Microvascular NG2 expression patterns in response to aging, ischemic injury, and disease in mouse spinotrapezius muscle

In unstimulated mature microvascular networks, NG2 expression is limited to perivascular cells located in the arterial tree (e.g. arterial vascular smooth muscle cells) and along capillaries (e.g. pericytes). NG2 expression according to immunohistochemistry is notably absent in the perivascular cells present in the venule tree. During microvascular remodeling in response to an inflammatory or hypoxic stimulus, however, the NG2 proteoglycan is transiently expressed by perivascular cells (e.g. smooth muscle cells) in venules. Expression of NG2 by perivascular cells in venules spatially and temporally coincides with an abundance of angiogenic capillary sprouting from venules in the rat mesentery, for example. The objective of this study is to determine, using immunohistochemistry, the spatial and temporal expression profile of NG2 in the microvasculature of the murine spinotrapezius muscle, a thin stabilizing muscle that enables en face visualization of entire microvascular networks, in young vs. old mice, before and after ischemic insult, and in healthy vs. obese (ob/ob) and diabetic (db/db) mice. Results suggest that NG2 exhibits a differential expression pattern in the perivascular cells of arterial vs. venous trees in the quiescent spinotrapezius muscle, and ischemic insult induces NG2 expression by smooth muscle cells along remodeling capillaries. Support provided by: NIH‐ HL082838 ‐02.