2. Academic Validation
  3. Single-cell analysis reveals the loss of FABP4-positive proliferating valvular endothelial cells relates to functional mitral regurgitation

Single-cell analysis reveals the loss of FABP4-positive proliferating valvular endothelial cells relates to functional mitral regurgitation

  • BMC Med. 2024 Dec 20;22(1):595. doi: 10.1186/s12916-024-03791-4.
Xiaohu Wang # 1,  Mengxia Fu # 2,  Weiteng Wang # 1,  Songren Shu 1 3,  Ningning Zhang 1 3,  Ruojin Zhao 1,  Xiao Chen 1 3,  Xiumeng Hua 1 3 4,  Xin Wang 1 3 4,  Wei Feng 1 3 4,  Xianqiang Wang 5 6 7 8 9,  Jiangping Song 10 11 12 13 14 15
Affiliations

Affiliations

  • 1 Present Address: State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Beijing, Xi Cheng District, 100037, China.
  • 2 Galactophore Department, Galactophore Center, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
  • 3 The Cardiomyopathy Research Group, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
  • 4 Department of Cardiovascular Surgery, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
  • 5 Present Address: State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Beijing, Xi Cheng District, 100037, China. qiangxianwang@163.com.
  • 6 The Cardiomyopathy Research Group, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. qiangxianwang@163.com.
  • 7 Department of Cardiovascular Surgery, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. qiangxianwang@163.com.
  • 8 Shenzhen Key Laboratory of Cardiovascular Disease, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, China. qiangxianwang@163.com.
  • 9 Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. qiangxianwang@163.com.
  • 10 Present Address: State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Beijing, Xi Cheng District, 100037, China. fwsongjiangping@126.com.
  • 11 The Cardiomyopathy Research Group, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. fwsongjiangping@126.com.
  • 12 Department of Cardiovascular Surgery, National Center for Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. fwsongjiangping@126.com.
  • 13 Shenzhen Key Laboratory of Cardiovascular Disease, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, China. fwsongjiangping@126.com.
  • 14 Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. fwsongjiangping@126.com.
  • 15 Department of Cardiac Surgery, Fuwai Yunnan Hospital, Chinese Academy of Medical Sciences, Affiliated Cardiovascular Hospital of Kunming Medical University, Kunming, China. fwsongjiangping@126.com.
  • # Contributed equally.
PMID: 39707349 DOI: 10.1186/s12916-024-03791-4
Abstract

Background: Functional mitral regurgitation (MR) is a common form of mitral valve dysfunction that often persists even after surgical intervention, requiring reoperation in some cases. To advance our understanding of the pathogenesis of functional MR, it is crucial to characterize the cellular composition of the mitral valve leaflet and identify molecular changes in each cell subtype within the mitral valves of MR patients. Therefore, we aimed to comprehensively examine the cellular and molecular components of mitral valves in patients with MR.

Methods: We conducted a single-cell RNA Sequencing (scRNA-seq) analysis of mitral valve leaflets extracted from six patients who underwent heart transplantation. The cohort comprised three individuals with moderate-to-severe functional MR (MR group) and three non-diseased controls (NC group). Bioinformatics was applied to identify cell types, delineate cell functions, and explore cellular developmental trajectories and interactions. Key findings from the scRNA-seq analysis were validated using pathological staining to visualize key markers in the mitral valve leaflets. Additionally, in vitro experiments with human primary valvular endothelial cells were conducted to further support our results.

Results: Our study revealed that valve interstitial cells are critical for adaptive valve remodelling, as they secrete extracellular matrix proteins and promote fibrosis. We discovered an abnormal decrease in a subpopulation of FABP4 (fatty acid binding protein 4)-positive proliferating valvular endothelial cells. The trajectory analysis identifies this subcluster as the origin of VECs. Immunohistochemistry on the expanded cohort showed a reduction of FABP4-positive VECs in patients with functional MR. Intervention experiments with primary cells indicated that FABP4 promotes proliferation and migration in mitral valve VECs and enhances TGFβ-induced differentiation.

Conclusions: Our study presented a comprehensive assessment of the mitral valve cellular landscape of patients with MR and sheds light on the molecular changes occurring in human mitral valves during functional MR. We found a notable reduction in the proliferating endothelial cell subpopulation of valve leaflets, and FABP4 was identified as one of their markers. Therefore, FABP4 positive VECs served as proliferating endothelial cells relates to functional mitral regurgitation. These VECs exhibited high proliferative and differentiative properties. Their reduction was associated with the occurrence of functional MR.

Keywords

FABP4; Functional mitral regurgitation; ScRNA-seq; Valvular endothelial cell.

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