Effect of mechanical stretch on HIF-1α and MMP-2 expression in capillaries isolated from overloaded skeletal muscles: laser capture microdissection study

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Abstract
Under physiological nonhypoxic conditions, angiogenesis can be driven by mechanical forces. However, because of the limitations of the specific gene expression analysis of microvessels from in vivo experiments, the mechanisms regulating the coordinated expression of angiogenic factors implicated in the process remain intangible. In this study, the technique of laser capture microdissection (LCM) was adapted for the study of angiogenesis in skeletal muscles. With a combination of LCM and real-time quantitative PCR it was demonstrated that capillary endothelial cells produce matrix metalloproteinase (MMP)-2 and that mechanical stretch of capillaries within muscle tissue markedly increases MMP-2 mRNA (2.5-fold increase vs. control; P < 0.05). In addition, we showed that transcription factor hypoxia-inducible factor (HIF)-1α expression was 13.5-fold higher in capillaries subjected to stretch compared with controls ( P < 0.05). These findings demonstrate the feasibility of this approach to study angiogenic gene regulation and provide novel evidence of HIF-1α induction in stretched capillary endothelial cells.