ROLE OF ENDOTHELIUM IN GRAFT INTIMAL HYPERPLASIA

这项建议的长期目标是了解 移植血管内膜增生中的内皮细胞。一种内皮细胞 假体移植物上的细胞(EC)衬里自被考虑以来一直被考虑 显示可降低移植物的血栓形成能力和血小板活化，以及 提高小口径移植物的短期通畅率。然而，欧共体已经 可能不受欢迎的功能，例如产生光滑的 肌细胞(SMC)有丝分裂原可能导致细胞过度增殖 内皮下组织中的细胞。事实上，内膜增生症是 通常最严重的是移植物内皮化的区域，在 吻合口附近的区域。此外，我们的初步研究 都认为种植在移植物上的EC会产生一种血小板衍生的 生长因子样蛋白(PDGFc)以非常高的速率表达。这种增长 因子刺激培养的SMC增殖，被认为是 参与动脉粥样硬化病变的发展。在这方面的实验 提案将检验EC o扩大的假设 聚四氟乙烯(EPTFE)移植物产生有丝分裂原，包括PDGFc， 它们是导致SMC增殖增加的原因 血管内皮下内膜增生。我们进一步建议这一点 内皮细胞激活产生SMC有丝分裂原可能受改变的调节 嫁接底物的物理和生化特性，或通过 体液环境的变化。 为了验证这些假设，EC衍生的生长因子在 EC植入ePTFE假体将与移植程度有关 犬类研究中的内皮化持续时间长达6个月。在… 在内皮化的中期，移植物将被移除，并且 将测量PDGFc的产量，并将其与邻近的 血管和培养细胞。由于SMC和巨噬细胞在某些情况下 条件也会产生PDGFc，这是负责PDGFc的移植细胞 产物将通过使用PDGF A链的原位杂交进行鉴定 和B链cDNAs探针。此外，还将培养EC和SMC 分别在体外测定PDGFc的产量。要确定 底物对总有丝分裂原和PDGFc产量、生长因子的影响 促胰液素的体外和体内研究将在改良的底物上进行。 此外，由于鱼油已被证明可以减少移植物的内膜 增殖，以及最近在体外抑制PDGFc的产生， 这些油脂对EC生产种子生长因子的影响 将对移植进行研究。如果拟议的研究表明，生长因子 血管移植物上细胞的产量仍然很高，即使在 实现稳定的内皮衬里，然后开发手段 抑制有丝分裂原的产生可能是必要的，以控制发展 吻合口内膜增生。

The long-term objective of this proposal is to understand the role of the endothelium in intimal hyperplasia of vascular grafts. An endothelial cell (EC) lining on a prosthetic graft is considered since it has been shown to reduce graft thrombogenicity and platelet activation, as well as improve the short-term patency of small caliber grafts. HOwever, EC have potentially undesirable functions, such as the production of smooth muscle cell (SMC) mitogens which may induce excessive proliferation of cells in the subendothelial tissue. In fact, intimal hyperplasia is often most severe in graft regions that are firs endothelialized, in the areas adjacent to the anastomoses. Furthermore, our preliminary studies have suggested that EC seeded onto grafts produce a platelet-derived growth factor-like protein (PDGFc) at very high rates. This growth factor stimulates the proliferation of cultured SMC and is thought to be involved in atherosclerotic lesion development. Experiments in this proposal will test the hypothesis that EC o expanded polytetrafluoroethylene (ePTFE) grafts produce mitogens, including PDGFc, which are responsible for increased SMC proliferation causing subendothelial intimal hyperplasia. We further propose that this activation of EC to produce SMC mitogens may be regulated by alteration of the physical and biochemical properties of the graft substrate, or by changes in the humoral environment. To test these hypotheses, the production of EC-derived growth factors on EC seeded ePTFE prostheses will be related to the degree of graft endothelialization in canine studies extending up to 6 months. At intermediate stages of endothelialization, the graft will be removed, and PDGFc production will be measured and compared to that of adjacent vessels and to cultured cells. Since SMC and macrophages under certain conditions also produce PDGFc, the graft cells responsible for PDGFc production will be identified by in situ hybridization using PDGF A-chain and B-chain cDNA probes. In addition, EC and SMC will be cultured separately and PDGFc production measured in vitro. To determine the effects of substrate on total mitogen and PDGFc production, growth factor secretin in vitro and in vivo will be studied on modified substrates. Furthermore, since fish oils have been shown to reduce graft intimal hyperplasia, and more recently to inhibit PDGFc production in vitro, the effect of these oils on production of growth factors by EC on seeded grafts will be studied. If the proposed studies show that growth factor production by cells on vascular grafts remains high, even after achievement of a stable endothelial lining, then development of means of inhibiting mitogen production may be necessary to control development of anastomotic intimal hyperplasia.