential in treatment many diseases including tissue injury and immune disorders. However, their regenerative potential profoundly depends on patients’ age. Age‐related deterioration of MSC is associated with cellular senescence mainly caused by increased DNA methylation status, accumulation of oxidative stress factors and mitochondria dysfunction. We found that DNA methyltransferase (DNMT) inhibitor i.e. 5‐Azacytidine (5‐AZA) reversed the aged phenotype of MSCs. Proliferation rate of cells cultured with 5‐AZA was increased while the accumulation of oxidative stress factors and DNA methylation status were decreased. Simultaneously the mRNA levels of TET proteins involved in demethylation process were elevated in those cells. Moreover, cells treated with 5‐AZA displayed reduced reactive oxygen species (ROS) accumulation, ameliorated superoxide dismutase activity and increased BCL‐2/BAX ratio in comparison to control group. Our results indicates that, treating MSCs with 5‐AZA can be justified therapeutic intervention, that can slow‐down and even reverse aged‐ related degenerative changes in those cells.

Cannabidiol Modulates the Immunophenotype and Inhibits the Activation of the Inflammasome in Human Gingival Mesenchymal Stem Cells

Human Gingival Mesenchymal Stem Cells (hGMSCs) are multipotential cells that can expand and differentiate in culture under specific and standardized conditions. In the present study, we have investigated whether in vitro pre-treatment of hGMSCs with Cannabidiol (CBD) can influence their expression profile, improving the therapeutic potential of this cell culture. Following CBD treatment (5 μM) for 24 h, gene expression analysis through Next Generation Sequencing (NGS) has revealed several genes differentially expressed between CBD-treated hGMSCs (CBD-hGMSCs) and control cells (CTR-hGMSCs) that were linked to inflammation and apoptosis. In particular, we have demonstrated that CBD treatment in hGMSCs prevented the activation of the NALP3-inflammasome pathway by suppressing the levels of NALP3, CASP1, and IL18, and in parallel, inhibited apoptosis, as demonstrated by the suppression of Bax. CBD treatment was also able to modulate the expression of the well-known mesenchymal stem cell markers (CD13, CD29, CD73, CD44, CD90, and CD166), and other surface antigens. Specifically, CBD led to the downregulation of genes codifying for antigens involved in the activation of the immune system (CD109, CD151, CD40, CD46, CD59, CD68, CD81, CD82, CD99), while it led to the upregulation of those implicated in the inhibition of the immune responses (CD47, CD55, CD276). In conclusion, the present study will provide a new simple and reproducible method for preconditioning hGMSCs with CBD, before transplantation, as an interesting strategy for improving the hGMSCs molecular phenotype, reducing the risk of immune or inflammatory reactions in the host, and in parallel, for increasing their survival and thus, their long-term therapeutic efficacy.

Biphasic Polyurethane/Polylactide Sponges Doped with Nano-Hydroxyapatite (nHAp) Combined with Human Adipose-Derived Mesenchymal Stromal Stem Cells for Regenerative Medicine Applications

Cartilage and bone tissue injuries are common targets in regenerative medicine. The degeneration of cartilage tissue results in tissue loss with a limited ability to regenerate. However, the application of mesenchymal stem cells in the course of such condition makes it possible to manage this disorder by improving the structure of the remaining tissue and even stimulating its regeneration. Nevertheless, in the case of significant tissue loss, standard local injection of cell suspensions is insufficient, due to the low engraftment of transplanted cells. Introduction of mesenchymal stem cells on the surface of a compatible biomaterial can be a promising tool for inducing the regeneration by both retaining the cells at the desired site and filling the tissue gap. In order to obtain such a cell-biomaterial hybrid, we developed complex, biphasic polymer blend biomaterials composed of various polyurethane (PU)-to-polylactide (PLA) ratios, and doped with different concentrations of nano-hydroxyapatite (nHAp). We have determined the optimal blend composition and nano-hydroxyapatite concentration for adipose mesenchymal stem cells cultured on the biomaterial. We applied biological in vitro techniques, including cell viability assay, determination of oxidative stress factors level, osteogenic and chondrogenic differentiation potentials as well as cell proteomic analysis. We have shown that the optimal composition of biphasic scaffold was 20:80 of PU:PLA with 20% of nHAp for osteogenic differentiation, and 80:20 of PU:PLA with 10% of nHAp for chondrogenic differentiation, which suggest the optimal composition of final biphasic implant for regenerative medicine applications.

A Prospective, Nonrandomized, no Placebo-Controlled, Phase I/II Clinical Trial Assessing the Safety and Efficacy of Intramuscular Injection of Autologous Adipose Tissue-Derived Mesenchymal Stem Cells in Patients With Severe Buerger's Disease

Buerger's disease is a rare and severe disease affecting the blood vessels of the limbs. Adipose tissue-derived mesenchymal stem cells (ADSCs) have the potential to cure Buerger's disease when developed as a stem cell drug. In the present study, we conducted a prospective, nonrandomized, no placebo-controlled, phase I/II clinical trial with a 2-year follow-up questionnaire survey. A total of 17 patients were intramuscularly administered autologous ADSCs at a dose of 5 million cells/kg. The incidence of adverse events (AEs), adverse drug reaction (ADR), and serious adverse events (SAEs) was monitored. No ADRs and SAEs related to stem cell treatment occurred during the 6-month follow-up. In terms of efficacy, the primary endpoint was increase in total walking distance (TWD). The secondary endpoint was improvement in rest pain, increase in pain-free walking distance (PFWD), toe-brachial pressure index (TBPI), transcutaneous oxygen pressure (TcPO₂), and arterial brachial pressure index (ABPI). ADSCs demonstrated significant functional improvement results including increased TWD, PFWD, and rest pain reduction. No amputations were reported during the 6-month clinical trial period and in the follow-up questionnaire survey more than 2 years after the ADSC injection. In conclusion, intramuscular injection of ADSCs is very safe and is shown to prompt functional improvement in patients with severe Buerger's disease at a dosage of 300 million cells per 60 kg of body weight. However, the confirmatory therapeutic efficacy and angiogenesis need further study.

