Exosome-mediated Craniofacial Bone Tissue Engineering by Controlled Release

摘要 健康的骨骼对全身健康至关重要。与颅面复合体有关， 需要在植入物放置和恢复牙列之前用骨填充空的牙槽。骨质量 和骨量与牙种植体的短期和长期成功密切相关。 基于生物材料的骨再生有望克服骨移植的缺点。这些 生物材料可以用引导组织再生的指导性组分功能化。外来体， 被认为是自然界的内源性生物分子递送平台，特别令人感兴趣，因为它们 与生俱来的生物相容性和与细胞通讯以调节其表型的能力。近期体外试验 数据表明，来源于矿化MC3T3前成骨细胞的外泌体能够诱导 幼稚骨髓基质细胞的矿化。然而，设计一种有效治疗的方法， 以临床和生物学相关的方式在体内递送是外来体介导的治疗中的挑战。 该项目的总体治疗目标是利用内源性间充质干细胞的再生能力， 通过用聚合物组织工程构建体模拟外泌体的天然分泌来培养干细胞。我 初步数据表明，通过可调的生物可降解共聚物的聚合物自组装可以 包裹外泌体，外泌体随着时间的推移以持续的方式释放。我的核心假设是 成骨外来体从聚合物基质中的受控释放将促进颅面骨 治愈 具体目标是：1）开发一种良好控制的制造方法，其允许将 外泌体释放模式进入三维组织工程构建体; 2）评估外泌体释放模式的完整性。 包封和释放过程中的生物活性外泌体含量，以及它们引起表型的能力 3）在两种体内模型中验证本文发明的技术， 颅面骨再生所提出的实验的结果将证明一种方法， 外泌体从聚合物基质中的包封和受控递送， 干细胞移植的好处有效的外泌体封装和释放策略， 保持其生物活性，对于推进外泌体介导的临床治疗领域至关重要， 可以应用于多种组织类型的再生。

Abstract Healthy bone is critically important to systemic health. Of relevance to the craniofacial complex, dental implants require that empty sockets are filled with bone prior to implant placement and restoring dentition. Bone quality and bone amount are strongly correlated with both the short- and long-term success of dental implants. Biomaterials-based bone regeneration is promising to circumvent shortcomings of bone grafting. These biomaterials can be functionalized with instructive components which guide tissue regeneration. Exosomes, thought to be nature's endogenous biomolecule delivery platform, are particularly interesting because of their innate biocompatibility and capacity to communicate with cells to modulate their phenotype. Recent in vitro data suggests that exosomes derived from mineralizing MC3T3 pre-osteoblasts are able to induce mineralization in naive bone marrow stromal cells. However, engineering a means for their efficient therapeutic delivery in vivo, in a clinically and biologically relevant manner is a challenge in exosome-mediated therapy. The overall therapeutic goal of this project is to exploit the regenerative capacity of endogenous mesenchymal stem cells by mimicking the natural secretion of exosomes with a polymeric tissue engineering construct. My preliminary data suggests that polymeric self-assembly via a tunable biodegradable copolymer can encapsulate exosomes, which are released in a sustained fashion over time. My central hypothesis is that controlled release of osteogenic exosomes from a polymer matrix will promote craniofacial bone healing. The specific aims are to 1) develop a well-controlled fabrication method which allows incorporation of an exosome-releasing modality into a three-dimensional tissue engineering construct; 2) evaluate the integrity of the bioactive exosome contents during encapsulation and release, and their ability to cause phenotype changes in downstream cells; and 3) validate the technology invented herein in two in vivo models of craniofacial bone regeneration. The outcomes of the proposed experiments will demonstrate a means for the encapsulation and controlled delivery of exosomes from a polymer matrix, causing craniofacial bone regeneration without stem cell transplantation. Effective exosome encapsulation and release strategies, which preserve their biologic activity, are critical to advancing the field of exosome-mediated clinical therapies, which can be applied to the regeneration of many tissue types.