Timing of induction of cardiomyocyte differentiation for in vitro cultured mesenchymal stem cells: a perspective for emergencies

The voltage-gated proton channel hHv1 is functionally expressed in human chorion-derived mesenchymal stem cells

The voltage-gated proton channel Hv1 is widely expressed, among others, in immune and cancer cells, it provides an efficient cytosolic H⁺extrusion mechanism and regulates vital functions such as oxidative burst, migration and proliferation. Here we demonstrate the presence of human Hv1 (hHv1) in the placenta/chorion-derived mesenchymal stem cells (cMSCs) using RT-PCR. The voltage- and pH-dependent gating of the current is similar to that of hHv1 expressed in cell lines and that the current is blocked by 5-chloro-2-guanidinobenzimidazole (ClGBI) and activated by arachidonic acid (AA). Inhibition of hHv1 by ClGBI significantly decreases mineral matrix production of cMSCs induced by conditions mimicking physiological or pathological (inorganic phosphate, Pi) induction of osteogenesis. Wound healing assay and single cell motility analysis show that ClGBI significantly inhibits the migration of cMSCs. Thus, seminal functions of cMSCs are modulated by hHv1 which makes this channel as an attractive target for controlling advantages/disadvantages of MSCs therapy.

AT1R-Mediated Apoptosis of Bone Marrow Mesenchymal Stem Cells Is Associated with mtROS Production and mtDNA Reduction

Angiotensin II (Ang II) is used as an inducer for the differentiation of mesenchymal stem cells (MSCs). Whether the commonly used doses of Ang II for MSC differentiation affect cell apoptosis has not been elucidated. In this study, we investigated the effect of Ang II on the apoptosis of bone marrow MSCs (BMMSCs), and its relations to the activation of Ang II receptor-1- (AT1R-) signaling, mitochondrial ROS (mtROS) generation, and mitochondrial DNA (mtDNA) leakage. AT1R expression in BMMSCs was identified by immunostaining and Western-blotting assays. BMMSC viability was measured by MTT assay following exposure to 1 nM~1 mM Ang II for 12 hours. Cell apoptosis, mtROS, and mtDNA levels were detected by FAM-FLICA® Poly Caspase, MitoSOX™ superoxide, and PicoGreen staining, respectively. The expressions of Bcl2 and Bax were measured by Western-blotting assays. Next, we used losartan to block AT1R-signaling and subsequently measured apoptosis, mtROS, and mtDNA levels, again. The maximum viability of BMMSCs was in response to 100 nM Ang II, after that it began to decrease with the increase of Ang II doses, indicating that Ang II (≧1 μM) may cause apoptosis of BMMSCs. As expected, 1 μM and 10 μM Ang II both caused BMMSC apoptosis. Furthermore, 1 μM and 10 μM Ang II could also induce mtROS generation and cause a marked mtDNA leakage. The application of losartan markedly inhibited Ang II-induced mtROS production, mtDNA leakage, and BMMSC apoptosis. In conclusion, the activation of AT1R-signaling stimulates apoptosis of BMMSCs, which is associated mtROS production and mtDNA reduction.

Therapeutic potential effect of bone marrow-derived mesenchymal stem cells on chronic liver disease in murine Schistosomiasis Mansoni

Some reports have shown that mesenchymal stem cells (MSCs) therapy could ameliorate chemically-induced hepatic fibrosis. This research assesses the therapeutic action of bone marrow mesenchymal stem cells (BM-MSCs) on chronic diseased liver in Schistosoma mansoni infected mice. All infected female mice divided into three groups, one group (15 mice) treated with oral praziquantel (PZQ), second group (15 mice) received intravenous injection of BM-MSCs and third group (15 mice) treated with both MSCs + PZQ. Two control groups (15 mice each) subdivided into one infected and second healthy one. BM-MSCs were obtained from bones of both femur and tibia of male mice (30 mice), then cultured and characterized morphologically by detection of CD105 by flow cytometer. Liver tissues for all groups were examined histopathologically. Measuring of the collagen 1 gene expression was done by real-time PCR and immunohistochemical study to detect stem cells differentiation for detection of MSCs engraftments in liver tissue. MSCs treatment caused marked improvement and regression of fibrosis, and prevents deposition of collagen and reduced the expression of collagen 1 gene in infected mice on their liver tissues, especially when used with PZQ in mice treatment. It can be concluded that, MSCs is a good therapeutic method for liver fibrosis caused by S. mansoni infection.

