Abstract 13291: Rejuvenation of Aged Bone Marrow Stem Cells with Microrna-195 for Cardiac Repair
Background;Stem cell mediated cardiac regeneration is impaired with age. Recently we have identified a sub-population of “small juvenile stem cells” (SJSCs) in aged bone marrow stem cells (BMSCs) which expressed mesenchymal stem cell markers (CD29+/CD44+/CD59+/CD90+ and CD45-/CD117-), cardiac lineage markers (Gata4 and Mef2C) as well as pluripotency markers (Oct4, Sox2, SSEA1 and Nanog). Transplantation of SJSCs remarkably improved functional recovery of ischemic heart compared to transplantation with BMSCs (22% smaller infarction size). However, underlying molecular mechanisms are unknown.
Methods and Results; SJSCs and BMSCs were isolated from young (2 months) and aged (24 months) mice and were cultured as described (Circulation supplement 2011). SJSCs showed significantly higher proliferative and differentiation potentials as compared to BMSCs with higher expression of telomeric repeat-binding factor 2 (TERF2) and Bcl-2. Since senescence-associated microRNAs (SA-miRs) are involved in cell aging by inhibiting anti-aging genes, we performed miR microarray to profile SA-miR expression in SJSCs and BMSCs. As a result, miR-140, miR-146a/b and miR-195 were significantly down regulated in SJSCs as validated by qRT-PCR (50.0%, 84.5%, 54.4% decreases, respectively). Computational analysis predicted that Sirtuin 1 (Sirt1) is one of the putative targets of miR-195 which is known as a key determinant for cellular senescence. Transfection of BMSCs with anti-miR-195 significantly increased Sirt1 protein expression and FOXO1 deacetylation as examined by Western blot (1.85 fold increase) and immunocytochemistry, suggesting FOXO1/Sirt1 signaling is regulated by miR-195. Furthermore, knockdown of miR-195 increased telomerase reverse transcriptase (TERT) activity, and decreased SAβ-GAL expression as well as TUNEL positive cells (78.7% and 80% decrease, respectively), indicating miR-195 plays a critical role in stem cell aging.
Conclusions; SJSCs are likely to have great potential for repair of aged heart. miR-195 plays a key role in BMSCs senescence by inhibiting anti-aging factors, Sirt1 and FOXO1, and therefore, downregulation of miR-195 is a potential therapeutic strategy for rejuvenation of aged stem cells for heart repair.
- © 2012 by American Heart Association, Inc.