In vitro biocompatibility and biomechanics study of novel, Microscopy Aided Designed and ManufacturEd (MADAME) materials emulating natural tissue weaves and their intrinsic gradients

This study conducted biomechanical and biocompatibility tests of textiles and textile composites, created using recursive logic to emulate the properties of natural tissue weaves and their intrinsic mechanical stiffness gradients. Two sets of samples were created, first to test feasibility on textile samples designed as periosteum substitutes with elastane fibers mimicking periosteum's endogenous elastin and nylon fibers substituting for collagen, and then on composites comprising other combinations of suture materials before and after sterilization. In the first part, the bulk tensile mechanical stiffness of elastane-nylon textiles were tuned through respective fiber composition and orientation, i.e., aligned with and orthogonal to loading direction. Cell culture biocompatibility studies revealed no significant differences in proliferation rates of embryonic murine stem cells seeded on textiles compared to collagen membrane controls. Until the 15th day of culture, cells were rarely observed in direct contact with the elastane fibers, similar to previous observations with elastomeric sheets used in periosteum substitute implants. In the second part of the study textile samples were created from FDA-approved medical sutures comprising silk, expanded polytetrafluoroethylene, and polybutester. Biocompatibility and mechanical stiffness were assessed as a function of sterilization/disinfection mode (steam, ethylene oxide, and serial disinfection with ethanol). Cell proliferation rates did not differ significantly from controls, except for silk-suture containing textiles, which showed bacterial contamination and no viable cells after 15 days' culture for all sterilization methods. Sterilization had mixed (mostly not significant) effects on textile stiffness, except for the case of polybutester suture-based textiles that showed a significant increase in stiffness with ethylene oxide sterilization. In general, all textile combinations exhibited significantly higher stiffness than periosteum. Textiles comprising medical sutures of different stiffnesses arranged in engineered patterns offer a novel means to achieve mechanical gradients in medical device materials, emulating those of nature's own.