Sphere-induced reprogramming of RPE cells into dual-potential RPE stem-like cells
Fenghua Chen,
Xiao Liu,
Yao Chen,
John Y. Liu,
Huayi Lu,
Wei Wang,
Xiaoqin Lu,
Kevin C. Dean,
Ling Gao,
Henry J. Kaplan,
Douglas C. Dean,
Xiaoyan Peng,
Yongqing Liu
Affiliations
Fenghua Chen
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, China
Xiao Liu
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; Department of Ophthalmology, Second Affiliated Hospital of Xiangya Medical School, Central South University, Changsha, China
Yao Chen
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
John Y. Liu
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA
Huayi Lu
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; Second Hospital of Jilin University, Changchun, Jilin Province, China
Wei Wang
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA
Xiaoqin Lu
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA
Kevin C. Dean
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA
Ling Gao
Department of Ophthalmology, Second Affiliated Hospital of Xiangya Medical School, Central South University, Changsha, China
Henry J. Kaplan
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA
Douglas C. Dean
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA; Birth Defects Center; University of Louisville School of Medicine, Louisville, Kentucky 40202, USA; Corresponding authors at: Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA.
Xiaoyan Peng
Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, China; Corresponding author. Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
Yongqing Liu
Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA; James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA; Birth Defects Center; University of Louisville School of Medicine, Louisville, Kentucky 40202, USA; Corresponding authors at: Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E Muhammad Ali Blvd, Louisville, Kentucky 40202, USA.
Background: The retinal pigment epithelium (RPE) has the potential to regenerate the entire neuroretina upon retinal injury in amphibians. In contrast, this regenerative capacity has been lost in mammals. The reprogramming of differentiated somatic cells into induced pluripotent stem cells (iPSCs) by viral transduction of exogenous stem cell factors has triggered a revolution in regenerative medicine. However, the risks of potential mutation(s) caused by random viral vector insertion in host genomes and tumor formation in recipients hamper its clinical application. One alternative is to immortalize adult stem cells with limited potential or to partially reprogram differentiated somatic cells into progenitor-like cells through non-integration protocols. Methods: Sphere-induced RPE stem cells (iRPESCs) were generated from adult mouse RPE cells. Their stem cell functionality was studied in a mouse model of retinal degeneration. The molecular mechanism underlying the sphere-induced reprogramming was investigated using microarray and loss-of-function approaches. Findings: We provide evidence that our sphere-induced reprogramming protocol can immortalize and transform mouse RPE cells into iRPESCs with dual potential to differentiate into cells that express either RPE or photoreceptor markers both in vitro and in vivo. When subretinally transplanted into mice with retinal degeneration, iRPESCs can integrate to the RPE and neuroretina, thereby delaying retinal degeneration in the model animals. Our molecular analyses indicate that the Hippo signaling pathway is important in iRPESC reprogramming. Interpretation: The Hippo factor Yap1 is activated in the nuclei of cells at the borders of spheres. The factors Zeb1 and P300 downstream of the Hippo pathway are shown to bind to the promoters of the stemness genes Oct4, Klf4 and Sox2, thereby likely transactivate them to reprogram RPE cells into iRPESCs. Fund: National Natural Science Foundation of China and the National Institute of Health USA. Keywords: RPE stem cells, Sphere-induced reprogramming, Retina degeneration, Cell transplantation
