title: Analysis of cell surface markers specific for transplantable rod photoreceptors.
abstract: OBJECTIVE
  Transplantation of cells into retinas affected by degenerative diseases to replace dying photoreceptors represents a promising therapeutic approach. Young photoreceptors of 4-day-old mice show the highest capacity to integrate into the retinas of adult mice following grafting. Additional enrichment of these donor cells before transplantation with cell surface marker-dependent sorting methods further increases success rates. Currently, defined cell surface markers specific for transplantable photoreceptors that can be used for enrichment are limited. Therefore, identifying alternative targets would be advantageous.
  
  
  METHODS
  Microarray data of young rod photoreceptors were analyzed using the Database for Annotation, Visualization and Integrated Discovery combined with a literature search to identify genes encoding for proteins containing extracellular domains. Candidate genes were further analyzed with reverse transcriptase polymerase chain reaction (RT-PCR) for their retinal specificity. In situ hybridization and immunohistochemistry were used to identify their localization within the retina.
  
  
  RESULTS
  Enrichment of candidates by Database for Annotation, Visualization and Integrated Discovery revealed 65 proteins containing extracellular domains. Reverse transcriptase polymerase chain reaction identified Atp8a2, Cacna2d4, Cadm2, Cnga1, Kcnv2, and Pcdh21 as expressed in the retina and only a few additional tissues. In situ hybridization and immunohistochemistry showed specificity of Cacna2d4, Kcnv2, and Pcdh21 for photoreceptors in the retinas of young mice.
  
  
  CONCLUSIONS
  Cacna2d4, Kcnv2, and Cnga1 were identified as specific for target cells in the retinas of young mice and could serve as candidates for rod photoreceptor enrichment to replace cells in retinal degenerative diseases.
authors.affiliation: DFG-Center for Regenerative Therapies Dresden (CRTD), Cluster of Excellence, Technische Universität Dresden, Dresden, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Postel
authors.forename: Jessica
authors.initials: J
authors.lastname: Bellmann
authors.forename: Victoria
authors.initials: V
authors.lastname: Splith
authors.forename: Marius
authors.initials: M
authors.lastname: Ader
mesh_terms: D000375:Aging / Q000235:genetics / Q000473:pathology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D058977:Molecular Sequence Annotation; D020411:Oligonucleotide Array Sequence Analysis; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism* / Q000637:transplantation*; D013194:Staining and Labeling
chemical_list: D015415:Biomarkers; D015820:Cadherins