RESUMO
INTRODUCTION: Induced pluripotent stem cell (iPSC)-derived endothelial cells (ECs) have the potential for therapeutic application in several cardiovascular diseases. Mechanical strain is known to regulate EC behavior and stem cell differentiation and may play a role in directing EC differentiation of iPSCs. H19, a long non-coding RNA (lncRNA), is known to affect ECs in several mechanically relevant pathologies and may play a role in this process as well. Therefore, we investigated expression changes of H19 resulting from mechanical stimulation during EC differentiation, as well as functional effects on EC tube formation. METHODS: iPSCs were subjected to 5% cyclic mechanical strain during EC differentiation. RT-PCR and flow cytometry were used to assess changes in mesoderm differentiation and gene expression in the final ECs as a result of strain. Functional outcomes of mechanically differentiated ECs were assessed with a tube formation assay and changes in H19. H19 was also overexpressed in human umbilical vein endothelial cells (HUVECs) to assess its role in non-H19-expressing ECs. RESULTS: Mechanical strain promoted mesoderm differentiation, marked by increased expression of brachyury 24 h after initiation of differentiation. Strain also increased expression of H19, CD31, VE-cadherin, and VEGFR2 in differentiated ECs. Strain-differentiated ECs formed tube networks with higher junction and endpoint density than statically-differentiated ECs. Overexpression of H19 in HUVECs resulted in similar patterns of tube formation. CONCLUSIONS: H19 expression is increased by mechanical strain and promotes tube branching in iPSC-derived ECs.