Experimental Study Of Using Acellular Porcine Cornea Stroma As A Wrapping Material For Hydroxyapatite Orbital Implants

Objective：To examine the efficacy of a novel method of decellularizing porcine cornealstroma and the feasibility of using acellular porcine cornea stroma as a wrappingmaterial for hydroxyapatite orbital implants in enucleation surgery.Method:1. The scaffold was prepared from fresh porcine corneas which were treated withfreezing and thawing and electrophoresis, the complete removal of corneal cells wasconfirmed by pathological section and HE staining, subcutaneous implantation wasput to detecting its biocompatibility2. Thirty New Zealand albino rabbits were divided into2groups randomly:group A and B, each of which has15rabbits. HA orbital implants were implanted intotheir left orbits. The rabbits of group A taken as control group underwent eviscerationwith placement of autologous sclera coated HA implants. The HA balls wereimplanted after coating with APCS in group B. The rabbits were clinically examinedfor inflammation and implants exposure every day after implantation.30rabbits (3ineach group) received enhanced MRI scan at1、2、3、4and5weeks postoperatively,in the mean time, the implants were exenterated for histopathological examination.All of these examinations were taken to compare the difference of the two groups inthe degree of fibrovascularization of the implants.Result:1. keratocytes were all removed after the decelluarized process of the porcinecornea，while the extracellular matrix scaffold was well reserved.2weeks aftersubcutaneous implantation, the implants in experimental group were surrounded withsome inflammatory cells, mainly neutrophils;4weeks after implantation, immunerejection was not observed in auto-cornea and APCS. In the experimental group, therewas no sign of infiltration of neutrophilic leukocytes or leukomonocytes into theAPCS. The APCS implant was coated with connective tissue formed by fibrocytes, and there was a clear boundary between them2.1week after operation, the implants of both groups presented littlefibrovascularization. HA balls in group A and B fibrovascularized at the periphery indifferent degree; the difference of enhanced magnetic resonance imaging scanbetween this two groups was significant (p＜0.05between A and B).2weeksafter operation, each group showed higher degree but incomplete fibrovascularingrowth; group B were still lower in fibervascularization progress than group A, thedifference of enhanced magnetic resonance imaging scan between each group wassignificant (p＜0.05between A and B).3weeks after operation, the implants of groupA and B demonstrated significantly improve in fibrovascularization; higher than thatof week2, but fibrovascularization didn’t extend to the center of the implants; thedifference of enhanced magnetic resonance imaging scan between this two groupswas not significant (p＞0.05between A and B).4weeks after operation, completefibrovascularization of the implants of group A and B occurred; there was nosignificant difference of enhanced magnetic resonance imaging scan between groups.5weeks after operation, each group showed few changes in comparison with that ofweek4; one rabbit of group B got dehiscence of bulber conjunctiva from week2butwas cured spontaneously at week4Conclusions:1. The acellular porcine corneal stroma (APCS) prepared by the means offreezing and thawing and electrophoresis showed no evidence of keratocytes, TheAPCS retained the structure of stromal collage, which was ordered and tough.2. APCS has few effects on early fibrovascularization in HA balls，and do notextend the time required for complete fibrovascularization of the HA orbital implants.3. It’s feasible to use APCS as a wrapping material for hydroxyapatite orbitalimplants.