Recapitulation of Human Retinal Development from Human Pluripotent Stem Cells Generates Transplantable Populations of Cone Photoreceptors

Abstract

SummaryTransplantation of rod photoreceptors, derived either from neonatal retinae or pluripotent stem cells (PSCs), can restore rod-mediated visual function in murine models of inherited blindness. However, humans depend more upon cone photoreceptors that are required for daylight, color, and high-acuity vision. Indeed, macular retinopathies involving loss of cones are leading causes of blindness. An essential step for developing stem cell-based therapies for maculopathies is the ability to generate transplantable human cones from renewable sources. Here, we report a modified 2D/3D protocol for generating hPSC-derived neural retinal vesicles with well-formed ONL-like structures containing cones and rods bearing inner segments and connecting cilia, nascent outer segments, and presynaptic structures. This differentiation system recapitulates human photoreceptor development, allowing the isolation and transplantation of a pure population of stage-matched cones. Purified human long/medium cones survive and become incorporated within the adult mouse retina, supporting the potential of photoreceptor transplantation for treating retinal degeneration.

Deciphering retinal diseases through the generation of three dimensional stem cell-derived organoids: Concise Review

“…In their studies, the electron microscopy imaging revealed other ultrastructural features of mature photoreceptors, including an outer limiting membrane, inner segments rich in mitochondria, and basal bodies with connecting cilia displaying a photoreceptor‐specific microtubule arrangement. Additional studies have obtained premature forms of stacks of outer segment discs, similar to those observed in the developing human retina .…”

“…Zhong et al , Parfitt et al , Wahlin et al , and others recently described the examples of organoid photoreceptor outer segments. In their studies, the electron microscopy imaging revealed other ultrastructural features of mature photoreceptors, including an outer limiting membrane, inner segments rich in mitochondria, and basal bodies with connecting cilia displaying a photoreceptor‐specific microtubule arrangement.…”

“…As previously mentioned, a number of described protocols have permitted the generation of retinal tissue from hPSCs with varying efficiencies allowing us to mimic the early stages of human eye development and to model human retinal disease pathogenesis and repair [15,17,19,[21][22][23][24][25][26][27] (Tables 1 and 2). These stratified structures display some human-specific features: they are larger in size compared with mouse counterparts and contain different retinal structures, including an outer nuclear layer with photoreceptors (rhodopsin+, recoverin+), an inner nuclear layer with horizontal (calbindin+, calretinin−), bipolar (Chx10+, Pax6−), amacrine (Pax6+, calretinin+), Müller glia cells (CRALBP+), and a RGC layer with RGCs (Brn3+, Pax6+, calretinin+) ( Fig.…”

Human iPSC differentiation to retinal organoids in response to IGF1 and BMP4 activation is line- and method-dependent

“…Induced pluripotent stem cell (IPSC)-derived retinal organoids have been shown to have a wide range of applications, including the study of human retinogenesis, 1-3 disease modeling, 4,5 drug discovery, 6,7 and cell therapy. [8][9][10] Numerous protocols have been developed for the generation of retinal organoids that follow basic developmental principles of forebrain development and eye formation. Despite the ability of these protocols to give rise to laminated retinal organoids, variability in the propensity of iPSCs to give rise to various retinal cell types is often reported.…”

Modelling and rescue of RP2 Retinitis Pigmentosa using iPSC Derived Retinal Organoids

“…Unlike previous models in 2D, these 3D structures contain photoreceptors with morphologically identifiable features; including, inner segments rich in mitochondria, rudimentary outer segments with connecting cilia, and synaptic pedicles in addition to bipolar, Müller glia, ganglion and amacrine cells, synaptic layers and an outer limiting membrane, arranged in retinal layers (reviewed in (Castro et al, 2019, Capowski et al, 2019. These advanced models have proven to have many translational research applications, including transplantation studies (Pearson et al, 2016, Gonzalez-Cordero et al, 2017, probing mechanisms of retinal development (Phillips et al, 2014), and specific retinal disease modelling and testing efficacy of potential therapies in human photoreceptor cells (Parfitt et al, 2016, Deng et al, 2018, Schwarz et al, 2017, Sharma et al, 2017, Quinn et al, 2019. To date, however, they have not been used to model and rescue photoreceptor cell death.…”