Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
Graefes Arch Clin Exp Ophthalmol. 2011 Jan;249(1):37-46. doi: 10.1007/s00417-010-1466-y. Epub 2010 Aug 3.
The generation of an atraumatic posterior vitreous detachment (PVD), a common goal in vitreoretinal surgery, is a challenge particularly in children and young trauma patients. Plasmin has been proposed as a surgical adjunct to enzymatically generate a PVD. This study assesses the performance and safety of a new system for rapid purification of plasmin as an adjunct to vitrectomy.
Plasminogen was isolated from human plasma by affinity chromatography using a disposable rapid purification kit, and activated to plasmin with streptokinase. Activities were assessed spectrophotometrically. For safety studies, 38 rabbits received intravitreal injections of one of the following compounds in 0.1 ml respectively: 4.7, 12.7 and 24 IU plasmin, 15 mg dextran, 4,100 U streptokinase, 500 μg ε-aminocaproic acid, 0.1 M potassium phosphate or balanced salt solution (BSS). Thirty min after injection, a two-port vitrectomy was performed. Rabbits were followed clinically and with bright flash electroretinography (ERG) for up to 9 months. The eyes were investigated by light and transmission electron microscopy.
The specific plasmin activity obtained from blood of healthy volunteers averaged 42.3 ± 6.6 IU/ml (range 21.6 IU/ml to 54.5 IU/ml). The identity and purity of the enzyme was confirmed by several methods. Clinically, a mild to moderate inflammatory response was seen in most eyes on day 1, but had disappeared by day 7. ERG showed moderate depressions of a- and b-wave amplitudes on day 2, particularly in the potassium phosphate (a: -29.16 ± 4.56, b: -21.23 ± 6.31), 4.7 (a: -34.38 ± 6.64, b: -26.66 ± 6.06) and 24 IU (a: -38.25 ± 4.05, b: -23.38 ± 4.29) plasmin groups, but also in the BSS- (a: -11.19 ± 21.78, b: -11.41 ± 15.47) and dextran- (a: -17.86 ± 14.18, b: -6.67 ± 18.14) treated eyes. ERG changes recovered during follow-up. One rabbit each from the 12.7 and the 24 IU plasmin groups showed a minimal discoloration of one medullary ray after 9 months. Histology did not reveal morphologic signs of toxicity.
The isolation system generated plasmin with a high degree of purity. A failure-mode analysis did not reveal significant risks of toxicity. A single preparation can provide a maximum dose of 10.9 IU/200 μl, the likely target clinical dose being 1.88 IU. Plasmin doses of at least 12.7 IU appear be safe when injected into rabbit eyes, followed by vitrectomy.
在玻璃体视网膜手术中，产生无创伤性玻璃体后脱离（PVD）是一个常见的目标，但在儿童和年轻创伤患者中这是一个挑战。纤溶酶已被提议作为一种手术辅助剂，以酶促方式产生 PVD。本研究评估了一种新的快速纯化纤溶酶系统作为玻璃体切除术辅助剂的性能和安全性。
通过使用一次性快速纯化试剂盒从人血浆中亲和层析分离纤溶酶原，并使用链激酶将其激活为纤溶酶。通过分光光度法评估活性。为了进行安全性研究，38 只兔子分别接受以下化合物之一的眼内注射：4.7、12.7 和 24IU 纤溶酶、15mg 葡聚糖、4100U 链激酶、500μgε-氨基己酸、0.1M 磷酸钾或平衡盐溶液（BSS）。注射后 30 分钟，进行两端口玻璃体切除术。兔子接受临床和明亮闪光视网膜电图（ERG）检查，最长可达 9 个月。通过光镜和透射电镜检查眼睛。
从健康志愿者的血液中获得的纤溶酶比活平均为 42.3±6.6IU/ml（范围为 21.6IU/ml 至 54.5IU/ml）。通过多种方法确认了酶的身份和纯度。临床上，大多数眼睛在第 1 天出现轻度至中度炎症反应，但在第 7 天已消失。ERG 显示第 2 天 a 波和 b 波振幅出现中度降低，尤其是在磷酸钾（a：-29.16±4.56，b：-21.23±6.31）、4.7（a：-34.38±6.64，b：-26.66±6.06）和 24IU（a：-38.25±4.05，b：-23.38±4.29）纤溶酶组中，但也在 BSS（a：-11.19±21.78，b：-11.41±15.47）和葡聚糖（a：-17.86±14.18，b：-6.67±18.14）治疗组中。ERG 变化在随访期间恢复。在 12.7 和 24IU 纤溶酶组中，各有一只兔子在 9 个月后出现一条髓射线的最小变色。组织学未显示出毒性的形态学迹象。
分离系统产生的纤溶酶具有高度的纯度。失效模式分析未显示出明显的毒性风险。单一制剂可提供 10.9IU/200μl 的最大剂量，可能的目标临床剂量为 1.88IU。当在兔子眼中注射至少 12.7IU 的纤溶酶剂量时，在进行玻璃体切除术之前是安全的。
