Histologic Comparison of the Dura Mater among Species

Abstract

The biocompatibility, biodegradation, feasibility, and efficacy of medical devices like dural sealants and substitutes are often evaluated in various animal models. However, none of these studies explain the rationale for choosing a particular species, and a systematic interspecies comparison of the dura is not available. We hypothesized that histologic characteristics of the dura would differ among species. We systematically investigated basic characteristics of the dura, including thickness, composition, and fibroblast orientation of the dura mater, in 34 samples representing 10 animal species and compared these features with human dura by using hematoxylin and eosin staining and light microscopy. Dura showed many similarities between species in terms of composition. In all species, dura consisted of at least one fibrovascular layer, which contained collagen, fibroblasts, and blood vessels, and a dural border cell layer beneath the fibrovascular layer. Differences between species included the number of fibrovascular layers, fibroblast orientation, and dural thickness. Human dura was the thickest (564 μm) followed by equine (313 μm), bovine (311 μm), and porcine (304 μm) dura. Given the results of this study and factors such as gross anatomy, feasibility, housing, and ethical considerations, we recommend the use of a porcine model for dural research, especially for in vivo studies.

Safety and biodegradability of a synthetic dural sealant patch (Liqoseal) in a porcine cranial model

“…Histological assessment of the dura of different species showed that porcine dura closely resembles the human dura. 9 We therefore performed a relatively large bilateral craniotomy with a large exposure of the dura in which a representative amount of sealant was applied. A second strength was the strict protocol adherence and objective results evaluation; the surgery was performed by a full trained neurosurgeon, the MRI follow up was done by a veterinary radiologist and the histological follow up was done by a veterinary pathologist.…”

“…Pig dura is 0.30 (±0.08) mm thick on average. 9 MRI measurements of dura plus sealant showed a mean thickness of 0.9 (±0.3) mm at 3 days, 2.0 (±1.2) mm at 14 days and 2.1 (±0.4) mm at 1 month. At 6 and 12 months no sealant was visible anymore on MRI.…”

Local Tolerance and Biodegradability of a Novel Artificial Dura Mater Graft Following Implantation Onto a Dural Defect in Rabbits

“…ArtiFascia and the Control device are indicated to repair human dura, a 0.5- to 1-mm-thick soft connective tissue. The rabbit’s dura is significantly thinner (99 µm in rabbit vs 564 in human), 27 and we estimated that this structural difference caused both implants to occupy the space where once the drilled bone piece was located. Consistent with this, Figures 3E and F show a relatively large empty cavity where the Control graft was implanted.…”

“…Neodura is defined by a well-delineated layer of densely collagenous connective tissue situated between newly formed bone and the brain surface or deep within the surgical fibrous scar that is parallel to the leptomeninges and of a thickness of the order of the normal dura. 27 A fibrous scar is typically thicker, not tangentially polarized and follows the surgical planes rather than the brain surface.…”

Characterization and Ex Vivo Application of Indocyanine Green Chitosan Patches in Dura Mater Laser Bonding

“…The dura mater is the outermost layer of the meninges that cover the central nervous system. It consists predominantly of collagen and elastin and possesses viscoelastic properties necessary to solve its biological functions [ 25 , 26 , 27 ]. Many biomaterials and sealants are used for dural closure, but the results are suboptimal.…”