In vitro simulation of in vivo degradation and cyclic loading of novel degradable electrospun meshes for prolapse repair

Synthetic durable textile meshes used in pelvic organ prolapse (POP) may lead to graft related complications (GRCs). Mechanisms involved in the genesis of GRCs include implant biocompatibility, biomechanical properties and the host response. Electrospinning allows production of micro-sized fibres, which can physically mimic the natural extracellular matrix of most connective tissues. When used for manufacturing implants it may reduce GRCs. With this study we aimed at getting better knowledge of the mechanical behaviour of the candidate implants, intended to match the host tissue as closely as possible. To do this the mechanical properties of novel prototype electrospun implants made of Ureido-Pyrimidinone-Polycaprolactone (UPy-PCL) were obtained by simulating in vivo degradation of the implants and its impact on the mechanical performance. Three types of UPy-PCL meshes, differing in their architecture were manufactured. For comparison, a reference non-degradable polypropylene knitted macroporous ultra-lightweight implant (Restorelle, Coloplast), clinically used for POP repair, was tested. First, the stability of UPy-meshes after sterilization by electron beam irradiation was confirmed. Then, implants were assessed by uniaxial tensile testing. To mimic an in vivo biological environment, meshes were placed for predefined durations in pH controlled baths, following cyclic loading. The electrospun meshes were 5–6 times more compliant and had higher maximum strains than the Restorelle mesh. UPy-PCL meshes are anisotropic, and a 10% reduction in strength after water absorption was measured. UPy-PCL meshes did not display significant weight loss or thinning after in vitro degradation. They underwent plastic deformation and a significant difference in elongation was found after degradation in acid medium. During the degradation tests, Restorelle meshes did not lose weight or thickness.