INFLUENCE OF EPTFE POLYMER IMPLANT PERMEABILITY ON THE RATE AND DENSITY OF CORNEAL EXTRACELLULAR-MATRIX SYNTHESIS

Microporous polymers have great potential for the production of cornea l keratoprosthetic devices. Keratocytes invade the pores of expanded p olytetrafluoroethylene implants (ePTFE) and collagen synthesis occurs. This ePTFE becomes translucent after its implantation in the stroma o f rabbit cornea. The rate and density of cell growth within this polym er depends on the implant thickness, pore size, and its placement in t he cornea. We have investigated the influence of the polymer permeabil ity on the collagen and protein contents of ePTFE implants. Rabbit cor neal stroma were implanted with ePTFE disks (6 mm in diameter) by intr alamellar keratoplasty. The implanted polymers were removed from the s troma after 3 or 6 months. The collagen and protein contents were dete rmined after pepsin solubilization. The collagen content of the high-p ermeability implant was 3.7-fold greater than that of the low-permeabi lity implant 3 months after implantation and 2.4-fold greater after 6 months. The total protein content of the high-permeability implant was 2.5-fold greater than that of the low permeability implant at 3 month s and was the same after 6 months. The collagen-to-protein ratio was 6 8% in the high-permeability implants, and thus similar to that of norm al corneal stroma. Thus, high polymer permeability increased both the rate and density of the corneal extracellular matrix ingrowth. (C) 199 7 John Wiley & Sons, Inc.