Myocardin-related transcription factor-A-overexpressing bone marrow stem cells protect cardiomyocytes and alleviate cardiac damage in a rat model of acute myocardial infarction

Research on Differentiation of Bone Marrow Stromal Cells (BMSCs) Prompted by MicroRNA-124 and Effect on Inflammatory Reaction of Spinal Cord Injury Nerve Cells

The major feature of spinal cord injury (SCI) was the damage of nervous tissue in spinal cord. The damaged spinal cord was difficult to be repaired and regenerated. MicroRNA-124 could play a role in the repairing and recovering the injured tissue. The BMSCs could participate in repairing the damage. However, the regulatory effect of MicroRNA-124 on BMSCs and the inflammatory response of SCI was still not illustrated. These spinal cord nerve cells were assigned into group of mechanical damage, BMSCs and BMSCs with miR-124 overexpression followed by analysis of proliferation of nerve cells by MTT assay, apoptotic activity, expression of miR-124, GFAP and BDNF by Real time PCR, levels of TNF-α and IL-6 by ELISA as well as MDH and SOD activity. miR-124 mimics transfection significantly promoted BMSCs proliferation and increased ALK activity and the expression of GFAP and BDNF. In conclusion, the proliferation and differentiation of BMSCs could be regulated by miR-124. The inflammation and oxidative stress could be restrained so as to prompt the proliferation and repair of SCI cells and restrain apoptosis, indicating that it might be beneficial to recover the SCI.

Bone Marrow Mesenchymal Stem Cells (BMSCs) Promote Neuronal Cell Repair in Spinal Cord Injury by Regulating Toll-Like Receptor 4/Nuclear Factor-Kappa B Signaling Pathway

SCI (SCI) poses a challenge to nerve cell repair strategies. SCI injury can lead to the development of inflammation, which in turn can exacerbate nerve cell damage. The TLR4/NF-kappa B signaling pathway is a common inflammatory signaling pathway. Since BMSCs are involved in injury repair, whether they can promote the repair of SCI neuronal cells have not been reported. Spinal cord nerve cells were cultured in vitro and divided into mechanical injury group and BMSCs group followed by analysis of cell proliferation activity and detection of altered apoptotic activity. Changes in the concentrations of IL-6 and IL-1β were measured by ELISA and cellular mitochondrial alterations was assessed by JG-B staining along with analysis of NF-kappa B, TLR4, related neurodevelopmental factor BDNF, and NGF expression by western blot. Mechanical damage to neuronal cells resulted in decreased cell proliferation, increased apoptotic activity, decreased cellular mitochondrial activity, increased TLR4 and NF-kappa B expression, decreased BDNF and NGF expression, as well as increased secertions of IL-6 and IL-1β (P < 0.05). In contrast, co-culture with BMSCs resulted in increased proliferation and decreased apoptosis of mechanically injured neuronal cells, increased cellular mitochondrial activity, with observation of the inverse changes in other factors (P < 0.05). In conclusion, BMSCs can suppress inflammation and promote repair of injured neuronal cells by inhibiting TLR4/NF-kappa B signaling.

Analyzing Impetus of Regenerative Cellular Therapeutics in Myocardial Infarction

Both vasculature and myocardium in the heart are excessively damaged following myocardial infarction (MI), hence therapeutic strategies for treating MI hearts should concurrently aim for true cardiac repair by introducing new cardiomyocytes to replace lost or injured ones. Of them, mesenchymal stem cells (MSCs) have long been considered a promising candidate for cell-based therapy due to their unspecialized, proliferative differentiation potential to specific cell lineage and, most importantly, their capacity of secreting beneficial paracrine factors which further promote neovascularization, angiogenesis, and cell survival. As a consequence, the differentiated MSCs could multiply and replace the damaged tissues to and turn into tissue- or organ-specific cells with specialized functions. These cells are also known to release potent anti-fibrotic factors including matrix metalloproteinases, which inhibit the proliferation of cardiac fibroblasts, thereby attenuating fibrosis. To achieve the highest possible therapeutic efficacy of stem cells, the other interventions, including hydrogels, electrical stimulations, or platelet-derived biomaterials, have been supplemented, which have resulted in a narrow to broad range of outcomes. Therefore, this article comprehensively analyzed the progress made in stem cells and combinatorial therapies to rescue infarcted myocardium.