Characterisation and immunosuppressive activity of human cartilage-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) exert potent immuno-regulatory activities on various immune cells and also differentiate into various mesodermal lineages besides retaining a distinct self-renewal ability. Such exclusive characteristics had enabled MSCs to be recognised as an ideal source for cell-based treatment in regenerative medicine and immunotherapy. Thus, considering MSCs for treating degenerative disease of organs with limited regenerative potential such as cartilage would serve as an ideal therapy. This study explored the feasibility of generating human cartilage-derived MSCs (hC-MSCs) from sports injured patients and characterised based on multipotent differentiation and immunosuppressive activities. Cartilage tissues harvested from a non-weight bearing region during an arthroscopy procedure were used to generate MSCs. Despite the classic morphology of fibroblast-like cells and a defined immunophenotyping, MSCs expressed early embryonic transcriptional markers (SOX2, REX1, OCT4 and NANOG) and differentiated into chondrocytes, adipocytes and osteocytes when induced accordingly. Upon co-culture with PHA-L activated T-cells, hC-MSCs suppressed the proliferation of the T-cells in a dose-dependent manner. Although, hC-MSCs did not alter the activation profile of T cells significantly, yet prevented the entering of activated T cells into S phase of the cell cycle by cell cycle arrest. The present study has strengthened the evidence of tissue-resident mesenchymal stem cells in human cartilage tissue. The endogenous MSCs could be an excellent tool in treating dysregulated immune response that associated with cartilage since hC-MSCs exerted both immunosuppressive and regenerative capabilities.

Transcription factor TBX18 promotes adult rat bone mesenchymal stem cell differentiation to biological pacemaker cells

Bone mesenchymal stem cells (BMSCs) are currently considered the optimal stem cells for biological pacemaker cell transformation. The cardiac-specific transcription factor T-Box protein 18 (TBX18) is essential for sinoatrial node (SAN) formation, particularly formation of the head region that generates the electrical impulses that induce heart contraction. The present study aimed to confirm the effects of TBX18 on biological pace-maker differentiation of rat BMSCs. Flow cytometry was used to identify the surface markers of BMSCs, in order to acquire pure mesenchymal stem cells. Subsequently, BMSCs were transduced with TBX18 or green fluorescent protein adenovirus vectors. The effects of TBX18 were evaluated using SAN-specific makers including TBX18, α-actin, cardiac troponin I, hyperpolarization-activated cyclic nucleotide-gated channel 4 and connexin 43 by reverse transcription-quantitative polymerase chain reaction, western blotting and immunofluorescence. The findings demonstrated that direct conversion of BMSCs to biological pacemaker cells via TBX18 is a feasible method in the field of cardiology.

Nanomaterial applications for neurological diseases and central nervous system injury

The effectiveness of noninvasive treatment for neurological disease is generally limited by the poor entry of therapeutic agents into the central nervous system (CNS). Most CNS drugs cannot permeate into the brain parenchyma because of the blood-brain barrier thus, overcoming this problem has become one of the most significant challenges in the development of neurological therapeutics. Nanotechnology has emerged as an innovative alternative for treating neurological diseases. In fact, rapid advances in nanotechnology have provided promising solutions to this challenge. This review highlights the applications of nanomaterials in the developing neurological field and discusses the evidence for their efficacies.

Regenerative pharmacology for the treatment of acute kidney injury: Skeletal muscle stem/progenitor cells for renal regeneration?

