Photoreceptor precursors derived from three-dimensional embryonic stem cell cultures integrate and mature within adult degenerate retina
TL;DR: This study shows conclusively that ESCs can provide a source of photoreceptors for retinal cell transplantation and adapted a recently reported three-dimensional differentiation protocol that generates neuroretina from mouse ESCs to isolate photoreceptor precursors fit for transplantation.
Abstract: Irreversible blindness caused by loss of photoreceptors may be amenable to cell therapy. We previously demonstrated retinal repair and restoration of vision through transplantation of photoreceptor precursors obtained from postnatal retinas into visually impaired adult mice. Considerable progress has been made in differentiating embryonic stem cells (ESCs) in vitro toward photoreceptor lineages. However, the capability of ESC-derived photoreceptors to integrate after transplantation has not been demonstrated unequivocally. Here, to isolate photoreceptor precursors fit for transplantation, we adapted a recently reported three-dimensional (3D) differentiation protocol that generates neuroretina from mouse ESCs. We show that rod precursors derived by this protocol and selected via a GFP reporter under the control of a Rhodopsin promoter integrate within degenerate retinas of adult mice and mature into outer segment-bearing photoreceptors. Notably, ESC-derived precursors at a developmental stage similar to postnatal days 4-8 integrate more efficiently compared with cells at other stages. This study shows conclusively that ESCs can provide a source of photoreceptors for retinal cell transplantation.
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TL;DR: In this paper, the authors induce human pluripotent stem cells to spontaneously form fully laminated three-dimensional retinal tissue containing functional photoreceptor cells, which holds great potential for modeling human developmental processes and diseases.
Abstract: Induced pluripotent stem cells (iPSCs) hold great potential for modelling human developmental processes and diseases. Here the authors induce human iPSCs to spontaneously form fully laminated three-dimensional retinal tissue containing functional photoreceptor cells.
729 citations
TL;DR: Genetically modifying AAV vectors to increase their transduction efficiency, vector tropism and ability to avoid the host immune response may further increase the success of AAV gene therapy.
Abstract: Adeno-associated virus (AAV) vector-mediated gene delivery was recently approved for the treatment of inherited blindness and spinal muscular atrophy, and long-term therapeutic effects have been achieved for other rare diseases, including haemophilia and Duchenne muscular dystrophy. However, current research indicates that the genetic modification of AAV vectors may further facilitate the success of AAV gene therapy. Vector engineering can increase AAV transduction efficiency (by optimizing the transgene cassette), vector tropism (using capsid engineering) and the ability of the capsid and transgene to avoid the host immune response (by genetically modifying these components), as well as optimize the large-scale production of AAV. Adeno-associated virus (AAV) vector-mediated gene delivery has had long-term therapeutic effects for several diseases, including haemophilia and Duchenne muscular dystrophy. Genetically modifying AAV vectors to increase their transduction efficiency, vector tropism and ability to avoid the host immune response may further increase the success of AAV gene therapy.
487 citations
TL;DR: This study provides a “proof of concept” for retinal sheet transplantation therapy for advanced retinal degenerative diseases and observed host-graft synaptic connections by immunohistochemistry.
Abstract: In this article, we show that mouse embryonic stem cell- or induced pluripotent stem cell-derived 3D retinal tissue developed a structured outer nuclear layer (ONL) with complete inner and outer segments even in an advanced retinal degeneration model (rd1) that lacked ONL. We also observed host-graft synaptic connections by immunohistochemistry. This study provides a "proof of concept" for retinal sheet transplantation therapy for advanced retinal degenerative diseases.
281 citations
Cites background from "Photoreceptor precursors derived fr..."
...Moreover, 3D differentiation provided a choice between preparing a sheet or cell suspension for grafting (Gonzalez-Cordero et al., 2013)....
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TL;DR: It is shown that while integration occurs the majority of donor-reporter-labelled cells in the host arises as a result of material transfer between donor and host photoreceptors, raising the possibility of materialtransfer as a strategy for the treatment of retinal disorders.
Abstract: Photoreceptor replacement by transplantation is proposed as a treatment for blindness. Transplantation of healthy photoreceptor precursor cells into diseased murine eyes leads to the presence of functional photoreceptors within host retinae that express an array of donor-specific proteins. The resulting improvement in visual function was understood to be due to donor cells integrating within host retinae. Here, however, we show that while integration occurs the majority of donor-reporter-labelled cells in the host arises as a result of material transfer between donor and host photoreceptors. Material transfer does not involve permanent donor-host nuclear or cell-cell fusion, or the uptake of free protein or nucleic acid from the extracellular environment. Instead, RNA and/or protein are exchanged between donor and host cells in vivo. These data require a re-evaluation of the mechanisms underlying rescue by photoreceptor transplantation and raise the possibility of material transfer as a strategy for the treatment of retinal disorders.
249 citations
TL;DR: The competency of hESC-retina as a graft source and the eligibility of two newly developed monkey models that may be useful in future, long-term, functional studies of retinal transplantation are demonstrated.
