Rabbit corneal endothelial cells modulated by polymorphonuclear leukocytes are fibroblasts. Comparison with...

The authors previously reported that polymorphonuclear leukocytes modulate rabbit corneal endothelial cells into fibroblasts, which acquire the characteristics of fibroblasts. The progeny of the fibroblastic corneal endothelial cells (FCEC) were further studied to compare the characteristics of the fibroblast with those of keratocytes as a function of culture age. During 11 days in culture, FCEC showed 32 population doublings, whereas keratocytes underwent 10 population doublings. When collagen phenotypes of both cultures were analyzed as a function of culture age, labeled collagens in both cultures were fractionated into types I, III, and V. The proportion of each collagen was relatively unchanged in keratocytes regardless of culture age: type I accounted for 92-96%, type III for 2-6% and type V for 2-5%. In contrast, the profiles were significantly changed in FCEC: at day 2, type I accounted for 57%, type III for 37.5%, and type V 5.5%. Over the following 2 days, type I increased to approximately 75%, whereas type III collagen decreased to approximately 20%. As FCEC multilayered, type I collagen synthesis reached a stationary level of 80%, with 12% of type III. When the stoichiometry of type I collagen was compared, the alpha 1/alpha 2 ratio was 6.2 in FCEC and the ratio was 3.5 in keratocytes at day 2. The ratio reached a normal value at day 7 in FCEC and at day 3 in keratocytes. The synthesis of type I trimer and transient alteration of type I/III and the rapid growth rate at early stages of growth, indicate that FCEC behave like cells seen in wound healing or other rapidly growing tissues, in contrast to the stabilized keratocytes.