Abstract 160: Differentially Regulated miRNAs Are Associated with HIF1A and VEGF in Human MSCs Under Hypoxic Conditions
Background: HIF1A and VEGF are the core transcript regulatory factors of human bone marrow-derived stromal cells (hMSCs) for ischemic regenerative therapy; in response to low oxygen conditions, HIF1A and VEGF are upregulated. MicroRNAs (miRNAs) regulate angiogenesis by controlling the genes via interfering transcriptional or translational processes. Methods: Using a stepwise approach that included a comprehensive differential miRNA expression analysis in a set of 12 hMSCs from healthy individuals, we attempted to identify any specific miRNA clusters that are associated with these two regulation factors. The hMSCs were cultured either in standard normoxia (N-) or modified hypoxia (H-: 1% O2, 8% CO2 and 1% FBS) for 6 and 24 hours to induce HIF1A and VEGF. Following tRNA and miRNA isolation and reverse transcription, the synthesized cDNAs were analyzed by miRNA PCR arrays. Results exhibited at least a two-fold up- or down-regulation change in the H-group, compared to the control N-group. To further delineate the mechansim, a separate cohort of 24hour N- or H-hMSCs samples expressing HIF1A silencing hMSC (HIF1As ) or VEGF silencing hMSC (VEGFs) were used to specifically test miR92a, miR144, miR429, miR210, miR488 and miR23 expression and their involvement in HIF1A and/or VEGF pathways.
Results: Our preliminary data discovered a dynamic miRNA regulating pattern in H-hMSC response to hypoxia; 5 and 17 miRNAs that were consistently down- or upregulated in H-hMSCs, respectively, were revealed. Furthermore, an inverse correlation was found in the following group of miRNAs in which both H-HIF1As and H-VEGFs were expressed: miR92a, miR182, miR208, miR429 and miR488. They formed clusters and upregulated in H-hMSCs but downregulated in both H-HIF1As and H-VEGFs. However, miR23b was downregulated in H-hMSCs but statistically upregulated in H-VEGFs.
Conclusions: This data indicate that the miRNAs, with different patterns of regulation, were stimulated via hypoxia thus forming complexes to adjust the cellular proliferation and differentiation via HIF1A and VEGF regulation pathways. The regulating miRNAs will be used as hypoxic targets for further study in understanding the mechanisms underlying hypoxia and ischemia in vivo.
- © 2012 by American Heart Association, Inc.