Local host response of commercially available dural patches for fetal repair of spina bifida aperta in rabbit model

Objective: Fetal surgery for spina bifida aperta (SBA) by open hysterotomy typically repairs anatomical native tissue in layers. Increasingly, fetoscopic repair is performed using a dural patch followed by skin closure. We studied the host response to selected commercially available patches currently being used in a fetal rabbit model for spina bifida repair. Methods: SBA was surgically induced at 23–24 days of gestation (term = 31 days). Fetal rabbits were assigned to unrepaired (SBA group), or immediate repair with Duragen™ or Durepair™. Non-operated littermates served as normal controls. At term, spinal cords underwent immunohistochemical staining including Nissl and glial fibrillary acidic protein. We hypothesized that spinal cord coverage with a dural patch and skin closure would preserve motor neuron density within the non-inferiority limit of 201.65 cells/mm2 and reduce inflammation compared to unrepaired SBA fetuses. Results: Motor neuron density assessed by Nissl staining was conserved both by Duragen (n = 6, 89.5; 95% CI −158.3 to −20.6) and Durepair (n = 6, 37.0; 95% CI −132.6 to −58.5), whereas density of GFAP-positive cells to quantify inflammation was lower than in unrepaired SBA-fetuses (SBA 2366.0 ± 669.7 cells/mm2 vs. Duragen 1274.0 ± 157.2 cells/mm2; p = 0.0002, Durepair 1069.0 ± 270.7 cells/mm2; p < 0.0001). Conclusions: Covering the rabbit spinal cord with either Duragen or Durepair followed by skin closure preserves motor neuron density and reduces the inflammatory response.