Abstract
Purpose:
A growing number of retinal dystrophies lack an appropriate small animal model,compromising further comprehension of the pathophysiology. In such cases, a viable alternative wouldbe to perform studies on human cellular models of the diseased retina. As a pilot project, we generateda human cellular model of the X-linked disease choroideremia (CHM). CHM represents 2% of retinaldystrophies and is characterised by night blindness in childhood leading to blindness by 50 y of age. Itis due to mutations in the CHM gene encoding Rab escort protein 1 (REP1). Knock-out mouse andzebrafish REP1-deficient models are lethal.
Methods:
To generate a pertinent human cellular model, we reprogrammed REP1-deficient fibroblastsfrom a CHM-/y patient into induced pluripotent stem cells (iPSc). We then differentiated thesepatient-specific iPSc into REP1-deficient retinal pigment epithelium (RPE).
Results:
The iPSc-derived CHM RPE is a monolayer that expresses RPE-specific markers, ispolarised, and has tight junctions. Ultra-structural studies demonstrate the presence of microvilli onthe surface and a characteristic RPE subcellular organisation. We are currently studying thedifferences in fluid transport, phagocytosis, melanosome trafficking and visual cycle differencesbetween wild type and patient RPE.
Conclusions:
We generated a bona fide RPE from a CHM patient, showing that the iPSc-derivedcellular models can potentially be used to better understand the pathophysiology of retinal dystrophieslacking an appropriate animal model.
Keywords: 636 pathobiology •
701 retinal pigment epithelium •
695 retinal degenerations: cell biology