Abstract
Purpose :
As contact lenses (CL) are evolving towards becoming diagnostic and therapeutic devices, there is a growing need for in vitro models that can efficiently assess ocular surface toxicity and biocompatibility of the technologies embedded in CL. While current in vitro ocular cell models allow for the characterization of cellular mechanisms, they can be too complex and costly for rapid testing. The aim of this project was to develop a co-culture cell model using the OcuFlow, an in vitro system which mimics tear flow between an eyelid and eyeball piece.
Methods :
Eyelid and eyeball pieces were synthesized with Sylgard 184; the two pieces fit together and permit a CL to be set on the corneal surface of the eyeball piece. After sterilization, HPV-immortalized and primary human corneal epithelial cells (HCEC) were grown to confluence on the outer curved eyeball surface and primary human conjunctival epithelial cells (HConjEC) on the inner concave surface of the eyelid piece. Cells were cultured in serum-free keratinocyte medium (KM). The pieces with confluent cells on their surfaces were then fitted together, placed on the OcuFlow and transferred to a cell incubator. Experiments were performed at 0 (immersion), 2 and 10µL of KM/min for up to 6 hours. Viability was then assessed using XTT, or cells were harvested and expression of ICAM-1, integrin α3β1 was characterized by flow cytometry.
Results :
Experiments with confluent monolayers of immortalized-HCEC on both the eyeball and eyelid pieces indicated that greater cell survival was obtained with a 10μL/min tear (KM) flow rate. The presence of a PBS-soaked CL did not reduce cell viability, while a BAK-soaked CL led to significant cell death. Comparing HCEC on the OcuFlow at 0 and 10 µL/min, no significant upregulation of ICAM-1 occurred while changes were observed in the expression of α3 and β1; exposure to flow-induced shear stress is likely responsible for the latter. Successful experiments were performed with HConjEC (eyelid piece) and HCEC (eyeball piece) mounted on the OcuFlow with 10µL/min flow-rates.
Conclusions :
Our results present a novel in vitro model where corneal and conjunctival epithelial cells can be exposed simultaneously to a CL and tear flow using the OcuFlow system. The OcuCell model mimics interactions at the ocular surface and has significant potential for the toxicological evaluation of therapeutic, diagnostic and conventional CL.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.