Proof of concept for a biologic closure device in a rodent model with evaluation of the animals’ overall burden

Abstract Disk herniation is a common disease in the population. In case of relevant neurologic deficits and/or pain syndrome a surgical approach is necessary. Therefore, an incision has to be made in the outer ring of the disk to remove all parts of the prolapse. To date, a reliable closure device is missing and a recurrent herniation after a pain free interval is a postoperative problem well-known in spine surgeons. The current study works on proof of concept and is the first which discusses cocoon silk as a possible closure material in intervertebral disk defects in a rat model. In addition, the burden of each animal due to the surgical procedure has been evaluated by Von Frey-filament testing and stress evaluation. The rats represented no or only minor stress response. In the filament testing the animals showed low-grade reactions in general as well. In the histological examination, inflammatory tissue response was detected directly to the silk, predominantly associated with macrophage. In some areas, cell death was visible. These reactions might be associated with remaining particles of the egg, not the silk itself. Further investigations would be necessary to overcome this problem.