Potency testing of mesenchymal stromal cell growth expanded in human platelet lysate from different human tissues

Background

Mesenchymal stromal cells (MSCs) have been largely investigated, in the past decade, as potential therapeutic strategies for various acute and chronic pathological conditions. MSCs isolated from different sources, such as bone marrow (BM), umbilical cord tissue (UCT) and adipose tissue (AT), share many biological features, although they may show some differences on cumulative yield, proliferative ability and differentiation potential. The standardization of MSCs growth and their functional amplification is a mandatory objective of cell therapies. The aim of this study was to evaluate the cumulative yield and the ex vivo amplification potential of MSCs obtained from various sources and different subjects, using defined culture conditions with a standardized platelet lysate (PL) as growth stimulus.

Methods

MSCs isolated from BM, UCT and AT and expanded in human PL were compared in terms of cumulative yield and growth potential per gram of starting tissue. MSCs morphology, phenotype, differentiation potential, and immunomodulatory properties were also investigated to evaluate their biological characteristics.

Results

The use of standardized PL-based culture conditions resulted in a very low variability of MSC growth. Our data showed that AT has the greater capacity to generate MSC per gram of initial tissue, compared to BM and UCT. However, UCT-MSCs replicated faster than AT-MSCs and BM-MSCs, revealing a greater proliferation capacity of this source irrespective of its lower MSC yield. All MSCs exhibited the typical MSC phenotype and the ability to differentiate into all mesodermal lineages, while BM-MSCs showed the most prominent immunosuppressive effect in vitro.

Conclusions

The adoption of standardized culture conditions may help researchers and clinicians to reveal particular characteristics and inter-individual variability of MSCs sourced from different tissues. These data will be beneficial to set the standards for tissue collection and MSCs clinical-scale expansion both for cell banking and for cell-based therapy settings.

Mesenchymal stem cells from cortical bone demonstrate increased clonal incidence, potency, and developmental capacity compared to their bone marrow-derived counterparts

In this study, we show that matrix dense cortical bone is the more potent compartment of bone than bone marrow as a stromal source for mesenchymal stem cells as isolated from adult rats. Lineage-depleted cortical bone-mesenchymal stem cells demonstrated >150-fold enrichment of colony forming unit-fibroblasts per cell incidence. compared to lineage-depleted bone marrow-mesenchymal stem cells, corresponding to a 70-fold increase in absolute recovered colony forming unit-fibroblasts. The composite phenotype Lin(-)/CD45(-)/CD31(-)/VLA-1(+)/Thy-1(+) enriched for clonogenic mesenchymal stem cells solely from cortical bone-derived cells from which 70% of clones spontaneously differentiated into all lineages of bone, cartilage, and adipose. Both populations generated vascularized bone tissue within subcutaneous implanted collagen scaffolds; however, cortical bone-derived cells formed significantly more osteoid than bone marrow counterparts, quantified by histology. The data demonstrate that our isolation protocol identifies and validates mesenchymal stem cells with superior clonal, proliferative, and developmental potential from cortical bone compared to the bone marrow niche although marrow persists as the typical source for mesenchymal stem cells both in the literature and current pre-clinical therapies.

Study of the involvement of allogeneic MSCs in bone formation using the model of transgenic mice

Mesenchymal stem cells (MSCs) are thought to be the most attractive type of cells for bone repair. However, much still remains unknown about MSCs and needs to be clarified before this treatment can be widely applied in the clinical practice. The purpose of this study was to establish the involvement of allogeneic MSCs in the bone formation in vivo, using a model of transgenic mice and genetically labeled cells. Polylactide scaffolds with hydroxyapatite obtained by surface selective laser sintering were used. The scaffolds were sterilized and individually seeded with MSCs from the bone marrow of 5-week-old GFP(+) transgenic C57/Bl6 or GFP(-)C57/Bl6 mice. 4-mm-diameter critical-size defects were created on the calvarial bone of mice using a dental bur. Immediately after the generation of the cranial bone defects, the scaffolds with or without seeded cells were implanted into the injury sites. The cranial bones were harvested at either 6 or 12 weeks after the implantation. GFP(+) transgenic mice having scaffolds with unlabeled MSCs were used for the observation of the host cell migration into the scaffold. GFP(-) mice having scaffolds with GFP(+)MSCs were used to assess the functioning of the seeded MSCs. The obtained data demonstrated that allogeneic MSCs were found on the scaffolds 6 and 12 weeks post-implantation. By week 12, a newly formed bone tissue from the seeded cells was observed, without an osteogenic pre-differentiation. The host cells did not appear, and the control scaffolds without seeded cells remained empty. Besides, a possibility of vessel formation from seeded MSCs was shown, without a preliminary cell cultivation under controlled conditions.

LNGFR+THY-1+ human pluripotent stem cell-derived neural crest-like cells have the potential to develop into mesenchymal stem cells

Mesenchymal stem cells (MSCs) are defined as non-hematopoietic, plastic-adherent, self-renewing cells that are capable of tri-lineage differentiation into bone, cartilage or fat in vitro. Thus, MSCs are promising candidates for cell-based medicine. However, classifications of MSCs have been defined retrospectively; moreover, this conventional criterion may be inaccurate due to contamination with other hematopoietic lineage cells. Human MSCs can be enriched by selection for LNGFR and THY-1, and this population may be analogous to murine PDGFRα⁺Sca-1⁺ cells, which are developmentally derived from neural crest cells (NCCs). Murine NCCs were labeled by fluorescence, which provided definitive proof of neural crest lineage, however, technical considerations prevent the use of a similar approach to determine the origin of human LNGFR⁺THY-1⁺ MSCs. To further clarify the origin of human MSCs, human embryonic stem cells (ESCs) and human induced pluripotent stem cells (iPSCs) were used in this study. Under culture conditions required for the induction of neural crest cells, human ESCs and iPSCs-derived cells highly expressed LNGFR and THY-1. These LNGFR⁺THY-1⁺ neural crest-like cells, designated as LT-NCLCs, showed a strong potential to differentiate into both mesenchymal and neural crest lineages. LT-NCLCs proliferated to form colonies and actively migrated in response to serum concentration. Furthermore, we transplanted LT-NCLCs into chick embryos, and traced their potential for survival, migration and differentiation in the host environment. These results suggest that LNGFR⁺THY-1⁺ cells identified following NCLC induction from ESCs/iPSCs shared similar potentials with multipotent MSCs.