Regenerative pharmacology and advanced therapy medicinal products is a relatively new and challenging field in drug development. Acute kidney injury (AKI) is a common clinical condition in nephrology with increasing incidence and high mortality rate. During the last few decades, researchers have been eagerly trying to find novel therapeutic strategies for AKI treatment, including advanced pharmacological therapies using mesenchymal stem cells (MSCs). Several types of MSCs have been thoroughly investigated, including bone marrow, adipose derived and umbilical cord blood MSCs and shown promising results in kidney repair. Research has demonstrated, that MSCs exert their effect through reduction of apoptosis, increased production of growth factors, suppression of oxidative stress and inflammatory processes, promotion of renal tubular cell proliferation, as well as by migration and direct incorporation into the renal tissue. Skeletal muscle-derived stem/progenitor cells (MDSPCs) are mesenchymal stem cell lineage of multipotent cells, demonstrating long-term proliferation, high self-renewal capacities, and ability to enhance endogenous tissue repair. The capacity of MDSPCs to regenerate a variety of different tissues following acute injury or destructive tissue diseases have been demonstrated in preclinical and clinical studies. MDSPCs were also reported to promote endogenous tissue repair via paracrine pathway. Considering advantageous properties of MDSPCs, the administration of these cells might be considered as a potential strategy for the treatment of AKI. However, to date, the therapeutic effect of MDSPCs for renal regeneration has not been investigated. This review reflects the current development in AKI treatment using different types of MSCs and the pilot results of the experimental study in vivo using a novel type of stem cells - MDSPCs for the treatment of gentamicin-induced AKI.

How to mend a broken heart: adult and induced pluripotent stem cell therapy for heart repair and regeneration

The recently developed ability to differentiate primary adult stem cells and induced pluripotent stem cells (iPSCs) into cardiomyocytes is providing unprecedented opportunities to produce an unlimited supply of cardiomyocytes for use in patients with heart disease. Here, we examine the evidence for the preclinical use of such cells for successful heart regeneration. We also describe advances in the identification of new cardiac molecular and cellular targets to induce proliferation of cardiomyocytes for heart regeneration. Such new advances are paving the way for a new innovative drug development process for the treatment of heart disease.

Nanoparticle labeling of bone marrow-derived rat mesenchymal stem cells: their use in differentiation and tracking

Mesenchymal stem cells (MSCs) are promising candidates for cellular therapies due to their ability to migrate to damaged tissue without inducing immune reaction. Many techniques have been developed to trace MSCs and their differentiation efficacy; however, all of these methods have limitations. Conjugated polymer based water-dispersible nanoparticles (CPN) represent a new class of probes because they offer high brightness, improved photostability, high fluorescent quantum yield, and noncytotoxicity comparing to conventional dyes and quantum dots. We aimed to use this tool for tracing MSCs' fate in vitro and in vivo. MSC marker expression, survival, and differentiation capacity were assessed upon CPN treatment. Our results showed that after CPN labeling, MSC markers did not change and significant number of cells were found to be viable as revealed by MTT. Fluorescent signals were retained for 3 weeks after they were differentiated into osteocytes, adipocytes, and chondrocytes in vitro. We also showed that the labeled MSCs migrated to the site of injury and retained their labels in an in vivo liver regeneration model. The utilization of nanoparticle could be a promising tool for the tracking of MSCs in vivo and in vitro and therefore can be a useful tool to understand differentiation and homing mechanisms of MSCs.

MicroRNA-10b promotes the migration of mouse bone marrow-derived mesenchymal stem cells and downregulates the expression of E-cadherin

The ability of mesenchymal stem cells (MSCs) to migrate is an important determinant of the efficiency of MSC transplant therapy. MicroRNA-10b (miR-10b) has been positively involved in the migration of a number of tumor cells lineages. To date, it remains unknown whether miR-10b affects the migration of MSCs. In the current study, the effect of miR-10b on the migration of mouse bone marrow-derived MSCs (bmMSCs) was investigated. Third-passage bmMSCs were transfected with miR-10b mimic and negative control precursor miRNA using Lipofectamine™ 2000. miR-10b and E-cadherin expression and bmMSC migration were determined. The present results showed that primary bmMSCs exhibit a spindled or triangular morphology and that third‑passage bmMSCs present a typical fibroblast-like morphology, exhibiting CD90-positive and CD45-negative expression. Compared with the transfection of negative control miRNA, transfection of miR-10b mimic markedly upregulated miR-10b expression in bmMSCs, increased their migration and downregulated E-cadherin expression. The current observations indicate that the upregulation of miR-10b increases bmMSC migration ability, which may be involved in the downregulation of E-cadherin.

