Abstract 11027: The Paracrine Factors Released From Mesenchymal Stem Cells Rejuvenate Cardiomyocytes Through Transfer of miRs and Regulation of Pten/ Akt Signaling Pathway
Our previous studies indicate that mesenchymal stem cells (MSC) overexpressing GATA-4 (MSCGATA-4) reduce infarction size and improve cardiac function in the myocardial ischemia via protecting cardiomyocytes (CM). In this study, we hypothesized that the paracrine factors of MSC rejuvenate CM through exosoemes (EXO) release resulting transferring bioactive factors and regulating the related signaling pathways.
We investigated the role of EXO on long-term culture-induced senescence. Primary neonatal CM were cultured in DMEM with 10% FBS for 3 days. The medium was replaced with serum free medium containing either EXO or 1% BSA. After 3 weeks, most CM displayed a senescent phenotype and a decreased beating frequency. While administration of EXO reduced significantly the percentage of SA β-gal positive CM and well restored the beating frequency of CM, particular EXOGATA-4 group showed a better Effect (Fig. A & B);
Two proliferation markers, Ki67 and Brdu, were examined in CM cultured for 7 days. EXO treatment showed significantly higher proportions of Ki67+ CM and Brdu+ CM. Furthermore, quantitative PCR results indicated that the expression of TNNI1 and Nkx2.5 were significantly up-regulated in CM treated with conditioned mediumCdM) obtained from MSC, as compared with medium control. However, the expression of Vimentin, a fibroblast marker, was dramatically reduced in cells treated with CdMGATA-4 compared with that treated with CdMNull(Fig. C);
The expression of miR-19a was significantly higher in EXOGATA-4 compared to that in EXONull. Moreover, miR-19a was increased significantly in CM cultured with EXOGATA-4 under hypoxic condition (Fig. D). PTEN, one of miR-19a target proteins was significantly downregulated and p-Akt was upregulated in CM treated with EXOGATA-4(Fig. E-G).
It is concluded that paracrine factors released from MSCGATA-4 rejuvenated CM through transfer of miRs, e. g. miR-19a, responsible for initiating the PTEN-Akt signaling pathway.
Author Disclosures: B. Yu: None. J. Wang: None. M. Gong: None. Y. Wang: None. M. Ronald W: None. M. Ashraf: None. M. Xu: None.
- © 2014 by American Heart Association, Inc.