Deferoxamine preconditioning to restore impaired HIF-1α-mediated angiogenic mechanisms in adipose-derived stem cells from STZ-induced type 1 diabetic rats

OBJECTIVES

Both excessive and insufficient angiogenesis are associated with progression of diabetic complications, of which poor angiogenesis is an important feature. Currently, adipose-derived stem cells (ADSCs) are considered to be a promising source to aid therapeutic neovascularization. However, functionality of these cells is impaired by diabetes which can result from a defect in hypoxia-inducible factor-1 (HIF-1), a key mediator involved in neovascularization. In the current study, we sought to explore effectiveness of pharmacological priming with deferoxamine (DFO) as a hypoxia mimetic agent, to restore the compromised angiogenic pathway, with the aid of ADSCs derived from streptozotocin (STZ)-induced type 1 diabetic rats ('diabetic ADSCs').

MATERIALS AND METHODS

Diabetic ADSCs were treated with DFO and compared to normal and non-treated diabetic ADSCs for expression of HIF-1α, VEGF, FGF-2 and SDF-1, at mRNA and protein levels, using qRT-PCR, western blotting and ELISA assay. Activity of matrix metalloproteinases -2 and -9 were measured using a gelatin zymography assay. Angiogenic potential of conditioned media derived from normal, DFO-treated and non-treated diabetic ADSCs were determined by in vitro (in HUVECs) and in vivo experiments including scratch assay, three-dimensional tube formation testing and surgical wound healing models.

RESULTS

DFO remarkably enhanced expression of noted genes by mRNA and protein levels and restored activity of matrix metalloproteinases -2 and -9. Compromised angiogenic potential of conditioned medium derived from diabetic ADSCs was restored by DFO both in vitro and in vivo experiments.

CONCLUSION

DFO preconditioning restored neovascularization potential of ADSCs derived from diabetic rats by affecting the HIF-1α pathway.

Generation, Characterization, and Multilineage Potency of Mesenchymal-Like Progenitors Derived from Equine Induced Pluripotent Stem Cells

Multipotent mesenchymal stromal cells (MSCs) are more and more frequently used to treat orthopedic injuries in horses. However, these cells are limited in their expandability and differentiation capacity. Recently, the first equine-induced pluripotent stem cell (iPSC) lines were reported by us [ 1 ]. In vitro differentiation of iPSCs into MSC-like cells is an attractive alternative to using MSCs derived from other sources, as a much larger quantity of patient-specific cells with broad differentiation potential could be generated. However, the differentiation capacity of iPSCs to MSCs and the potential for use in tissue engineering have yet to be explored. In this study, equine iPSCs were induced to differentiate into an MSC-like population. Upon induction, the iPSCs changed morphology toward spindle-shaped cells similar to MSCs. The ensuing iPSC-MSCs exhibited downregulation of pluripotency-associated genes and an upregulation of MSC-associated genes. In addition, the cells expressed the same surface markers as MSCs derived from equine umbilical cord blood. We then assessed the multilineage differentiation potential of iPSC-MSCs. Although chondrogenesis was not achieved after induction with transforming growth factor-beta 3 (TGFβ3) and/or bone morphogenic protein 4 (BMP-4) in 3D pellet culture, mineralization characteristic of osteogenesis and lipid droplet accumulation characteristic of adipogenesis were observed after chemical induction. We demonstrate a protocol for the derivation of MSC-like progenitor populations from equine iPS cells.

Intracoronary Delivery of Human Mesenchymal/Stromal Stem Cells: Insights from Coronary Microcirculation Invasive Assessment in a Swine Model

BACKGROUND

Mesenchymal stem/stromal cells have unique properties favorable to their use in clinical practice and have been studied for cardiac repair. However, these cells are larger than coronary microvessels and there is controversy about the risk of embolization and microinfarctions, which could jeopardize the safety and efficacy of intracoronary route for their delivery. The index of microcirculatory resistance (IMR) is an invasive method for quantitatively assessing the coronary microcirculation status.

OBJECTIVES

To examine heart microcirculation after intracoronary injection of mesenchymal stem/stromal cells with the index of microcirculatory resistance.

METHODS

Healthy swine were randomized to receive by intracoronary route either 30x106 MSC or the same solution with no cells (1% human albumin/PBS) (placebo). Blinded operators took coronary pressure and flow measurements, prior to intracoronary infusion and at 5 and 30 minutes post-delivery. Coronary flow reserve (CFR) and the IMR were compared between groups.

RESULTS

CFR and IMR were done with a variance within the 3 transit time measurements of 6% at rest and 11% at maximal hyperemia. After intracoronary infusion there were no significant differences in CFR. The IMR was significantly higher in MSC-injected animals (at 30 minutes, 14.2U vs. 8.8U, p = 0.02) and intragroup analysis showed a significant increase of 112% from baseline to 30 minutes after cell infusion, although no electrocardiographic changes or clinical deterioration were noted.

CONCLUSION

Overall, this study provides definitive evidence of microcirculatory disruption upon intracoronary administration of mesenchymal stem/stromal cells, in a large animal model closely resembling human cardiac physiology, function and anatomy.

Intracoronary Delivery of Human Mesenchymal/Stromal Stem Cells: Insights from Coronary Microcirculation Invasive Assessment in a Swine Model

BACKGROUND

Mesenchymal stem/stromal cells have unique properties favorable to their use in clinical practice and have been studied for cardiac repair. However, these cells are larger than coronary microvessels and there is controversy about the risk of embolization and microinfarctions, which could jeopardize the safety and efficacy of intracoronary route for their delivery. The index of microcirculatory resistance (IMR) is an invasive method for quantitatively assessing the coronary microcirculation status.

