Functionalization of biomimetic apatite with mineral binding peptides for bone tissue engineering

项目摘要摘要： 每年要进行数百万次骨移植手术，以修复口腔中的骨缺陷。 虽然自体移植物和同种异体移植物在临床上被用于这种目的，但它们的局限性在很大程度上促使了人们 合成接枝材料的研究。尽管已经开发出了许多生物兼容材料，但缺乏 生物活性的变化往往会导致不理想的结果。生物活性多肽在细菌表面的应用 材料可以帮助在材料和活组织之间建立一个界面。使用噬菌体展示技术，我们的 实验室已经开发出一种双功能多肽DPI-VTK，它既包含间充质干细胞 (MSC)结合域和羟基磷灰石结合域。这样的多肽不仅可以增强 MSCs与羟基磷灰石的黏附，但也可以促进宿主MSCs的特异性迁移，绕过 细胞移植的必要性。此外，该多肽可以与BMP多肽结合，以便 创造双功能的骨传导和骨诱导界面，促进MSCs的归巢 以及它们随后的分化。这项提议的总体假设是，增强 含有细胞特异性多肽的材料的骨传导性和骨诱导性将增加 骨再生，不依赖外源细胞。 本项目的主要目的是：1)确定DPI-VTK是否能促进再生 2)DPI-VTK能否与BMP协同作用 3)确定DPI-VTK的MSC结合机制。体内研究将是 使用小鼠颅骨缺损模型完成，并使用Micro-CT和 组织学染色。肽结合研究将使用基于ELISA法的蛋白质分析来完成， 亲和下拉分析和质谱分析。这些实验的结果将增强我们的 在组织工程的背景下理解细胞-材料界面以及确定潜在的 本实验室矿物质结合肽的临床应用。由于羟基磷灰石基材的广泛使用 DPI-VTK在颅面骨移植中的应用 变成天然的骨组织。开发既能招募宿主细胞又能诱导分化的双功能材料 分化可能是再生大量缺陷的关键策略，而不需要外源 细胞或自体移植。

Project Summary Abstract: Millions of bone grafting procedures are performed annually to repair bone defects in the oral cavity. While autografts and allografts are used clinically for such purposes, their limitations have motivated much research into synthetic graft materials. Although numerous biocompatible materials have been developed, lack of bioactivity often times results in suboptimal results. The use of bioactive peptides on the surface of a material can help create an interface between materials and living tissue. Using phage-display technology, our laboratory has developed a dual-functional peptide DPI-VTK that contains both a mesenchymal stem cell (MSC) binding domain and a hydroxyapatite binding domain. Such a peptide could not only enhance the adhesion of MSCs to hydroxyapatite, but could also promote the specific migration of host MSCs, bypassing the need for cell transplantation. Additionally, this peptide could be combined with BMP peptides in order to create dual-functional osteoconductive and osteoinductive interfaces that encourage the homing of MSCs along with their subsequent differentiation. The overall hypothesis of this proposal is that enhancing the osteoconductivity and osteoinductivity of materials with cell-specific peptides will result in increased bone regeneration without reliance on exogenous cells. This project proposes the following aims: 1) Determine if DPI-VTK can enhance the regeneration of bone defects in acellular scaffold models, 2) Determine if DPI-VTK can behave synergistically with BMP derived peptides, and 3) Determine the MSC binding mechanism of DPI-VTK. The in-vivo studies will be accomplished using a mouse calvarial defect model and the data analyzed using Micro-CT along with histological staining. The peptide binding studies will be accomplished using ELISA based protein assays, affinity pull-down assays, and mass spectrometry. The outcomes of these experiments will enhance our understanding of cell-material interfaces in the context of tissue engineering as well as determine the potential clinical utility of our laboratory's mineral binding peptides. Due to the widespread use of hydroxyapatite-based biomaterials in craniofacial bone grafting, DPI-VTK could be very useful clinically for enhancing their integration into native bone tissue. Developing dual-functional material that both recruit host cells and induce differentiation could be a key strategy for regenerating large-volume defects without the need for exogenous cells or autografts.