Immunomodulation to Improve the Clinical Performance of BMP2

项目总结/摘要 骨再生通过初级骨形成（膜内骨化）或通过TEM发生。 多孔软骨模板（软骨内骨化）。骨再生未能完成 代表临床负担的重要来源。在这种情况下，金标准治疗是骨骼 自体移植，包括外科手术，将骨采集并移植到受损的再生部位， 气。这种疗法会产生额外的发病率，并且受到组织可用性的显着限制。骨形- 移植生长因子作为自体移植手术的替代方法具有巨大的潜力。其中，骨 形态发生蛋白2（BMP 2）是一种成骨形态原，其已在临床上被批准促进骨形成。 骨骼生长然而，体内形成骨需要非常大量的BMP 2，这是一个限制， 赞扬与其使用相关的大量成本和多种副作用，其中一些严重。解决 这些缺点，我们的长期目标是提高BMP 2的临床性能。的总体目标 本申请旨在了解炎症对BMP 2刺激的骨形成的影响。白细胞介素-1 IL-1是一种由BMP-2诱导的炎性细胞因子，其抑制骨骼肌的软骨形成分化。 祖细胞这一建议的中心假设是BMP 2刺激的IL-1表达阻断了内皮细胞的表达。 软骨骨形成需要过量的BMP 2来克服这一障碍，并导致- 产生形态和机械上的下骨的跨膜骨化。中央卫生- 假设将通过追求两个具体目标进行测试：1）使用非骨形成来定义体内骨形成的途径。 2）确定IL-1受体拮抗剂对骨愈合刺激的影响 低剂量或高剂量的BMP 2。第一个目标将包括两组互补的转基因大鼠， 能够在骨再生过程中在体内观察I型胶原和II型胶原的表达， 膜内和软骨内骨形成。股骨临界尺寸缺损（CSD）， 平行组的转基因动物将接受临床相关量的BMP 2治疗并成像 在整个治疗过程中。在第二个目标中，野生型大鼠中的股骨CSD将用亚甲基双胍治疗。 在IL-1受体拮抗剂存在或不存在的情况下，治疗或临床相关量的BMP 2。 这些研究将确定是否有针对性的抗炎策略可以促进骨形成， 通过减少BMP 2的量来改善骨质量。拟议的研究是创新的，因为它探讨了 新的假设，膜内骨化是高剂量参与的主要再生途径， BMP 2。此外，这些研究将通过抑制IL-1， 从而允许用先前亚治疗量的BMP 2进行骨再生。这一贡献意义重大-- 因为它将直接解决目前限制使用的成本，安全性和有效性的限制 BMP 2是一种具有巨大潜力的疗法，可在广泛的临床情况下诱导骨形成。

PROJECT SUMMARY/ABSTRACT Bone regeneration occurs by either primary bone formation (intramembranous ossification) or through a tem- porary cartilage template (endochondral ossification). Failure of bone regeneration to proceed to completion represents a significant source of clinical burden. The gold standard treatment in these circumstances is bone autografting, which involves surgical procedures to harvest and transplant bone to the site of impaired regen- eration. This therapy produces additional morbidity and is significantly limited by tissue availability. Bone form- ing growth factors hold tremendous potential as an alternative to autografting procedures. Among them, bone morphogenetic protein 2 (BMP2) is an osteogenic morphogen that has been clinically approved to promote bone growth. However, very large amounts of BMP2 are required to form bone in vivo, a limitation which con- tributes to the substantial costs and multiple side-effects, some serious, associated with its use. To address these shortcomings, our long-term goal is to improve the clinical performance of BMP2. The overall objective of this application is to understand the effect of inflammation on bone formation stimulated by BMP2. Interleukin-1 (IL-1) is an inflammatory cytokine induced by BMP2 that inhibits the chondrogenic differentiation of skeletal progenitor cells. The central hypothesis of this proposal is that BMP2-stimulated IL-1 expression blocks endo- chondral bone formation. Excessive amounts of BMP2 are required to overcome this barrier and result in in- tramembranous ossification which produces morphologically and mechanically inferior bone. The central hy- pothesis will be tested by pursuing two specific aims: 1) Define pathways of in vivo bone formation using non- invasive longitudinal imaging 2) Determine the effect of IL-1 receptor antagonism on bone healing stimulated by either low- or high-dose BMP2. The first aim will incorporate two complementary sets of transgenic rats en- abling in vivo visualization of collagen I and collagen II expression during bone regeneration to discriminate intramembranous and endochondral bone formation, respectively. Femoral critical size defects (CSDs) in par- allel groups of transgenic animals will be treated with clinically-relevant amounts of BMP2 and imaged throughout the course of healing. In the second aim, femoral CSDs in wild-type rats will be treated with sub- therapeutic or clinically-relevant amounts of BMP2 in the presence or absence of the IL-1 receptor antagonist. These studies will determine whether targeted anti-inflammatory strategies can promote bone formation and improve bone quality with reduced amounts of BMP2. The proposed research is innovative as it explores the novel hypothesis that intramembranous ossification is the primary regenerative pathway engaged by high-dose BMP2. Furthermore, these studies will redirect healing towards endochondral ossification by inhibiting IL-1, thus permitting bone regeneration with previously sub-therapeutic amounts of BMP2. This contribution is signif- icant because it will directly address the limitations of cost, safety, and efficacy which currently restrict the use of BMP2, a therapy with tremendous potential to induce bone formation in a broad range of clinical scenarios.