OBJECTIVES

To examine heart microcirculation after intracoronary injection of mesenchymal stem/stromal cells with the index of microcirculatory resistance.

METHODS

Healthy swine were randomized to receive by intracoronary route either 30x106 MSC or the same solution with no cells (1% human albumin/PBS) (placebo). Blinded operators took coronary pressure and flow measurements, prior to intracoronary infusion and at 5 and 30 minutes post-delivery. Coronary flow reserve (CFR) and the IMR were compared between groups.

RESULTS

CFR and IMR were done with a variance within the 3 transit time measurements of 6% at rest and 11% at maximal hyperemia. After intracoronary infusion there were no significant differences in CFR. The IMR was significantly higher in MSC-injected animals (at 30 minutes, 14.2U vs. 8.8U, p = 0.02) and intragroup analysis showed a significant increase of 112% from baseline to 30 minutes after cell infusion, although no electrocardiographic changes or clinical deterioration were noted.

CONCLUSION

Overall, this study provides definitive evidence of microcirculatory disruption upon intracoronary administration of mesenchymal stem/stromal cells, in a large animal model closely resembling human cardiac physiology, function and anatomy.

Elastin-based biomaterials and mesenchymal stem cells

Elastin is the dominant mammalian elastic protein found in soft tissue. Elastin-based biomaterials have the potential to repair elastic tissues by improving local elasticity and providing appropriate cellular interactions and signaling. Studies that combine these biomaterials with mesenchymal stem cells have demonstrated their capacity to also regenerate non-elastic tissue. Mesenchymal stem cell differentiation can be controlled by their immediate environment, and their sensitivity to elasticity makes them an ideal candidate for combining with elastin-based biomaterials. With the growing accessibility of the elastin precursor, tropoelastin, and elastin-derived materials, the amount of research interest in combining these two fields has increased and, subsequently, is leading to the realization of a potentially new strategy for regenerative medicine.

Tailoring material properties of cardiac matrix hydrogels to induce endothelial differentiation of human mesenchymal stem cells

Cardiac matrix hydrogel has shown great promise as an injectable biomaterial due to the possession of cardiac-specific extracellular matrix composition. A cardiac matrix hydrogel facilitating neovascularization will further improve its therapeutic outcomes in cardiac repair. In this study, we explored the feasibility of tailoring material properties of cardiac matrix hydrogels using a natural compound, genipin, to promote endothelial differentiation of stem cells. Our results demonstrated that the genipin cross-linking could increase the mechanical properties of the cardiac matrix hydrogel to a stiffness range promoting endothelial differentiation of human mesenchymal stem cells (hMSCs). It also decreased the swelling ratio and prolonged degradation without altering gelation time. Human mesenchymal stem cells cultured on the genipin cross-linked cardiac matrix hydrogels showed great viability. After 1 day culture, hMSCs demonstrated down-regulation of early endothelial marker expression and up-regulation of mature endothelial marker expression. Especially for 1 mM genipin cross-linked cardiac matrix hydrogels, hMSCs showed particularly significant expression of mature endothelial cell marker vWF. These attractive results indicate the potential of using genipin cross-linked cardiac matrix hydrogels to promote rapid vascularization for cardiac infarction treatment through minimally invasive therapy.

Bone marrow mesenchymal stem cell transplantation retards the natural senescence of rat hearts

Bone marrow mesenchymal stem cells (BMSCs) have been shown to offer a wide variety of cellular functions including the protective effects on damaged hearts. Here we investigated the antiaging properties of BMSCs and the underlying mechanism in a cellular model of cardiomyocyte senescence and a rat model of aging hearts. Neonatal rat ventricular cells (NRVCs) and BMSCs were cocultured in the same dish with a semipermeable membrane to separate the two populations. Monocultured NRVCs displayed the senescence-associated phenotypes, characterized by an increase in the number of β-galactosidase-positive cells and decreases in the degradation and disappearance of cellular organelles in a time-dependent manner. The levels of reactive oxygen species and malondialdehyde were elevated, whereas the activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were decreased, along with upregulation of p53, p21(Cip1/Waf1), and p16(INK4a) in the aging cardiomyocytes. These deleterious alterations were abrogated in aging NRVCs cocultured with BMSCs. Qualitatively, the same senescent phenotypes were consistently observed in aging rat hearts. Notably, BMSC transplantation significantly prevented these detrimental alterations and improved the impaired cardiac function in the aging rats. In summary, BMSCs possess strong antisenescence action on the aging NRVCs and hearts and can improve cardiac function after transplantation in aging rats. The present study, therefore, provides an alternative approach for the treatment of heart failure in the elderly population.

Role of nanotopography in the development of tissue engineered 3D organs and tissues using mesenchymal stem cells

Recent regenerative medicine and tissue engineering strategies (using cells, scaffolds, medical devices and gene therapy) have led to fascinating progress of translation of basic research towards clinical applications. In the past decade, great deal of research has focused on developing various three dimensional (3D) organs, such as bone, skin, liver, kidney and ear, using such strategies in order to replace or regenerate damaged organs for the purpose of maintaining or restoring organs' functions that may have been lost due to aging, accident or disease. The surface properties of a material or a device are key aspects in determining the success of the implant in biomedicine, as the majority of biological reactions in human body occur on surfaces or interfaces. Furthermore, it has been established in the literature that cell adhesion and proliferation are, to a great extent, influenced by the micro- and nano-surface characteristics of biomaterials and devices. In addition, it has been shown that the functions of stem cells, mesenchymal stem cells in particular, could be regulated through physical interaction with specific nanotopographical cues. Therefore, guided stem cell proliferation, differentiation and function are of great importance in the regeneration of 3D tissues and organs using tissue engineering strategies. This review will provide an update on the impact of nanotopography on mesenchymal stem cells for the purpose of developing laboratory-based 3D organs and tissues, as well as the most recent research and case studies on this topic.

