Abstract
Purpose::
Microplasmin is a low molecular weight recombinant protein that contains the proteolytic activity of plasmin. As with plasmin, it is highly autolytic, requiring rapid administration and cold storage. The aim of this study is to investigate (1) the safety of a stabilized form of microplasmin on retinal morphology and (2) its ability to induce posterior vitreous detachment (PVD) following intravitreal injection in post-mortem porcine eyes.
Methods::
Fresh post-mortem porcine eyes were injected with 62.5µg, 125 µg or 250 µg of stabilized microplasmin in 0.1 ml normal saline or balanced salt solution plus (BSS+) respectively. Control eyes were injected with 0.1 ml normal saline or BSS plus. Eyes were incubated for 1 hour at 37 °C, and then fixed for microscopy. Morphologic alterations and the extent of PVD induction were assessed by light microscopy and by transmission electron microscopy (TEM). Stabilized and non stabilized microplasmin at room temperature for 1 hour was studied using the same protocol.
Results::
Normal retinal cellular and morphologic anatomy was demonstrated in all eyes from both the control group and all microplasmin treated eyes irrespective of the vehicle used. No PVD was observed in the control group. A dose dependent PVD was seen in microplasmin treated eyes. Non stabilized microplasmin left at room temperature for 1 hour did not lead to the induction of a PVD.
Conclusions::
Stabilized microplasmin does not induce structural changes within porcine eyes and retains the ability to induce a PVD in a dose dependent fashion similar to microplasmin injected at a physiologic pH. The stabilized version retains its pharmacologic activity for a longer period of time, and may be more appropriate for clinical use.
Keywords: proteolysis • vitreous • inner retina dysfunction: biochemistry and cell biology