[Isolation, culture and validation of CD34 vascular wall-resident stem cells from mice].

Vascular wall-resident stem cells (VW-SCs) play a critical role in maintaining normal vascular function and regulating vascular repair. Understanding the basic functional characteristics of the VW-SCs will facilitate the study of their regulation and potential therapeutic applications. The aim of this study was to establish a stable method for the isolation, culture, and validation of the CD34 VW-SCs from mice, and to provide abundant and reliable cell sources for further study of the mechanisms involved in proliferation, migration and differentiation of the VW-SCs under various physiological and pathological conditions. The vascular wall cells of mouse aortic adventitia and mesenteric artery were obtained by the method of tissue block attachment and purified by magnetic microbead sorting and flow cytometry to obtain the CD34 VW-SCs. Cell immunofluorescence staining was performed to detect the stem cell markers (CD34, Flk-1, c-kit, Sca-1), smooth muscle markers (SM22, SM MHC), endothelial marker (CD31), and intranuclear division proliferation-related protein (Ki-67). To verify the multipotency of the isolated CD34 VW-SCs, endothelial differentiation medium EBM-2 and fibroblast differentiation medium FM-2 were used. After culture for 7 days and 3 days respectively, endothelial cell markers and fibroblast markers of the differentiated cells were evaluated by immunofluorescence staining and q-PCR. Furthermore, the intracellular Ca release and extracellular Ca entry signaling were evaluated by TILLvisION system in Fura-2/AM loaded cells. The results showed that: (1) High purity (more than 90%) CD34 VW-SCs from aortic adventitia and mesenteric artery of mice were harvested by means of tissue block attachment method and magnetic microbead sorting; (2) CD34 VW-SCs were able to differentiate into endothelial cells and fibroblasts in vitro; (3) Caffeine and ATP significantly activated intracellular Ca release from endoplasmic reticulum of CD34 VW-SCs. Store-operated Ca entry (SOCE) was activated by using thapsigargin (TG) applied in Ca-free/Ca reintroduction protocol. This study successfully established a stable and efficient method for isolation, culture and validation of the CD34 VW-SCs from mice, which provides an ideal VW-SCs sources for the further study of cardiovascular diseases.