The expression of neurogenic markers after neuronal induction of chorion-derived mesenchymal stromal cells

OBJECTIVES

Chorion is a tissue of early embryologic period that is discarded after delivery. It might be the potential source of mesenchymal stromal cells (MSCs) that can be used for research and eventually for therapeutic studies. At present, the biological properties and the differentiation capacity of chorion-derived MSCs are still poorly characterised. The objective of this study is to characterise and explore the differentiating potential of chorion-derived MSCs towards the neuronal lineages.

METHODS

Chorionic membrane was digested with enzyme and cultured in Dulbecco's Modified Eagle's medium supplemented with 10% fetal bovine serum. The expression of MSC markers was examined using flow cytometry. The adipogenic, osteogenic and neurogenic differentiation were examined by culturing in appropriate induction media. The expression of neuronal markers was determined by immunofluorescence and quantitative real time-PCR.

RESULTS

Chorion-derived MSCs were easily expanded up to 20 passages. They were positive for MSC markers (CD73, CD90 and CD105), and negative for haematopoietic markers (CD34 and CD45). Chorion-derived MSCs could differentiate into several mesodermal-lineages including adipocytes and osteoblasts. Moreover, chorion-derived MSCs could differentiate into neuronal-like cells as characterised by cell morphology and the presence of neural markers including MAP-2, glial fibrillary acidic protein (GFAP) and beta-tubulin III.

DISCUSSION

Chorion-derived MSCs can be readily obtained and expanded in culture. These cells also have transdifferentiation capacity as evidenced by their neuronal differentiation potential. Therefore, chorion can be used as an alternative source of MSCs for stem cell therapy in nervous system disorders.

Beneficial effects of intramyocardial mesenchymal stem cells and VEGF165 plasmid injection in rats with furazolidone induced dilated cardiomyopathy

To explore the impact of myocardial injection of mesenchymal stem cells (MSCs) and specific recombinant human VEGF₁₆₅ (hVEGF₁₆₅) plasmid on collagen remodelling in rats with furazolidone induced dilated cardiomyopathy (DCM). DCM was induced by furazolidone (0.3 mg/bodyweight (g)/day per gavage for 8 weeks). Rats were then divided into four groups: (i) PBS group (n = 18): rats received equal volume myocardial PBS injection; (ii) MSCs group (n = 17): 100 μl culture medium containing 10⁵ MSCs were injected into four sites of left ventricular free wall (25 μl per site); (iii) GENE group (n = 18): pCMVen-MLC2v-EGFP-VEGF₁₆₅ plasmid [5 × 109 pfu (0.2 ml)] were injected into four sites of left ventricular free wall (0.05 ml per site)] and (iv) MSCs+GENE group (n = 17): rats received both myocardial MSCs and pCMVen-MLC2v-EGFP-VEGF₁₆₅ plasmid injections. After 4 weeks, cardiac function was evaluated by echocardiography. Myocardial mRNA expressions of type I, type III collagen and transforming growth factor (TGF)-β1 were detected by RT-PCR. The protein expression of hVEGF₁₆₅ was determined by Western blot. Myocardial protein expression of hVEGF₁₆₅ was demonstrated in GENE and MSCs+GENE groups. Cardiac function was improved in MSCs, GENE and MSCs+GENE groups. Collagen volume fraction was significantly reduced and myocardial TGF-β1 mRNA expression significantly down-regulated in both GENE and MSCs+GENE groups, collagen type I/III ratio reduction was more significant in MSCs+GENE group than in MSCs or GENE group. Myocardial MSCs and hVEGF₁₆₅ plasmid injection improves cardiac function possibly through down-regulating myocardial TGF-β1 expression and reducing the type I/III collagen ratio in this DCM rat model.

Alteration of histone acetylation pattern during long-term serum-free culture conditions of human fetal placental mesenchymal stem cells

Increasing evidence suggests that the mesenchymal stem cells (MSCs) derived from placenta of fetal origin (fPMSCs) are superior to MSCs of other sources for cell therapy. Since the initial number of isolated MSCs is limited, in vitro propagation is often required to reach sufficient numbers of cells for therapeutic applications, during which MSCs may undergo genetic and/or epigenetic alterations that subsequently increase the probability of spontaneous malignant transformation. Thus, factors that influence genomic and epigenetic stability of MSCs following long-term expansions need to be clarified before cultured MSCs are employed for clinical settings. To date, the genetic and epigenetic stability of fPMSCs after long-term in vitro expansion has not been fully investigated. In this report, alterations to histone acetylation and consequence on the expression pattern of fPMSCs following in vitro propagation under serum-free conditions were explored. The results show that fPMSCs maintain their MSC characteristics before they reached a senescent state. Furthermore, acetylation modification patterns were changed in fPMSCs along with gradually increased global histone deacetylase (HDAC) activity and expression of HDAC subtypes HDAC4, HDAC5 and HDAC6, as well as a down-regulated global histone H3/H4 acetylation during in vitro culturing. In line with the acetylation alterations, the expression of oncogenes Oct4, Sox2 and TERT were significantly decreased over the propagation period. Of note, the down-regulation of Oct4 was strongly associated with changes in acetylation. Intriguingly, telomere length in fPMSCs did not significantly change during the propagating process. These findings suggest that human fPMSCs may be a safe and reliable resource of MSCs and can be propagated under serum-free conditions with less risk of spontaneous malignancy, and warrants further validation in clinical settings.

Transplantation of placenta-derived mesenchymal stem cell-induced neural stem cells to treat spinal cord injury

Because of their strong proliferative capacity and multi-potency, placenta-derived mesenchymal stem cells have gained interest as a cell source in the field of nerve damage repair. In the present study, human placenta-derived mesenchymal stem cells were induced to differentiate into neural stem cells, which were then transplanted into the spinal cord after local spinal cord injury in rats. The motor functional recovery and pathological changes in the injured spinal cord were observed for 3 successive weeks. The results showed that human placenta-derived mesenchymal stem cells can differentiate into neuron-like cells and that induced neural stem cells contribute to the restoration of injured spinal cord without causing transplant rejection. Thus, these cells promote the recovery of motor and sensory functions in a rat model of spinal cord injury. Therefore, human placenta-derived mesenchymal stem cells may be useful as seed cells during the repair of spinal cord injury.

