Progressive Pseudorheumatoid Arthropathy of Childhood

当标准方法不能描述突变的机制时，需要新的策略 会导致疾病。这就是严重的退行性关节疾病，发生在 WISP3基因突变引起的儿童进行性假性类风湿关节炎(PPAC)。许多 在大量PPAC患者中已发现WISP3功能缺失等位基因。青少年PPAC 对于终末期关节软骨衰竭，患者需要进行全髋关节和膝关节置换手术。然而，在 关节置换时，PPAC软骨与常见的终末期骨关节炎没有什么区别 软骨。因为PPAC在童年中期出现症状，然后迅速发展到末期- 晚期关节衰竭，从伦理上讲，之前很难请求父母允许收集他们孩子的软骨 症状在退化过程中出现或较早出现。因此，只收集了患者样本 并未能解释WISP3缺陷的软骨早熟的原因。老鼠 缺乏Wisp3的人也未能确定该基因的生物学功能。目前还没有骨骼表型 在2个不同的基因敲除小鼠和2个不同的Wisp3过表达小鼠中检测到。此外，体外研究 在各种培养细胞中使用的各种分析表明WISP3具有多种生物学活性； 这些发现的体内相关性或软骨特异性尚不确定。因此，为了更好地理解PPAC， 在查尔斯·H·胡德基金会的支持下，我们从 5名PPAC患者(WISP3缺失)，通过CRISPR/Cas9基因编辑，我们正在使他们成为WISP3 足够了。有了R21-Funding，我们打算通过区分WISP3缺乏导致疾病的方式来确定 IPSCs分化为关节软骨和生长板软骨细胞。我们将比较同基因突变产生的软骨 和WISP3校正的IPSCs的组织学、机械学、生化和转录学研究 一致的差异将让我们了解WISP3的功能。我们获得的知识将使患者受益于 PPAC，并可能指出保护软骨免受常见退行性关节疾病影响的新方法 例如与年龄相关的和创伤后骨关节炎。其他实验室将对我们的WISP3感兴趣 缺陷和纠正的细胞系，在我们开发的方法和分析方法中，使用ipscs来 研究软骨生长和动态平衡。

Novel strategies are needed when standard approaches fail to delineate the mechanism by which a mutation causes disease. This is the case for the severe, degenerative joint disease that occurs in patients with Progressive Pseudorheumatoid Arthropathy of Childhood (PPAC) caused by mutations in WISP3. Many WISP3 loss-of-function alleles have been identified in large numbers of PPAC patients. Teenage PPAC patients require total hip and knee replacement surgery for end-stage articular cartilage failure. However, at the time joints are replaced, PPAC cartilage is indistinguishable from common end-stage osteoarthritic cartilage. Because PPAC becomes symptomatic during mid-childhood and then rapidly progresses to end- stage joint failure, it is ethically difficult to ask parents for permission to collect their child's cartilage before symptoms appear or early during the degenerative process. Thus, patient samples have only been collected at the time of arthroplasty and have failed to elucidate why WISP3 deficient cartilage fails precociously. Mice lacking Wisp3 have also failed to identify the gene's biologic function. No skeletal phenotypes have been detected in 2 different knockout mice and 2 different Wisp3 overexpressing mice. Additionally, in vitro studies in a variety of cultured cells using a variety of assays have suggested multiple biologic activities for WISP3; yet the in vivo or cartilage-specific relevance of these findings is uncertain. Therefore, to better understand PPAC, with support from the Charles H. Hood Foundation, we generated induced pluripotent stem cells (iPSCs) from 5 patients with PPAC (WISP3 deficient), and with CRISPR/Cas9 gene editing we are making them WISP3 sufficient. With R21-funding, we intend to determine how WISP3 deficiency causes disease by differentiating iPSCs into articular and growth plate chondrocytes. We will compare cartilages produced from isogenic mutant and WISP3-corrected iPSCs histologically, mechanically, biochemically, and transcriptomically to search for consistent differences that will inform us about WISP3 function. Knowledge we gain will benefit patients with PPAC and could point to new approaches for protecting cartilage from common degenerative joint disorders such as age-related and post-traumatic osteoarthritis. Other laboratories will be interested in our WISP3 deficient and corrected cell lines, and in the methods and analytic approaches we develop that use iPSCs to study cartilage growth and homeostasis.