Molecularly regulated release of angiogenic factors from superporous hydrogels

 描述：血管化对于各种缺血性疾病的治疗和组织工程化构建物的存活是重要的。因此，血管生成策略的发展一直受到各个领域的高度关注。然而，实现成功的血管生成是具有挑战性的，因为血管的形成和成熟涉及不同阶段的多种生长因子。此外，尽管血管生成因子不足，但不会 诱导有效的血管生成，过量的血管生成因子会导致有缺陷和渗漏的血管的形成。因此，治疗性血管生成不仅需要多种生长因子，还需要调节生长因子输送的时间、剂量和顺序的机制。虽然团注是控制生长因子注射时间、剂量和顺序的最简单方法，但这种注射方式需要非常高水平的生长因子。它可能会导致严重的全身毒性。相比之下，聚合物递送系统在局部递送生长因子和降低全身毒性方面具有很大的前景。然而，开发一种聚合物系统来控制多种生长因子的释放时间、剂量和顺序是具有挑战性的。本应用的目的是开发一种新颖的分子控释机制和基于水凝胶的聚合物体系，能够以不同和独立的时间和剂量控制释放多种血管生成因子，从而以动态的方式调节血管生成。核心假设是多种生长因子通过与水凝胶连接的核酸适配子的特异性结合而被隔离在同一水凝胶中，并通过互补序列(CS)触发器的竞争结合而特异性地释放。为了验证这一假设，我们将致力于三个具体目标：1)合成适配子功能化的超孔水凝胶(AS-Gel)，用于高容量地隔离和保留多种生长因子；2)设计和优化适配子和CS序列，并在体外确定AS-Gel中分子调控的生长因子释放；以及3)研究AS-Gel中分子调控的生长因子释放和小鼠血管生成。我们已经进行了初步研究，并获得了令人信服的数据，表明AS-Gel可以隔离生长因子，并在CS触发剂存在的情况下释放它们。更重要的是，AS-Gel可以被触发释放生长因子，以刺激体内血管生成。因此，该项目的完成将带来一种按需交付多种增长因素的新战略。它将有利于治疗各种缺血性疾病，如内脏修复，在这些疾病中，直接向组织重复注射生长因子是太有害或不可能的。

 DESCRIPTION: Vascularization is important for the treatment of various ischemic diseases and the survival of tissue-engineered constructs. Thus, the development of angiogenesis strategies has continuously attracted great attention in various fields. However, the realization o successful angiogenesis is challenging, because vascular formation and maturation involve multiple growth factors at different stages. Moreover, while insufficient angiogenic factors do not induce effective angiogenesis, excess angiogenic factors can lead to the formation of defective and leaky blood vessels. Thus, therapeutic angiogenesis requires not only multiple growth factors, but also mechanisms for modulating the time, dosage, and sequential order of growth factor delivery. While bolus injections are the simplest way to control the time, dosage, and sequential order of growth factor delivery, this mode of delivery requires very high levels of growth factors. It can lead to severe systemic toxicity. By contrast, polymeric delivery systems hold great promise for localized delivery of growth factors with reduced systemic toxicity. However, it is challenging to develop a polymeric system to control the release time, dosage and sequential order of multiple growth factors. The objective of this application is to develop a novel molecularly controlled release mechanism and a hydrogel-based polymeric system that can release multiple angiogenic factors with differential and independent timing and dose control, hence regulating angiogenesis in a dynamic manner. The central hypothesis is that multiple growth factors would be sequestered within the same hydrogel by specific binding to hydrogel-linked nucleic acid aptamers, and released specifically by competitive binding of complementary sequence (CS) triggers. To test this hypothesis, we will work on three specific aims: 1) to synthesize aptamer-functionalized superporous hydrogels (AS-gels) for high-capacity sequestration and retention of multiple growth factors; 2) to design and optimize aptamer and CS sequences and to determine molecularly regulated growth factor release from AS-gels in vitro; and 3) to investigate molecularly regulated growth factor release from AS-gels and angiogenesis in mice. We have performed preliminary studies and acquired compelling data showing that AS-gels can sequester growth factors and release them in the presence of CS triggers. More importantly, AS-gels can be triggered to release growth factors to stimulate angiogenesis in vivo. Therefore, the accomplishment of this project will lead to a novel strategy for on-demand delivery of multiple growth factors. It will benefit the treatment of various ischemic diseases such as repair of internal organs where it is too harmful or impossible to repeatedly inject growth factors directly into the tissue.