Single-cell transcriptome analysis reveals CD34 as a marker of human sinoatrial node pacemaker cardiomyocytes

Area of Science:

• Cardiology
• Molecular Biology
• Stem Cell Research

Background:

• The sinoatrial node is the heart's primary pacemaker, crucial for regulating heart rate.
• Dysfunction of the sinoatrial node leads to life-threatening bradycardia.
• The cellular and molecular makeup of the human sinoatrial node remains incompletely understood, lacking specific cell surface markers.

Purpose of the Study:

• To resolve the cellular and molecular composition of the human sinoatrial node.
• To identify novel cell surface markers for sinoatrial node pacemaker cells.
• To validate the utility of identified markers for stem cell-based applications.

Main Methods:

• Single-nuclei/cell RNA sequencing was performed on fetal and human pluripotent stem cell-derived sinoatrial node cells.
• Gene expression analysis was used to identify cell subtypes and molecular markers.
• Flow cytometry and cell sorting were employed using the identified cell surface antigen CD34.

Main Results:

• Three distinct subtypes of sinoatrial node pacemaker cells were identified: Core Pacemaker, Sinus Venosus, and Transitional Cells.
• Novel sinoatrial node pacemaker cell markers, including MYH11, BMP4, and the cell surface antigen CD34, were discovered.
• Sorting CD34+ cells from stem cell differentiation cultures significantly enriched for functional sinoatrial node pacemaker cells.

Conclusions:

• The identification of three pacemaker cell subtypes refines our understanding of sinoatrial node heterogeneity.
• CD34 serves as a valuable cell surface marker for isolating functional sinoatrial node pacemaker cells.
• This discovery has significant implications for stem cell-based disease modeling, drug discovery, and regenerative therapies for cardiac rhythm disorders.