Establishment of selective laser trabeculoplasty effect model in human trabecular cell in vitro / 中华实验眼科杂志

ABSTRACT

Background Selective laser trabeculoplasty (SLT) plays lowing-intraocular pressure (IOP)effect by irradiating pigmented trabecular cells selectively using 532 nm NdYAG laser.However,its affect pattern is not fully known.Objective This study was to establish a human trabecular cells (HTCs) model of SLT effect,and to observe the morphological changes of HTCs after they were exposed to different energies of SLT.Methods Immortalized HTCs were incubated in DMEM/F12 with pigmental granules for 16 hours (overnight) to prepare pigmented trabecular cells.The cells were irradiated with modified laser lens with the spot of 400 μm and emitting duration of 3 ns.The energy scale of 0.2 mJ was set for standardized energy and 0.1 mJ was used as the low energy.The morphology and ultrastructure of the cells were examined under the light microscope and transmission electron microscope 1 hour,4,8,12,24 hours after irradiation.Trypan blue staining and TUNEL fluorescence staining were used to evaluate the death and apoptosis of the cells after laser irradiation.Results The brown pigment particles were seen in cytoplasm around nuclei of trabecular cells after cultured for 16 hours.After laser irradiation,there was no obvious change in the shape of nonpigmented trabcular cells,but a 400 μm spot was found in the pigmented trabecular cells under the light microscope,and the pigmented particles released as the cell disruption.After 0.2 mJ laser irradiation,cell loss zone was seen at the center of the laser spot,and the positive cells for trypan blue and TUNEL staining were found;while the abnormal manifestations were slight after the 0.1 mJ irradiation.With the lapse of the time,the number of positive staining cells was gradually decreased.Twenty-four hours after laser irradiation,proliferative trabecular cells emerged and migrated to the center area of laser spot.Statistical analysis showed that the numbers of the positive cells for trypan blue and TUNEL staining were significantly reduced in the lower energy group in comparison with the standardized energy group at various time points (all at P＜0.001),and those of both energy groups were gradually reduced with lapse of time with the significant differences between any two time points (all at P＜0.01).Conclusions An in vitro laser effect model of HTCs can be established by exposing pigmented HTCs to SLT laser.After exposed to SLT,the gasification,necrosis-like death,apoptosis-like change appear at the laser center.The laser destroyed cells can be replaced by proliferative cells with the lapse of time.Low-energy laser irradiation cause a similar morphological change of the cells to high-energy irradiation,but the number of abnormal cells is much less.