Abstract Body (Do not enter title and authors here): Background: Transplantation arteriosclerosis is one of the major complications for the mid- and long-term survival of recipients with organ transplantation. Although previous studies suggest that CD34 stem/progenitor cells are involved in this process, the heterogeneity and potential adverse effects of CD34⁺ SPCs have not been fully determined.

Methods and Results: A mouse model of transplant arteriosclerosis was established by using Balb/c, C57BL/6J, CD34-CreERT2, R26-tdTomato, Rosa26-iDTR, CD34-Dre, PI16-CreERT2, CAG-LSL-RSR-tdTomato-2A-DTR mice. Using single-cell RNA-seq and the innovative application of genetic lineage tracing with dual recombinases, we identified a subpopulation of fibroblast progenitor cells marked by high CD34 and PI16 expression. Interestingly, this progenitor cell group gave rise to a distinct chemotactic fibroblast subset. Based on chemokine antibody microarray assay and transcriptome analysis, the subgroup with increased CD34 expression and decreased PI16 expression promoted intimal hyperplasia, acting through the paracrine release of a specific chemokine CCL11 (eotaxin-1). Moreover, the binding of CCL11 to its receptor CCR3 triggered the PI3K-AKT signaling pathway in smooth muscle cells, promoting their proliferation and migration to form neointimal lesions. Overexpression of CCL11 by adeno-associated virus can promote neointimal hyperplasia in vivo, while neutralization of CCL11 or inhibition of receptor CCR3 can alleviate neointimal lesions.

Conclusion: Our findings identified CD34⁺/PI16⁺ fibroblast progenitors able to differentiate into specific chemotactic fibroblasts that release chemokines pivotal for neointima formation, implicating a therapeutic potential targeting the chemotactic behavior of these cells.