Curcumin-loaded Chitosan Liposomes For The Treatment Of Rabbit Corneal Alkali Burn

Purpose The aim of the project was to prepare a novel curcumin-loaded chitosan liposomes for ophthalmic delivery. Curcumin-loaded chitosan liposomes were used on eyes without its side effect. The therapeutic effect of curcumin-loaded chitosan liposomes were evaluated on the models of rabbit corneal alkali burn. Its possible mechanism also explored. This research provided experimental basis for the clinical application of curcumin-loaded chitosan liposomes for ophthalmic delivery.Methods(1)Preparation and characteristics of curcumin-loaded chitosan liposomes. The curcumin-loaded chitosan liposomes were prepared by thin film dispersion method. The particle size and zeta potential and encapsulation efficiency of liposomes were determined.(2)The safety evaluation of curcumin-loaded chitosan liposomes for ophthalmic delivery.Six rabbits were randomly divided into two groups, including the curcumin-loaded chitosan liposomes group and the physiological saline group(0.9%Nacl), with 3 rabbits in each group. The curcumin-loaded chitosan liposomes were given to the right eyes of curcumin-loaded chitosan liposomes group, and physiological saline was given to the right eyes of 0.9% Nacl group, with 4 times per day, and continuous administration for14 days. The toxicity of curcumin-loaded chitosan liposomes were observed by praxiology,slit-lamp biomicroscope. Pathological specimens were made to observe the differences under a light microscope at the 14 th day after using medication.(3) Curcumin-loaded chitosan liposomes for the treatment of rabbit corneal alkali burn.35 rabbits were randomly divided into 5 groups: the normal control group(n = 3), the physiological saline group(n = 8),the blank chitosan coated liposomes group(n = 8),the dexamethasone group(n = 8) and the curcumin-loaded chitosan liposomes group(n= 8). The corneal alkali burn models were built at the central corneas of the right eye,and all groups respectively processed with the above medicines, for 4 times per day, and continuous administration for 14 days. The cornea neovascularization(CNV) and the proportion of corneal epithelium healing were analyzed by slit-lamp microscopy and digital photographs. The evaluation index included the length and area of the cornea neovascularization at the fourth, seventh, fourteenth and twenty-eighth day. The ratio of corneal epithelium wound healing at the first, second, fourth, seventh and fourteenth day.The expression of interleukin-8(IL-8) of the rabbit aqueous humor at the first, fourth,seventh and fourteenth day. Rabbits of each group, which was randomly selected from the five groups, were killed at the seventh, fourteenth and twenty-eighth day after alkali burn separately. Corneas were taken to make tissue sections. Tissue sections were stained with histological examination to observe the morphology of the corneas, the expression of VEGF in the corneal tissue were detected by immunohistochemical staining.Results(1) The average particle size was 96.6 ± 14.7 nm, with the average zeta potential 58.8 ±2.3 m V, and average encapsulation efficiency 51.41 ±1.05 %. Curcumin-loaded chitosan liposomes were appropriate, as a novel ophthalmic delivery for the animal experiments.(2) The safety of curcumin-loaded chitosan liposomes were good. Throwing head,scratching eye, photophobia were not observed. Conjunctival congestion, corneal edema, exudations of iris and len’s opacity were not found after dropped with curcumin-loaded chitosan liposomes on normal rabbit’s cornea. The corneal histological structure was normal without the infiltration of inflammatory cell in all corneas.(3) On the 4 、 7 、 14 、 28 d after cornea alkali injury, the growth of corneal neovascularization of curcumin-loaded chitosan liposomes group and dexamethasone group were effectively inhibited(p<0.05). No significant difference in corneal neovascularization were found between blank chitosan coated liposomes group and physiological saline group(p>0.05). At the early stage, curcumin-loaded chitosan liposomes group showed worse inhibitory effect on the growth of CNV compared with dexamethasone group(p<0.05). However, at the later stage, the area of curcumin-loaded chitosan liposomes group was equal to that of the dexamethasone group(p >0.05).Compared to the physiological saline group, curcumin-loaded chitosan liposomes promoted recovery of corneal epithelium(p<0.05), reduced inflammation, the expression of the VEGF in the corneal tissue(p < 0.05), and the expression of interleukin-8(IL-8) of the rabbit aqueous humor.Conclusions Curcumin-loaded chitosan liposomes were high encapsulation efficiency, and good safety. It can obviously reduce the inflammatory of corneal alkali burn, inhibit the growth of corneal neovascularization, promote recovery of corneal epithelium, and reduce expression of VEGF in the cornea and IL-8 expression in aqueous humor.Curcumin-loaded chitosan liposomes are expected to be a new therapeutic formulation for the treatment of corneal alkali burn, which provides a new idea for the treatment of corneal alkali burn.