A novel lacrimal duct prosthesis and its biodegradation and biocompatibility

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). 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. Key words: Lacrimal duct; Stents; Polymers/chemistry; Biodegradability; Biocompatibility; Lacrimal duct obstruction/therapy; Rabbits, Japanese