Human lung telocytes could promote the proliferation and angiogenesis of human pulmonary microvascular endothelial cells in vitro

BACKGROUND: In the previous studies, telocytes were found near the capillaries in many tissues, especially on the extracellular matrix of blood vessels and positive to CD34 and c-kit. Therefore, the present study aimed to explore if telocytes could produce angiogenesis associated cytokines, promote the proliferation and the angiogenesis of vascular endothelial cells in vitro. METHODS: Human lung telocytes were isolated and cultured, and were identified by immunofluorescence cytochemistry with CD34, c-kit and vimentin. Telocytes conditional media (TCM) was prepared, and the expressions of angiogenesis associated cytokines in TCM were detected by ELISA. Human pulmonary microvascular endothelial cells (HPMECs) were cultured with DMEM media or TCM for 72 hours. The proliferation of HPMECs was continuously detected with CCK-8 kit at an interval of 12 hours. HPMECs were also injured by lipopolysaccharide, and cultured with TCM and DMEM respectively, and the tube formation capacity was detected. RESULTS: Telocytes were positive for CD34, c-kit and vimentin. The expressions of VEGF and EGF in TCM were significantly higher, the proliferation of HPMECs cultured with TCM significantly increased, and the tube formation of HPMECs injured by endotoxin was improved with the culture of TCM, as compared with the culture of DMEM. CONCLUSION: The present study provides the evidence that human lung telocytes could produce the growth factors, such as VEGF and EGF. Telocytes conditional media induced the proliferation of pulmonary endothelial cells and prevented from endotoxin-induced compromise of pulmonary endothelial angiogenesis.