Name

Le bioréacteur cornéen avec l'option airlifting améliore les bénéfices montrés par la version standard du dispositif sur un mois de conservation

Our laboratory patented a bioreactor (BR) also called active storage machine for long-term eye banking: by restoring intraocular pressure and medium renewal, it maintains corneas viability over 1 month and even up to 3 months, without deswelling step contrary to standard passive organ-culture. Although our BR aims to recreate in vivo like status, in the validated standard version for 1 and 3 months storage, corneas were immersed from both sides, probably contributing to greater thickness compared to in vivo status. Pneumatic airlifting option (e.g cyclic air-liquid exposure) was created to mimic blinking corneal surface. Aim: to assess bioreactor with airlifting (BRAL) on quality 1 month-stored human corneas versus standard BR (stdBR).

Ten fresh pairs of human corneas (ECD>2000cells/mm2 and <10% difference between both) were randomly stored with the same commercial medium (CorneaMax, Eurobio), with same batches numbers: one in stdBR (21mmHg, 2.6μL/min of medium renewal), the other in BRAL (same settings than stdBR, except airlifiting option using CorneaMax renewed every 2 days, with filling/épiON/emptying/épiOFF settings as close as possible to physiological blinking). Primary endpoints: ECD monitored by non-invasive specular microscopy, central thickness (CCT) (by SS-OCT) at Day (D)2, D26, D28. Secondary endpoints: transparency (transparometer), microbiological tests. At D28, pancorneal viable ECD (Hoechst/Ethidium/Calcein-AM), histology,  immunostaining with confocal microscope, western blot for epithelial cells structure (CK12; CA125; ZO-1) & endothelial cells (ECs) structure/functions (NaK ATPase; COX IV; NCAM; ZO-1).

No contamination occurred in both groups. Mean age of donors was 74±18 years, 20% of corneas were retrieved on pseudophakic eyes. At D2, ECD in BRAL was 2412±222 versus 2385±251 cells/mm2 in stdBR (p=0.349). At D26, ECD in BRAL versus (vs) stdBR was: 2109±165 vs 2119±199 cells/mm2 (p=0.621). At D28, the viable ECD didn’t differ between BRAL (2170±321 cells/mm2) and stdBR (2185±275 cells/mm2) (p=0.794). Corneas remained thin and transparent all along 1-month of storage in both devices: Transparency didn’t differ in BRAL vs in stdBR all along storage. At D2, D26, D28, CCT in BRAL vs in stdBR were respectively: 708±92 vs 682±66μm (p=0.415), 658±62 vs 669±67μm (p=0.482), 667±60 vs 695±55μm (p=0.0475). No qualitative difference was observed on epithelium, but more layers and thicker epithelium were found in BRAL 49±20µm vs 23±7µm in stdBR (p=0.001). Endothelial cells structure/functions didn’t differ between both groups.

The BRAL allows to deliver slightly thinner corneas after 1-month storage, with a better and thinner stroma, closer to physiologic conditions. Pneumatic airlifting option could be interesting to promote epithelial growth with physiological epithelial thickness restored, while maintaining the benefits on endothelial structure/functions observed in the 1 and 3 months studies with stdBR.

By mimicking the blinking, the BRAL enhances epithelium structure, closer to physiologic conditions than stdBR: it may be a useful option for transplantation (PKP or KLAP), but also a pertinent tool for preclinical research. Global pachymetry is better in BRAL, closer to in vivo status. No difference is observed on endothelium structure/functions or survival as expected.