Corneal endothelial cell-based therapy: an evaluation of two different approaches; cell injection and tissue-engineered endothelial keratoplasty

Abstract

Purpose : Visual impairment from corneal endothelial dysfunction is an important indication for corneal transplantation. Global shortages of donor corneas limit the number of transplants performed, driving the search for alternative approaches. This study evaluated the functional outcomes of cell injection (CI) therapy and tissue-engineered endothelial keratoplasty (TE-EK) in a rabbit model of bullous keratopathy.

Methods : Primary human corneal endothelial cells (CEC) were isolated and propagated for 1-2 passage using the dual media culture approach. New Zealand white rabbits were used to assess functionality of CEC by cell injection and TE-EK. Cataract extraction was performed on investigated eyes 1 week prior to surgery. For CI, CEC were injected in medium containing Y-27632. Rabbit corneal endothelium was scraped from its Descemet’s membrane (DM) or DM was stripped. Approximately 6 X 10⁵ CEC were injected into the anterior chamber. Rabbits were immediately positioned eyes down for 3 hours. For TE-EK surgery, a TE-EK graft was prepared at least 2 days before. Central 7mm of host DM was stripped. The graft was inserted as per standard Descemet’s stripping endothelial keratoplasty. EK was also performed with carrier alone. Central corneal thickness(CCT) and corneal clarity were assessed weekly. Rabbits were sacrificed after 28 days. Excised corneas were analyzed (histology, immunohistochemistry, and scanning electron microscopy).

Results : In the TE-EK group, CCT increased to >1000μm in the first 4 days. This was followed by gradual thinning close to pre-operative CCT by the second week. Mean CCT were 476.7±62.6μm(day 21) and 457.1±79.6μm(day 28). An area of corneal clarity corresponding to the size of the graft was seen. In the CI group, CCT prior to injection was 389.3±54.5μm. Following CI, CCT increased to 636.7±333.9μm(day 1). This declined to 575.2±50.5μm(day 7), 588.0±53.0μm(day 14) and 438.3±19.0μm(day 21). Corneas remained clear to day 21. At day 28, graft rejection was seen and CCT increased to 1225.0±115.2μm. In control groups (DM stripping with CI or TE-EK without cells), CCT was >1000μm in the 28 day period.

Conclusions : Cultured CEC used in CI therapy and TE-EK restored corneal endothelial function by the third week in our model of bullous keratopathy. CI approach was associated with more inconsistencies in restoring corneal function compared to TE-EK.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.