Corneal stroma PDGF blockade and myofibroblast development

Myofibroblast development and haze generation in the corneal stroma is mediated by cytokines, including transforming growth factor-beta (TGF-β), and possibly other cytokines. This study examined the effects of stromal PDGF-β blockade on the development of myofibroblasts in response to −9.0 diopter photorefractive keratectomy in the rabbit. Rabbits that had haze generating photorefractive keratectomy (PRK, for 9 diopters of myopia) in one eye were divided into three different groups: stromal application of plasmid pCMV.PDGFRB.23KDEL expressing a subunit of PDGF receptor b (domains 2–3, which bind PDGF-B), stromal application of empty plasmid pCMV, or stromal application of balanced salt solution (BSS). The plasmids (at a concentration 1000 ng/μl) or BSS was applied to the exposed stroma immediately after surgery and every 24 h for 4–5 days until the epithelium healed. The group treated with pCMV.PDGFRB.23KDEL showed lower αSMA+ myofibroblast density in the anterior stroma compared to either control group (P ≤ 0.001). Although there was also lower corneal haze at the slit lamp at one month after surgery, the difference in haze after PDGF-B blockade was not statistically significant compared to either control group. Stromal PDGF-B blockade during the early postoperative period following PRK decreases stromal αSMA+ myofibroblast generation. PDGF is an important modulator of myofibroblast development in the cornea.