| PVR is the primary reason of the common combication andfailure in the rhegmatogenous retinal detachment. The therapy ofPVR currently is vitrectomy.However, the relapse incidence of RDis enhanced because the remain mambrane on the retina is difficultto be removed and continues to proliferate after surgery.Therefore,medicine intervening in the occurrence and development of PVRcurrently becomes focal in the field of ophthalmology.Triamcinolone acetonide is one kind of corticosteriods, which canreduce excudation,inhibit proliferation of fibroblast and granulationtissue to control inflammatory and cell proliferations.So far, TA isgradually used in eye diseases. In our study, to investigate therelation between the inhibitory effect , active time and concentrationof TA, we desire to observe the effect of TA(0,10,30,300 mg.L-1)on proliferations of cultured human retinal pigmentepithelium(ARPE-19)cells subsequently for 24 and 72 hours in vitro,using MTT colorimetric and TUNEL assays andtransmission electron microscope, which is as the basis of a theoryabout intravitreal triamcinolone acetonide injection in clinicintervening the occurrence and development of PVR. Apoptosis index of ARPE-19 cells were performed byTUNNEL assay: brown staining in the karyon wasTUNEL-positive cell while TUNEL-negative cell's was thinyellow . In control group, ARPE-19 cell's karyon is thin yellow,while in TA-treated groups karyons were partly stained brown andpartly thin yellow as well as black apoptotic bodies were shown.Five different visual fields were observed at random by OlympusBH-2 type microscope ( 200 ×) . Apoptosis index was theproportion of TUNEL-positive cells. All results were analyzed withstatistics, we can see that there is no significant difference aboutapoptosis index of ARPE-19 cells treated with 10 mg. L-1TAcompared with 0 mg. L-1(t=2.120, P > 0.05), however, cellapoptosis was caused by 30 mg. L-1 TA, and there is highlysignificant difference about the apoptosis stress when ARPE-19cells treated with 300 mg. L-1 TA compared with above threeconcentrations(t=2.921, P<0.01). Absorbance reading of ARPE-19 cells in the presence ofvaried concentrations of TA was performed by MTTcolorimetric assay: the results were expressed as units ofabsorbance of MTT and analyzed with statistics when ARPE-19cells were exposed to four different concentrations of TA for 24 and72 hours: TA-treated time and contration all have significant effecton proliferations of ARPE-19 cells, the inhibitory effects weresignificant different as time and concentrationincreased(F0.05,3,16=3.24 , P < 0.05 ; F0.05,1,16=4.49, P <0.05).Moreover, there is statistic significance in the reciprocityeffects of TA-treated time and concentrations on inhibitingproliferations of cells (F0.05,1,16 =4.49, P<0.05). The ultrastructure of ARPE-19 cells exposed to differentconcentrations of TA for 24 hours were observed bytransmission electron microscope: (1)at 0,10 mg. L-1 TA:ARPE-19 cells have plentiful and extrusive slight microvilli,abundant cellular apparatuses and dark pigment granules.Cellkaryon is clearly, in which chromatin is distributed uniformly. (2)at30 mg. L-1 TA: we can see shorter or disappeared microvilli,compact cytoplasm, reduced dark pigment granules, proliferatedand gently swelled mitochondrions and dilatated endoplasmicreticulums. Agglomerate chromatin is gathered underlying the cellnuclear mambrane. (3)at 300 mg. L-1 TA: there is no microvilli onthe surface of ARPE-19 cells. We can see further compactcytoplasm , obviously decreased dark pigment granules, increasedempty vesicles, compact and splited cell nucleus and apoptoticbodies. ARPE-19 cells are spontaneously arised from primary humanretinal pigment epithelium cell lines and have structural andfunctional properties characteristic of RPE cells in vivo. In ourstudy, we observed the effect of TA on proliferation of ARPE-19cells in vitro, the results are shown that low concentration of TAcan't cause apoptosis, but certain concentration of TA can induce it,and more exposed time and treated concentrations are, more thestress of apoptosis and the effect of proliferation is. In addition,TA-treated time and concentrations are also affect proliferations ofARPE-19 cells one another.Conclusions: TA can inhibit the proliferations of retinal pigmentepethilium cells. Therefore, injections of TA or combined withpars plana vitrectomy may be effective therapy on proliferativevitreoretinopathy . Because the long-term therapeutic effects andcytotoxicity of TA on retina aren't known , further animalexperiment is required to prove the safety property and minimumeffective concentration of TA. |
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