The homing of bone marrow stem cells is differentially activated in ischemic and valvular heart diseases and influenced by beta-blockers

Modifying strategies for SDF-1/CXCR4 interaction during mesenchymal stem cell transplantation

Mesenchymal stem cell (MSC) transplantation is regarded as a promising candidate for the treatment of ischaemic heart disease. The major hurdles for successful clinical translation of MSC therapy are poor survival, retention, and engraftment in the infarcted heart. Stromal cell-derived factor-1/chemokine receptor 4 (SDF-1/CXCR4) constitutes one of the most efficient chemokine/chemokine receptor pairs regarding cell homing. In this review, we mainly focused on previous studies on how to regulate the SDF-1/CXCR4 interaction through various priming strategies to maximize the efficacy of mesenchymal stem cell transplantation on ischaemic hearts or to facilitate the required effects. The strengthened measures for enhancing the therapeutic efficacy of the SDF-1/CXCR4 interaction for mesenchymal stem cell transplantation included the combination of chemokines and cytokines, hormones and drugs, biomaterials, gene engineering, and hypoxia. The priming strategies on recipients for stem cell transplantation included ischaemic conditioning and device techniques.

Role of the HIF‑1α/SDF‑1/CXCR4 signaling axis in accelerated fracture healing after craniocerebral injury

The hypoxic state of the brain tissue surrounding craniocerebral injury induces an increase in the secretion of HIF-1α during the healing process. HIF-1α can promote mesenchymal stem cell (MSC) migration to ischemic and hypoxic sites by regulating the expression levels of molecules such as stromal cell-derived factor-1 (SDF-1) in the microenvironment. Stem cells express the SDF-1 receptor C-X-C chemokine receptor type 4 (CXCR4) and serve a key role in tissue repair, as well as a number of physiological and pathological processes. The present study aimed to determine the role of HIF-1α/SDF-1/CXCR4 signaling in the process of accelerated fracture healing during craniocerebral injury. Cultured MSCs underwent HIF-1α knockdown to elucidate its effect on the proliferative ability of MSCs, and the effect of SDF-1 in MSCs was investigated. It was also determined whether HIF-1α could promote osteogenesis via SDF-1/CXCR4 signaling and recruit MSCs. The results indicated that HIF-1α knockdown suppressed MSC proliferation in vitro, and SDF-1 promoted cell migration via binding to CXCR4. Furthermore, HIF-1α knockdown inhibited MSC migration via SDF-1/CXCR4 signaling. Considering the wide distribution and diversity of roles of SDF-1 and CXCR4, the present results may form a basis for the development of novel strategies for the treatment of craniocerebral injury.

Gene therapy for refractory angina and cell therapy for heart failure: experience of a Brazilian research group

Cell therapy has shown impressive effects in experimental cardiomyopathy models. To a lesser extent, gene therapy has also been studied. In both cases, translation to clinical therapy has been disappointing. This paper is intended to describe the experience and achievements of a multicenter working group located in Porto Alegre, southern Brazil, in experimental and translational research projects for cell-based and gene therapy methods in the treatment of dilated and ischemic cardiomyopathies. The results of preclinical and clinical studies showed that bone marrow mononuclear stem cells indeed have an effect in improving myocardial perfusion and contractile function, but the overall results are poorly translated to the clinical level. Gene therapy studies with direct myocardial injections of naked VEGF 165 plasmid showed improvement in myocardial perfusion and function in animal models. A randomized clinical trial found that this method is safe and improved myocardial perfusion, but the benefits disappeared after 1 year. An animal experiment associating VEGF 165 with angiopoietin was undertaken in mini pigs to extend the durability of that therapy. In conclusion, our efforts to better understand the mechanisms and functions of gene and cell-based therapies in cardiology resulted in significant findings and propose a future look at cell-free therapeutic approaches.

Enhanced Migration of Bone Marrow-Derived Mesenchymal Stem Cells with Tetramethylpyrazine and Its Synergistic Effect on Angiogenesis and Neurogenesis After Cerebral Ischemia in Rats

Bone marrow-derived mesenchymal stem cells (BMSCs) hold great promise for treating ischemic stroke owing to their capacity to secrete various trophic factors with potent angiogenic and neurogenic potentials. However, the relatively poor migratory capacity of BMSCs toward infarcted regions limits effective therapies for the treatment of stroke. The combination of BMSCs and pharmacological agent can promote the migration of BMSCs toward infarcted regions and improve the therapeutic effects after stroke. In this study, we aimed to investigate whether BMSCs combined with tetramethylpyrazine (TMP) enhanced BMSC migration into the ischemic brain, which had better therapeutic effect in the treatment of stroke. In a rat stroke model, we found that combination treatment significantly upregulated ischemic brain stromal-derived factor-1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) expressions, and promoted BMSCs homing toward the ischemic regions than BMSC monotherapy. Moreover, BMSCs combined with TMP synergistically increased the expression of vascular endothelial growth factor and brain-derived neurotrophic factor, promoted angiogenesis and neurogenesis, and improved functional outcome after stroke. These results suggest that combination treatment could not only enhance the migration of BMSCs into the ischemic brain but also act in a synergistic way to potentiate endogenous repair processes and functional recovery after ischemic stroke.

Pancreatic resident endocrine progenitors demonstrate high islet neogenic fidelity and committed homing towards diabetic mice pancreas

Pancreatic progenitors have been explored for their profound characteristics and unique commitment to generate new functional islets in regenerative medicine. Pancreatic resident endocrine progenitors (PREPs) with mesenchymal stem cell (MSC) phenotype were purified from BALB/c mice pancreas and characterized. PREPs were differentiated into mature islet clusters in vitro by activin-A and swertisin and functionally characterized. A temporal gene and protein profiling was performed during differentiation. Furthermore, PREPs were labeled with green fluorescent protein (GFP) and transplanted intravenously into streptozotocin (STZ) diabetic mice while monitoring their homing and differentiation leading to amelioration in the diabetic condition. PREPs were positive for unique progenitor markers and transcription factors essential for endocrine pancreatic homeostasis along with having the multipotent MSC phenotype. These cells demonstrated high fidelity for islet neogenesis in minimum time (4 days) to generate mature functional islet clusters (shortest reported period for any isolated stem/progenitor). Furthermore, GFP-labeled PREPs transplanted in STZ diabetic mice migrated and localized within the injured pancreas without trapping in any other major organ and differentiated rapidly into insulin-producing cells without an external stimulus. A rapid decrease in fasting blood glucose levels toward normoglycemia along with significant increase in fasting serum insulin levels was observed, which ameliorated the diabetic condition. This study highlights the unique potential of PREPs to generate mature islets within the shortest period and their robust homing toward the damaged pancreas, which ameliorated the diabetic condition suggesting PREPs affinity toward their niche, which can be exploited and extended to other stem cell sources in diabetic therapeutics.