Manipulating the host-biomaterial interface for enhanced scaffold vascularization

摘要 这项研究具有重要的意义，因为它将促进新一代可再生支架的形成。海绵状软组织 受伤后经常会遇到损失，重建程序也不是最理想的。在过去的二十年里， 以胶原蛋白为基础的支架提供了一个组织血管重建的平台，对外科医生来说已经变得至关重要 重建。然而，植入后缓慢的随机血管形成往往会导致失败，并阻止 真正概括了天然组织血管的层次结构。因此，可以快速引导微血管的支架 发育与用相似组织取代相似组织非常相关，而相似组织是重建的标志 做手术。这项提案的目标是开发一种协调的工程-外科方法，用于快速和 引导支架血管化。我们开发了一种新的显微外科手术策略，称为血管 “微穿孔”(MP)，它增加了大鼠受体大血管系统的血管生成能力 快速将相邻放置的大型脚手架血管化。我们认为由此产生的毛细血管外延生长是由 免疫细胞的瞬间渗出，尤指巨噬细胞。虽然这在一定程度上加快了 在相邻放置的块状胶原支架中血管形成，所产生的新的微血管具有随机的 图案。目前使用的块状支架具有比细胞大小小一个数量级的纳米级孔洞 并且缺乏互联互通。这不允许快速和引导的细胞渗透；因此血管形成缓慢。 而且是随机的。为了解决这一问题，我们率先开发了原位形成细胞外基质(ECM)- 具有可定制微结构和细胞渗透能力的仿生颗粒支架。我们的预赛 数据表明，我们的微孔颗粒支架非常适合于指导MP诱导的血管形成。我们的 中心假设是定制的微孔颗粒支架可以与MP一起使用来增强 引导血管重建化。理由是，这些研究的完成将揭示如何最好地优化 引导工程化组织血管化多方面问题的补充策略。我们的中央 假设将通过三个具体的目标来验证：1)开发模拟ECM的原位形成的微孔颗粒 水凝胶支架，调节与促进血管生成相关的细胞活动；2) 通过改变受体MP间隔和直径来控制支架的血管化；3)控制巨噬细胞 通过脚手架设计渗透和血管建筑。我们将以创新的方式追求这些目标 来自外科和工程科学的组合技术。预期的结果是迅速的 具有可控微血管层次的血管化支架，同时还创造了实验技术 在工程与显微外科的交界处。这些结果将产生积极的影响，为 开发新的可翻译的大体积组织丢失重建方法。

Abstract This research is significant as it will facilitate a new generation of regenerative scaffolds. Voluminous soft tissue loss is often encountered after injury, and reconstructive procedures are suboptimal. Over the past two decades, collagen-based scaffolds have become vital to surgeons by providing a platform for tissue revascularization and reconstruction. However, their slow random vascularization upon implantation often leads to failure and prevents true recapitulation of native tissue vascular hierarchy. Thus, scaffolds which could rapidly guide microvascular development would be exceedingly relevant to replacing ‘like tissue with like tissue’, a hallmark of reconstructive surgery. This proposal’s objective is to develop a coordinated engineering-surgical approach for rapid and guided scaffold vascularization. We have developed a novel microsurgical tactic, termed vascular “micropuncture” (MP), which increases the angiogenic capabilities of the rat recipient macrovasculature to quickly vascularize an adjacently placed bulk scaffold. We believe the resulting capillary outgrowth is induced by the instantaneous extravasation of immune cells, especially macrophages. While this partially expedites vascularization in an adjacently placed bulk collagen scaffold, the resulting neo-microvasculature has a random pattern. Currently used bulk scaffolds have nanoscale pores that are orders of magnitude smaller than cell size and lack interconnectivity. This does not permit for rapid and guided cell infiltration; hence vascularization is slow and random. To address this, we have pioneered the development of in situ forming extracellular matrix (ECM)- mimetic granular scaffolds with customizable microarchitectures and cell permeating capabilities. Our preliminary data suggests that our microporous granular scaffolds are well suited to guide MP-induced vascularization. Our central hypothesis is that customized microporous granular scaffolds can be used alongside MP to enhance and guide vascularization. The rationale is that completion of these studies will reveal how to best optimize complementary tactics for the multifaceted problem of guided engineered tissue vascularization. Our central hypothesis will be tested by three specific aims: 1) To develop ECM-mimetic in situ forming microporous granular hydrogel scaffolds that regulate cellular activities pertinent to accelerating angiogenesis in vitro and in vivo; 2) Controlling scaffold vascularization by varying recipient MP interval and diameter; and 3) Controlling macrophage infiltration and vascular architecture by scaffold design. We will pursue these aims using innovative combinatorial techniques from both the surgical and engineering sciences. The expected outcome is a rapidly vascularized scaffold having a controllable microvascular hierarchy while also creating experimental techniques at the engineering-microsurgery interface. These results will have a positive impact by laying the foundation in developing new and translatable reconstructive approaches for large volume tissue loss.