Abstract: Retinal transplantation therapy for retinitis pigmentosa is increasingly of interest due to accumulating evidence of transplantation efficacy from animal studies and development of techniques for the differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells into retinal tissues or cells. In this study, we aimed to assess the potential clinical utility of hESC-derived retinal tissues (hESC-retina) using newly developed primate models of retinal degeneration to obtain preparatory information regarding the potential clinical utility of these hESC-retinas in transplantation therapy. hESC-retinas were first transplanted subretinally into nude rats with or without retinal degeneration to confirm their competency as a graft to mature to form highly specified outer segment structure and to integrate after transplantation. Two focal selective photoreceptor degeneration models were then developed in monkeys by subretinal injection of cobalt chloride or 577-nm optically pumped semiconductor laser photocoagulation. The utility of the developed models and a practicality of visual acuity test developed for monkeys were evaluated. Finally, feasibility of hESC-retina transplantation was assessed in the developed monkey models under practical surgical procedure and postoperational examinations. Grafted hESC-retina was observed differentiating into a range of retinal cell types, including rod and cone photoreceptors that developed structured outer nuclear layers after transplantation. Further, immunohistochemical analyses suggested the formation of host–graft synaptic connections. The findings of this study demonstrate the clinical feasibility of hESC-retina transplantation and provide the practical tools for the optimization of transplantation strategies for future clinical applications.
249 citations
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TL;DR: The establishment in tissue culture of pluripotent cell lines which have been isolated directly from in vitro cultures of mouse blastocysts are reported, able to differentiate either in vitro or after innoculation into a mouse as a tumour in vivo.
Abstract: Pluripotential cells are present in a mouse embryo until at least an early post-implantation stage, as shown by their ability to take part hi the formation of chimaeric animals1 and to form teratocarcinomas2. Until now it has not been possible to establish progressively growing cultures of these cells in vitro, and cell lines have only been obtained after teratocarcinoma formation in vivo. We report here the establishment in tissue culture of pluripotent cell lines which have been isolated directly from in vitro cultures of mouse blastocysts. These cells are able to differentiate either in vitro or after innoculation into a mouse as a tumour in vivo. They have a normal karyotype.
8,144 citations
TL;DR: The dynamic, autonomous formation of the optic cup (retinal primordium) structure from a three-dimensional culture of mouse embryonic stem cell aggregates is reported, demonstrating that optic-cup morphogenesis in this simple cell culture depends on an intrinsic self-organizing program involving stepwise and domain-specific regulation of local epithelial properties.
Abstract: Balanced organogenesis requires the orchestration of multiple cellular interactions to create the collective cell behaviours that progressively shape developing tissues. It is currently unclear how individual, localized parts are able to coordinate with each other to develop a whole organ shape. Here we report the dynamic, autonomous formation of the optic cup (retinal primordium) structure from a three-dimensional culture of mouse embryonic stem cell aggregates. Embryonic-stem-cell-derived retinal epithelium spontaneously formed hemispherical epithelial vesicles that became patterned along their proximal-distal axis. Whereas the proximal portion differentiated into mechanically rigid pigment epithelium, the flexible distal portion progressively folded inward to form a shape reminiscent of the embryonic optic cup, exhibited interkinetic nuclear migration and generated stratified neural retinal tissue, as seen in vivo. We demonstrate that optic-cup morphogenesis in this simple cell culture depends on an intrinsic self-organizing program involving stepwise and domain-specific regulation of local epithelial properties.
1,633 citations
TL;DR: It is demonstrated that an optic cup structure can form by self-organization in human ESC culture and an optimized vitrification method enables en bloc cryopreservation of stratified neural retina of human origin.
1,200 citations
TL;DR: It is shown that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis, and the ontogenetic stage of donor cells for successful rod photoreceptor transplantation is defined.
Abstract: Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors need only make single, short synaptic connections to contribute to the retinotopic map. So far, brain- and retina-derived stem cells transplanted into adult retina have shown little evidence of being able to integrate into the outer nuclear layer and differentiate into new photoreceptors(1-4). Furthermore, there has been no demonstration that transplanted cells form functional synaptic connections with other neurons in the recipient retina or restore visual function. This might be because the mature mammalian retina lacks the ability to accept and incorporate stem cells or to promote photoreceptor differentiation. We hypothesized that committed progenitor or precursor cells at later ontogenetic stages might have a higher probability of success upon transplantation. Here we show that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis(5). These transplanted cells integrate, differentiate into rod photoreceptors, form synaptic connections and improve visual function. Furthermore, we use genetically tagged postmitotic rod precursors expressing the transcription factor Nrl (ref. 6) ( neural retina leucine zipper) to show that successfully integrated rod photoreceptors are derived only from immature post-mitotic rod precursors and not from proliferating progenitor or stem cells. These findings define the ontogenetic stage of donor cells for successful rod photoreceptor transplantation.
1,013 citations
TL;DR: Overexpression of Crx using a retroviral vector increased the frequency of clones containing exclusively rod photoreceptors and reduced the frequencyof clones containing amacrine interneurons and Müller glial cells.
871 citations