Study On Bacterial Cellulose As The Scaffold Of Tissue Engineering Of Cornea

Objective:Bacterial cellulose as a biological scaffold were chosen to fabricate tissue engineering of corneal stroma and study its biocompatibility and degradation in vivo and ex vivo.Materials and methods:Rabbits corneal stromal cells were separated in vitro, cultivated and propagationed, then seeded onto the bacterial cellulose membrane. The biomembrane was implanted into the same corneal stroma sac when the cells spread all over the bacterial cellulose membrane.The histomorphological change in transplanted lagophthalmos and the degradation of biomembrane were observed by applying slit lamp,anterior segment OCT and corneal confocal microscope Cs-4.Whether lagophthalmos corneas had inflammatory reaction and neovascularization or not were observed at the same time.Respectively in the second, fifth and seventh months after transplantation, the right corneas were removed with sterile cornea scissors, and fixed in 4% glutaraldehyde, then they were observed by applying HE staining, immunohistochemistry and scanning electron microscopy.Results:Rabbit corneal stromal cells grew well on biomembrane.In the first week after transplantation, the corneal had no irritation and there was no neovascularization at the graft.In the first month after transplantation, there were neovascularization through the grafts without corneal edema. But the transparency of corneal tissue surrounding the graft improved.In the second month after transplantation, the cornea was translucent.The size of the biomembrane reduced and the neovascularization got better.In the seventh month after transplantation, the blood vessels reduced and became thinner in the cornea, the transparency of cornea got better too.Anterior segment OCT and confocal microscopy:In the first week after transplantation, the density of the biomembrane was significantly higher than that of normal corneal tissue.After four months, the boundaries became blurred and the density was close to normal corneal,which indicating that the biomembrane came to degradation.In the second months after transplantation, the endothelial cell number and morphology near the graft was normal.In the seventh months after transplantation, the density of stromal cells decreased and nerve fibers can be seen occasionally.Pathological examination:In the fifth months after transplantation,the corneal epithelial cells proliferated and disordered. The fibril organization of bacterial cellulose were different from the normal stroma and they did not adhesion closely.The cornea had inflammatory cells infiltration but didn't serious and there were no necrosis and dissolve.In the seventh months after transplantation, the corneal epithelial cells remain proliferated but had regular arrangement. There was no vacuoles and had similar structures to stroma in the composite membrane, which indicating that the biomembrane did not occur rapid degradation, in the biomembrane and at both sides can be seen same structures with corneal stromal cells.There were a small amount of inflammatory cells infiltration and no necrosis and dissolve.Immunohistochemistry:All the biomembranes composed by stromal cells and bacterial cellulose express a-SMA in the second, fifth and seventh months after transplantation.It was indicated that the cornea stromal cells were activated to myofibroblasts in vivo, but the number of a-SMA positive cells were decreased with time going on.Scanning electron microscopy:The biomembrane composed by stromal cells and bacterial cellulose still exist in the seventh months after transplantation.The boundaries between normal cornea and the biomembrane were clear.Conclusion:Bacterial cellulose has a good cellular compatibility, corneal stromal biomembrane were reconstructed successfully applying the bacterial cellulose. It has the capable of degradation, but the speed of corneal stromal biomembrane applying the bacterial cellulose is slow in vivo. Corneal neovascularization and the proliferation of myofibroblasts are associated with corneal transparency.