Characterization of host response, resorption, and strength properties, and performance in the presence of bacteria for fully absorbable biomaterials for soft tissue repair.

Purpose: The objective was to evaluate the host response, resorption, and strength properties, and to assess the performance in the presence of bacteria for Phasix™ Mesh (Phasix™) and Gore Bio-A Tissue Reinforcement (Bio-A) in preclinical models.

Methods: In a rat model, one mesh (2 × 2 cm) was implanted subcutaneously in n = 60 rats. Animals were euthanized after 2, 4, 8, 12, 16, or 24 weeks (n = 5/mesh/time point), and implant sites were assessed for host inflammatory response and overall fibrotic repair thickness. In a rabbit model, meshes (3.8 cm diameter) were bilaterally implanted in subcutaneous pockets in n = 20 rabbits (n = 10 rabbits/mesh) and inoculated with 10 CFU clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). One mesh type was implanted per animal. Animals were euthanized after 7 days, and implants were assessed for abscess formation, bacterial colonization, and mechanical strength.

Results: In the rat study, Phasix™ and Bio-A exhibited similar biocompatibility, although Bio-A demonstrated a significantly greater inflammatory response at 4 weeks compared to Phasix™ (p < 0.01). Morphometric analysis demonstrated rapid resorption of Bio-A implants with initially thicker repair sites at 2, 4, 8, and 12 weeks (p < 0.0001), which transitioned to significantly thinner sites compared to Phasix™ at 16 and 24 weeks (p < 0.0001). In the rabbit bacterial inoculation study, Phasix™ exhibited significantly lower abscess score (p < 0.001) and bacterial colonization (p < 0.01), with significantly greater mechanical strength than Bio-A (p < 0.001).

Conclusions: Host response, resorption, repair thickness, strength, and bacterial colonization suggest a more stable and favorable outcome for monofilament, macroporous devices such as Phasix™ relative to multifilament, microporous devices such as Bio-A over time.