Facilitating cartilage regeneration by heterogeneous progenitor cells

描述(申请人提供)：由于关节软骨缺乏内在修复能力，创伤后的损伤持续存在，最终可能导致创伤后骨关节炎(OA)，并导致疼痛、关节活动范围缩小和严重损害生活质量。目前软骨损伤的护理标准不能可靠地提供持续的临床改善，因此人们对开发替代的生物修复/再生方法很感兴趣。组织工程方法通常涉及内源性间充质祖细胞(MFC)在缺损处的招募或移植。在受控条件下，这些细胞具有增殖、沿着相关肌肉骨骼谱系分化和再生受损组织基质的潜力。然而，关节内环境通常不利于软骨形成；具体地说，损伤关节内的炎症可以抑制组织再生。关节炎症是由局部水平的细胞因子如白介素1和肿瘤坏死因子α介导的。尽管促炎细胞因子在骨性关节炎的发病机制中发挥重要作用，但几乎没有文献报道它们如何影响涉及MFC的软骨修复策略。推动这项研究计划的中心假设是，继发于关节创伤或随后的手术干预的炎症可以抑制引入软骨缺损的MFC的再生活性，从而抑制修复。在该计划的指导阶段，将学习更多的工具来更好地表征体外和体内的MPC活性。具体地说，将开发一个用于监测人类MPC分化状态的报告构建工具集，在体外软骨形成的背景下表征该工具集。在此期间，还将熟练掌握成像技术，使用裸鼠模型将MPC输送到软骨缺损处，以非侵入性地跟踪体内的炎症和软骨形成活动。在过渡到该奖项的独立阶段(Rod)后，将评估促炎症细胞因子活性抑制剂在体外挽救MPC软骨形成行为的能力。有希望的再生方案将被应用于免疫功能正常和功能不全的关节损伤动物模型，以确定当MPC受到致炎细胞因子病理水平的保护时，修复/再生软骨的能力。在这个项目期结束时，我们将更好地了解关节环境--特别是炎症信号级联--如何影响使用异种祖细胞群的软骨再生策略的最终成功。

DESCRIPTION (provided by applicant): Because articular cartilage lacks the ability for intrinsic repair, injuries following trauma persist and can ultimately lead to post-traumatic osteoarthritis (OA) with resulting pain, reduced range of joint motion and severely impaired quality-of-life. Current standards-of-care for cartilage injuries cannot reliably provide sustained clinical improvement, so there is much interest in the development of alternative, biological approaches towards repair/regeneration. Tissue engineering approaches typically involve the recruitment or transplantation of endogenous mesenchymal progenitor cells (MFCs) to the defect site. Under controlled conditions, these cells have the potential to proliferate, differentiate along the relevant musculoskeletal lineage and regenerate damaged tissue matrix. However, the intra-articular environment is often hostile to chondrogenesis; specifically, inflammation within the injured joint can inhibit tissue regeneration. Joint inflammation is mediated by local levels of cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)'-a. Although pro-inflammatory cytokines play an important role in the pathogenesis of OA, there is almost no literature on how they affect cartilage repair strategies involving MFCs. The central hypothesis driving this research plan is that inflammation secondary to joint trauma or subsequent surgical intervention can inhibit the regenerative activity of MFCs introduced to the cartilage defect, thus inhibiting repair. During the mentored phase of this plan, additional tools will be learned to better characterize MPC activity both in vitro and in vivo. Specifically, a toolset of reporter constructs will be developed for monitoring the state of human MPC differentiation, characterizing this toolset in the context of chondrogenesis in vitro. This period will also be spent becoming proficient in imaging techniques for non-invasively tracking inflammatory and chondrogenic activity in vivo, using a nude rat model of MPC delivery to cartilage defects. Upon transition to the independent phase (ROD) of this award, inhibitors of pro-inflammatory cytokine activity will be evaluated for their capability to rescue the chondrogenic behavior of MPCs in vitro. Promising regenerative regimens will be applied to both immunologically-competent and -incompetent animal models of joint injury to determine the ability of MPCs to repair/regenerate cartilage when protected from pathological levels of pro- inflammatory cytokines. At the end of this project period, we will have a better understanding of how the joint environment - particularly inflammatory signaling cascades - impacts the ultimate success of cartilage regeneration strategies using heterogeneous progenitor cell populations.