Enhancing venous adaptation to the arterial environment

 描述（由申请人提供）：用于人类疾病的几种常见疗法的基础是外科手术使用静脉作为动脉导管。外科医生经常创建动静脉内瘘（AVF），这是血液透析的首选通路。然而，AVF的成熟和通畅性差，需要额外的重做程序和手术，反映了我们对静脉重塑生物学的不完善理解，导致静脉成功适应动脉环境。这种知识差距造成了对新方法的未满足的医疗需求，以增强静脉适应和成熟，增加静脉导管的成功使用。 酪氨酸激酶受体Eph-B4是静脉的胚胎决定因子。Eph-B4表达减少与剪切应力条件和层流样流动相关，例如在人和小鼠的静脉移植适应期间发生。我们提出了令人兴奋的新数据：1）我们创新的AVF小鼠模型忠实地再现了人类AVF成熟，包括存在干扰的剪切应力和约1/3的失败率; 2）在人类和小鼠中，Eph-B4表达最初在AVF适应动脉环境期间增加; 3）Eph-B4功能对于AVF重塑至关重要; 4）Eph-B4酪氨酸-774是体外Eph-B4磷酸化和下游信号传导激活的关键调节剂; 5）通过体内递送野生型或突变型Eph-B4来操纵Eph-B4功能改变AVF重塑;和6）Akt-1敲除小鼠具有减少的AVF重塑和改变的对Eph-B4刺激的反应。 我们的数据表明，手术将静脉置入动脉环境调节Eph-B4磷酸化和/或表达，这对成功的静脉适应和AVF成熟至关重要。我们假设改变Eph-B4活性将改善静脉对动脉循环的适应，从而改善AVF成熟。我们将使用我们创新的AVF成熟体内模型，以及使用生物反应器，可以控制和提供血流动力学负荷的小直径血管和内皮细胞单层在体外，以测试我们的假设与以下具体目标：目的I：确定最佳的Eph-B4的操作和交付，以提高静脉适应动脉环境，提高AVF成熟。 目的II：确定Akt功能是否是Eph-B4介导AVF成熟的机制。 这项提案中的工作将通过确定Eph-B4是静脉中机械转导机制的组成部分而产生持久的影响。我们将测试我们的新假设，即Eph-B4活性或其缺乏定义静脉表型和功能。我们使用创新的策略以及创新的体内和体外模型来操纵Eph-B4信号传导并优化体内递送以改变血管身份，从而改善AVF成熟。

 DESCRIPTION (provided by applicant): A cornerstone of several common therapies for human diseases is the surgical use of a vein as an arterial conduit. Surgeons frequently create arteriovenous fistulae (AVF), the preferred access for hemodialysis. However, the poor maturation and patency of AVF, requiring additional re-do procedures and surgery, reflects our imperfect understanding of the biology of venous remodeling that leads to successful venous adaptation to the arterial environment. This knowledge gap creates an unmet medical need for novel approaches to enhance venous adaptation and maturation, to increase successful use of venous conduits. The tyrosine kinase receptor Eph-B4 is an embryonic determinant of veins. Diminished Eph-B4 expression is associated with shear stress conditions with laminar-like flow such as occurs during vein graft adaptation in humans and mice. We present exciting new data that: 1) our innovative mouse model of AVF faithfully recapitulates human AVF maturation including the presence of disturbed shear stress and an approximately 1/3 failure rate; 2) in both humans and mice, Eph-B4 expression initially increases during AVF adaptation to the arterial environment; 3) Eph-B4 function is essential for AVF remodeling; 4) Eph-B4 tyrosine- 774 is a critical regulator of Eph-B4 phosphorylation and activation of downstream signaling in vitro; 5) manipulation of Eph-B4 function via delivery of wild type or mutant Eph-B4 in vivo alters AVF remodeling; and 6) Akt-1 knockout mice have reduced AVF remodeling and altered responses to Eph-B4 stimulation. Our data suggests that surgical placement of a vein into the arterial environment regulates Eph-B4 phosphorylation and/or expression that is critical for successful venous adaptation and AVF maturation. We hypothesize that altering Eph-B4 activity will improve venous adaptation to the arterial circulation, thereby improving AVF maturation. We will use our innovative in vivo model of AVF maturation, as well as use a bioreactor that can control and deliver hemodynamic loads to small diameter vessels and endothelial monolayers in vitro, to test our hypothesis with the following specific aims: Aim I: Determine optimal Eph-B4 manipulation and delivery to enhance venous adaptation to the arterial environment and improve AVF maturation. Aim II: Determine whether Akt function is a mechanism of Eph-B4-mediated AVF maturation. The work in this proposal will have lasting impact by establishing that Eph-B4 is a component of the mechanotransduction mechanism in veins. We will test our novel hypothesis that Eph-B4 activity, or lack thereof, defines venous phenotype and function. We use an innovative strategy, as well as innovative in vivo and in vitro models, to manipulate Eph-B4 signaling and optimize delivery in vivo to alter vessel identity and thereby improve AVF maturation.