A new modified dura mater implant: characteristics in recipient dogs.

Duraplasty is critical to the maintenance of anatomical integrity and the protection of brain tissue. Allotransplantation of cadaveric dura mater was abandoned after it was found to transmit Creutzfeldt-Jakob disease (CJD). In this study, the usefulness of a xenogeneic dura mater for dural reconstruction was tested. Twelve dogs were randomly assigned to 4 groups. To simulate the condition of patients with brain surface injury, an area of approximately 2 cm x 1.5 cm of the dura mater was removed to create a defect. Xenogeneic dura mater derived from porcine pericardium was trimmed to the shape and size of the defect and sutured to the endogenous dura mater. Muscles at the apex of the skull and scalp were also sutured. Three dogs were euthanized at 3, 6, 9, and 12 months after implantation and the xenogeneic dura mater and surrounding endogenous tissue were examined macroscopically and microscopically. Three months after implantation, the graft site had begun to heal. Macroscopically, at 6, 9, and 12 months after implantation, the graft had healed completely with the surrounding tissue. No boundary between the graft and surrounding tissue was distinguishable, and the two could not be separated. The graft was smoothly epithelialized and nonadherent to the brain surface. Microscopically, the inner surface of the implant was covered with epithelial cells, and internal capillaries, subepithelial fibrous tissue deposition, and fibroblast proliferation were observed. The xenogeneic dura mater progressively degraded over time. No cysts and no neutrophilic or lymphocytic inflammatory cell response developed between the implant and the recipient brain parenchyma. The modified xenogeneic dura mater is sufficiently biocompatible to allow epithelialization of its inner surface without adherence to brain tissue. No abnormalities develop in recipients, and the xenograft is gradually biodegraded and replaced by endogenous tissue identical to the endogenous dura mater.