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Updated: Jun 21, 2026
Murine Heterotopic Heart Transplant Technique
Published on: July 8, 2014
Circulating CD34+ Fibroblast Progenitors Engaged in Heart Fibrosis of Allograft
Xiaotong Sun1, Ting Wang1, Hui Gong1,2
1Department 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.
Insights
Recipient CD34+ cells are a new source of fibroblasts that cause cardiac allograft fibrosis. Targeting these cells may offer new treatments for heart transplant fibrosis.
Area of Science:
- Cardiovascular Science
- Transplantation Immunology
- Cell Biology
Background:
- Cardiac allograft fibrosis is a major cause of graft dysfunction.
- The origin and mechanisms of recipient-derived fibroblasts in allografts are not fully understood.
Purpose of the Study:
- To investigate the role of recipient-derived cells in cardiac allograft fibrosis.
- To identify the cellular sources and mechanisms driving allograft fibroblast generation.
Main Methods:
- Analysis of human heart allografts and murine transplant models.
- Single-cell RNA sequencing, genetic cell lineage tracing, and in vivo/in vitro experiments.
- Investigated CD34+ cell contribution, recruitment, and differentiation pathways.
Main Results:
- Recipient-derived CD34+ cells were identified as a source of allograft fibroblasts.
- Circulating CD34+ cells were recruited via CXCL12-ACKR3 and MIF-ACKR3 interactions.
- Fibroblast differentiation occurred through the TGFβ/GFPT2/SMAD2/4 pathway, and CD34+ cell ablation reduced fibrosis.
Conclusions:
- Circulating CD34+ cells are novel fibroblast progenitors contributing to cardiac allograft fibrosis.
- Targeting recipient CD34+ cells presents a potential therapeutic strategy for post-transplant cardiac fibrosis.
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 (cluster of differentiation 34)-CreERT2; R26-tdTomato, mRFP (cell membrane labeled with red fluorescence protein) mice, Rosa26-iDTR, Postn-CreERT2; 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 (C-X-C motif chemokine ligand 12)-ACKR3 (atypical chemokine receptor 3) and MIF (macrophage migration inhibitory factor)-ACKR3 interactions and differentiated via the TGFβ (transforming growth factor beta)/GFPT2 (glutamine-fructose-6-phosphate transaminase 2)/SMAD2/4 (small mother against decapentaplegic 2/4) 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.
