类骨膜新型分子内交联自支持膜负载BMP-2机制及其调控干细胞作用机理研究

材料与机体组织整合并诱导组织新生是组织工程研究的热点与难点。材料表面控释生长因子是诱导组织再生重要途径，而基质材料是否影响生长因子对干细胞作用活性及影响机制并不明确。骨膜是增加骨与周围组织融合的关键，我们前期以氧化硫酸软骨素与胶原构建分子内交联聚电解质膜，发现其具有类骨膜功能。本项目拟进一步以该体系制备类骨膜结构和功能的分子内交联自支持（FS）膜，研究组装条件对膜性质影响；通过研究膜内BMP-2负载、释放、扩散及结合行为，揭示负载方式对细胞作用形式的影响；从受体水平研究膜内BMP-2对干细胞行为的调控机制，阐明BMP-2作用形式对其作用活性的影响；通过对比研究胶原和壳聚糖组成膜上干细胞成骨分化及膜重塑情况，揭示膜体系依赖性BMP-2与整合素协同作用机制及其对骨再生的影响。通过相关基础科学问题探究，了解该FS膜体系诱导组织整合与再生机理，推进其组织修复应用，为生长因子控释材料设计开辟新思路。

The integration of biomaterials with host tissue and induction of tissue regeneration is a hot and challenge topic in tissue engineering. There, the controlled release of growth factors within matrix materials has emerged as a promising way to induce tissue regeneration. Yet, it is not clear whether the matrix material can affect the way of action and activity of growth factors and its potential mechanism underlying. Periosteum plays a significant role in connecting bone with its surrounding tissues. We developed previously an innovative intrinsic cross-linked multilayer system using oxidized chondroitin sulfate (oCS) and collagen I (Col I) that resembles to the function of periosteum. Here, the layer by layer dip coating method is applied to further build up a periosteum-liked and intrinsic cross-linked freestanding multilayer films (FS) using this system. Studies will be carried out to investigate the effect of assembly conditions on the bulk and surface properties of FS films. The action of BMP-2 in the films particularly regarding uptake, release and also diffusion and bonding of BMP-2 inside the films will further studied to conclude whether the immobilization of BMP-2 determines the way of presentation to cells (soluble or matrix-bounded). In addition, we will investigate how BMP-2 is regulating cell adhesion, differentiation and the ability of matrix remodeling at receptor level depending on its way of presentation either being diffusible or ionically/covalently tethered to FS films. Since there is cross-talk between growth factor- and integrin-related signal transduction, underlying molecular mechanism will be studied in depth to understand better, how the presence of extracellular matrix molecules Col I and the way of BMP-2 immobilization depending on the kind of FS films affect osteogenic differentiation. This project will provide a better understanding on this novel intrinsic cross-linked FS film system and its role on driving tissue integration and regeneration, and thus promote its application for repair of damaged tissues. The success of this project may also open new perspectives for the designing of controlled delivery system.