PTH Effects of Craniofacial Allografts

 描述（由申请人提供）：虽然骨组织具有能够自我修复骨折的再生能力，但在极端情况下，不会发生完全的关键缺损愈合。颅面复合体中的这种骨缺损通常是出生缺陷、创伤或癌症手术的结果。不幸的是，颅颌面重建的长期效果非常差，这是由于手术后发生的压倒性的组织纤维化和瘢痕形成。这种对移植生物材料的炎症-异物反应仍然是治疗这些患者的巨大挑战之一。为了解决这一问题，我们的多机构研究团队保持了长期合作，在该领域取得了一些进展，包括用重组甲状旁腺激素（rPTH，teriparthrin）非手术治疗几例骨折不愈合患者的非凡成功。为了阐明这些rPTH对骨愈合的作用机制，并将其转化为用于严重骨缺损的肌肉骨骼组织工程（MTE）解决方案，我们发表了几项临床前发现。与该更新申请最相关的是：1）调节大血管血管发生的血管生成素（Ang）1和Ang-2通过rPTH治疗被间接调节以抑制同种异体移植物近端的大血管;和2）rPTH还抑制邻近大血管的促纤维化肥大细胞的积累。基于此，我们假设rPTH治疗通过以下方式促进严重缺损愈合：1）其对成骨细胞（Col1（2.3）+）的众所周知的合成代谢作用，以增加骨愈合超过严重缺损的限度，2）成骨细胞诱导的 愈合前沿的小血管血管生成，和3）对大血管血管生成、肥大细胞积聚和纤维化的抑制作用。在技术上，我们：1）开发了一种用于体内多光子激光扫描显微镜（MPLSM）的慢性颅骨缺损窗室模型; 2）建立了小型猪下颌骨关键缺损愈合的临床相关模型; 3）开发了定制的3D打印骨支架来替代大块同种异体移植物;以及4）开发了具有增强的骨形成特性和降低的转化潜力的自体成骨iPS细胞（iMSC）。在这里，我们建议使用这些创新技术：1）测试我们对颅面骨严重缺损性质的假设，2）正式阐明rPTH治疗抑制炎症和纤维化以实现严重颅颌面骨缺损愈合的机制，3）在大型动物模型中为这一具有挑战性的临床问题提供转化MTE解决方案。考虑到这些概念验证的高度临床相关性，成功的潜在影响对于这个重大问题可能是巨大的。

 DESCRIPTION (provided by applicant): While bone tissues have regenerative capabilities that enable self-repair of fractures, in extreme cases complete critical defect healing will not occur. Such bone defects in the craniofacial complex are often a result of birth defects, trauma or cancer surgery. Unfortunately, the long- term results of craniomaxillofacial reconstructions are very poor due to the overwhelming tissue fibrosis and scarring that occurs following surgery. This inflammatory-foreign body response to the grafted biomaterial remains one of the great challenges in treating these patients. To address this, our multi-institutional investigative team has sustained a long-term collaboration that produced several advances in this field including extraordinary success in treating several patients with facture non-unions non-surgically with recombinant parathyroid hormone (rPTH, teriparatide). To elucidate the mechanisms responsible for these rPTH effects on bone healing, and translate it to a Musculoskeletal Tissue Engineering (MTE) solution for critical bone defects, we published several preclinical discoveries. The most relevant to this renewal application are: 1) angiopoietins (Ang) 1 & Ang-2, which regulate large vessel vasculogenesis, are reciprocally regulated by rPTH therapy to inhibit large blood vessels proximal to the allograft; and 2) rPTH also inhibits the accumulation of pro-fibrotic mast cells adjacent to the large vessels. Based on this we hypothesize that rPTH therapy facilitates critical defect healing by: 1) its well-known anabolic effects on osteoblasts (Col1(2.3)+) to increase bone healing beyond the limits of a critical defect, 2) osteoblast-induced small vessel angiogenesis at the healing front, and 3) inhibitory effects on large vessel vasculogenesis, mast cell accumulation and fibrosis. Technologically, we: 1) developed a chronic cranial defect window chamber model for in vivo multiphoton laser scanning microscopy (MPLSM); 2) established a clinically relevant model of critical defect healing in the minipig mandible: 3) developed custom 3D-printed bone scaffolds to replace massive allografts; and 4) developed autologous osteogenic-iPS cells (iMSC) with enhanced bone forming properties and reduced transformation potential. Here we propose to use these innovative technologies to: 1) test our hypotheses on the nature of critical defects in craniofacial bones, 2) formally elucidate the mechanism by which rPTH therapy inhibits inflammation and fibrosis to allow for critical craniomaxillofacial bone defect healing, and 3) provide a translational MTE solution for this challenging clinical problem in a large animal model. Given the high clinical relevance of these proofs of concept, the potential impact of success could be huge for this significant problem.