CD34 is a sialomucin surface marker expressed on hematopoietic stem cells (HSCs), progenitor cells, and endothelial cells that mediates stem cell attachment to bone marrow stromal components 1. As an adhesion molecule, CD34 facilitates the binding of primitive cells to the bone marrow extracellular matrix through presentation of carbohydrate ligands to selectins and scaffolding for lineage-specific glycans 1. CD34 expression is downregulated during hematopoietic differentiation, making it useful for identifying early-stage HSCs and progenitors 1. CD34 expression exhibits tissue-specific heterogeneity: it is strongly expressed in fenestrated endothelium of renal glomeruli and lung alveolar capillaries but shows variable expression in hepatic and splenic vasculature 2. Clinically, CD34+ cell selection has become standard for HSC transplantation and gene editing applications 3. However, functional HSCs lacking detectable CD34 expression exist in cord blood and bone marrow, indicating CD34 is not exclusively required for stem cell repopulating activity 14. In cardiac pathology, non-bone-marrow-derived CD34+ cells differentiate into fibroblasts via Wnt-β-catenin and TGFβ1/Smad signaling, contributing to myocardial fibrosis during heart failure 5. CD34+ stromal cells also function as tissue connectors in parathyroid development and pathology, associating with collagen and connecting parenchymal cells and vessels 6.