Autologus adipose tissue grafts to inhibit hemodialysis access stenosis

描述(由申请人提供)：慢性血液透析(HD)获得高血流量的途径通常是通过建立动静脉(AV)通路实现的。虽然天然的房室瘘在功能发挥作用后并发症较少，但高达60%的患者永远不会发展成功能正常的通路。房室移植物早期更可靠，但随后会受到移植物血管吻合口增生的困扰，第一年有高达50%的移植物失败。如果能降低狭窄的发生率，房室移植物将是治疗慢性血液透析的较好选择。遗憾的是，目前尚无预防房室移植物狭窄的临床治疗方法，因此迫切需要有效的治疗方法。脂肪细胞释放许多多肽，其中包括脂联素(ADPN)，它具有有益的血管作用，如减少细胞黏附分子和炎症细胞因子的表达。例如，ADPN基因敲除小鼠与野生型小鼠相比，血管损伤后增殖显著增加，而血管附近的皮下脂肪组织(AT)已被证明对血管损伤具有保护作用。因此，AT有可能被用来抑制房室移植物的狭窄。抗糖尿病药物格列酮对导致血管狭窄的关键过程也有抑制作用，包括炎症和血管平滑肌细胞(SMC)增殖。值得注意的是，格列酮还可增加AT对ADPN的表达。格列酮是亲脂性的，并且可以被贪婪地分配到AT中，因此可以被认为是药物的内源性仓库。因此，这一策略将开发AT的血管保护特性及其作为格列酮仓库的潜力。此外，格列酮的血管保护作用及其促进ADPN释放的能力也将得到利用。自体AT皮下移植修复软组织缺损是整形外科常用的方法。因此，这里的策略是将自体格列酮负载的AT移植到AV移植物上，既作为格列酮局部给药的仓库，又作为格列酮增强型ADPN生产的内源性工厂。有两个具体目标。目的1优化猪血管紧张素转换酶与格列酮的体外混合物，为其在动物实验中的应用做准备。将培养的AT与不同浓度的格列酮混合产生的条件培养液，比较它们对SMC增殖的抑制能力。目的2将载自体格列酮的血管紧张素转换酶(AT)移植到猪模型的房室周围血管周围。根据磁共振成像的结果，移植血管的管腔面积和血流速度将被用作疗效结果。伤口愈合也将被评估为安全结果。这项工作提出了一种非常新颖和简单的药物和内源性激素传递方法，由于其局部性质和使用天然组织，其毒性应该非常有限。这项技术还可以改善瘘管的可用性，并对其他血管病变具有广泛的适用性。 公共卫生相关性：血液透析血管通路是通过手术创建的部位，通常位于手臂上，用于在肾功能衰竭患者的血液透析过程中取出和替换血液。不幸的是，这些通路的失败率很高，因为通路部位的细胞过度生长，导致更多的手术，显著增加了感染的风险，并增加了患者的死亡风险。这项工作使用患者自己的脂肪组织与一种药物混合进行移植，以靶向将药物和有益蛋白质释放到通路部位，从而抑制细胞过度生长，并有望改善这些通路的功能寿命。

DESCRIPTION (provided by applicant): Access to high blood flow rate for chronic hemodialysis (HD) is usually achieved by the creation of an arteriovenous (AV) access. While native AV fistulas have fewer complications once they become functional, up to 60% never develop into a functioning access. The AV grafts are more reliable early but are plagued later with hyperplasia at the graft-vessel anastomoses and up to 50% fail in the first year. If the incidence of stenosis can be decreased, the AV graft would be a better option for chronic HD. Regrettably, there are no established clinical treatments for the prevention of AV graft stenosis; therefore, effective therapies are urgently needed. Adipocytes release many peptides, including adiponectin (ADPN) which has beneficial vascular effects, such as decreasing the expression of cellular adhesion molecules and inflammatory cytokines. For example, hyperplasia increased markedly following vascular injury in ADPN knock-out mice versus wild-type mice, while the placement of subcutaneous adipose tissue (AT) near blood vessels has been shown to have protective effects against vascular injury. Thus, it is likely AT can be exploited to inhibit stenosis in AV grafts. The anti-diabetic glitazone drugs also have inhibitory effects on key processes that contribute to vascular stenosis, including inflammation and vascular smooth muscle cell (SMC) proliferation. Of particular relevance, glitazones also increase the expression of ADPN by AT. The glitazones are lipophilic and avidly partition into AT, which can therefore be considered an endogenous depot for the drug. Thus, this strategy will exploit the vasculo-protective properties of AT and its potential to serve as a depot for glitazones. Also, the vasculo- protective effects of glitazones, and their ability to promote the release of ADPN will be utilized. Autologous grafting of subcutaneous AT to repair soft-tissue defects is commonly used in plastic surgery. Hence, herein the strategy is to transplant autologous glitazone-loaded subcutaneous AT to the AV graft, as both a depot for local delivery of glitazones and as an endogenous factory for the glitazone-enhanced production of ADPN. There are two Specific Aims. Aim 1 will optimize the mixture of porcine AT and glitazone in vitro in preparation for its use in animal studies. The conditioned media produced from cultured AT mixed with different concentrations of glitazone will be compared for their ability to inhibit SMC proliferation. Aim 2 will transplant autologous glitazone-loaded subcutaneous AT to the perivascular space around the anastomoses of AV graft in a porcine model. The lumen area and blood flow rate in the AV graft will be used as efficacy outcomes as determined by magnetic resonance imaging. Wound healing will also be assessed as a safety outcome. This work proposes a very novel and simple means of drug and endogenous hormone delivery that should have very limited toxicity due to its localized nature and the use of native tissue. This technique may also improve fistula usability and has broad applicability to other vascular pathologies. PUBLIC HEALTH RELEVANCE: Hemodialysis vascular accesses are surgically created sites, typically in the arms that are used to remove and replace blood during hemodialysis for patients with kidney failure. Unfortunately these accesses fail at a high rate due to cell overgrowth in the access site resulting in more surgeries, significantly increased risks of infection, and increased risk of death for patients. This work uses the transplant of the patient's own fat tissue mixed with a drug to target the release of drug and beneficial proteins to the access site that will inhibit cell overgrowth and hopefully improve the functioning lifespan of these accesses.