ABSTRACT
Background The primary management for nasolacrimal duct obstruction is the combination of lacrimal duct probing with lacrimal duct stent implantation.However,conventional implant is undegradable.New degradable lacrimal duct prosthesis based on biopolymer materials is a research hotspot.Objective This study described herein a preparation method of novel degradable lacrimal duct prosthesis and its application.Methods A new degradable lacrimal tube stent was prepared with compound of poly L lactic acid (PLLA) and polycaprolactone (PCL) (6:4) and 15％ polyethylene glycol (PEG).Thirty-two Japanese rabbits aged 3-4 months were randomized into postoperative 1-week group,postoperative 4-week group,postoperative 8-week group and postoperative 16-week group.The degradable lacrimal tube stents were inserted into the lacrimal ducts of the left eyes of the rabbits.The prosthesis was removed in corresponding time points according to grouping,and the integrity and weight of the prosthesis were evaluated.The mucosal findings of the operative eyes were examined under the endoscope,and the histopathological and inflammatory reaction was observed by hematoxylin & eosin stain.The ultrastructure of the lacrimal mucosal surface was examined under the scanning electron microscope.The use and care of the rabbits complied with the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission.Results The new degradable PLLA:PCL+15％ PEG lacrimal duct stents were smooth,flexible and hydrophilic tubes.The removed tubes were intact in the postoperative 1-week group,however,the rupture of the tubes appeared in the postoperative 4-week group,while discrete pieces of the tubes were seen in the postoperative 16-week group.The weight-loss rates of the tubes were (13.44±6.59)％,(23.96±6.33)％,(55.08-± 6.55) ％ and (78.00±8.74) ％ in the postoperative 1-week group,postoperative 4-week group,postoperative 8-week group and postoperative 16-week group,respectively,and the weight-loss rate of the tubes was significantly higher in the postoperative 16-week group than those in the postoperative 8-week group (q =4.27,P＜0.05).No significant difference was found in the weight-loss rate of the tubes between postoperative 1-week group and postoperative 4-week group (q =1.71,P＞0.05).The edema,hyperemia and mild proliferation of the lacrimal mucosal were exhibited in the eyes of the postoperative 4-and 8-week groups,and the mucosal findings were almost normal in the eyes of the postoperative 16-week group under the endoscope.Histopathological examination showed a large number of inflammatory cells in the postoperative 1-,4-and 8-week groups.However,few inflammatory cells were seen in the postoperative 16-week group.Mucosal folds,microvillus decrease and disorder were displayed in the lacrimal duct of the postoperative 8-week group,and no evident abnormality was seen in the lacrimal duct mucosal surface.No postoperative complication occurred in all the rabbits.Conclusions PLLA:PCL+15％ PEG lacrimal duct stent has an appropriate degradation speed and good biocompatibility after implant in rabbits,and its decay period of mechanical strength could match lacrimal duct healing period.
ABSTRACT
Background Researchers are paying increasing attention to the effect of cellular senescence in vascular dysfunctional diseases,and it is hypothesized that cellular senescence may also be involved in the development of diabetes related vascular complications.The outstanding feature of cellular senescence is the upregulation of beta-galactosidase.Objective This study was to investigate the effects of high glucose on cell senescent in vitro and in vivo on bovine retinal endothelial cells (BRVECs) and mouse retina.Methods BRVECs were cultured and passaged,and the seventh generation of cells were employed in this study.The cells were divided into the control group and the high glucose culture group and cultivated using M199 medium containing 5.5 mmol/L or 25.0 mmol/L glucose,respectively.5-bromine-chlorine-4-3-indole-beta D galactose glucoside (X-Gal) staining was used to examine the expression of beta-galactosidase in the cells.Diabetic models were established in the SPF male C57BL/6J mice aged 8-10 weeks by intraperitoneal injection of streptozotocin (STZ),and the age-and gendermatched normal mice served as controls.The mouse retinas were collected and starched in the 48-well plates 3 months later.X-Gal staining was employed to calculate the positive cells.Results BRVECs grew well 24 hours after culture but showed irregular arrangement.Forty-eight hours later,the cells reached confluence with a tight connect.The ratios of positive BRVECs and total cells were (51.4±5.4) ％ and (36.6-±3.8) ％ in the high glucose culture group and the control group,with a significant difference between the two groups (t =-3.204,P =0.033).The number of positive cells for X-Gal in mouse retinas was (94.0± 15.1) /field in the diabetic group,which was higher than that in the control group ([60.0 ± 5.7]/field) (t =-2.974,P =0.041).Conclusions High glucose environment accelerates senescence of retinal cells,and high glucose induces premature cell senescence,which likely plays an important role in the pathogenesis of diabetic retinopathy.