Published online Feb 26, 2019. doi: 10.4252/wjsc.v11.i2.84
Peer-review started: July 24, 2018
First decision: October 5, 2018
Revised: November 1, 2018
Accepted: January 1, 2019
Article in press: January 1, 2019
Published online: February 26, 2019
The cornea provides two thirds of the eye’s refractive power as well as being the major barrier to the inner content of the eye. At present, the most effective treatment of a diseased or damaged cornea is transplantation of a donor cornea (keratoplasty). However, this is not feasible for 8-10 million individuals. Corneal research has turned to the use of stem cell-based regenerative therapies for corneal tissue regeneration. Recent in vitro studies have shown that mesenchymal stem cell-like cells from the corneal stroma (corneal-derived stromal stem cells, CSSC) contribute to corneal tissue homeostasis, presenting an immunomodulatory response, a non-immunogenic profile, and a regenerative role. Thus, CSSC may be considered an appropriate cell source for the treatment of inflammatory disorders of the cornea.
To investigate whether CSSC seeded on an amniotic membrane (AM) substrate have the ability to modulate an inflamed environment, and therefore whether they were suitable candidates for developing a cell therapy for the front of the eye.
The first objective was to optimise an in vitro injury model mimicking a corneal surface using human corneal epithelial cells (hCEC) stimulated with various injurious agents. Once optimised the second objective was to investigate whether CSSC conditioned media and then CSSC in co-culture could modulate the injury environment. The final objective was to seed CSSC on AM and investigate whether the CSSC-AM construct provided an anti-inflammatory, healing response to the injury.
Treatment of hCEC with ethanol and pro-inflammatory cytokines were compared in terms of viability loss, cytotoxicity, and pro-inflammatory cytokine release in order to generate the novel in vitro injury. Co-culture experiments were performed with CSSC alone and with CSSC-AM constructs. The effect of injury and co-culture on viability, cytotoxicity, interleukin (IL)-6 and IL-8 production, and IL1B, TNF, IL6, and CXCL8 mRNA expression were assessed.
An optimal injury of 20% (v/v) ethanol for 30 s with 1 ng/mL IL-1 beta was developed. Co-culture of the injury model with CSSC inhibited loss of hCEC viability caused by injury. Enzyme linked immunosorbent assay and PCR showed a significant reduction in the production of IL-6 and IL-8 pro-inflammatory cytokines and reduction in pro-inflammatory cytokine mRNA expression during co-culture with CSSC alone and with the AM construct.
The novel findings of this study confirm the therapeutic potential of the CSSC and the possible use of AM as a cell carrier for application to the ocular surface.
The novel injury model developed in this study can be adapted for studying the therapeutic effects of many different agents. The findings of this study may lead to the development of practise changing cell therapies for treatment of inflammatory disorders of the cornea in clinic.