Towards the development of a bioengineered uterus: comparison of different protocols for rat uterus decellularization

Uterus transplantation (UTx) may be the only possible curative treatment for absolute uterine factor infertility, which affects 1 in every 500 females of fertile age. We recently presented the 6-month results from the first clinical UTx trial, describing nine live-donor procedures. This routine involves complicated surgery and requires potentially harmful immune suppression to prevent rejection. However, tissue engineering applications using biomaterials and stem cells may replace the need for a live donor, and could prevent the required immunosuppressive treatment. To investigate the basic aspects of this, we developed a novel whole-uterus scaffold design for uterus tissue engineering experiments in the rat. Decellularization was achieved by perfusion of detergents and ionic solutions. The remaining matrix and its biochemical and mechanical properties were quantitatively compared from using three different protocols. The constructs were further compared with native uterus tissue composition. Perfusion with Triton X-100/dimethyl sulfoxide/H2O led to a compact, weaker scaffold that showed evidence of a compromised matrix organization. Sodium deoxycholate/dH2O perfusion gave rise to a porous scaffold that structurally and mechanically resembled native uterus better. An innovative combination of two proteomic analyses revealed higher fibronectin and versican content in these porous scaffolds, which may explain the improved scaffold organization. Together with other important protocol-dependent differences, our results can contribute to the development of improved decellularization protocols for assorted organs. Furthermore, our study shows the first available data on decellularized whole uterus, and creates new opportunities for numerous in vitro and in vivo whole-uterus tissue engineering applications.

A gene therapy induced emphysema model and the protective role of stem cells

BACKGROUND

Chronic obstructive pulmonary disease presents with two different phenotypes: chronic bronchitis and emphysema with parenchymal destruction. Decreased expression of vascular endothelial growth factor and increased endothelial cell apoptosis are considered major factors for emphysema. Stem cells have the ability of vascular regeneration and function as a repair mechanism for the damaged endothelial cells. Currently, minimally invasive interventional procedures such as placement of valves, bio-foam or coils are performed in order to improve the disturbed mechanical function in emphysema patients. However, these procedures cannot restore functional lung tissue. Additionally stem cell instillation into the parenchyma has been used in clinical studies aiming to improve overall respiratory function and quality of life.

METHODS

In our current experiment we induced emphysema with a DDMC non-viral vector in BALBC mice and simultaneously instilled stem cells testing the hyposthesis that they might have a protective role against the development of emphysema. The mice were divided into four groups: a) control, b) 50.000 cells, c) 75.000 and d) 100.000 cells.

RESULTS

Lung pathological findings revealed that all treatment groups had less damage compared to the control group. Additionally, we observed that emphysema lesions were less around vessels in an area of 10 μm.

CONCLUSIONS

Our findings indicate that stem cell instillation can have a regenerative role if applied upon a tissue scaffold with vessel around.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_195.

Current Status and Perspectives in Stem Cell Therapy for Heart

For most patients, the prognosis of heart failure remains poor despite therapeutic advancement in recent decades. The option of cardiac transplantation is high risk and limited by a shortage of donors. Traditionally, the heart had been considered a terminally differentiated organ incapable of regeneration. However, numerous preclinical and clinical studies have been performed since the first report of cell therapy in heart failure using skeletal myoblasts in 2001. These investigations looked at the promising potential and use of several kinds of stem cells, which could some day dramatically alter the understanding of the regenerative capacity of the heart. To date, although there is no existing cardiac cell therapy that has been conclusively reported to be effective, stem cell-related cardiomyocyte regeneration strategies have become significant areas of research in modern cardiovascular medicine. In this review, we outline a variety of common cell sources, surface biomarkers of stem cells, and provide information related to cardiac cell therapy clinical trials.

KEY WORDS

Clinical trial; Stem cell.

Human umbilical cord-derived mesenchymal stem cells do not undergo malignant transformation during long-term culturing in serum-free medium

BACKGROUND

Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) are in the foreground as a preferable application for treating diseases. However, the safety of hUC-MSCs after long-term culturing in vitro in serum-free medium remains unclear.

METHODS

hUC-MSCs were separated by adherent tissue culture. hUC-MSCs were cultured in serum-free MesenCult-XF medium and FBS-bases DMEM complete medium. At the 1st, 3rd, 5th, 8th, 10th, and 15th passage, the differentiation of MSCs into osteogenic, chondrogenic, and adipogenic cells was detected, and MTT, surface antigens were measured. Tumorigenicity was analyzed at the 15th passage. Conventional karyotyping was performed at passage 0, 8, and 15. The telomerase activity of hUC-MSCs at passage 1-15 was analyzed.

RESULTS

Flow cytometry analysis showed that very high expression was detected for CD105, CD73, and CD90 and very low expression for CD45, CD34, CD14, CD79a, and HLA-DR. MSCs could differentiate into osteocytes, chondrocytes, and adipocytes in vitro. There was no obvious chromosome elimination, displacement, or chromosomal imbalance as determined from the guidelines of the International System for Human Cytogenetic Nomenclature. Telomerase activity was down-regulated significantly when the culture time was prolonged. Further, no tumors formed in rats injected with hUC-MSCs (P15) cultured in serum-free and in serum-containing conditions.

CONCLUSION

Our data showed that hUC-MSCs met the International Society for Cellular Therapy standards for conditions of long-term in vitro culturing at P15. Since hUC-MSCs can be safely expanded in vitro and are not susceptible to malignant transformation in serum-free medium, these cells are suitable for cell therapy.

