Abstract
Purpose :
Retinal degeneration is one of the major causes of untreatable blindness in the developed world. Despite very different aetiologies, outer retinal degeneration (ORD) culminates in the loss of photoreceptors and vision. A potential treatment for end stage retinal degeneration is the use of cell transplantation strategies to repair the damaged retina. Progress has been rapid, and transplanted cells from a range of types and sources have been shown to restore visual function in animal models of human disease. Furthermore, clinical trials involving the transplantation of human embryonic stem cell (hESC)-derived retinal pigment epithelium into patients with macular degeneration have been shown to be safe and to have partial efficacy.
Recently Collin and colleagues (2015) created a hESC lines harbouring the green fluorescent protein (GFP) reporter at the endogenous loci of the Cone-Rod Homeobox (CRX) gene, a key transcription factor in retinal development. This is an applicable tool for the purification of hESC-derived retinal photoreceptor precursors for transplantation. The aim of the present study is to define the most optimal differentiation stage to achieve a robust and functional integration of human photoreceptor precursors in mammalian diseased retina.
Methods :
The differentiation of the hESC CRX-GFP reporter line towards retinal organoids was performed as described in Mellough et al. 2015. The retinal organoids were dissociated, analysed and purified by fluorescence-activated cell sorting. Sorted GFP positive cells were then trans-vitreally transplanted into the sub-retinal space of rd1 mice, an animal model of autosomal recessive form of Retinitis Pigmentosa.
Results :
Our results so far show that photoreceptors obtained from day 60 and 90 of differentiation are often observed in the host inner nuclear layer and begin to form a distinct layer in direct contact with the second order neurons of rd1 mice.
Conclusions :
Identification of the most favourable age of human pluripotent stem cell derived photoreceptors to achieve engraftment and functional connectivity following transplantation is a vital step in optimising this potential therapy. Further transplants as well as behavioural, electrophysiological and morphological analyses are required to determine the presence of any light response from these grafts and the feasibility of this approach.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.