Researchers used stem cells from an individual with retinitis pigmentosa (RP) caused by mutations in their USH2A gene to create retinal organoids (ROs), that mimics the retina to be used as an in vitro RP disease model. They observed that USH2A mutations caused apoptosis and cell death of the stem cells and ROs, and depleted extracellular matrix (ECM) components such as laminin and collagen IV. Abnormal interactions between the extracellular matrix and retinal organoids may be the driving force behind the cell death in these stem cells with the USH2A mutation. The researchers then created a microfluidic chip to provide more retinal pigment epithelium (RPE) cells to the retinal organoids to improve their survival rate.
What this means for Usher syndrome: Having a “retina-on-a-chip” serves as a viable disease model to study the pathogenesis and the initial steps leading to disease progression of Usher syndrome without needing to rely on animal models.