Tissue bioengineering for surgical bleb defects: an animal study

Background To assess the effectiveness of OloGen (also named iGen), a porous, bioengineered, biodegradable, collagen-glycoaminoglycan matrix implant, in preventing poor bleb formation and early failure after trabeculectomy in eyes with a surgical wound defect. Methods The right eyes of 30 female New Zealand albino rabbits underwent trabeculectomy with OloGen implanted subconjunctivally on top of the scleral flap, while six right eyes received trabeculectomy without the implant to serve as a control group. A 1-2 mm diameter circular conjunctival defect was created in all eyes. Six rabbits in the group receiving the implant were sacrificed on days 3, 5, 7, 21, and 28. Rabbits in the control group were sacrificed on day 28. Perkins applanation tonometry, Seidel test and measurement of both the extent of the conjunctival defect and the anterior chamber depth were performed. Enucleated eyes were fixed in 4% formaldehyde and stained with hematoxylin and eosin (H&E) for general histological observation, and with Sirius and Fast-green stains to assess collagen deposition and cell migration. Results Seidel tests were negative for all operated and control eyes. No flat anterior chamber occurred in either group. With the exception of days 5 and 7, post-operative mean IOP difference is significant in both groups, (P > 0.05 for day 5, 7 and P < 0.05 for day 3, 14, 21 and 28). In the implant group, the mean IOP was reduced by between 42% and 35% at days 14, 21, and 28, whereas the mean IOP in the control group was reduced by between only 12% and 2%. In the implant group, histology showed randomized collagen deposition and microcyst formation in the bleb after the matrix had degraded completely at day 28. In the control group, histology showed dense collagen deposition subconjunctivally at day 28. Conclusions OloGen successfully serves as a 3-dimensional scaffold for cell migration and proliferation, and can prevent failure by maintaining the size of the bleb in the presence of a large wound defect. It might also be successful at repairing postoperative bleb leaks.