Retina Specific Laminin 523 Drives Differentiation of Pluripotent Human Stem Cells to Photoreceptor Progenitors Promoting Retina Function

Abstract

Purpose : Advanced stages of macular degeneration are the main causes of blindness that involve irreversible photoreceptor loss. Visual cycle is dependent on the photosensitive photoreceptors and retinal pigmented epithelium (RPE). Provision of RPE alone is insufficient and existing methods to generate photoreceptors are not reproducible and inefficient. Therefore, our aim is to develop an alternative method that generates clinically safe and functional photoreceptors to treat vision loss. Our hypothesis is that transplantable competent photoreceptor progenitors are able to engraft and mature in vivo, thereby promoting visual response.

Methods : We have generated a previously unavailable human recombinant retina-specific laminin isoform LN523 that recapitulates the inter-photoreceptor matrix. Human pluripotent stem cells are efficiently differentiated towards photoreceptor progenitors after 32 days in a two steps method, with the support of this analogous retina matrix. This method is chemically defined and xenogen-free which does not involve re-plating and manual dissections. Day 32 photoreceptor progenitors co-expressing CRX and RCVRN were transplanted in the sub-retinal space of rabbit and rd10 mice model. Electroretinogram (ERG) was performed to test the functional visual response in the post-transplanted mice model.

Results : This method is highly reproducible based on the single cell transcriptomic and immunohistochemical analyses tested on four different human pluripotent stem cell lines. The differentiated photoreceptor progenitors were found to engraft and express mature photoreceptor markers in the retina in vivo where they also present promising evidence of synaptic connectivity with degenerated rabbit host retina. Additionally, the transplanted photoreceptor progenitors preserve the host photoreceptor outer nuclear layer and also exhibited statistically significant improved photoreceptor a-wave response based on ERG analysis in nine P30 rodent rd10 model.

Conclusions : We found an alternative photoreceptor differentiation platform using our novel retina specific laminins. This method potentially promotes retina function and may constitute an important step towards the future use of hESC-derived photoreceptors to treat vision loss.

This is a 2021 ARVO Annual Meeting abstract.