Endothelial Progenitor Cells and Macrophage Subsets Recruitment in Postischemic Mouse Hind Limbs

Area of Science:

• Vascular Biology
• Regenerative Medicine
• Ischemia Research

Background:

• Peripheral arterial disease (PAD) involves atherosclerotic blockages in lower extremity arteries.
• Restoring blood flow (perfusion) in PAD necessitates angiogenesis and arteriogenesis.
• The precise timing of endothelial progenitor cell (EPC) and macrophage recruitment is not well understood.

Purpose of the Study:

• To investigate the infiltration dynamics of EPCs and macrophages in a murine hind limb ischemia (HLI) model of PAD.
• To correlate cell recruitment timing with muscle regeneration and perfusion recovery.

Main Methods:

• Quantification of EPCs, M1-like, and M2-like macrophages in ischemic hind limbs using flow cytometry.
• Analysis at multiple time points: day 0, 1, 3, 7, and 14 post-HLI.
• Assessment of muscle regeneration and capillary density.

Main Results:

• EPC abundance increased from day 1, peaking between days 7 and 14.
• M1-like macrophages peaked at day 14, while M2-like macrophages were higher than M1-like at baseline and surpassed M1-like levels by day 7.
• Muscle regeneration and capillary density increased, peaking at days 3 and 7, respectively, with near-complete perfusion recovery by day 14.

Conclusions:

• A gradual increase in EPCs was observed, temporally paralleling the recruitment of M1-like and subsequently M2-like macrophages.
• This cellular infiltration pattern is associated with muscle regeneration, increased capillary density, and successful perfusion recovery post-HLI.
• Findings elucidate the temporal recruitment of key cellular players in PAD recovery.