Microplasmin degrades fibronectin and laminin at vitreoretinal interface and outer retina during enzymatic vitrectomy.

Purpose: To determine whether intravitreal administration of microplasmin (microPlm) will degrade fibronectin (FN) and laminin (LN) in rat retina during microPlm-induced posterior vitreous detachment (PVD).

Methods: Increasing doses of microPlm, from 0.01 U to 0.03 U, were injected into the left eyes of 60 Sprague-Dawley rats to induce PVD. The right eyes were injected with the same volume of balanced salt solution (BSS). Histochemistry, scanning electron microscopy (SEM), and phase contrast microscopy were performed after 1 day and 7 days, to assess the remnant vitreous cortex. The FN and LN level located at the vitreoretinal interface and the outer retina were detected by immunohistochemistry.

Results: microPlm induced complete PVD in a dose-dependent fashion, without internal limiting membrane (ILM) damage (P = 0.0001, r = -0.479). The FN and LN in the photoreceptor cell layer (PCL) were completely degraded in all microPlm-treated eyes. In eyes with complete PVD, the FN, but not the LN, was completely removed from the ILM by microPlm treatment.

Conclusion: Intravitreal injection of microplasmin degraded FN and LN at the vitreoretinal junction as well as at the outer retina.