Host-biomaterial interactions in mesh complications after pelvic floor reconstructive surgery.

Polypropylene (PPL) mesh is widely used in pelvic floor reconstructive surgery for prolapse and stress urinary incontinence. However, some women, particularly those treated using transvaginal PPL mesh placement for prolapse, experience intractable pain and mesh exposure or extrusion. Explanted tissue from patients with complications following transvaginal implantation of mesh is typified by a dense fibrous capsule with an immune cell-rich infiltrate, suggesting that the host immune response has a role in transvaginal PPL mesh complications through the separate contributions of the host (patient), the biological niche within which the material is implanted and biomaterial properties of the mesh. This immune response might be strongly influenced by both the baseline inflammatory status of the patient, surgical technique and experience, and the unique hormonal, immune and microbial tissue niche of the vagina. Mesh porosity, surface area and stiffness also might have an effect on the immune and tissue response to transvaginal mesh placement. Thus, a regulatory pathway is needed for mesh development that recognizes the roles of host and biological factors in driving the immune response to mesh, as well as mandatory mesh registries and the longitudinal surveillance of patients.

Pyridine as an additive to improve the deposition of continuous electrospun filaments.

Electrospun filaments are leading to a new generation of medical yarns that have the ability to enhance tissue healing through their biophysical cues. We have recently developed a technology to fabricate continuous electrospun filaments by depositing the submicron fibres onto a thin wire. Here we investigate the influence of pyridine on the fibre deposition. We have added pyridine to polydioxanone solutions at concentrations ranging from 0 to 100 ppm, increasing the conductivity of the solutions almost linearly from 0.04 uS/cm to 7 uS/cm. Following electrospinning, this led to deposition length increasing from 1 cm to 14 cm. The samples containing pyridine easily underwent cold drawing. The strength of drawn filaments increased from 0.8 N to 1.5 N and this corresponded to a decrease in fibre diameter, with values dropping from 2.7 µm to 1 µm. Overall, these findings are useful to increase the reliability of the manufacturing process of continuous electrospun filaments and to vary their biophysical properties required for their application as medical yarns such as surgical sutures.

Synthetic sutures: Clinical evaluation and future developments.

Today's sutures are the result of a 4000-year innovation process with regard to their materials and manufacturing techniques, yet little has been done to enhance the therapeutic value of the suture itself. In this review, we explore the historical development, regulatory database and clinical literature of sutures to gain a fuller picture of suture advances to date. First, we examine historical shifts in suture manufacturing companies and review suture regulatory databases to understand the forces driving suture development. Second, we gather the existing clinical evidence of suture efficacy from reviewing the clinical literature and the Food and Drug Administration database in order to identify to what extent sutures have been clinically evaluated and the key clinical areas that would benefit from improved suture materials. Finally, we apply tissue engineering and regenerative medicine design hypotheses to suture materials to identify routes by which bioactive sutures can be designed and passed through regulatory hurdles, to improve surgical outcomes. Our review of the clinical literature revealed that many of the sutures currently in use have been available for decades, yet have never been clinically evaluated. Since suture design and development is industry driven, incremental modifications have allowed for a steady outflow of products while maintaining a safe regulatory position and limiting costs. Until recently, there has been little academic interest in suture development, however the rise of regenerative medicine strategies is shifting the suture paradigm from an inert material, which mechanically approximates tissue, to a bioactive material, which also actively promotes cell-directed repair and a positive healing response. These materials hold significant therapeutic potential, but could be associated with an increased regulatory burden, cost, and clinical evaluation compared with current devices.