Construction Of An Improved Animal Model Of Prefabricated Flap And An Experimental Study Of VEGF Increasing Neovascularization Of Prefabricated Flap

Objective To make a simple and stable animal model of prefabricated flap , and to investigate the feasibility of locally administration of VEGF to increase neovascularization and augment the survival areas in a rat model of prefabricated flap .Methods and Results: Part 1 Animal model : Prefabricated Flap was generated by ligating the end of the right femoral vascular pedicle and implanting them underneath the abdominal flap. To induce the appropriate necorsis of prefabricated flap , different vascular carriers were used in three groups: group I(long pedicle , from inguinal groove to ankle, n=10), groupⅡ(short pedicle , from inguinal groove to articular genu , n=15 ) , groupⅢ(no pedicle, n=3) . Four weeks later, an abdominal island flap based solely on the implanted vessels was elevated. The prefabricated island flap was sutured back, then neovascularization and flap viability was evaluated on day 7. As a result , there was a significant difference in survival of prefabricated flaps in group I compared to groupⅡ: group I(long pedicle)96.10±9.15%,vs.55.59±13.06%(P<0.05),groupⅢ0. In groupⅠ, vascularization demonstated by microangiography was distributed in a larger area compared with groupⅡ. The microvessel with ink stained located in epidermis, dermis, subcutaneous . The capillary density of group I and groupⅡwere respectively 32.10±7.05 capillary/mm2,26.50±5.61 capillary /mm2(P>0.05).Part 2 Feasibility of VEGF : 30 rats were randomly divided into two groups equally. Short pedicle was used vascular carrier to prefabricate abdominal flap as described in part 1 . The site around the pedicle was injected with VEGF165 in groupⅠ, and with PBS in control groupⅡ. Four weeks later, an abdominal island flap based solely on the implanted vessels was elevated. The prefabricated island flap was sutured back, then neovascularization and flap viability was evaluated on day 7. As a result , there was a significant difference in survival of prefabricated flaps in group I compared to groupⅡ: group (Ilong pedicle)96.10±9.15%,vs.55.59±13.06%(P<0.05),groupⅢ0. In groupⅠ, vascularization demonstated by microangiography was distributed in a larger area compared with groupⅡ. The microvessel with ink stained located in epidermis, dermis, subcutaneous . The capillary density of group I and groupⅡwere respectively 32.10±7.05 capillary/mm2,26.50±5.61 capillary /mm2(P>0.05).2,There was a significant increase in survival of prefabricated flaps in group I compared to groupⅡ: VEGF165 66.13±9.90% vs. PBS 55.59±13.06%(P<0.05). In groupⅠ, vascularization demonstated by microangiography was distributed in a larger area compared with groupⅡ. The microvessel with ink stained located in epidermis, dermis, subcutaneous . The capillary density of two groups were respectively 25.83±6.33 capillary/mm2, 26.50±5.61 capillary/mm2(P>0.05).Conclusions A simple and stabile animal model of prefabricated flap can be made by implanting the short pedicle of femoral vascular vessels . Locally administration of VEGF can increase neovascularization and augment the survival areas of prefabricated flaps,but the effect is limited.