Chondrogenesis In Situ

描述(申请人提供)：关节软骨损伤和退化是导致残疾的主要原因[1，2]。通过微骨折获取骨髓细胞以修复软骨在临床上是很常见的。然而，经常是纤维性的修复产生了不同的结果[3，4]。因此，在体内安全、局部地使用生物活性因子促进人骨髓细胞(BMC)原位软骨生成以修复软骨具有显著的公共卫生影响。转化生长因子-β1(转化生长因子-β1)持续诱导人骨髓基质细胞软骨形成[5，6]。体内应用转化生长因子β1的主要挑战包括控制和抑制转化生长因子β1效应。通过其II型受体(TbR-11)传递的转化生长因子-b信号对细胞对转化生长因子-b的反应和软骨内环境平衡非常重要[7]。以软骨形成为终点，我们建议研究一个有趣的问题，即TBR-II的表达模式，特别是持续的TBR-II表达，是否是决定骨髓细胞是否在体内经历软骨样分化的机制。这一建议的中心假设是，持续上调Tbr-11对于体内骨髓细胞的软骨形成是必要的，这可以通过持续给予转化生长因子-β1来实现。这一建议的具体目的是：1.验证在腹泻环境中，持续上调TBR-II对于成人BMC在活体内的软骨形成是必要的假设。2.验证从染料木平交联聚乙二醇膜支架中控释转化生长因子-β_1可诱导宿主骨髓细胞(BMC)局部、持续、体内表达TbR-1上调，促进骨软骨修复，对关节的影响最小。3.通过从聚乙二醇基尼平支架中逐渐释放的腺相关病毒(AAV)-转化生长因子-β载体，验证转化生长因子-β1基因在腹泻性关节高度定位、稳定和可调控表达的假说。这种基因的表达有望在体内诱导TBR-11的局部上调，宿主骨髓修复细胞的软骨形成，并在最小的关节影响下改善骨软骨修复。该建议的独特翻译方面包括(1)一个临床医生-科学家领导的多学科团队来优化相关但独立的策略，以局部、可控地输送生长因子，以提高骨髓细胞的软骨修复潜力；以及(2)为创新支架技术和可控基因疗法的临床翻译提供直接途径，以改善软骨修复，以及关节镜下新型无损先进软骨成像技术的应用。

DESCRIPTION (provided by applicant): Articular cartilage injury and degeneration are leading causes of disability [1, 2]. Accessing bone marrow cells for cartilage repair through microfracture is commonly performed clinically. However, the frequently fibrous repairs yield mixed results [3, 4]. Safe, localized in vivo use of bioactive factors to improve chondrogenesis in situ of human bone marrow cells (BMC) for cartilage repair therefore has compelling public health impacts. Transforming growth factor-beta-1 (TGF-b1) consistently induces chondrogenesis of hBMC [5, 6]. Major challenges for in vivo administration of TGF-b1 include controlling and containing TGF-b1 effects. TGF-b signaling through its type II receptor (TbR-ll) is important to cellular responsiveness to TGF-b and to cartilage homeostasis [7]. Using chondrogenesis as the desired endpoint, we propose to study an intriguing question as to whether the pattern of TbR-II expression, in particular sustained TbR-II expression, is the mechanism that determines whether bone marrow cells will undergo chondroid differentiation in vivo. The central hypothesis of this proposal is that sustained upregulation of TbR-ll is necessary for in vivo chondrogenesis of bone marrow cells and that this can be achieved through sustained administration of TGF-B1. The specific aims of this proposal are: 1. To test the hypothesis that sustained upregulation of TbR-II is necessary for chondrogenesis of adult human BMC in vivo, within the diarthrodial environment. 2. To test the hypothesis that controlled release of TGF-b1 from genipin crosslinked polyethylene glycol (PEG-genipin) scaffolds will induce localized, sustained in vivo TbR-ll upregulation, chondrogenesis of host bone marrow cells (BMC), and improve osteochondral repair with minimal joint effects. 3. To test the hypothesis that highly localized, stable and regulatable TGF-b1 gene expression in diarthrodial joints can be achieved by adeno-associated virus (AAV)-TGF-b vectors that are gradually released from PEG-genipin scaffolds. Such gene expression is anticipated to induce localized in vivo upregulation of TbR-ll, chondrogenesis of host bone marrow repair cells, and improve osteochondral repair with minimal joint effects. The unique translational aspects of this proposal include (1) a Clinician-Scientist led multidisciplinary team to optimize related but independent strategies for localized, controlled in vivo delivery of growth factors to improve the cartilage repair potential of bone marrow cells; and (2) provision of a direct pathway for clinical translation of innovative scaffold technology and controlled gene therapy to improve cartilage repair, and the arthroscopic use of novel nondestructive advanced cartilage imaging technologies.