[Preparation of high-purity and safe autologous plasmin and its clinical application]

To report an improved preparation of safer and highly-purified autologous plasmin and to demonstrate its clinical applications.

Prior to clinical application, animal experiments were carried out. In addition, the activity of plasmin in the vitreous cavity after injection was measured serially. In preparation for clinical use, the proteinase inhibitors aprotinin and benzamidine were used for suppression of protein denaturation. The samples were incubated for 48 hours to check for contamination. The preparation was applied to patients with idiopathic macular hole and diabetic macular edema.

The plasmin detached the vitreous body from the inner limiting membrane of the retina without any ill effects in animal experiments. The specific activity reached a peak in 5-10 minutes and decreased rapidly thereafter. By adding a suppressor of protein denaturation in the purification process, 0.2 IU (0.1 ml) of high-purity plasmin could be prepared from each patient. No bacterial contamination was noted. Complete vitreous detachment could be induced in two clinical cases. Urokinase was used instead of streptokinase to activate plasminogen.

Vitreous detachment is considered to be induced safely and consistently by injection of plasmin prepared using a protein denaturation suppressor and activated with urokinase. This method is expected to be of clinical value.