Mesenchymal stem cells (MSCs) modulate cardiac healing after myocardial injury through the release of paracrine factors, but the exact mechanisms are still unknown. One possible mechanism is through mobilization of endogenous cardiac stem cells (CSCs). This study aimed to test the pro-migratory effect of MSC conditioned medium (MSC-CM) on endogenous CSCs from human cardiac tissue. By using a three-dimensional collagen assay, we found that MSC-CM improved migration of cells from human cardiac tissue. Cell counts, perimeter and area measurements were utilized to quantify migration effects. To examine whether resident stem cells were among the migrating cells, specific stem cell properties were investigated. The migrating cells displayed strong similarities with resident Cardiac Atrial appendage Stem Cells (CASCs), including a clonogenic potential of ~21.5% and expression of pluripotency associated genes like Oct-4, Nanog, c-Myc and Klf-4. Similar to CASCs, migrating cells demonstrated high aldehyde dehydrogenase activity and were able to differentiate towards cardiomyocytes. Receptor tyrosine kinase analysis and collagen assays performed with recombinant platelet derived growth factor (PDGF)-AA and Imatinib Mesylate, a PDGF receptor inhibitor, suggested a role for the PDGF-AA/PDGF receptor α axis in enhancing the migration process of CASCs. In conclusion, our findings demonstrate that factors present in MSC-CM improve migration of resident stem cells from human cardiac tissue. These data open doors towards future therapies in which MSC secreted factors, like PDGF-AA, can be utilized to enhance the recruitment of CASCs towards the site of myocardial injury.
Keywords: 3D; ALDH; AT; Aldehyde dehydrogenase; Annealing temperature; Axl receptor; AxlR; BM-SCs; Bone marrow stem cells; CASCs; CFU-Fs; CSCs; Cardiac Atrial appendage Stem Cells; Cardiac stem cells; Cardiac troponin; Colony-forming-unit fibroblasts; Conditioned medium; DEAB; Diethylamino-benzaldehyde; EGFR; ELISA; Enzyme-linked immunosorbent assay; Epidermal growth factor receptor; FAK; FCS; FGFR; FMO; Fetal calf serum; Fibroblast growth factor receptor; Fluorescence minus one; Focal adhesion kinase; GFP; Green fluorescent protein; IHD; InsR; Insulin receptor; Ischemic heart disease; LG-DMEM; Low-glucose Dulbecco's Modified Eagle Medium; MI; MMPs; MSC-CM; MSCs; Matrix metalloproteinases; Mesenchymal stem cell conditioned medium; Mesenchymal stem cells; Migration; Myocardial infarction; NRCMs; Neonatal rat cardiomyocytes; P/S; PDGF; PDGFR; PI3K; PLC-γ; Penicillin/streptomycin; Phospho-inositide-3 kinase; Phospholipase C-γ; Platelet derived growth factor; Platelet derived growth factor receptor; RALDH2; RT-PCR; RTK; Receptor tyrosine kinase; Retinaldehyde dehydrogenase 2; Reverse transcriptase PCR; T-Box 18; TGF-β; Tbx18; Three-dimensional; Thymosin β4; Transforming growth factor-β; Tβ4; VEGF; VEGFR; Vascular endothelial growth factor; Vascular endothelial growth factor receptor; Wilm's tumor 1; Wt1; cTn.
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