SRA01-04 Cells

The SRA01/04 cell line is an immortalized human lens epithelial cell line developed to overcome the limitations associated with primary cultures of human lens epithelial (HLE) cells. These limitations include their low proliferative capacity and the difficulty of obtaining sufficient quantities of cells from donor lenses. SRA01/04 was derived from primary HLE cells obtained from infants undergoing surgery for retinopathy of prematurity. The immortalization was achieved by transfection with a plasmid carrying the SV40 large T antigen gene under the control of the RSV promoter. This approach avoids the use of live virus and permits selection of a uniform clone with consistent characteristics.

SRA01/04 cells exhibit stable proliferation over 130 passages with a population doubling level of approximately 3.5 per passage. Morphologically, they maintain a monolayer with epithelial characteristics. Chromosomal analysis revealed a hypotetraploid karyotype, consistent with an immortalized status. The isozyme phenotype confirmed their human origin. Importantly, the cell line retains lens-specific molecular features, including the expression of αA- and βB-crystallins and aldose reductase, though at lower protein levels than seen in primary HLE cultures. mRNA for both crystallins was also detected via RT-PCR, and sequencing confirmed 100% identity with published human sequences. This makes SRA01/04 the first established human lens cell line shown to express both αA- and βB-crystallins.

In addition to crystallin expression, SRA01/04 expresses aldose reductase, an enzyme involved in the polyol pathway, which is relevant to cataractogenesis. While optimal growth requires 20% fetal bovine serum, the cells can survive and proliferate with reduced serum levels or even in serum-free conditions if pre-attached to culture dishes. This adaptability, along with their stable lens-specific phenotype, renders SRA01/04 a valuable model for studying lens physiology, gene regulation in the lens epithelium, and mechanisms underlying cataract formation.