MRTF-A promotes angiotensin II-induced inflammatory response and aortic dissection in mice

Aortic dissection (AD) is a major cause of acute aortic syndrome with high mortality due to the destruction of aortic walls. Although recent studies indicate the critical role of inflammation in the disease mechanism of AD, it is unclear how inflammatory response is initiated. Here, we demonstrate that myocardin-related transcription factor A (MRTF-A), a signal transducer of humoral and mechanical stress, plays an important role in pathogenesis of AD in a mouse model. A mouse model of AD was created by continuous infusion of angiotensin II (AngII) that induced MRTF-A expression and caused AD in 4 days. Systemic deletion of Mrtfa gene resulted in a marked suppression of AD development. Transcriptome and gene annotation enrichment analyses revealed that AngII infusion for 1 day caused pro-inflammatory and pro-apoptotic responses before AD development, which were suppressed by Mrtfa deletion. AngII infusion for 1 day induced pro-inflammatory response, as demonstrated by expressions of Il6, Tnf, and Ccl2, and apoptosis of aortic wall cells, as detected by TUNEL staining, in an MRTF-A-dependent manner. Pharmacological inhibition of MRTF-A by CCG-203971 during AngII infusion partially suppressed AD phenotype, indicating that acute suppression of MRTF-A is effective in preventing the aortic wall destruction. These results indicate that MRTF-A transduces the stress of AngII challenge to the pro-inflammatory and pro-apoptotic responses, ultimately leading to AD development. Intervening this pathway may represent a potential therapeutic strategy.

Sphingosine 1-phosphate elicits RhoA-dependent proliferation and MRTF-A mediated gene induction in CPCs

Although c-kit(+) cardiac progenitor cells (CPCs) are currently used in clinical trials there remain considerable gaps in our understanding of the molecular mechanisms underlying their proliferation and differentiation. G-protein coupled receptors (GPCRs) play an important role in regulating these processes in mammalian cell types thus we assessed GPCR mRNA expression in c-kit(+) cells isolated from adult mouse hearts. Our data provide the first comprehensive overview of the distribution of this fundamental class of cardiac receptors in CPCs and reveal notable distinctions from that of adult cardiomyocytes. We focused on GPCRs that couple to RhoA activation in particular those for sphingosine-1-phosphate (S1P). The S1P2 and S1P3 receptors are the most abundant S1P receptor subtypes in mouse and human CPCs while cardiomyocytes express predominantly S1P1 receptors. Treatment of CPCs with S1P, as with thrombin and serum, increased proliferation through a pathway requiring RhoA signaling, as evidenced by significant attenuation when Rho was inhibited by treatment with C3 toxin. Further analysis demonstrated that both S1P- and serum-induced proliferation are regulated through the S1P2 and S1P3 receptor subtypes which couple to Gα12/13 to elicit RhoA activation. The transcriptional co-activator MRTF-A was activated by S1P as assessed by its nuclear accumulation and induction of a RhoA/MRTF-A luciferase reporter. In addition S1P treatment increased expression of cardiac lineage markers Mef2C and GATA4 and the smooth muscle marker GATA6 through activation of MRTF-A. In conclusion, we delineate an S1P-regulated signaling pathway in CPCs that introduces the possibility of targeting S1P2/3 receptors, Gα12/13 or RhoA to influence the proliferation and commitment of c-kit(+) CPCs and improve the response of the myocardium following injury.

Mesenchymal stem cells in cardiac regeneration: a detailed progress report of the last 6 years (2010-2015)

Mesenchymal stem cells have been used for cardiovascular regenerative therapy for decades. These cells have been established as one of the potential therapeutic agents, following several tests in animal models and clinical trials. In the process, various sources of mesenchymal stem cells have been identified which help in cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Although mesenchymal cell therapy has achieved considerable admiration, some challenges still remain that need to be overcome in order to establish it as a successful technique. This in-depth review is an attempt to summarize the major sources of mesenchymal stem cells involved in myocardial regeneration, the significant mechanisms involved in the process with a focus on studies (human and animal) conducted in the last 6 years and the challenges that remain to be addressed.