Young-derived M2-like macrophages ameliorate hindlimb ischemia injury by promoting neovascularization in aged mice.

BACKGROUND

Peripheral artery disease, an age-related ischemic disease, primarily affects the elderly. Cell therapy is a promising treatment for peripheral artery disease. This study aims to investigate the effects of macrophages derived from young mice on neovascularization and recovery in a hindlimb ischemia model of aged mice.

METHODS

Monocytes were isolated from the bone marrow of young mice and cultured in vitro to generate bone marrow-derived macrophages. After polarization, young-derived M2-like bone marrow-derived macrophages were obtained. Aged mice were divided into 3 groups: saline group, young-derived nonpolarized bone marrow-derived macrophages group, and young-derived M2-like bone marrow-derived macrophages group. Hindlimb ischemia was induced in aged mice via femoral artery ligation. Three days after surgery, saline, young-derived nonpolarized bone marrow-derived macrophages, or young-derived M2-like bone marrow-derived macrophages were intramuscularly injected into the ischemic hindlimb. Doppler imaging, ischemia and mobility scores, and histological analysis were used to assess blood flow, functional recovery, and tissue repair. Neovascularization was further evaluated using micro-computed tomography and immunofluorescence staining.

RESULTS

Compared with the saline group, aged mice in the young-derived M2-like bone marrow-derived macrophages group exhibited notable blood flow recovery, along with corresponding improvements in tissue and functional recovery. In addition, in terms of neovascularization, the young-derived M2-like bone marrow-derived macrophages group demonstrated a richer vascular bed, with significant increases in both arteriogenesis and angiogenesis, as well as enhanced endothelial cell function.

CONCLUSION

M2-like macrophages derived from young mice enhance neovascularization of aged mice with ischemia, leading to improved blood perfusion and tissue functional recovery. This suggests that macrophages represent a promising new therapeutic strategy for peripheral artery disease in the elderly.