Comparison of mechanical properties and host tissue response to OviTex™ and Strattice™ surgical meshes

Abstract

Purpose: This study compared the in vitro/benchtop and in vivo mechanical properties and host biologic response to ovine rumen-derived/polymer mesh hybrid OviTex™ with porcine-derived acellular dermal matrix Strattice™ Firm.

Methods: OviTex 2S Resorbable (OviTex 2S-R) and Strattice morphology were examined in vitro using histology and scanning electron microscopy; mechanical properties were assessed via tensile test; in vivo host biologic response and explant mechanics were evaluated in a rodent subcutaneous model. Separately, OviTex 1S Permanent (OviTex 1S-P) and Strattice were evaluated in a primate abdominal wall repair model.

Results: OviTex 2S-R demonstrated layer separation, whereas Strattice retained its structural integrity and demonstrated higher maximum load than OviTex 2S-R out-of-package (124.8 ± 11.1 N/cm vs 37.9 ± 5.5 N/cm, p < 0.001), 24 h (55.7 ± 7.4 N/cm vs 5.6 ± 3.8 N/cm, p < 0.001), 48 h (45.3 ± 14.8 N/cm vs 2.8 ± 2.6 N/cm, p = 0.003), and 72 h (29.2 ± 10.5 N/cm vs 3.2 ± 3.1 N/cm, p = 0.006) following collagenase digestion. In rodents, inflammatory cell infiltration was observed between OviTex 2S-R layers, while Strattice induced a minimal inflammatory response. Strattice retained higher maximum load at 3 (46.3 ± 27.4 N/cm vs 9.5 ± 3.2 N/cm, p = 0.041) and 6 weeks (28.6 ± 14.1 N/cm vs 7.0 ± 3.0 N/cm, p = 0.029). In primates, OviTex 1S-P exhibited loss of composite mesh integrity whereas Strattice integrated into host tissue with minimal inflammation and retained higher maximum load at 1 month than OviTex 1S-P (66.8 ± 43.4 N/cm vs 9.6 ± 4.4 N/cm; p = 0.151).

Conclusions: Strattice retained greater mechanical strength as shown by lower susceptibility to collagenase degradation than OviTex 2S-R in vitro, as well as higher maximum load and improved host biologic response than OviTex 2S-R in rodents and OviTex 1S-P in primates.

Keywords: Acellular dermal matrix; Biologic mesh; Hernia; Hybrid mesh; Primates; Rodents.

Fig. 1

Representative hematoxylin and eosin (H&E)-stained images prior to implantation. A Strattice consisted of a dense layer of reticular collagen. B OviTex 2S-Resorbable (OviTex 2S-R) had less dense collagen than Strattice, as well as large void spaces. Each of the layers showed variable thickness. Arrowheads indicate the membranous side of the tissue layers, highlighting their anisotropy and possible differences in permeability. Images are shown at 100× magnification

Fig. 2

Representative scanning electron microscopy cross-sectional images prior to implantation. A Strattice showed an intact collagen matrix. B OviTex 2S-Resorbable (OviTex 2S-R) showed a porous collagen matrix. The multifilament polymer suture material of OviTex 2S-R (indicated by red circles) is evident between the separated biologic component layers. Micrographs are shown at 100×(Strattice) and 40×(OviTex 2S-R) magnification

Fig. 3

Results of in vitro tensile strength testing (maximum load, N/cm), both out-of-package (time 0) and following digestion via excess collagenase enzyme exposure. **p < 0.01, ***p ≤ 0.001

Fig. 4

Strattice and OviTex 2S-Resorbable (OviTex 2S-R) over the time course of excess collagenase treatment. A Over the course of excess collagenase treatment, Strattice became slightly opaque, with hair follicles becoming apparent over time, but with the overall material remaining intact. OviTex 2S-R became degraded in the presence of collagenase, as shown by the loss in shape starting 24 h post-collagenase digestion and with the collagen component of OviTex 2S-R being completely digested by 48 h. B Strattice retained more of its initial strength measured as maximum load following a 24-, 48-, and 72-h collagenase digestion compared with OviTex 2S-R

Fig. 5

Representative hematoxylin and eosin images post-implantation in a rodent subcutaneous model. A Strattice showed minimal host inflammatory response. B OviTex 2S-Resorbable (OviTex 2S-R) demonstrated a considerable inflammatory response and separation of layers. Arrowheads indicate areas of inflammation. Images are shown at  × 100 magnification

Fig. 6

Representative macroscopic images of A Strattice and B OviTex 1S-P following 1, 3, and 6, months in a primate abdominal wall repair model. While Strattice appeared to integrate into the surrounding host tissue, OviTex 1S-P showed extensive biologic component resorption, resulting in synthetic component migration (ie, blue permanent polypropylene suture material) and loss of overall mesh integrity. For each test material, the top images show the peritoneal-facing surfaces, and the bottom images show the cross-sections

Fig. 7

Representative histologic micrographs of surgical meshes explanted from a primate abdominal wall repair model (3 months post-implantation). A Hematoxylin and eosin images of Strattice showed diffuse cellular infiltration with evidence of collagen turnover, indicated by the lighter pink–stained areas (top images). OviTex 1S-Permanent (OviTex 1S-P) showed migration of the synthetic component away from the biologic components; the synthetic component is encapsulated by host tissue (bottom images). OviTex 1S-P also showed large areas of persistent inflammation. B CD-68-positive brown staining macrophages. Compared with Strattice, OviTex 1S-P showed robust host tissue inflammation. Images are shown at 20×, 40×, and 100× magnification