An Experimental Study On Lamellar Corneal Transplantation With Porcine Type I Atelocollagen In Rabbit

Objective:1.To develop a substitude for corneal grafting which have excellent clarity, corneal power and mechanical intensity and explore the performance of the substitute.2.To evaluate quantitatively the treatment of corneal wound healing using lamellar keratoplasty with porcine typeⅠatelocollagen as substitute, and analyze related factors.3.To detect the repair effect of porcine typeⅠatelocollagen on superficial corneal defects, and to provide a theoretical basis of developing a more mature corneal graft substitute.Methods:One hundred healthy Chinese white rabbits were used in this study. Eighty rabbits (80 eyes) were randomly selected as an experimental group. According to the source of corneal transplant,80 rabbits were randomly divided into collagen materials group (group A) and allograft group (group B), and two groups were all done for the operation of cornea layer board transplantation for one eye. According to the different time of putting to death,each group was randomly divided into 3thd,14thd, 1th,3th, and 6th month groups, and each group contained eight eyes.The left 20 rabbits'eyes (40 eyes) were as the source of cornea transplant for group B.After operation, the rabbits'eyes were observed by naked eyes and slit lamp, observed whether the cornea was healing and recorded the grade. The rabbit corneas were taken and observed by histopathology, and the epithelial cells marker protein K3 were detected by immunohistochemistry, which could appraise the healing of the corneal epithelium.Results:1.Porcine typeⅠatelocollagen performance:white light transmittance of collagen material is up to 91±2%,the refractive index is 1.3520±0.0002, closed to refractive index of human corneal stroma(1.373-1.380), tensile strength is 285±14KPa, elastic modulus is 1.7±0.2MPa, elongation at break is 16±3%,has a good optical performance and corneal curvature, has a certain tensile strength.2.General observing:the score of cornea clarity gradually decreased after layers transplantation operation in A and B groups.The score of cornea clarity of group A in the third day, the seventh day and the fourteenth day more than that of group B (p<0.05);cornea clarity of group A compared with that of group B,the difference has not statistics significance in the first month, third month and sixth month (p>0.05).3.Histopathology:3 days after surgery of group A, central corneal uniform red staining of collagen material covered surface; After 6 months, corneal epithelial surface is smooth. After 3 days after surgery, the corneal epithelium were integrity in group B;after 6 months, corneal epithelial were fully repaired.4.Immunohistochemistry:AE5 antibody of the marking proteinum K3 in corneal epithelium cells of group A and B after operation express masccline, which indicated the repaired cell of corneal epithelium is epithelium.Conclusion:1.The transparency of the collagen material is quite good, but the corneal curvature and certain mechanical strength, mechanical performance needs to be strengthened2.As a new material, corneal collagen material and corneal allograft have no difference compared to implant chips on the recovery of the transparency of corneal after transplant, but residual corneal vessles are obvious.Therefore the corneal collagen cannot completely replace the corneal allograft.3.As shallow defect repair of the rabbit corneal,artificial cornea of porcine type I atelocollagen has some feasibility as a temporary artificial cornea.4.Collagen materials provided theoretical basis for further improvement and direction for cornea transplant surgery.