The role of vascular smooth muscle cell integrins in the compaction and mechanical strengthening of a tissue-engineered blood vessel

Vascular smooth muscle cells (VSMC) influence vessel structure and function during normal development, and in disease states. VSMC interactions with extracellular matrix, via cell surface integrins, play an important role in these processes. A greater understanding of the molecular basis of these interactions is also critical to advances in the field of cardiovascular tissue engineering. This study examined the role of VSMC integrins in the spontaneous compaction and eventual strengthening of a rudimentary tissue- engineered blood vessel (TEBV) consisting of a fibrillar type I collagen network populated by human aortic smooth muscle cells. Using integrin subunit-specific antibodies, we demonstrated that anti-β1 (Mab13 and P4C10) and anti-α2 (P1E6) antibodies that inhibit aortic smooth muscle cell (AoSMC) adhesion to collagen, also significantly inhibit TEBV compaction during the 24-hour period following TEBV construction. However, no difference in the tensile stress of antibody-treated and control TEBVs was observed at this time point. In contrast, 72 hours after construction, the inhibitory effect of anti-integrin antibodies on compaction had been overcome but tensile stress was decreased in TEBVs treated with anti-α2/anti-β1 antibodies when compared to controls. These data provide evidence linking VSMC integrins, specifically the α2β1 integrin, with the initial compaction, as well as, the postcompaction strengthening of the TEBV.