Autologus adipose tissue grafts to inhibit hemodialysis access stenosis

描述（由申请人提供）：获得高血流量的慢性血液透析（HD）通常通过创建动静脉（AV）通道来实现。虽然天然的房室瘘管一旦具有功能，并发症较少，但高达60%的房室瘘管从未发展成为功能通畅的通道。早期的AV移植物比较可靠，但在移植物血管吻合处会出现增生，并且在第一年失败的比例高达50%。如果狭窄的发生率可以降低，房室移植物将是慢性HD的更好选择。遗憾的是，目前还没有成熟的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，包括脂联素（ADPN），它对血管有有益的作用，如降低细胞粘附分子和炎症因子的表达。例如，与野生型小鼠相比，ADPN敲除小鼠的血管损伤后增生明显增加，而血管附近皮下脂肪组织（AT）的放置已被证明对血管损伤具有保护作用。因此，AT很可能被用来抑制房颤移植物的狭窄。抗糖尿病药物格列酮对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。特别相关的是，格列酮也通过AT增加ADPN的表达。格列酮是亲脂性的，并且极易分裂成AT，因此可以认为是药物的内源性储库。因此，该策略将利用AT的血管保护特性及其作为格列酮储存库的潜力。此外，还将利用格列酮的血管保护作用及其促进ADPN释放的能力。自体皮下移植修复软组织缺损是整形外科中常用的一种方法。因此，本文的策略是将自体负载格列酮的皮下AT移植到AV移植物中，既作为格列酮局部递送的仓库，又作为格列酮增强ADPN生产的内源性工厂。有两个具体目标。目的1将优化猪AT和格列酮的体外混合制剂，以用于动物研究。用不同浓度的格列酮混合培养AT产生的条件培养基将比较其抑制SMC增殖的能力。目的2将载格列酮的自体皮下AT移植到猪模型AV移植物吻合口周围血管间隙。通过核磁共振成像确定AV移植物的管腔面积和血流速率作为疗效指标。伤口愈合也将作为安全结果进行评估。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递送手段，由于其局部性质和使用天然组织，应该具有非常有限的毒性。该技术还可以提高瘘管的可用性，并广泛适用于其他血管病变。

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.