Bone marrow-derived mesenchymal stem cells promote hepatic regeneration after partial hepatectomy in rats

OBJECTIVES

Our goal was to study the ability of mesenchymal stem cells (MSCs) to stimulate liver regeneration after partial hepatectomy in rats.

METHODS

MSCs were isolated from bone marrow and cultured in vitro. Their characteristics were analyzed by flow cytometry. After 70% partial hepatectomy, Sprague-Dawley rats were randomly divided into three groups: a control group that was injected with saline, animals that received bone marrow-derived MSCs (BM-MSCs) by tail vein injection (the BM-MSC-TV group) and animals that received BM-MSCs by portal vein injection (the BM-MSC-PV group). The injected BM-MSCs were traced by labeling with 4',6-diamidino-2-phenylindole, and cell proliferations were determined by immunohistochemical staining with Ki-67 and 5-bromo-2'-deoxyuridine.

RESULTS

After the third passage, the cultured BM-MSCs had a fibroblast-like morphology and expressed high levels of stem cell markers CD29 and CD90. The levels of albumin rose significantly in the BM-MSC-TV and BM-MSC-PV groups compared with the control group. The number of 4',6-diamidino-2-phenylindole-positive liver cells in the BM-MSC-PV group was significantly higher than in the BM-MSC-TV group. The levels of Ki-67 and 5-bromo-2'-deoxyuridine were significantly higher in the BM-MSC-TV and the BM-MSC-PV groups than in the controls.

CONCLUSION

Taken together, these results indicate that BM-MSC injections enhance liver regeneration after partial hepatectomy in rats.

Patterned carbon nanotubes as a new three-dimensional scaffold for mesenchymal stem cells

We investigated the cellular adhesive features of mesenchymal stem cells (MSC) on non-coated and collagen coated patterned and vertically aligned carbon nanotube (CNT) structures mimicking the natural extra cellular matrix (ECM). Patterning was achieved using the elasto-capillary induced by water treatment on the CNT arrays. After confirmation with specific markers both at transcript and protein levels, MSCs from different passages were seeded on either collagen coated or non-coated patterned CNTs. Adhesion and growth of MSCs on the patterned CNT arrays were examined using scanning electron microscopy image analysis and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazolium bromide (MTT) assays. The highest MSC count was observed on the non-coated patterned CNTs at passage zero, while decreasing numbers of MSCs were found at the later passages. Similarly, MTT assay results also revealed a decrease in the viability of the MSCs for the later passages. Overall, the cell count and viability experiments indicated that MSCs were able to better attach to non-coated patterned CNTs compared to those coated with collagen. Therefore, the patterned CNT surfaces can be potentially used as a scaffold mimicking the ECM environment for MSC growth which presents an alternative approach to MSC-based transplantation therapy applications.

S100A16 inhibits osteogenesis but stimulates adipogenesis

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have the capacity to differentiate into osteoblasts and adipocytes. Bone marrow adipogenesis exerts an inhibitory effect on osteogenesis, which leads to osteoporosis. S100A16, a novel member of the S100 family, is ubiquitously expressed, and markedly enhances adipogenesis. The aim of this study was to demonstrate, in the mouse BM-MSC model, whether S100A16 significantly stimulates adipogenic, rather than osteogenic differentiation. The overexpression of S100A16 led to a significant increase in Oil Red O staining (a marker of adipocyte differentiation) but a decrease in Alizarin Red S staining (a marker of osteoblast differentiation). In contrast, reducing the expression of S100A16 resulted in minimal Oil Red O staining but increased Alizarin Red S staining. During differentiation into osteoblasts, RUNX2 expression increased fourfold in the S100A16(KO+/-) BM-MSCs, but only increased by approximately 1.5-fold in the S100A16(TG+/+) BM-MSCs. And BMP2 occurred in the same changes. Upon induction of BM-MSC differentiation into adipocytes, peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein-α expression were significantly higher in the cells overexpressing S100A16 protein but lower in the cells with reduced expression of S100A16 protein, compared with the control cells, which were BM-MSCs derived from C57/BL6. S100A16 increased PPARγ promoter luciferase activity and decreased RUNX2 promoter luciferase activity. ERK1/2 phosphorylation was stimulated during osteogenesis, whereas p-JNK phosphorylation was increased by stimulation of adipogenesis. Our results suggest that S100A16 inhibits osteogenesis but stimulates adipogenesis by increasing the transcription of PPARγ and decreasing the transcription of RUNX2. The ERK1/2 pathway is involved in the regulation of osteogenesis whereas the JNK pathway is involved in adipogenesis.