TGF-β1 induces senescence of bone marrow mesenchymal stem cells via increase of mitochondrial ROS production

Background

Bone marrow derived mesenchymal stem cells (bmMSCs) are multipotent cells that can differentiate into diverse cell types, including cardiomyocytes. BmMSC-based transplantation is capable of repairing acute and chronic myocardial infarction. Prior to the transplantation, MSCs are usually induced in vitro by biological reagents and chemicals for directional differentiation. Transforming growth factor beta (TGF-β) is one of the most commonly used biological reagents for induction of cardiomyocyte differentiation of bmMSCs. Previous studies have shown that TGF-β induces senescence in several cell types. However, whether TGF-β affects senescence of bmMSCs has not been elucidated. The goal of this study was to investigate the effect of TGF-β1 on senescence of bmMSCs and the underlying mechanisms.

Results

We found that TGF-β1 increased activity of senescence-associated-galactosidase (SA-Gal) and production of mitochondrial reactive oxygen species (mtROS) in bmMSCs in a dose-dependent manner. TGF-β1 also significantly decreased expression of superoxide dismutase 2 (SOD2) and Id1, and increased expression of 4-Hydroxynonenal (4-HNE) subunits and p16 in bmMSCs in a dose-dependent manner. Pre-treatment with mtROS inhibitor acetyl-L-carnitine (ALCAR, 0.1 mM) significantly inhibited TGF-β1-induced mtROS production and SA-Gal activity.

Conclusion

TGF-β1 can induce senescence of bmMSCs, which at least partially depends on mtROS production.

IKVAV regulates ERK1/2 and Akt signalling pathways in BMMSC population growth and proliferation

Objectives

The molecular mechanism of bone marrow mesenchymal stem cell (BMMSC) population growth and proliferation, induced by Isoleucyl‐lysyl‐valyl‐alanyl‐valine (IKVAV), was explored in this study.

Materials and methods

IKVAV peptides were synthesized by the solid‐phase method. Influence of IKVAV on BMMSC population growth and proliferation were investigated by assays of CCK‐8, flow cytometry, real‐time PCR and western blotting.

Results

IKVAV peptide was found to induce proliferation and proliferating cell nuclear antigen (PCNA) synthesis of BMMSC in a dose‐ and time‐dependent manner. Cell cycle analysis showed that the proportion of IKVAV‐treated BMMSC in S phase in was higher than controls. Western blot results suggested that mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK) and phosphatidylinositol 3‐kinase/protein kinase B (PI3K/Akt) signalling pathways were activated by IKVAV by enhancing phosphorylation levels of ERK1/2 and Akt in the BMMSCs. Meanwhile, phosphorylation levels of ERK1/2 and Akt were partially blocked by ERK1/2 inhibitor (PD98059) and Akt inhibitor (wortmannin), respectively.

Conclusions

Our results demonstrated that IKVAV stimulated BMMSC population growth and proliferation by activating MAPK/ERK1/2 and PI3K/Akt signalling pathways. This study is the first to reveal an enhancement effect of IKVAV peptide on BMMSC at the signal transduction level, and the outcome could provide experimental evidence for application of IKVAV‐grafted scaffolds in the field of BMMSC‐based tissue engineering.

Umbilical cord mesenchymal stem cells: the new gold standard for mesenchymal stem cell-based therapies?

Due to their self-renewal capacity, multilineage differentiation potential, paracrine effects, and immunosuppressive properties, mesenchymal stromal cells (MSCs) are an attractive and promising tool for regenerative medicine. MSCs can be isolated from various tissues but despite their common immunophenotypic characteristics and functional properties, source-dependent differences in MSCs properties have recently emerged and lead to different clinical applications. Considered for a long time as a medical waste, umbilical cord appears these days as a promising source of MSCs. Several reports have shown that umbilical cord-derived MSCs are more primitive, proliferative, and immunosuppressive than their adult counterparts. In this review, we aim at synthesizing the differences between umbilical cord MSCs and MSCs from other sources (bone marrow, adipose tissue, periodontal ligament, dental pulp,…) with regard to their proliferation capacity, proteic and transcriptomic profiles, and their secretome involved in their regenerative, homing, and immunomodulatory capacities. Although umbilical cord MSCs are until now not particularly used as an MSC source in clinical practice, accumulating evidence shows that they may have a therapeutic advantage to treat several diseases, especially autoimmune and neurodegenerative diseases.

Tissue engineering chamber promotes adipose tissue regeneration in adipose tissue engineering models through induced aseptic inflammation

Tissue engineering chamber (TEC) makes it possible to generate significant amounts of mature, vascularized, stable, and transferable adipose tissue. However, little is known about the role of the chamber in tissue engineering. Therefore, to investigate the role of inflammatory response and the change in mechanotransduction started by TEC after implantation, we placed a unique TEC model on the surface of the groin fat pads in rats to study the expression of cytokines and tissue development in the TEC. The number of infiltrating cells was counted, and vascular endothelial growth factor (VEGF) and monocyte chemotactic protein-1 (MCP-1) expression levels in the chamber at multiple time points postimplantation were analyzed by enzyme-linked immunosorbent assay. Tissue samples were collected at various time points and labeled for specific cell populations. The result showed that new adipose tissue formed in the chamber at day 60. Also, the expression of MCP-1 and VEGF in the chamber decreased slightly from an early stage as well as the number of the infiltrating cells. A large number of CD34+/perilipin- perivascular cells could be detected at day 30. Also, the CD34+/perilipin+ adipose precursor cell numbers increased sharply by day 45 and then decreased by day 60. CD34-/perilipin+ mature adipocytes were hard to detect in the chamber content at day 30, but their number increased and then peaked at day 60. Ki67-positive cells could be found near blood vessels and their number decreased sharply over time. Masson's trichrome showed that collagen was the dominant component of the chamber content at early stage and was replaced by newly formed small adipocytes over time. Our findings suggested that the TEC implantation could promote the proliferation of adipose precursor cells derived from local adipose tissue, increase angiogenesis, and finally lead to spontaneous adipogenesis by inducing aseptic inflammation and changing local mechanotransduction.

