Abstract 17503: Potential Role of Sphingosine-1-Phosphate in Cardiac and Endothelial Differentiation of Mobilized Bone Marrow Stem/Progenitor Cells- A Potential Therapeutic Target
Background: Tissue ischemia and injury, such as occurs during myocardial infarction (MI), mobilizes marrow (BM) stem/progenitor cells (SPCs) into peripheral circulation. The mobilized cells home to areas of tissue injury where they participate in the reparative process. We previously demonstrated that plasma sphingosine-1 phosphate (S1P) levels are elevated early in the course of MI. We hypothesized that S1P could stimulate differentiation of BM and mobilized BMSPCs, based on its ability to promote the differentiation of human umbilical cord mesenchymal stem cells into cardiomyocytes.
Methods: G-CSF mobilized human peripheral blood cells (mPBCs) (N = 25) were cultured in basal medium (BM) supplemented with 250 nM S1P or vehicle. Gene expression of cardiac (Nkx-2.5 and GATA4) and endothelial (VWF and VE-cadherin) markers were measured at 48 and 72 hours using RQ-PCR, and protein expression (myosin heavy chain, troponin I, VWF, PDGFRα, and PDGFRβ) at 4 weeks using confocal microscopy. Endothelial commitment was further assessed by matrigel assays after 2 weeks of culture.
Results: Phosphorylation of JNK and ERK occurred in mPBCs within 15 min of exposure to S1P. By 72 hours, SIP increased the expression of cardiac and endothelial markers 4 - 6 fold (P < 0.05). The effects of S1P were sustained, in that a 8-fold higher percentage of mPBCs expressed cardiac and endothelial proteins after four weeks in culture with S1P (P < 0.05). In parallel, mPBCs exposed to S1P demonstrated functional endothelial lineage commitment as demonstrated by 10-fold higher tube formation in matrigel assays (P < 0.05).
Conclusion: Exposure to S1P initiates cardiac and endothelial differentiation of mobilized BMSPCs. Treatment with S1P may be a viable strategy for priming BMSPCs prior to transplantation for cardiac repair and in vivo studies utilizing this approach are underway. This approach may be of clinical significance in refining bone marrow stem cell therapy for ischemic heart disease. .
- © 2012 by American Heart Association, Inc.