Similar to the effect of co-culture with neonatal mouse retinal cells, Taurine and RA promoted upregulation of retinal progenitor markers in human LNS. This suggests that defined culture conditions may replace the use of animal tissue in the future. We did not observe LNS cell migration or integration into the host retina following sub-retinal transplantation into neonatal mice. Cell integration into the retina remains challenging. Despite being derived from the same origin as neural retina, iris or CB derived cells have also shown limited ability for retinal integration. The proportions of cells which integrate into embryonic retinal explants or retina from degenerate animal models are small. Studies using retinal progenitor cells from embryonic retina have also shown little integration into host retina, although mature retinal phenotypes have been observed following sub-retinal transplantation. MacLaren et al. investigated the optimal cell resource for functional integration into adult retina. The cells which migrated and integrated were shown to be post-mitotic rod precursor cells. Therefore, the ontogenetic stage of transplanted cells is important for successful cell integration. Grafted LNS cells in this study were not fully committed post-mitotic cells. This may explain why cell integration was not observed. The host Cycloheximide microenvironment is also essential for inducing cell differentiation and migration. In a study involving transplantation of IPE derived cells, the grafted cells expressed the photoreceptor specific marker rhodopsin when they were transplanted into the SRS of embryonic chicken eyes. On the contrary, they did not express rhodopsin or other neural markers when they were transplanted into the vitreous cavity. This is in accordance with our observation that the LNS cells transplanted into the vitreous do not express photoreceptor markers. LNS display plasticity, the potential to cross the tissue/germ layer boundary and generate cells other than their origin. However, LNS have limited potential to generate photoreceptorlike cells. The highest rhodopsin expression level noted using LNS derived cells was,3% of that observed compared to using neonatal mouse retinal tissue. Reports on other ocular stem-like/ progenitor cells also show limited success in the generation of photoreceptor regardless of cell origin. Recently two independent groups showed CE-derived cells failed to give rise to photoreceptor cells. Retinal neurosphere cells derived from neonatal mice also had a low efficiency in generation of rhodopsin positive cells during spontaneous differentiation. It has been suggested that cell reprogramming is likely to be needed for robust photoreceptor cell production. LNS cells would also be an optimal cell resource for reprogramming and/or transdifferentiation and subsequent retinal repair. They are readily accessible, highly proliferative and multipotent ocular stem cells. iPSCs have been generated from mouse and human somatic cells by ectopic expression of four transcription factors including OCT4, SOX2, c-Myc and KLF4. Due to risks such as insertional mutagenesis or tumour formation, it is desirable to use the minimal number of transcription factors and to eliminate oncogenic factors.