Comparison of the effect of autologous and homologous injections of vitreous body with Hyalgan into the knee joint of the rabbit as an animal model

Abstract

The histopathological properties of vitreous body have not yet been well clarified. This study compares the histopathological effects of autologous and homologous injections of vitreous body with Hyalgan into the knee joint of a rabbit. Thirty-six white New Zealand rabbits were divided into three equal groups. Under anesthesia and sterile conditions, rabbit vitreous body was obtained through the clear corneal incision with a trephine after lens delivery. In the first group, 0.5 ml of vitreous body was autologously injected into the rabbit's knee. In the second group, homologous vitreous body from one rabbit was injected into the left knee of another rabbit. In the third group, 0.5 ml of sodium hyaluronate (Hyalgan) was similarly injected into the rabbit's knee. Twelve rabbits were considered as control group and received just normal saline. Each group was subdivided into two groups, A and B. The rabbits' articular cartilages and synovial membranes were histologically investigated for any inflammation after 1 week for group A and after 12 weeks for group B. After 1 week, no significant difference was found between the autologous and homologous vitreous body and Hyalgan injection groups. In comparison with the control group, no significant histological differences were noted. After 3 months, in both homologous and autologous vitreous-treated groups, no signs of chronic inflammation were noticed. However, in the Hyalgan group, there were signs of mild synovial hyperplasia, moderate infiltration of lymphocytes, and mild increased vascularity without any signs of fibrosis. It seems that vitreous body can be a safe and proper substitute for Hyalgan to be injected into the joint space.