Regression and persistence: remodelling in a tissue engineered axial vascular assembly

In later stages of vasculoangiogenesis a vascular network is going through a metamorphosis for optimal perfusion and economy of energy. In this study we make a quantitative approach to phenomena of remodelling in a bioartificial neovascular network and suggest variance of calibre as a parameter of neovascular maturation. For this study, 18 male Lewis rats were subjected to the AV loop operation in combination with a hard porous biogenic matrix and an isolation chamber. The animals were allocated into three groups for different explantation intervals set to 2, 4 and 8 weeks, respectively. Collective attributes like vascular density, percent fractional area and variance of calibre were evaluated for a predefined region of interest (ROI). Late morphogenesis was evaluated by means of scanning electron microscopy. After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02). The variance in calibre was significantly increased in the 8-week group (P < 0.05). Lymphatic growth after week 4, early pericyte migration as well as intussusceptive angiogenesis were identified immunohistologically. Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.