Proliferative Cells Isolated from the Adult Human Peripheral Retina only Transiently Upregulate Key Retinal Markers upon Induced Differentiation

ABSTRACT

Purpose/Aim: The adult human retina has limited regenerative potential, and severe injury will result in permanent damage. Lower vertebrates handle retinal injury by activating neural stem cells (NSCs) in the ciliary marginal zone (CMZ). Müller glia-like cells expressing markers of NSCs are also present in the peripheral retina (PR) of the adult human eye, leading to the hypothesis that a CMZ-like zone might exists also in humans. In order to shed further light on this hypothesis we investigated the in vitro differentiation potential of proliferative cells isolated from the adult human PR towards a retinal phenotype.

Materials and Methods: Proliferative cells were isolated from the peripheral retina of human eyes (n = 6) within 24 to 48 hours post mortem and further expanded for 2 or 3 passages before being differentiated for 1–3 weeks. Gene expression was analyzed by microarray and qRT-PCR analysis, while protein expression was identified by immunocytochemistry.

Results: A high density of cells co-staining with markers for progenitor cells and Müller glia was found in situ in the PR. Cells isolated from this region and cultured adherently showed fibrillary processes and were positive for the immature marker Nestin and the glial marker GFAP, while a few co-expressed PAX6. After 7 days of differentiation, there was a transient upregulation of early and mature photoreceptor markers, including NRL, CRX, RHO and RCVRN, as well as the Müller cell and retinal pigmented epithelium (RPE) marker CRALBP, and the early RPE marker MITF. However, the expression of all these markers dropped from Day 14 and onwards.

Conclusions: Upon exposure of proliferating cells from the adult human PR to differentiating conditions in culture, there is a widespread change in morphology and gene expression, including the upregulation of key retinal markers. However, this upregulation is only transient and decreases after 14 days of differentiation.

KEYWORDS:

• Neural
• stem cell
• progenitor cell
• peripheral retina
• Müller glia
• differentiation

Acknowledgements

The authors would like to thank all the staff at Center for Eye Research and Department of Opthalmology (OUH/UiO) for their excellent collaboration and support in the project.

Declaration of interests

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Supplemental material

Supplemental data for this article can be access on the publisher’s website.

Funding

The work has been supported by the Research Council of Norway, the Norwegian Association of the Blind and Partially Sighted, Blindemissionen IL, the Faculty of Medicine University of Oslo and Oslo University Hospital. Furthermore, it was supported by a GINOP-2.3.2-15-2016-00006 project co-financed by the European Union and the European Regional Development Fund.

Additional information

Funding

The work has been supported by the Research Council of Norway, the Norwegian Association of the Blind and Partially Sighted, Blindemissionen IL, the Faculty of Medicine University of Oslo and Oslo University Hospital. Furthermore, it was supported by a GINOP-2.3.2-15-2016-00006 project co-financed by the European Union and the European Regional Development Fund.