In vivo evaluation of bilayer ORC/PCL composites in a rabbit model for using as a dural substitute.

OBJECTIVE: After a neurosurgical procedure, dural closure is commonly needed to prevent cerebrospinal fluids (CSF) leakage and to reduce the risk of complications, including infections and chronic inflammatory reactions. Although several dural substitutes have been developed, their manufacturing processes are complicated and costly and that many of them have been implicated in causing postoperative complications. This study aimed to assess the effectiveness and safety of new bilayer ORC/PCL composites in a rabbit model. METHODS: Two formulations of bilayer oxidized regenerated cellulose (ORC)/poly ε-caprolactone (PCL) knitted fabric-reinforced composites and an autologous graft (pericranium) were employed for dural closure in forty-five male rabbits. Systemic reaction and the local reaction of the samples were assessed and compared at one-, three- and six-months post-implantation by blood chemistry and gross, and microscopic assessment using hematoxylin-eosin and Masson's trichrome stains. RESULTS: No signs of CSF leakage or systemic infection were seen for all samples. All samples demonstrated minimal adhesion to adjacent tissues. The degree of host fibrous connective tissue ingrowth into both composites was comparable to that of the autologous group, but bone formation and osteoclast activities were significantly greater. Both composites progressively degraded over times and the residual thickness of the nonporous layer was 50% of the initial thickness at six months post-implantation. DISCUSSION: Bilayer ORC/PCL composites were successfully employed for dural closure in the rabbit model. They were biocompatible and could support dural regeneration comparable to that of the autologous group, but induced greater osteogenesis.

Comparison of Rabbit, Kitten and Mammal Milk Replacer Efficiencies in Early Weaning Rabbits.

Early weaned rabbits should be fed using a milk replacer in order to survive. Therefore, a rabbit milk replacer (RMR) was developed and compared with a kitten milk replacer (KMR®: KMR) and a mammal milk replacer (Zoologic® Milk matrix 30/52: MMR). Thirty-six native crossbred rabbits aged 18 days were divided into three experimental groups (six replicates/group, two rabbits/replicate), fed RMR, KMR or MMR daily until they were 36 days old and euthanized at 38 days, while a complete pelleted diet and water were provided ad libitum. No statistically significant differences were observed in growth performance parameters, water intake, faecal weight, nutrient digestibility, internal organ weight, caecal pH, caecal cellulose activity, number of faecal pellets and amount of crude protein intake (p > 0.05). Caecal amylase activity in the KMR group and caecal protease activity in the RMR group were higher than in the MMR group (p < 0.05). The villus height and crypt depth of the MMR group were greater than in the RMR and KMR group (p < 0.05). In conclusion, it is possible to feed RMR to early weaning rabbits without serious adverse effects. However, probiotics and/or prebiotics should be supplemented in milk replacers and their benefits studied.