Stem cell mediated cardiovascular repair

Recent increase in the interest in stem and progenitor cells may be attributed to their behavioural characteristics. A consensus has been reached that embryonic or adult stem cells have therapeutic potential. As cardiovascular health issues are still the major culprits in many developed countries, stem and progenitor cell driven approaches may give the clinicians a new arsenal to tackle many significant health issues. However, stem and progenitor cell mediated cardiovascular regeneration can be achieved via complex and dynamic molecular mechanisms involving a variety of cells, growth factors, cytokines, and genes. Functional contributions of transplanted cells on target organs and their survival are still critical problems waiting to be resolved. Moreover, the regeneration of contracting myocardial tissue has controversial results in human trials. Thus, moderately favourable clinical results should be interpreted carefully. Determining the behavioural programs, genetic and transcriptional control of stem cells, mechanisms that determine cell fate, and functional characteristics are the primary targets. In addition, ensuring the long-term follow-up of cells with efficient imaging techniques in human clinical studies may provide a resurgence of the initial enthusiasm, which has faded over time. Here, we provide a brief historical perspective on stem cell driven cardiac regeneration and discuss cardiac and vascular repair in the context of translational science.

Trichostatin a promotes cardiomyocyte differentiation of rat mesenchymal stem cells after 5-azacytidine induction or during coculture with neonatal cardiomyocytes via a mechanism independent of histone deacetylase inhibition

This study was to investigate the effect of trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, on cardiac differentiation of bone marrow mesenchymal stem cells (MSCs) in vitro. Rat MSCs were isolated and divided into six groups: 1) control; 2) 5-azacytidine treatment (5-aza, 10 μM); 3) treatment with TSA (100, 300, and 500 nM); 4) treatment with 5-aza followed by incubation with TSA; 5) coculture with neonatal cardiomyocytes (CMs); and 6) treatment with TSA then coculture with CMs. HDAC activity was significantly inhibited in TSA-treated cells with the maximal inhibition after 24 h of exposure to TSA at 300 nM. No changes in HDAC activity were observed in control, 5-aza-treated, or coculture groups. Following 7 days of differentiation, the expression of early cardiac transcription factors GATA-4, NKx2.5, MEF2c, and cardiac troponin T (cTnT) was increased by 6-8 times in the cells in 5-aza-treated, coculture, or TSA-treated groups over control as determined using real-time PCR, immunofluorescence staining, and Western blotting. However, the percent cTnT-positive cells were dramatically different with 0.7% for control, 10% for 5-aza-treated, 25% for coculture, and 4% for TSA-treated group (500 nM). TSA treatment of the cells pretreated with 5-aza or cocultured with CMs dramatically increased the expression of GATA-4, NKx2.5, and MEF2c by 35-50 times over control. The cTnT protein expression was also significantly increased by over threefold by TSA treatment (500 nM) in both 5-aza-treated and coculture group over control. The percent cTnT-positive cells in both 5-aza-pre-treated and coculture groups were significantly increased by TSA treatment after 1 week of differentiation by up to 92.6% (from 10.3% to 19.8%) and 23.9% (from 24.5% to 30.2%), respectively. These data suggested that TSA enhanced the cardiac differentiation of MSCs after 5-aza induction or during coculture with CMs through a mechanism beyond the inhibition of HDAC activity.