Long-Term Quantitative Biodistribution and Side Effects of Human Mesenchymal Stem Cells (hMSCs) Engraftment in NOD/SCID Mice following Irradiation

There is little information on the fate of infused mesenchymal stem cells (MSCs) and long-term side effects after irradiation exposure. We addressed these questions using human MSCs (hMSCs) intravenously infused to nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice submitted to total body irradiation (TBI) or local irradiation (abdominal or leg irradiation). The animals were sacrificed 3 to 120 days after irradiation and the quantitative and spatial distribution of hMSCs were studied by polymerase chain reaction (PCR). Following their infusion into nonirradiated animals, hMSCs homed to various tissues. Engraftment depended on the dose of irradiation and the area exposed. Total body irradiation induced an increased hMSC engraftment level compared to nonirradiated mice, while local irradiations increased hMSC engraftment locally in the area of irradiation. Long-term engraftment of systemically administered hMSCs in NOD/SCID mice increased significantly in response to tissue injuries produced by local or total body irradiation until 2 weeks then slowly decreased depending on organs and the configuration of irradiation. In all cases, no tissue abnormality or abnormal hMSCs proliferation was observed at 120 days after irradiation. This work supports the safe and efficient use of MSCs by injection as an alternative approach in the short- and long-term treatment of severe complications after radiotherapy for patients refractory to conventional treatments.

Mesenchymal stem cells for regenerative therapy: optimization of cell preparation protocols

Administration of bone marrow-derived mesenchymal stem cells (MSCs) is an innovative approach for the treatment of a range of diseases that are not curable by current therapies including heart failure. A number of clinical trials have been completed and many others are ongoing; more than 2,000 patients worldwide have been administered with culture-expanded allogeneic or autologous MSCs for the treatment of various diseases, showing feasibility and safety (and some efficacy) of this approach. However, protocols for isolation and expansion of donor MSCs vary widely between these trials, which could affect the efficacy of the therapy. It is therefore important to develop international standards of MSC production, which should be evidence-based, regulatory authority-compliant, of good medical practice grade, cost-effective, and clinically practical, so that this innovative approach becomes an established widely adopted treatment. This review article summarizes protocols to isolate and expand bone marrow-derived MSCs in 47 recent clinical trials of MSC-based therapy, which were published after 2007 onwards and provided sufficient methodological information. Identified issues and possible solutions associated with the MSC production methods, including materials and protocols for isolation and expansion, are discussed with reference to relevant experimental evidence with aim of future clinical success of MSC-based therapy.

Stem cells' guided gene therapy of cancer: New frontier in personalized and targeted therapy

INTRODUCTION

Diagnosis and therapy of cancer remain to be the greatest challenges for all physicians working in clinical oncology and molecular medicine. The statistics speak for themselves with the grim reports of 1,638,910 men and women diagnosed with cancer and nearly 577,190 patients passed away due to cancer in the USA in 2012. For practicing clinicians, who treat patients suffering from advanced cancers with contemporary systemic therapies, the main challenge is to attain therapeutic efficacy, while minimizing side effects. Unfortunately, all contemporary systemic therapies cause side effects. In treated patients, these side effects may range from nausea to damaged tissues. In cancer survivors, the iatrogenic outcomes of systemic therapies may include genomic mutations and their consequences. Therefore, there is an urgent need for personalized and targeted therapies. Recently, we reviewed the current status of suicide gene therapy for cancer. Herein, we discuss the novel strategy: genetically engineered stem cells' guided gene therapy.

REVIEW OF THERAPEUTIC STRATEGIES IN PRECLINICAL AND CLINICAL TRIALS

Stem cells have the unique potential for self renewal and differentiation. This potential is the primary reason for introducing them into medicine to regenerate injured or degenerated organs, as well as to rejuvenate aging tissues. Recent advances in genetic engineering and stem cell research have created the foundations for genetic engineering of stem cells as the vectors for delivery of therapeutic transgenes. Specifically in oncology, the stem cells are genetically engineered to deliver the cell suicide inducing genes selectively to the cancer cells only. Expression of the transgenes kills the cancer cells, while leaving healthy cells unaffected. Herein, we present various strategies to bioengineer suicide inducing genes and stem cell vectors. Moreover, we review results of the main preclinical studies and clinical trials. However, the main risk for therapeutic use of stem cells is their cancerous transformation. Therefore, we discuss various strategies to safeguard stem cell guided gene therapy against iatrogenic cancerogenesis.

PERSPECTIVES

Defining cancer biomarkers to facilitate early diagnosis, elucidating cancer genomics and proteomics with modern tools of next generation sequencing, and analyzing patients' gene expression profiles provide essential data to elucidate molecular dynamics of cancer and to consider them for crafting pharmacogenomics-based personalized therapies. Streamlining of these data into genetic engineering of stem cells facilitates their use as the vectors delivering therapeutic genes into specific cancer cells. In this realm, stem cells guided gene therapy becomes a promising new frontier in personalized and targeted therapy of cancer.

Application of bone marrow and adipose-derived mesenchymal stem cells for testing the biocompatibility of metal-based biomaterials functionalized with ascorbic acid

In this study, metal-based biomaterials were functionalized with ascorbic acid (LAA). Two types of substrates were used: austenitic steel 316L and titanium Ti6Al4V. Coatings were prepared with the sol-gel method and applied on metal surfaces using the dip-coating technique. Ascorbic acid was delivered with SiO2-coating at concentrations of 0.1 and 0.4 M. The morphology of the surfaces and coatings was determined using scanning electron microscope (SEM), whereas their elemental composition by SEM-EDX. Immobilization of ascorbic acid in the coatings was confirmed with Raman spectroscopy. The biocompatibility of the materials obtained was tested in vitro using both bone marrow- and adipose-derived mesenchymal stem cells (BMMSC and ADMSC, respectively). Proliferation rate and morphology of cells cultured in the presence of designed biomaterials were monitored after 24, 48, 120 and 168 h of propagation. The results obtained indicated that silica coatings doped with 0.4 M LAA had a positive effect on the proliferation rate of investigated cells, and in some cases on the growth pattern of culture.