Regulation and Enhancement of Angiogenesis in Dense Fibrin Matrices

血管生成，即从现有的血管系统中长出新的毛细血管，是一个复杂的生物学过程。 对多种病理的治疗和组织的成功至关重要的过程 工程学。在组织工程中促进血管生成的许多有希望的策略中 包括具有精确的空间和时间控制的促血管生成分子的受控输送。一个 另一种方法是提供一种合适的细胞类型，可以提供更具生理学意义的促进- 血管生成的线索，将加速招募宿主血管。与两位资深合作伙伴- 研究人员表示，PI已经开始在一种强大的、基于纤维蛋白的3D体外模型中探索后一种策略。 毛细血管形态发生。使用这个模型系统，支持形成稳定的(&gt；3周) 管腔清楚的毛细血管样结构，我们已经证明了毛细血管的形态发生是 显著抑制增加纤维蛋白基质密度。此外，我们已经证明了这种纤维蛋白密度 阻断的部分原因是内皮细胞不能上调基质金属蛋白酶的一个亚群 (MMPs)局部重塑基质和维持毛细血管侵袭所需。然而，骨骼的添加 骨髓间充质干细胞(MSCs)向三维组织构建明显增强毛细血管 形态发生，通过上调基质密度部分克服基质密度增加引起的抑制 MMPs的这个子集的表达和/或活性。基于这些初步发现，这一新的 研究人员生物工程研究拨款提案寻求测试MSCs可以刺激 致密的3-D纤维蛋白基质在体外和体内的血管生成。这些目标将通过以下途径实现 具体目标如下：1.量化植入致密纤维蛋白基质中的MSCs的能力 促进体外毛细管样网络的形成。2.)探索MMPs子集(MMPs-2)所扮演的角色 和-9以及膜型MT1-MMPs)在MSCs促血管生成中的作用。3.)确定 骨髓间充质干细胞在SCID小鼠模型皮下部位刺激体内血管形成的能力。 成功完成这些研究将有助于我们从根本上了解 ECM和MMPs在血管生成中的作用，并最终将影响合成ECM类似物的设计和使用 干细胞在组织工程中的应用。

Angiogenesis, the sprouting of new capillary blood vessels from existing vasculature, is a complex biological process of critical importance to the treatment of numerous pathologies and the success of tissue engineering. Amongst the many promising strategies to promote angiogenesis in tissue engineering includes the controlled delivery of pro-angiogenic molecules with precise spatial and temporal control. An alternative approach is to deliver an appropriate cell type that can provide a more physiologic mixture ofpro- angiogenic cues that will accelerate the recruitment of host vessels. In conjunction with two senior co- investigators, the PI has begun to explore this latter strategy in a robust, fibrin-based 3-D in vitro model of capillary morphogenesis. Using this model system, which supports the formation of stable (> 3 weeks) capillary-like structures with well-defined lumens, we have shown that capillary morphogenesis is significantly inhibited by increasing fibrin matrix density. Furthermore, we have shown that this fibrin denisty block is partially due to the inability of endothelial cells to upregulate a subset of matrix metalloproteinases (MMPs) required to locally remodel the matrix and sustain capillary invasion. However, the addition of bone marrow-derived mesenchymal stem cells (MSCs) to the 3-D tissue construct significantly enhances capillary morphogenesis, partially overcoming the inhibition caused by increased matrix density by upregulating the expression and/or activity of this subset of MMPs. Building on these preliminary findings, this new investigator Bioengineering Research Grant proposal seeks to test the hypothesis that MSCs can stimulate angiogenesis within dense 3-D fibrin matrices both in vitro and in vivo. These objectives will be achieved via three specific aims as follows: 1.) Quantify the ability of MSCs embedded throughout dense fibrin matrices to enhance capillary-like network formation in vitro. 2.) Probe the roles played by a subset of MMPs (MMPs-2 and -9 and the membrane-type MT1-MMP) in the angiogenic enhancement by MSCs. 3.) Determine the ability of MSCs to stimulate vascularization in vivo in a subcutaneous site in a SCID-mouse model. Successful completion of these studies will contribute to our fundamental understanding of the role of the ECM and MMPs in angiogenesis, and will ultimately impact the design of synthetic ECM analogs and the use of stem cells in tissue engineering applications.