Mesenchymal stem cells or cardiac progenitors for cardiac repair? A comparative study

In the past, clinical trials transplanting bone marrow-derived mononuclear cells reported a limited improvement in cardiac function. Therefore, the search for stem cells leading to more successful stem cell therapies continues. Good candidates are the so-called cardiac stem cells (CSCs). To date, there is no clear evidence to show if these cells are intrinsic stem cells from the heart or mobilized cells from bone marrow. In this study we performed a comparative study between human mesenchymal stem cells (hMSCs), purified c-kit(+) CSCs, and cardiosphere-derived cells (CDCs). Our results showed that hMSCs can be discriminated from CSCs by their differentiation capacity towards adipocytes and osteocytes and the expression of CD140b. On the other hand, cardiac progenitors display a greater cardiomyogenic differentiation capacity. Despite a different isolation protocol, no distinction could be made between c-kit(+) CSCs and CDCs, indicating that they probably derive from the same precursor or even are the same cells.

Mesenchymal stem cells at the intersection of cell and gene therapy

IMPORTANCE OF THE FIELD

Mesenchymal stem cells have the ability to differentiate into osteoblasts, chondrocytes and adipocytes. Along with differentiation, MSCs can modulate inflammation, home to damaged tissues and secrete bioactive molecules. These properties can be enhanced through genetic-modification that would combine the best of both cell and gene therapy fields to treat monogenic and multigenic diseases.

AREAS COVERED IN THIS REVIEW

Findings demonstrating the immunomodulation, homing and paracrine activities of MSCs followed by a summary of the current research utilizing MSCs as a vector for gene therapy, focusing on skeletal disorders, but also cardiovascular disease, ischemic damage and cancer.

WHAT THE READER WILL GAIN

MSCs are a possible therapy for many diseases, especially those related to the musculoskeletal system, as a standalone treatment, or in combination with factors that enhance the abilities of these cells to migrate, survive or promote healing through anti-inflammatory and immunomodulatory effects, differentiation, angiogenesis or delivery of cytolytic or anabolic agents.

TAKE HOME MESSAGE

Genetically-modified MSCs are a promising area of research that would be improved by focusing on the biology of MSCs that could lead to identification of the natural and engrafting MSC-niche and a consensus on how to isolate and expand MSCs for therapeutic purposes.

The effect of telomerase template antagonist GRN163L on bone-marrow-derived rat mesenchymal stem cells is reversible and associated with altered expression of cyclin d1, cdk4 and cdk6

Telomerase activity is essential for the continued growth and survival of malignant cells, therefore inhibition of this activity presents an attractive target for anti-cancer therapy. The telomerase inhibitor GRN163L, was shown to inhibit the growth of cancer cells both in vitro and in vivo. Mesenchymal stem cells (MSCs) also show telomerase activity in maintaining their self-renewal; therefore the effects of telomerase inhibitors on MSCs may be an issue of concern. MSCs are multipotent cells and are important for the homeostasis of the organism. In this study, we sought to demonstrate in vitro effects of GRN163L on rat MSCs. When MSCs were treated with 1 microM GRN163L, their phenotype changed from spindle-shaped cells to rounded ones and detached from the plate surface, similar to cancer cells. Quantitative-RT-PCR and immunoblotting results revealed that GRN163L holds MSCs at the G1 state of the cell cycle, with a drastic decrease in mRNA and protein levels of cyclin D1 and its cdk counterparts, cdk4 and cdk6. This effect was not observed when MSCs were treated with a mismatch control oligonucleotide. One week after GRN163L was removed, mRNA and protein expressions of the genes, as well as the phenotype of MSCs returned to those of untreated cells. Therefore, we concluded that GRN163L does not interfere with the self-renewal and differentiation of MSCs under short term in vitro culture conditions. Our study provides additional support for treating cancers by administrating GRN163L without depleting the body's stem cell pools.

Mesenchymal stromal cells: current understanding and clinical status

Multipotent mesenchymal stromal cells (MSCs) represent a rare heterogeneous subset of pluripotent stromal cells that can be isolated from many different adult tissues that exhibit the potential to give rise to cells of diverse lineages. Numerous studies have reported beneficial effects of MSCs in tissue repair and regeneration. After culture expansion and in vivo administration, MSCs home to and engraft to injured tissues and modulate the inflammatory response through synergistic downregulation of proinflammatory cytokines and upregulation of both prosurvival and antiinflammatory factors. In addition, MSCs possess remarkable immunosuppressive properties, suppressing T-cell, NK cell functions, and also modulating dentritic cell activities. Tremendous progress has been made in preclinical studies using MSCs, including the ability to use allogeneic cells, which has driven the application of MSCs toward the clinical setting. This review highlights our current understanding into the biology of MSCs with particular emphasis on the cardiovascular and renal applications, and provides a brief update on the clinical status of MSC-based therapy.

