Synergistic Molecule Delivery Using Hydrogels for BoneTissue Repair

描述（由申请人提供）：骨形态发生蛋白（BMP）的使用显示出作为改善骨再生的治疗剂的前景;然而，所需骨诱导作用所需的高超生理浓度、成本和患者变异性阻碍了基于BMP的治疗剂的全部优势的实现。因此，临床上需要开发生长因子递送策略，其将优化释放动力学并克服对非生理高浓度的需要以促进骨修复。所提出的方法利用基质金属蛋白酶（MMP）敏感的透明质酸（HA）为基础的水凝胶支架作为细胞介导的运载工具，其中凝胶的重塑释放的分子。支架降解动力学可以通过改变蛋白水解肽的MMP敏感性和通过交联密度来控制。已知典型Wnt信号传导促进成骨细胞生成、成骨细胞功能和骨再生，并且可以使用分泌分子的R-spondin（Rspo）家族来促进。通过使用工程化的合成的基于HA的水凝胶协同递送BMP 2和Rsp 〇 2来增强经典Wnt信号传导应允许改善骨组织修复。考虑到这些特征，这项工作的目的是双重的：（1）评估水凝胶重塑和BMP 2生长因子释放动力学对体内组织修复的影响，以及（2）确定Rsp 〇 2和BMP 2的协同递送是否改善BMP 2诱导的骨生成。将使用体外表征技术评价生长因子释放动力学和生物活性。将使用颅骨缺损大鼠模型来确定生长因子释放曲线以及Rsp 〇 2和BMP 2的组合递送对骨组织形成的影响。因此，该工作的具体目的是：（1）使用不同敏感性的MMP敏感性水凝胶确定BMP 2释放动力学对骨生成的影响（a）体外和（B）体内，和（2）Rsp 〇 2和BMP 2的协同递送以改善骨组织修复。在完成这项工作后，将获得对基于BMP的治疗的更透彻的理解，并致力于临床可转化的方法，以改善骨丢失患者的治疗。

DESCRIPTION (provided by applicant): The use of bone morphogenic proteins (BMPs) shows promise as therapeutics for improving bone regeneration; however, high supraphysiological concentrations required for desired osteoinductive effect, costs, and patient variability have prevented the full advantages of BMP-based therapeutics from being realized. Thus, there is a clinical need to develop growth factor delivery strategies that will optimize release kinetics and overcome the need for non-physiologic high concentrations to promote bone repair. The proposed approach utilizes a matrix metalloprotease (MMP)-sensitive hyaluronic acid (HA)-based hydrogel scaffold as a cell-mediated delivery vehicle, where the remodeling of the gel releases the molecules. Scaffold degradation kinetics can be controlled through varying the MMP sensitivity of the proteolytic peptide and through cross-link density. Canonical Wnt signaling is known to promote osteoblastogenesis, osteoblast function, and bone regeneration and can be promoted using the R-spondin (Rspo) family of secreted molecules. Enhancing canonical Wnt signaling through the synergistic delivery of BMP2 and Rspo2 using an engineered synthetic HA-based hydrogel should allow for improved bone tissue repair. With these features in mind, the objective of this work is two-fold: (1) evaluate the influence of hydrogel remodeling and BMP2 growth factor release kinetics on in vivo tissue repair and (2) determine if the synergistic delivery of Rspo2 and BMP2 improves BMP2 induced osteogenesis. Growth factor release kinetics and bioactivity will be evaluated using in vitro characterization techniques. A cranial defect rat model will be used to determine the influence of both growth factor release profiles and the combined delivery of Rspo2 and BMP2 on bone tissue formation. Thus, the specific aims of the work are: (1) Determine the effect of BMP2 release kinetics on osteogenesis (a) in vitro and (b) in vivo using MMP-sensitive hydrogels of varying sensitivity and (2) Synergistic delivery of Rspo2 and BMP2 for improved bone tissue repair. Upon completion of this work, a more thorough understanding of BMP-based therapies will be obtained, as well as work towards a clinically translatable approach to improve the treatment of patients with bone loss.