Abstract 1147: Differential Roles of ROCK1 and ROCK2 in Ischemia-induced Revacularization
Background: Rho and Rho-associated kinase (ROCK) are the key regulators of focal adhesion, stress fiber formation, and cell motility. The contribution of the ROCK isoforms, ROCK1 and ROCK2, on angiogenesis and endothelial regeneration is not known.
Objective: To determine the role of ROCK in ischemia-induced angiogenesis in mice with targeted deletion of ROCK1 and ROCK2.
Methods and Results: Following hindlimb ischemia, the flow recovery and postnatal neovascularization in both ROCK1+/− and ROCK2+/− mice were impaired compared with wild-type (WT) mice (n=10 in each group, p<0.05 by ANOVA). This corresponded with decreased capillary density in the implanted subcutaneous Matrigel and the ischemic hindlimb muscle in ROCK1+/− and ROCK2+/− mice. Indeed, endothelial sprouting in Matrigel from aortas of ROCK mutant mice was substantially less compared to that of WT mice. Endothelial cells isolated from ROCK mutant mice showed decreased ROCK activity. Cell migration and adhesion were impaired in endothelial cells from ROCK mutant mice without changes in proliferation or survival compared to that of WT mice. To determine the contribution of ROCK in bone marrow (BM)-derived cells neovascular regeneration, we performed BM transplantations (BMT) on irradiated mice with BM from ROCK1−/−, ROCK2−/− and WT mice (n=12 in each group). Interestingly, only BM from ROCK1−/− but not ROCK2−/− or WT mice showed impaired blood flow recovery and neovascularization. Indeed, the impaired angiogenic response in ROCK1+/− mice, but not ROCK2+/− mice, could be reversed with BMT from WT mice.
Conclusion: These findings indicate that ROCK1 in BM-derived cells and ROCK2 in vascular cells mediate postnatal angiogenesis. These results suggest that ROCK may be a novel therapeutic target for improving angiogenic response and blood flow recovery in ischemic limbs.