Figure 4. mRNA for plasminogen is found in cornea tissue but not in cultured cells

A: The three layers of human donor corneas and cultured corneal epithelial, stromal fibroblasts, and stromal myofibroblasts were solubilized in Trizol and total RNA was extracted. RT-PCR was carried out using primers from exons 16 and 19 selected to produce a 418 bp product. The sample in the control lane (Ctl) was subjected to the PCR step but not to the RT step. Epithelium (Epi), stroma (Str), and endothelium (End) all contained mRNA for plasminogen as determined by sequencing of the cDNA. The cultured corneal epithelial cells (Epi), stromal fibroblasts (Fib), and stromal myofibroblasts (Myo) did not contain plasminogen mRNA. B: Supernatant fractions of extracts of the three layers of the cornea, cornea organ culture medium, epithelial, stromal fibroblast, and stromal myofibroblast conditioned medium were separated by SDS-PAGE and the proteins transferred to nitrocellulose and probed with two antibodies to K1-3 of plasminogen. Plasminogen was present in the three layers of the cornea and in the corneal organ culture medium but not in the corneal cultured cell medium.