SummaryIncreasing demand for clinical retinal degeneration therapies featuring human ESC/iPSC-derived retinal tissue and cells warrants proof-of-concept studies. Here, we established two mouse models of end-stage retinal degeneration with immunodeficiency, NOG-rd1-2J and NOG-rd10, and characterized disease progress and immunodeficient status. We also transplanted human ESC-derived retinal sheets into NOG-rd1-2J and confirmed their long-term survival and maturation of the structured graft photoreceptor layer, without rejection or tumorigenesis. We recorded light responses from the host ganglion cells using a multi-electrode array system; this result was consistent with whole-mount immunostaining suggestive of host-graft synapse formation at the responding sites. This study demonstrates an application of our mouse models and provides a proof of concept for the clinical use of human ESC-derived retinal sheets.

Immune attacks are key issues for cell transplantation. To assess the safety and the immune reactions after iPS cells-derived retinal pigment epithelium (iPS-RPE) transplantation, we transplanted HLA homozygote iPS-RPE cells established at an iPS bank in HLA-matched patients with exudative age-related macular degeneration. In addition, local steroids without immunosuppressive medications were administered. We monitored immune rejections by routine ocular examinations as well as by lymphocytes-graft cells immune reaction (LGIR) tests using graft RPE and the patient’s blood cells. In all five of the cases that underwent iPS-RPE transplantation, the presence of graft cells was indicated by clumps or an area of increased pigmentation at 6 months, which became stable with no further abnormal growth in the graft during the 1-year observation period. Adverse events observed included corneal erosion, epiretinal membrane, retinal edema due to epiretinal membrane, elevated intraocular pressure, endophthalmitis, and mild immune rejection in the eye. In the one case exhibiting positive LGIR tests along with a slight fluid recurrence, we administrated local steroid therapy that subsequently resolved the suspected immune attacks. Although the cell delivery strategy must be further optimized, the present results suggest that it is possible to achieve stable survival and safety of iPS-RPE cell transplantation for a year.

To conduct comprehensive characterization of molecular properties in organisms, we established an efficient method to produce knockout (KO)-rescue mice within a single generation. We applied this method to produce 20 strains of almost completely embryonic stem cell (ESC)-derived mice ("ES mice") rescued with wild-type and mutant Cry1 gene under a Cry1:Cry2 background. A series of both phosphorylation-mimetic and non-phosphorylation-mimetic CRY1 mutants revealed that multisite phosphorylation of CRY1 can serve as a cumulative timer in the mammalian circadian clock. KO-rescue ES mice also revealed that CRY1-PER2 interaction confers a robust circadian rhythmicity in mice. Surprisingly, in contrast to theoretical predictions from canonical transcription/translation feedback loops, the residues surrounding the flexible P loop and C-lid domains of CRY1 determine circadian period without changing the degradation rate of CRY1. These results suggest that CRY1 determines circadian period through both its degradation-dependent and -independent pathways.

The basic helix-loop-helix transcription factor NeuroD1 has been implicated in the neurogenesis and early differentiation of pancreatic endocrine cells. However, its function in relation to cancer has been poorly examined. In this study, we found that NeuroD1 is involved in the tumorigenesis of neuroblastoma. NeuroD1 was strongly expressed in a hyperplastic region comprising neuroblasts in the celiac sympathetic ganglion of 2-weekold MYCN transgenic (Tg) mice and was consistently expressed in the subsequently generated neuroblastoma tissue. NeuroD1 knockdown by short hairpin RNA (shRNA) resulted in motility inhibition of the human neuroblastoma cell lines, and this effect was reversed by shRNA-resistant NeuroD1. The motility inhibition by NeuroD1 knockdown was associated with induction of Slit2 expression, and knockdown of Slit2 could restore cell motility. Consistent with this finding, shRNA-resistant NeuroD1 suppressed Slit2 expression. NeuroD1 directly bound to the first and second E-box of the Slit2 promoter region. Moreover, we found that the growth of tumor spheres, established from neuroblastoma cell lines in MYCN Tg mice, was suppressed by NeuroD1 suppression. The functions identified for NeuroD1 in cell motility and tumor sphere growth may suggest a link between NeuroD1 and the tumorigenesis of neuroblastoma. Indeed, tumor formation of tumor sphere-derived cells was significantly suppressed by NeuroD1 knockdown. These data are relevant to the clinical features of human neuroblastoma: high NeuroD1 expression was closely associated with poor prognosis. Our findings establish the critical role of the neuronal differentiation factor NeuroD1 in neuroblastoma as well as its functional relationship with the neuronal repellent factor Slit2. Cancer Res; 71(8); 2938-48. Ó2011 AACR.