title: Transplanted photoreceptor precursors transfer proteins to host photoreceptors by a mechanism of cytoplasmic fusion.
abstract: Photoreceptor transplantation is a potential future treatment for blindness caused by retinal degeneration. Photoreceptor transplantation restores visual responses in end-stage retinal degeneration, but has also been assessed in non-degenerate retinas. In the latter scenario, subretinal transplantation places donor cells beneath an intact host outer nuclear layer (ONL) containing host photoreceptors. Here we show that host cells are labelled with the donor marker through cytoplasmic transfer-94±4.1% of apparently well-integrated donor cells containing both donor and host markers. We detect the occurrence of Cre-Lox recombination between donor and host photoreceptors, and we confirm the findings through FISH analysis of X and Y chromosomes in sex-discordant transplants. We do not find evidence of nuclear fusion of donor and host cells. The artefactual appearance of integrated donor cells in host retinas following transplantation is most commonly due to material transfer from donor cells. Understanding this novel mechanism may provide alternate therapeutic strategies at earlier stages of retinal degeneration.
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
authors.forename: Mandeep S
authors.identifier: 0000-0003-1749-0088
authors.initials: MS
authors.lastname: Singh
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Balmer
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
authors.forename: Alun R
authors.identifier: 0000-0002-0662-1073
authors.initials: AR
authors.lastname: Barnard
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.|UK Ministry of Defence Army Medical Services, London SW1A 2HB, UK.
authors.forename: Sher A
authors.initials: SA
authors.lastname: Aslam
authors.affiliation: Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Daniela
authors.initials: D
authors.lastname: Moralli
authors.affiliation: Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Green
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
authors.forename: Alona
authors.identifier: 0000-0002-7604-0346
authors.initials: A
authors.lastname: Barnea-Cramer
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
authors.forename: Isabel
authors.initials: I
authors.lastname: Duncan
authors.affiliation: Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.|UK Ministry of Defence Army Medical Services, London SW1A 2HB, UK.|Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London EC1V 2PD, UK.
authors.forename: Robert E
authors.initials: RE
authors.lastname: MacLaren
mesh_terms: D000818:Animals; D002459:Cell Fusion; D003593:Cytoplasm / Q000502:physiology*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D019426:Integrases / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology / Q000637:transplantation*; D011995:Recombination, Genetic / Q000502:physiology; D012038:Regeneration; D012160:Retina / Q000166:cytology / Q000502:physiology*; D012162:Retinal Degeneration / Q000628:therapy*; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics
chemical_list: C045073:Cre recombinase; D019426:Integrases