跨区穿支皮瓣血管从choke vessels转化为真性吻合的机制研究

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.

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。

跨区穿支皮瓣是修复烧伤、创伤或癌症切除后大面积皮肤缺损的重要手术方式。然而，由缺血引起的皮瓣远端坏死对于整形外科和重建外科医生仍然是一个棘手的问题。如何解决这一问题，本研究通过体外实验检测内皮细胞在缺氧状态下HIF-1a,iNOS,VEGF表达变化及沉默和过表达HIF-1a对细胞增殖率，细胞凋亡的影响。通过体内实验干扰SD大鼠HIF-1a表达对皮瓣VEGF,iNOS表达、皮瓣坏死面积及choke vessel 转变为真性吻合的影响。体外实验结果证实：在低氧状态下HIF-1a可诱导下游因子VEGF、iNOS表达从而增强内皮细胞缺氧耐受，减少细胞凋亡。通过动物实验进一步证实HIF-1a能够诱导iNOS,VEGF表达促进跨区穿支皮瓣choke vessels 向真性吻合转变从而减少跨区穿支皮瓣远端坏死。因此，本研究证实了HIF-1α调控下游因子iNOS、VEGF表达可有效改善缺血性多区域穿支皮瓣的存活率，有望为进一步研究跨区穿支皮瓣choke vessels向真性吻合的转变提供了新的干预靶点。在本项目的支持下在国内外期刊发表学术论著23篇（SCI论著7篇）；培养了博士生2名，硕士生3名，多次在国外、全国及地方性会议作特邀报告；主办了2届“中国显微外科穿支皮瓣高峰论坛”（第7、8届），及1届国际学术会议（第11届全国显微外科学术会议）。获得奖项：湖南省科技进步二等奖；湖南省穿支皮瓣移植系列创新研究二等奖；中南大学医疗新技术成果二等奖；第十四届湖南医学科技奖二等奖；并获得两项发明专利。