The article details how the loss of capillary-associated macrophages (CAMs) in the skin contributes to age-related decline in vascular function in both mice and humans. Researchers used intravital microscopy to observe that CAMs, which are essential for repairing obstructed capillary blood flow through phagocytosis of vascular debris, are selectively lost over time, outpacing capillary loss. This reduction in CAM density leads to impaired capillary reperfusion and eventual pruning of the vascular network. Crucially, the study finds that CAM renewal through local proliferation is insufficient in the upper dermis and that replenishment only occurs effectively after acute tissue damage or with the introduction of a growth factor like CSF1, suggesting that targeted macrophage expansion could be a viable strategy to rejuvenate aged capillaries.

References:

• Mesa K R, O’Connor K A, Ng C, et al. Niche-specific dermal macrophage loss promotes skin capillary ageing[J]. Nature, 2025: 1-9.