Characterisation of human corneal epithelial cell cultures maintained under serum-free conditions

Three-dimensional tissue constructs have been proposed as in vitro screening models for ocular irritancy. Based on our previous studies, in which a full-thickness corneal model based exclusively on SV40-immortalised cell lines was generated, we have currently evaluated the effects of a range of commercially-available cell culture media on several cellular parameters in cultures of a human corneal epithelial (HCE) cell line. This cell line was used in an attempt to establish a rational basis for the development of serum-free culture media for the assembly and long-term tissue culture of full-thickness corneal models. Briefly, we investigated the impact of serum-free culture on the proliferation, morphology, barrier function and cytokine expression of HCE cells. The number of cell layers and the epithelial differentiation were evaluated by histology. Barrier properties were characterised via the determination of transepithelial electrical resistance (TEER), fluorescein permeation, and the expression of the tight junction-related protein, zona occludin 1 (ZO-1). The cytokine expression pattern in response to serum-free culture was measured by using an antibody array system. Our results revealed that both the morphology and the barrier function of the epithelial constructs were comparable to those of human donor corneas, when serum-free media were supplemented with ascorbic acid, calcium, hydrocortisone and retinoic acid. Under these conditions, the artificial epithelium based on serum-free HCE cultures represented a valid model for the natural ocular surface.