Study Of Mechanism On Development Of Posterior Capsular Opacification

In the current time, posterior capsular opacification (PCO) is oneof the common complication of the cataract operation. At the sametime, it is also the most important reason that affect the postsurgicalvisual energy. In the clinic, all of the ophthalmologist try to eradicate thecataract when do the operation to make sure that there is little corticalleft to lessen the recurrent of the cataract. But the incidence of thePCO is yet very high. It is reported that the incidence of the PCO is ashigh as up to 20-50% because it is very difficult for us to eradicate thelens epithelial cells-induced PCO in the equator part. These days, it isbelieved that the leading mechanism of PCO is the proliferation andthe translocation of the rudimental lens epithelial cells. According toall of the questions, the cataract operation style and the design of theartificial lens have a big amelioration.what's more, manyantimetabolic drugs and immunity-armed drugs are gradually used inthe clinic. Unfortunately, all of the methods are not excellent. Theyhave corresponding disadvantages and limitation. In the end, theproblem of the replication of the lens epithelial cells have not beenresolved. Taking all the above facts into consideration, it is emergentto find one safe and effective way to solve this problem.Epidermal growth factor (EGF) was found by Cohen in 1962. Itis a small molecular polypeptide and it has the effect to stimulate thegrowth and replication of the epithelial cells and fibroblast cells. So ithas the function to revise and regenerate of the tissue. At the presenttime, there is a profound and wide research about EGF and it has beenpurified from the bovine and mice. In the contrast, the research aboutthe EGF in the PCO is not reported. Two author promoted that theconcentration of EGF in the aqueous humor is respectively0.62-1.40ng/ml and 1.0ng/ml. Mamingqingru reformed throughimmunohistochemistry method that there is epidermal growth factorreceptor (EGFR) in the normal and cataract lens. The expression ofthe EGFR in the normal lens cells is not reported yet.EGFR is the expressed production of the proto-oncogene c-erbB-1 (HER-1). Ireland ME testified that the EGFR can be expressed inthe differentiated lens cells of postincubated and cultured chicken.EGFR can affect not only the gene expression style of the postnatallens but also affect the proliferation and the development of the lenscells.RNA interfering is a typical post-transcripition gene-expression-modifying model, a conventionary action in biologicalevolution and it has the function of antiviral erosion and gene stabilitymaintainence. The recent study testified that it can produce a smallinterfering RNA medi-thing during RNA interfering. This medi-thingcan degrade the mRNA in the mammal cells effectively. Theappearance of siRNA, gives the new expectation to medicalresearchers with taking advantage of gene-silence technique in genetreatment area. Compared with anti-RNA, siRNA has much morepotential in gene treatment and it is more effective. Up to the present,siRNA can inhibit the expression of target-gene effectively in all thetested mammal. It has been reported about treating tumor and antiviralthrough RNA in and out country. There is no yet about siRNAinhibition the expression of lens epithelial cells epidermal growthfactor receptor and no report about the inhibiting the over-proliferationof lens epithelial cells.In this study, EGFR is the aim gene and we discussed therelationship between EGFR and the proliferation of the human lensepithelial cells to confirm the mechanism of the PCO. In this study, wecultured the human lens epithelial cells in vitro and get the cells to doprimary culture using digestion-separation method, then get thegrowth curve through methyl thiazolyl tetrazolium (MTT) colorimetry.According to the growth curve, we determined the test-point as 48hours. From the cell-growth-serum dependent study, we get theconcentration of the bovine serum as 10-15%. Then regulate theconcentration during observing the condition of cell growth. We usereverse transcription and polymerase chainrectiom (RT-PCR) toanalyze the expression of the EGFR mRNA. According to humanEGFR gene sequence, we design PCR upper and down primerseparately. The upper sequence is 5'-gaagtcctggtagtacag-3', thedownward sequence is 5'-ggatgaagaagacatggacga-3'. Just as what thePCR agent box said, we do RT-PCR with the lens epithelial cell andepithelial tissue cultured in vitro. In the result, RT-PCR proved thathuman lens epithelial cells expressed EGFR mRNA. We do theimmunohistochemistry with lens epithelial cells cultured in vitro andthe human lens epithelial cells tissue by anti-EGFR monocloneantibody from mice and SP hypersensitivity agent box.Immunohistochemistry testified that human lens epithelial cellexpressed the mature protein EGFR. We observed the promotionfunction of EGF to the lens epithelial cells cultured in vitro. Inconclusion, we found that EGF can promote the proliferation ofhuman lens epithelial cells and this function is concentrationdependent. At the same time, the promotion function of EGF isinhibited obviously by adding the EGFR antibody. But this inhibitionhas limitation that is more obvious in the lower concentration than inthe higher concentration. This is because that EGF can compete theEGFR with the EGFR antibody. We use the siRNA comprising-agentbox to comprise EGFR siRNA and use lipofectamine 2000 totransinfect the lens epithelial cells, and then we observe theproliferation condition of the lens epithelial cells. In the end, we foundthat EGFR siRNA can inhibited the promotion function of EGF to theepithelial cells. This inhibition is not weaken with the concentration ofthe EGF. So, we believed that no matter whether the concentration ofthe EGF in the human aqueous humor is high or not after the cataractoperation, if only the EGFR is not expressed or expressed in a lowlevel, the proliferation of the lens epithelial cells can be inhibited toprevent the occurrence of PCO. In another hand, the operation styleand the inflammation action also play a very important role in theoccurrence of the PCO, it is to say that inflammation also take part inthe reason of PCO. Inflammation is a complex course according to allkinds of the stimulant factor including bacteria, trauma and immunityaction. In this study, we observe the function of LPS to human lensepithelial cells proliferation, measure the replication energy ofepithelial cells through the MTT colorimetry method. Also wemeasure the expression of EGFR mRNA through RT-PCR method.The result proved that LPS can promote the proliferation of the humanlens epithelial cells obviously. It can also stimulate the expression ofthe EGF. From all of these, we deduce that the function of LPSpromotion the proliferation of the human lens epithelial cells comesfrom promotion the expression of the EGF. This study prove thatinflammation play a part of role in PCO.Conclusion: The expression of the EGFR can promote theproliferation of the human epithelial cells and this function can beaffected to aggravate by inflammation stimulant factor such as LPS.EGFR siRNA can inhibit the promotion function of EGF. So it isbelieved that the high expression of the EGFR may be one of theimportant reason in PCO. siRNA method can make the aim gene silentand no protein is expressed. This may be a effective method to preventand treat the PCO in the future.