Directed differentiation of human pluripotent stem cells into articular cartilage reveals effects caused by absence ofWISP3, the gene responsible for progressive pseudorheumatoid arthropathy of childhood

Abstract

ObjectivesProgressive pseudorheumatoid arthropathy of childhood (PPAC), caused by deficiency ofWNT1 inducible signalling pathway protein 3(WISP3), has been challenging to study because no animal model of the disease exists and cartilage recovered from affected patients is indistinguishable from common end-stage osteoarthritis. Therefore, to gain insights into why precocious articular cartilage failure occurs in this disease, we made in vitro derived articular cartilage using isogenicWISP3-deficient andWISP3-sufficient human pluripotent stem cells (hPSCs).MethodsWe generated articular cartilage-like tissues from induced-(i) PSCs from two patients with PPAC and one wild-type human embryonic stem cell line in which we knocked out WISP3. We compared these tissues to in vitro-derived articular cartilage tissues from two isogenicWISP3-sufficient control lines using histology, bulk RNA sequencing, single cell RNA sequencing and in situ hybridisation.ResultsWISP3-deficient andWISP3-sufficient hPSCs both differentiated into articular cartilage-like tissues that appeared histologically similar. However, the transcriptomes ofWISP3-deficient tissues differed significantly fromWISP3-sufficient tissues and pointed to increased TGFβ, TNFα/NFκB, and IL-2/STAT5 signalling and decreased oxidative phosphorylation. Single cell sequencing and in situ hybridisation revealed thatWISP3-deficient cartilage contained a significantly higher fraction (~4 fold increase, p<0.001) of superficial zone chondrocytes compared with deeper zone chondrocytes than didWISP3-sufficient cartilage.ConclusionsWISP3-deficient andWISP3-sufficient hPSCs can be differentiated into articular cartilage-like tissues, but these tissues differ in their transcriptomes and in the relative abundances of chondrocyte subtypes they contain. These findings provide important starting points for in vivo studies when an animal model of PPAC or presymptomatic patient-derived articular cartilage becomes available.