Intracellular Ca 2+ stores are essential for injury induced Ca 2+ signaling and re‐endothelialization

Endothelialization repairs the lining of damaged vasculature and is a key process in preventing thrombosis and restenosis. It has been demonstrated that extracellular calcium ([Ca 2+ ] o ) influx is important for subsequent endothelialization. The role of intracellular Ca 2+ stores in mechanical denudation induced intracellular calcium ([Ca 2+ ] i ) rise and endothelialization remains to be demonstrated. Using monolayer culture of a human endothelial cell line (human umbilical vein endothelial cell, HUVEC), we investigated [Ca 2+ ] i wave propagation and re‐endothelialization following mechanical denudation. Consistent with previous reports for other types of cells, mechanical denudation induces calcium influx, which is essential for [Ca 2+ ] i rise and endothelialization. Moreover, we found that intracellular Ca 2+ stores are also essential for denudation induced [Ca 2+ ] i wave initiation and propagation, and the subsequent endothelialization. Thapsigargin which depletes intracellular Ca 2+ stores completely abolished [Ca 2+ ] i wave generation and endothelialization. Xestospongin C (XeC), which prevents Ca 2+ release from intracellular Ca 2+ stores by inhibition of inositol 1,4,5‐trisphosphate (IP 3 ) receptor, inhibited intercellular Ca 2+ wave generation and endothelialization following denudation. Purinergic signaling through a suramin sensitive mechanism and gap junction communication also contribute to in intercellular Ca 2+ wave propagation and re‐endothelialization. We conclude that intracellular Ca 2+ stores, in addition to extracellular Ca 2+ , are essential for intracellular Ca 2+ signaling and subsequent endothelialization following mechanical denudation. J. Cell. Physiol. 214: 595–603, 2008. © 2007 Wiley‐Liss, Inc.