Immunomagnetic Isolation of the Vascular Wall-Resident CD34<sup>+</sup> Stem Cells from Mice

Resident CD34+ vascular wall-resident stem and progenitor cells (VW-SCs) are increasingly recognized for their crucial role in regulating vascular injury and repair. Establishing a stable and efficient method to culture functional murine CD34+ VW-SCs is essential for further investigating the mechanisms involved in the proliferation, migration, and differentiation of these cells under various physiological and pathological conditions. The described method combines magnetic bead screening and flow cytometry to purify primary cultured resident CD34+ VW-SCs. The purified cells are then functionally identified through immunofluorescence staining and Ca2+ imaging. Briefly, vascular cells from the adventitia of the murine aorta and mesenteric artery are obtained through tissue block attachment, followed by subculturing until reaching a cell count of at least 1 × 107. Subsequently, CD34+ VW-SCs are purified using magnetic bead sorting and flow cytometry. Identification of CD34+ VW-SCs involves cellular immunofluorescence staining, while functional multipotency is determined by exposing cells to a specific culture medium for oriented differentiation. Moreover, functional internal Ca2+ release and external Ca2+ entry is assessed using a commercially available imaging workstation in Fura-2/AM-loaded cells exposed to ATP, caffeine, or thapsigargin (TG). This method offers a stable and efficient technique for isolating, culturing, and identifying vascular wall-resident CD34+ stem cells, providing an opportunity for in vitro studies on the regulatory mechanisms of VW-SCs and the screening of targeted drugs.