Functionalized Collagen-based Materials For Corneal Regeneration And Repair

Cornea is located at the outermost layer of the eye tissue and is vulnerable to injury.China is a large industrial and agricultural country,and the corneal damage is also common.Corneal disease constitute the second most frequent eye disease in China.At present,there are more than 5 million patients blinded by various corneal diseases in China.Vision loss and even blindness not only seriously affect the quality of patients’ life,but also place a heavy burden on families and society.Although most of them can see the light through corneal transplant surgery,the shortage of transplant materials is a world problem.Due to the lack of donor corneal donor sources,only 10,000 corneal transplants can be performed each year in China.Corneal disease is gradually becoming the main cause of irreversible blindness that cannot be treated.Collagen is the main component of the corneal stroma,so it is an incomparable advantage in many natural polymers.However,the collagen-based material has the problem of insufficient mechanical strength and intolerance of stitching,which limits its wide application.At the same time,the recovery of corneal transplantation is likely to lead to scar healing of the corneal stroma,and the formation of leukoma affects visual function reconstruction.In addition,most studies in the past have focused on the modification of collagen-based materials,such as better strength and antibacterial properties of the materials,and less research on the role of collagen itself in corneal tissue repair.The interaction between collagen and cells or tissues is not clear enough.Thus,collagen was modified by edible organic acid which contains multiple functional groups and high biocompatibility high-efficiency aldehyde cross-linking agent synthesized by laboratory.Compared with traditional collagen cross-linking agents,it has the advantages of high cross-linking efficiency,small color reaction and good biosafety.Further,another new materials are obtained by combining biofunctional small molecule miRNAs for scarless repair of corneal tissue for the first time.Compared with growth factors which also have regulatory effects,miRNAs have the advantage of being cheaper,more stable,and easier to control.In addition,the interaction between corneal epithelial cells,corneal stromal cells and collagenbased materials in an inflammatory environment was further studied.The biological functions of collagen-based materials in corneal tissue repair were further explored.The main findings are as follows:(1)Modification of collagen by edible organic acid which contained a plurality of functional groups and highly biocompatible high-performance aldehyde cross-linking agent independently synthesized in the laboratory.These materials maintained the good cell compatibility of the collagen-based material.The mechanical properties of the material,especially the stitching resistance were promoted.The material can be completely sutured to the ocular surface and achieve rapid postoperative epithelialization without irritation to the ocular surface.However,from the detection of postoperative corneal stroma recovery,it was found that there was a certain degree of scar healing in the stroma,which affected the recovery of visual function.(2)To combine the biofunctional small molecule miR-133 b with collagen-based materials,the material had the ability of inhibiting scar formation of the corneal stroma after surgery.Studies have shown that AuNP can bind well to miR-133 b and has good protection against RNase.Under the conditions of membrane formation of collagen solution,miR-133 b can remain intact,which can maintain function in material preparation.The addition of AuNP does not affect the excellent physical and chemical properties of collagen-based materials.AuNP/miR-133 b can be released from the material and enter the corneal stromal cells or corneal tissue to further exert its scar inhibition function.The experiment group has a good postoperative corneal repair,compared with the control group and the Col membrane group.It has obvious scar inhibition ability,and the repaired cornea has higher transparency.(3)IL-1β can effectively stimulate the secretion of IL-6 and MMP-1 by corneal epithelial cells and corneal stromal cells.When corneal cells were seeded on collagen-based materials,the expression of IL-6 and MMP-1 in the supernatant of the culture system was decreased after IL-1β stimulation compared with the control group seeded on tissue culture plate;The IL-1β stimulated corneal cell increased the amount of degradation of the collagen-based material.Further studies have found that collagen-based materials have a certain adsorption effect on IL-6 and MMP-1,and degradation products produced by collagen-based materials can reduce the secretion of IL-6 in corneal cells,collagen.The collagen-base material can reduce the secretion of IL-6 in the corneal cells through the dual action of physical adsorption and degradation products,and has certain anti-inflammatory effects.The anti-inflammatory effect of collagen membrane was further verified in LKP model in vivo.