促红细胞生成素缓释微球玻璃体腔注射对视网膜神经节细胞的保护作用

目的 探讨乳酸/羟基乙酸共聚物（PLGA）装载的促红细胞生成素（EPO）缓释微球（EPO-PLGA微球）经玻璃体腔注射对大鼠视神经挫伤模型中受损视网膜神经节细胞（RGC）的保护作用.方法 选取成年SD大鼠,建立视神经挫伤模型.建模后分别经玻璃体腔内注射含10 IU EPO的PLGA微球（EPO-PLGA组）、10 IU EPO（EPO组）、5 μl空白PLGA（PLGA组）、5 μl PBS（PBS组）,另设未治疗组不予玻璃体腔注药.术后5 d和2周,做视网膜切片,对各组RGC凋亡情况行TUNEL检测;术后23 d,DiI上丘逆标RGC,并于术后4周处死大鼠,视网膜铺片观察各组RGC存活情况;每组各个时间点分别处死6只SD大鼠.采用方差分析对结果进行比较.结果 TUNEL检测显示,术后5 d和2周,各组均可见TUNEL阳性细胞,其中EPO-PLGA组和EPO组TUNEL阳性细胞显著减少,其细胞凋亡率明显少于PLGA组、PBS组及未治疗组.术后4周,视网膜铺片RGC计数显示,正常SD大鼠RGC密度为（2387.7±164.9）个/mm^2,未治疗组为（748.3±58.8）个/mm^2,EPO-PLGA组为（1296.7±157.6）个/mm^2,EPO组为（1418.5±154.9）个/mm^2,PLGA组为（821.7±52.1）个/mm^2,PBS组为（804.4±86.4）个/mm^2;可见EPO-PLGA组和EPO组较未治疗组细胞密度显著增高,具有明显的RGC保护作用（P均＜0.01）,而EPO-PLGA组和EPO组间差异无统计学意义（P=0.065）.结论 EPO-PLGA缓释微球与EPO具有等效的RGC保护作用,这为进一步观察EPO-PLGA缓释微球的长效神经保护作用奠定了基础.

Intravitreal injection of erythropoietin sustained-release microspheres protects damaged retinal ganglion cells in rats

Objective To investigate the protective effect of erythropoietin (EPO) encapsulated in poly (L-lactic-co-glycolic acid) (PLGA) microspheres on damaged retinal ganglion cell (RGC) by intravitreal injection after optic nerve crush. Methods Adult SD rats were selected to establish an optic nerve crush model. Immediately after the crush, the animals received intravitreal doses of 10 IU EPO of EPO-PLGA microspheres (EPO-PLGA group), 10 IU EPO (EPO group), blank PLGA microshperes (PLGA group), and PBS (PBS group) or untreated (untreated group). Five days and 2 weeks after crush, apoptotic RGC were detected with TUNEL labeling in frozen retinal sections.Twenty-three days after optic nerve crush, retinal ganglion cells were retrogradely labeled by injecting DiI into the superior colliculi of the brain. The animals were scarificed 4 weeks after the crush. Mounted retinal photographs were assessed for the number of surviving RGC. Six rats were prepared from each group at every time point. Results TUNEL-positive cells could be identified in all groups 5 days and 2 weeks after the operation. However, there were fewer in both the EPO-PLGA and EPO groups. Retinal mounts revealed that the density of RGC was (2387.7±164.9)cells/mm2 in normal adult rats, and (748.3±58.8)cells/mm2 in the untreated group, (1296.7±157.6)cells/mm2 in the EPO-PLGA group, (1418.5±154.9)cells/mm2 in the EPO group, (821.7±52.1)cells/mm2 in the PLGA group, and (804.4±86.4)cells/mm2 in the PBS group 4 weeks after the operation. Compared to the untreated group, the EPO-PLGA and EPO groups showed a significant neuroprotective effect on RGC (P＜0.01), and no significant differences were found between these two groups (P=0.065).Conclusion The protective effect of EPO-PLGA microspheres on RGC is equal to EPO, which provides evidence for further study on the long-term neuroprotective effect of EPO-PLGA microspheres.