Synergistic Molecule Delivery Using Hydrogels for BoneTissue Repair

描述(申请人提供)：骨形态发生蛋白(BMP)的使用显示出改善骨再生的治疗前景；然而，预期的骨诱导效果、成本和患者变异性所需的高超生理学浓度阻碍了基于BMP的治疗的全部优势的实现。因此，临床上有必要开发生长因子传递策略，以优化释放动力学，并克服非生理性高浓度促进骨修复的需要。该方法利用基质金属蛋白酶(MMPs)敏感的透明质酸(HA)水凝胶支架作为细胞介导的输送载体，凝胶的重塑释放分子。支架的降解动力学可以通过改变蛋白水解肽对基质金属蛋白酶的敏感性和通过交联剂的密度来控制。经典的Wnt信号被认为可以促进成骨细胞的形成、成骨细胞的功能和骨再生，并且可以通过R-响应蛋白(RSPO)家族的分泌分子来促进。通过使用工程合成HA水凝胶协同传递BMP2和Rsp2来增强规范的Wnt信号，应该可以改善骨组织修复。考虑到这些特点，这项工作的目的有两个：(1)评估水凝胶重塑和BMP2生长因子释放动力学对体内组织修复的影响；(2)确定Rspo2和BMP2协同传递是否促进BMP2诱导的成骨。生长因子的释放动力学和生物活性将使用体外表征技术进行评估。我们将使用一种大鼠颅骨缺损模型来确定生长因子的释放情况以及Rsp2和BMP2的联合应用对骨组织形成的影响。因此，这项工作的具体目的是：(1)确定BMP2释放动力学对成骨的影响(A)体外和(B)使用不同敏感性的基质金属蛋白酶敏感的水凝胶和(2)协同输送RspO2和BMP2以促进骨组织修复。这项工作完成后，将获得对基于骨形态发生蛋白的疗法的更彻底的理解，以及朝着临床可翻译的方法努力，以改善对骨丢失患者的治疗。

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.