Circulating CD34+ Fibroblast Progenitors Engaged in Heart Fibrosis of Allograft

Xiaotong Sun; Ting Wang; Hui Gong; Yichao Qiu; Yuesheng Zhang; Mengjia Chen; Jianing Xue; Guoguo Ye; Rong Mou; Peng Teng; Weidong Li; Ting Chen; Li Zhang; Xiaogang Guo; Wei Mao; Haige Zhao; Liang Ma; Qingbo Xu

doi:10.1161/CIRCRESAHA.125.326558

Circulating CD34⁺ Fibroblast Progenitors Engaged in Heart Fibrosis of Allograft

Circ Res. 2026 Jan 14. doi: 10.1161/CIRCRESAHA.125.326558. Online ahead of print.

Authors

Xiaotong Sun^#¹, Ting Wang^#¹, Hui Gong^#^{1

2}, Yichao Qiu³, Yuesheng Zhang¹, Mengjia Chen¹, Jianing Xue¹, Guoguo Ye¹, Rong Mou¹, Peng Teng³, Weidong Li³, Ting Chen^{1

4}, Li Zhang⁵, Xiaogang Guo¹, Wei Mao⁶, Haige Zhao³, Liang Ma³, Qingbo Xu¹

Affiliations

¹ Department of Cardiology, the First Affiliated Hospital (X.S., T.W., H.G., Y.Z., M.C., J.X., G.Y., R.M., T.C., X.G., Q.X.), Zhejiang University School of Medicine, Hangzhou, China.
² Nanhu Brain-computer Interface Institute, Hangzhou, China (H.G.).
³ Department of Cardiothoracic Surgery, the First Affiliated Hospital (Y.Q., P.T., W.L., H.Z., L.M.), Zhejiang University School of Medicine, Hangzhou, China.
⁴ Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare (T.C.).
⁵ Department of Cardiology, and Institute for Cardiovascular Development and Regenerative Medicine, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, China (L.Z.).
⁶ Department of Cardiology, Affiliated Zhejiang Hospital, Zhejiang University School of Medicine, and Zhejiang Key Laboratory of Integrative Chinese and Western Medicine for Diagnosis and Treatment of Circulatory Diseases, Hangzhou (W.M.).

^# Contributed equally.

PMID: 41532318
DOI: 10.1161/CIRCRESAHA.125.326558

Abstract

Background: Fibrosis is one of the major causes of cardiac allograft malfunction and is mainly driven by fibroblasts. However, the role of recipient-derived cells in generating allograft fibroblasts and the underlying mechanisms remain to be explored.

Methods: We analyzed human heart allograft samples and used murine transplant models (C57BL/6J, Cd34-CreER^T2; R26-tdTomato, mRFP mice, Rosa26-iDTR, Postn-CreER^T2; R26-tdTomato, double-tdTomato, and immunodeficient mice with BALB/c donors). Human progenitor cells were cultivated from blood. Single-cell RNA sequencing, Western blotting, quantitative polymerase chain reaction, and immunohistochemistry, whole-mount staining with 3-dimensional reconstruction, and in vivo/in vitro experiments were applied to characterize allograft cellular composition and communication.

Results: Single-cell RNA sequencing was introduced to delineate the allograft cell atlas of patients and mice. Y chromosome analysis identified that recipient-derived cells contributed to allograft fibroblasts in both patients and murine models. Combining the genetic cell lineage tracing technique, we found that recipient-derived CD34⁺ cells could give rise to activated fibroblasts. Bone marrow transplantation and parabiosis models revealed that the recipient's circulating non-bone marrow Cd34⁺ cells could generate allograft fibroblasts. Human CD34⁺ cells could differentiate into fibroblasts both in vivo and in vitro. CD34⁺ fibroblast progenitors were recruited by CXCL12-ACKR3 and MIF-ACKR3 interactions and differentiated via the TGFβ (transforming growth factor beta)/GFPT2 (glutamine-fructose-6-phosphate transaminase 2)/SMAD2/4 axis. Ablation of recipient Cd34⁺ cells reduced activated fibroblasts and alleviated allograft fibrosis.

Conclusions: We identify circulating CD34⁺ cells as a novel source of fibroblast progenitors that contribute to cardiac allograft fibrosis, suggesting that targeting recipient CD34⁺ cells could be a novel therapeutic potential for treating cardiac fibrosis after heart transplantation.

Keywords: allografts; fibroblast; fibrosis; heart transplantation; stem cells.