Downregulation of the CXC chemokine receptor 4/stromal cell-derived factor 1 pathway enhances myocardial neovascularization, cardiomyocyte survival, and functional recovery after myocardial infarction

Mesenchymal stromal cell therapies: immunomodulatory properties and clinical progress

Mesenchymal stromal cells (MSCs) are a subset of heterogeneous non-hematopoietic fibroblast-like cells that can differentiate into cells of multiple lineages, such as chondrocytes, osteoblasts, adipocytes, myoblasts, and others. These multipotent MSCs can be found in nearly all tissues but mostly located in perivascular niches, playing a significant role in tissue repair and regeneration. Additionally, MSCs interact with immune cells both in innate and adaptive immune systems, modulating immune responses and enabling immunosuppression and tolerance induction. Understanding the biology of MSCs and their roles in clinical treatment is crucial for developing MSC-based cellular therapy for a variety of pathological conditions. Here, we review the progress in the study on the mechanisms underlying the immunomodulatory and regenerative effects of MSCs; update the medical translation of MSCs, focusing on the registration trials leading to regulatory approvals; and discuss how to improve therapeutic efficacy and safety of MSC applications for future.

Role of axl in preeclamptic EPCs functions

Axl encodes the tyrosine-protein kinase receptor, participating in the proliferation and migration of many cells. This study examined the role of Axl in functions of endothelial progenitor cells (EPCs). Axl was detected by RT-PCR and Western blotting in both placentas and EPCs from normal pregnancy and preeclampsia patients. The Axl inhibitor, BMS777-607, was used to inhibit the Axl signalling pathway in EPCs. Cell proliferation, differentiation, migration and adhesion were measured by CCK-8 assay, cell differentiation assay, Transwell assay, and cell adhesion assay, respectively. Results showed the expression levels of Axl mRNA and protein were significantly higher in both placentas and EPCs from preeclampsia patients than from normal pregnancy (P<0.05). After treatment with BMS777-607, proliferation, differentiation, migration and adhesion capability of EPCs were all significantly decreased. Our study suggests Axl may play a role in the function of EPCs, thereby involving in the pathogenesis of preeclampsia.

Exendin-4 enhances the migration of adipose-derived stem cells to neonatal rat ventricular cardiomyocyte-derived conditioned medium via the phosphoinositide 3-kinase/Akt-stromal cell-derived factor-1α/CXC chemokine receptor 4 pathway

Adipose-derived stem cells (ADSCs) are considered a suitable source of cells for the repair of tissue following acute myocardial infarction (AMI); however, the transplantation efficiency of ADSCs remains low. Therefore, identification of an efficient method to enhance the migration of engrafted cells to the target site is required. The present study used exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, to optimize the migratory capacity of ADSCs. The aim was to determine the effect and mechanisms of Ex-4 on the migration of ADSCs to neonatal rat ventricular cardiomyocyte-derived conditioned medium (NRVC-CM). The ADSCs and cardiomyocytes were cultured in vitro. Following incubation of the ADSCs with Ex-4, cell proliferation was measured using an MTT assay and the expression levels of CXC chemokine receptor 4 (CXCR4) were investigated by reverse transctiption quantitative polymerase chain reaction (RT-qPCR), western blot analysis and flow cytometry. In addition, the expression levels of stromal cell-derived factor-1α (SDF-1α) were evaluated in the NRVC-CM treated with Ex-4 by ELISA, RT-qPCR and western blot analysis. The migration of the ADSCs to the NRVC-CM was examined using a Transwell assay. Changes in the protein expression levels of phosphorylated (p−)Akt were examined in the two types of cell by western blot analysis. The results suggested that Ex-4 promoted the proliferation and expression of CXCR4 in the ADSCs, increased the secretion of SDF-1α in the cardiomyocytes and increased the expression levels of p-Akt in both cells. However, the alterations to the SDF-1α/C XC R4 cascade in the cells were abrogated following pretreatment with LY-294002, a phosphoinositide 3-kinase(PI3K) inhibitor. Furthermore, a Transwell migration assay revealed marked translocation of the ADSCs through the membranes, towards the NRVC-CM, following treatment with Ex-4. However, these effects were reduced significantly by pretreatment of the cells with the SDF-1α/CXCR4 cascade antagonist, AMD3100, and the PI3K inhibitor, LY-294002. These results indicated that Ex-4 augmented the SDF-1α/CXCR4 cascade by activating the PI3K/Akt pathways in the ADSCs and NRVCs. Furthermore, enhancement of the PI3K/Akt-SDF-1α/CXCR4 pathway may be important in the migratory response of ADSCs to NRVC-CM in vitro.

Myocardial tissue elastic properties determined by atomic force microscopy after stromal cell-derived factor 1α angiogenic therapy for acute myocardial infarction in a murine model

OBJECTIVES

Ventricular remodeling after myocardial infarction begins with massive extracellular matrix deposition and resultant fibrosis. This loss of functional tissue and stiffening of myocardial elastic and contractile elements starts the vicious cycle of mechanical inefficiency, adverse remodeling, and eventual heart failure. We hypothesized that stromal cell-derived factor 1α (SDF-1α) therapy to microrevascularize ischemic myocardium would rescue salvageable peri-infarct tissue and subsequently improve myocardial elasticity.

METHODS

Immediately after left anterior descending coronary artery ligation, mice were randomly assigned to receive peri-infarct injection of either saline solution or SDF-1α. After 6 weeks, animals were killed and samples were taken from the peri-infarct border zone and the infarct scar, as well as from the left ventricle of noninfarcted control mice. Determination of tissues' elastic moduli was carried out by mechanical testing in an atomic force microscope.

RESULTS

SDF-1α-treated peri-infarct tissue most closely approximated the elasticity of normal ventricle and was significantly more elastic than saline-treated peri-infarct myocardium (109 ± 22.9 kPa vs 295 ± 42.3 kPa; P < .0001). Myocardial scar, the strength of which depends on matrix deposition from vasculature at the peri-infarct edge, was stiffer in SDF-1α-treated animals than in controls (804 ± 102.2 kPa vs 144 ± 27.5 kPa; P < .0001).

CONCLUSIONS

Direct quantification of myocardial elastic properties demonstrates the ability of SDF-1α to re-engineer evolving myocardial infarct and peri-infarct tissues. By increasing elasticity of the ischemic and dysfunctional peri-infarct border zone and bolstering the weak, aneurysm-prone scar, SDF-1α therapy may confer a mechanical advantage to resist adverse remodeling after infarction.