Fig. 7. Mechanism of haze clearance following quiescent corneal stromal keratocyte versus stromal fibroblast injections.

Following corneal injury, inflammatory and proliferative cytokines induced by the fibroblastic transformation of the native corneal stromal keratocytes (CSKs) result in abnormal extracellular matrix (ECM) or disorganized collagen fibers. Due to the relatively quiescent nature of injected quiescent CSKs (qCSKs), they are likely able to exert their intrinsic function to secrete the proper ECM and reorganize the collagen fibers. In contrast, the injected stromal fibroblasts (SFs) released cytokines/chemokines that compound the myofibroblastic transformation and inflammatory responses in the injured cornea. Cell injection of SFs likely results in the persistent presence of abnormal ECM, which in turn causes unabated corneal haze. Furthermore, the cytokines/chemokines naturally released by SFs likely contribute to increased neovascularization.