Delayed enrichment of mesenchymal cells promotes cardiac lineage and calcium transient development

Bone marrow-derived mesenchymal stem cells (BM-MSCs) can be induced to differentiate into myogenic cells. Despite their potential, previous studies have not been successful in producing a high percentage of cardiac-like cells with a muscle phenotype. We hypothesized that cardiac lineage development in BM-MSC is related to cell passage, culture milieu, and enrichment for specific cell subtypes before and during differentiation. Our study demonstrated that Lin(-) BM-MSC at an intermediate passage (IP; P8-P12) expressed cardiac troponin T (cTnT) after 21 days in culture. Cardiac TnT expression was similar whether IP cells were differentiated in media containing 5-azacytidine+2% FBS (AZA; 14%) or 2% FBS alone (LS; 12%) and both were significantly higher than AZA+5% FBS. This expression was potentiated by first enriching for CD117/Sca-1 cells followed by differentiation (AZA, 39% and LS, 28%). A second sequential enrichment for the dihydropyridine receptor subunit alpha2delta1 (DHPR-alpha2) resulted in cardiac TnT expressed in 54% of cultured cells compared to 28% of cells after CD117/Sca-1(+) enrichment. Cells enriched for CD117/Sca-1 and subjected to differentiation displayed spontaneous intracellular Ca(2+) transients with an increase in transient frequency and a 60% decrease in the transient duration amplitude between days 14 and 29. In conclusion, IP CD117/Sca-1(+) murine BM-MSCs display robust cardiac muscle lineage development that can be induced independent of AZA but is diminished under higher serum concentrations. Furthermore, temporal changes in calcium kinetics commensurate with increased cTnT expression suggest progressive maturation of a cardiac muscle lineage. Enrichment with CD117/Sca-1 to establish lineage commitment followed by DHPR-alpha2 in lineage developing cells may enhance the therapeutic potential of these cells for transplantation.

Allogeneic non-adherent bone marrow cells facilitate hematopoietic recovery but do not lead to allogeneic engraftment

Background

Non adherent bone marrow derived cells (NA-BMCs) have recently been described to give rise to multiple mesenchymal phenotypes and have an impact in tissue regeneration. Therefore, the effects of murine bone marrow derived NA-BMCs were investigated with regard to engraftment capacities in allogeneic and syngeneic stem cell transplantation using transgenic, human CD4⁺, murine CD4^−/−, HLA-DR3⁺ mice.

Methodology/Principal Findings

Bone marrow cells were harvested from C57Bl/6 and Balb/c wild-type mice, expanded to NA-BMCs for 4 days and characterized by flow cytometry before transplantation in lethally irradiated recipient mice. Chimerism was detected using flow cytometry for MHC-I (H-2D[b], H-2K[d]), mu/huCD4, and huHLA-DR3). Culturing of bone marrow cells in a dexamethasone containing DMEM medium induced expansion of non adherent cells expressing CD11b, CD45, and CD90. Analysis of the CD45⁺ showed depletion of CD4⁺, CD8⁺, CD19⁺, and CD117⁺ cells. Expanded syngeneic and allogeneic NA-BMCs were transplanted into triple transgenic mice. Syngeneic NA-BMCs protected 83% of mice from death (n = 8, CD4⁺ donor chimerism of 5.8±2.4% [day 40], P<.001). Allogeneic NA-BMCs preserved 62.5% (n = 8) of mice from death without detectable hematopoietic donor chimerism. Transplantation of syngeneic bone marrow cells preserved 100%, transplantation of allogeneic bone marrow cells 33% of mice from death.

Conclusions/Significance

NA-BMCs triggered endogenous hematopoiesis and induced faster recovery compared to bone marrow controls. These findings may be of relevance in the refinement of strategies in the treatment of hematological malignancies.