Purpose: To investigate the effect of prostaglandins (PGs) on the permeability of human sclera in vitro.
Methods: Twenty-three pairs of human eye bank eyes were studied. Circular pieces of sclera were cultured in low-serum DMEM/F-12 media. Scleral hydration was assessed by measuring wet and dry weight of scleral cultures incubated with medium for 3 days and with Hanks' buffered saline solution (HBSS) for 4 hours. To assess scleral permeability, organ-cultured scleral tissues were exposed to 100 to 500 nM PGF(2alpha), 17-phenyltrinor PGF(2alpha), or PhXA85 (the active form of latanoprost) for 1, 2, and 3 days. Scleral permeability was measured using a two-chamber Ussing apparatus and rhodamine-dextran polymers dissolved in HBSS (MW = 10,000, 40,000, and 70,000). The movement of each rhodamine-dextran across the cultured sclera was measured using a spectrofluorometer. To understand the biological basis of the permeability change, the media were collected from the treated cultures, and the concentration of MMP-1, 2, and 3 was measured using an enzyme-linked immunosorbent assay.
Results: There was no difference in scleral hydration among fresh sclera and sclera incubated with medium for 3 days, with HBSS for 4 hours, or with medium for 3 days followed by HBSS for 4 hours. Compared to tracer movement across untreated scleral cultures (1.5 x 10(-6) cm/sec for 10 kDa dextran, 0.7 x 10(-6) cm/sec for 40 kDa dextran, and 0.4 x 10(-6) cm/sec for 70 kDa dextran), exposure to PGF(2alpha), 17-phenyltrinor PGF(2alpha), or PhXA85 each increased scleral permeability in a dose- and time-dependent manner. Increases in permeability were greater with the10 kDa dextran than with the 40 or 70 kDa dextran. The magnitude of these effects was greatest with exposure to PhXA85 and similar with exposure to PGF(2alpha) or 17-phenyltrinor-PGF(2alpha). MMP expression also was significantly increased after PG exposure. These increases were generally time and dose dependent and greater with MMP-2 and -3 than with MMP-1.
Conclusions: There is increased permeability of human sclera exposed to various PGs in organ culture. This increased permeability is accompanied by increased expression of MMPS: