跨区供血的扩大穿支皮瓣血供的不确定性是目前临床处理创伤或肿瘤根治性切除所致巨大创面未能解决的难题。我们的前期研究显示choke vessels转变为真性吻合能扩大皮瓣的成活面积，但其机制尚不明确。已有研究表明缺氧诱导因子（HIF）-1α能诱导iNOS、VEGF和SDF-1表达，扩张微血管，促进新生血管形成。 据此，我们提出HIF-1α通过上调iNOS、VEGF、SDF-1可能促进皮瓣的choke vessels向真性吻合转变。 本课题拟分别采用siRNA特异性沉默和siRNA抑制脯氨酰羟化酶（PHD）选择性激活HIF-1α，观察HIF-1α被沉默和激活后皮瓣组织中iNOS、VEGF和SDF-1表达变化，应用"微血管直视"等技术观测跨区穿支皮瓣choke vessels变化，探索choke vessels向真性吻合转变的可能机制，为临床预构血供可靠的跨区穿支皮瓣奠定理论基础。

Perforator flap is a hot topic in recent years in the field of microsurgical reconstruction, The uncertainty blood supply of the cross-boundary perforator flap is challenging problem in clinical treatment of huge wound which caused by trauma or tumor radical resection. Choke vessels transformation and angiogenesis are the two major factors which affect the blood supply of cross-boundary perforator flap. Recently, we have observed the process of choke vessels transforming into true anastomosis vascular in vivo. However, the specific regulating mechanisms of microvascular remodeling of the cross-boundary perforator flap remain unclearly. Some authors have reported that hypoxia inducible factor-1α (HIF-1α) can expand capillaries and promote neovascularization by inducing inducible nitric oxide synthase(iNOs), vascular endothelial growth factor(VEGF), stromal cell-derived factor-1(SDF-1). We hypothesis that HIF-1α involved with microvascular remodeling in the cross-boundary perforator flap by inducing iNOs, VEGF and SDF-1 to promote choke vessels transforming into true anastomosis. In order to verify the hypotheses, we intend to use small interfering RNA(siRNA) to silence the HIF-1α and take siRNA to silence the prolylhydroxylase(PHD) so that activate the HIF-1αselectly,respectively,and then measure the express level of HIF-1α,iNOS, VEGF, SDF-1 in the cross-boundary perforator flap. we also observe the change of morphology, hemodynamic in choke vessel zone, and the change of vascular density and the survival area in the flap in vivo,for elucidating the relation HIF-1α with the change of choke vessels in the cross-boundary perforator flap.Purposes of this study are to reveal the effect and mechanism of HIF-1α in the cross-boundary perforator flap, and establish a theoretical foundation for pre-building a large cross-boundary perforator flap with reliable blood supply in clinic.