Progressive Pseudorheumatoid Arthropathy of Childhood

当标准方法无法描述突变的机制时，就需要新的策略。 导致疾病。这是严重的，退行性关节疾病，发生在患者的情况下， WISP 3突变引起的儿童进行性假性关节炎（PPAC）。许多 WISP 3功能丧失等位基因已在大量PPAC患者中鉴定。青少年PPAC 患者需要全髋关节和膝关节置换手术以治疗终末期关节软骨衰竭。但 关节置换时，PPAC软骨与常见的终末期骨关节炎没有区别， 软骨由于PPAC在儿童中期出现症状，然后迅速发展到晚期， 阶段性关节衰竭，从伦理上讲，很难要求父母允许在孩子的关节衰竭之前收集他们的软骨。 在退化过程中出现或早期出现症状。因此，仅收集了患者样本 但未能阐明WISP 3缺陷软骨过早失效的原因。小鼠 缺乏Wisp 3的人也未能确定该基因的生物学功能。没有骨骼表型 在2个不同的敲除小鼠和2个不同的Wisp 3过表达小鼠中检测到。此外，体外研究 使用多种测定在多种培养细胞中的结果表明WISP 3具有多种生物活性;然而， 这些发现的体内或软骨特异性相关性是不确定的。因此，为了更好地理解PPAC， 在Charles H的支持下Hood基金会，我们产生了诱导多能干细胞（iPSC）， 5名PPAC患者（WISP 3缺陷），通过CRISPR/Cas9基因编辑，我们使他们成为WISP 3 足够了。有了R21的资助，我们打算通过区分WISP 3缺陷如何导致疾病， iPSC转化为关节和生长板软骨细胞。我们将比较同基因突变体产生的软骨 和WISP 3-校正的iPSC在组织学、机械学、生物化学和转录组学上寻找 一致的差异，这将告诉我们关于WISP 3的功能。我们获得的知识将使患者受益， PPAC可以指出保护软骨免受常见退行性关节疾病的新方法 例如与年龄相关的和创伤后的骨关节炎。其他实验室将对我们的WISP 3感兴趣 缺陷和纠正的细胞系，以及我们开发的使用iPSC的方法和分析方法， 研究软骨生长和体内平衡。

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.