Epicardium: interstitial Cajal-like cells (ICLC) highlighted by immunofluorescence

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Cell Biology

Background:

• The epicardium is increasingly recognized for its roles in cardiac development, remodeling, repair, and regeneration.
• Previous research has established the presence of interstitial Cajal-like cells (ICLCs) in human and mammalian myocardium.
• The specific cell types within the subepicardial connective tissue remain an area of active investigation.

Purpose of the Study:

• To identify and characterize interstitial Cajal-like cells (ICLCs) within the adult mouse epicardium.
• To investigate the morphology and immunophenotype of epicardial ICLCs.
• To explore the potential role of epicardial ICLCs in cardiac progenitor cell populations.

Main Methods:

• Phase contrast microscopy was employed to observe cell morphology.
• Immunophenotyping was performed to identify cell markers.
• In situ analysis using frozen sections and primary cell cultures were utilized.
• MitoTracker Green FM labelling was used to identify mitochondria within cell dilations.

Main Results:

• ICLCs were identified in adult mouse epicardium with characteristic spindle-shaped or polygonal cell bodies and long, thin cytoplasmic processes exhibiting a 'beads-on-a-string' appearance.
• These cells contain mitochondria, confirmed by live-cell labelling.
• Epicardial ICLCs expressed markers such as c-kit/CD117 and/or CD34, with some also positive for vimentin.
• Two subpopulations of ICLCs were suggested: c-kit/CD34-positive and only c-kit-positive.

Conclusions:

• Interstitial Cajal-like cells (ICLCs) represent a distinct cell type in the subepicardium of adult mice.
• Epicardial ICLCs possess unique morphological and immunophenotypic characteristics.
• These cells are potentially crucial as progenitor or promoter cells for cardiomyocyte lineages during normal cardiac development and following injury.