A Low-Cost, Easily Deployable Vesicovaginal Fistula Occluding Device for Providing Interim Continence

Vesicovaginal fistulas (VVFs), abnormal openings between the vagina and bladder, disrupt the lives of millions of people worldwide due to resulting incontinence and infections. VVFs are commonly treated with surgery after the fistula has had time to heal over several months. In low-resource areas, the immediate incontinence often leads to ostracization from the community, and can be devastating for the patient. To occlude the fistula and enable full continence until the patient is able to access surgery, we have designed a three-tiered silicone plug consisting of a bladder-dwelling disc, a mid-fistula disc, and a vagina-dwelling cross-shaped tapered plug, all supported on a central stem.

The device withstands typical expulsion forces from the bladder and does not leak under typical bladder filling or urination pressures. The maximum device expulsion force is 3.69 N and it is watertight up to 100 cmH2O or 9.8 kPa. It is designed to be easily deployed by trained community members without medical qualifications.

An Injectable Meta-Biomaterial: From Design and Simulation to In Vivo Shaping and Tissue Induction

A novel type of injectable biomaterial with an elastic softening transition is described. The material enables in vivo shaping, followed by induction of 3D stable vascularized tissue. The synthesis of the injectable meta-biomaterial is instructed by extensive numerical simulation as a suspension of irregularly fragmented, highly porous sponge-like microgels. The irregular particle shape dramatically enhances yield strain for in vivo stability against deformation. Porosity of the particles, along with friction between internal surfaces, provides the elastic softening transition. This emergent metamaterial property enables the material to reversibly change stiffness during deformation, allowing native tissue properties to be matched over a wide range of deformation amplitudes. After subcutaneous injection in mice, predetermined shapes can be sculpted manually. The 3D shape is maintained during excellent host tissue integration, with induction of vascular connective tissue that persists to the end of one-year follow-up. The geometrical design is compatible with many hydrogel materials, including cell-adhesion motives for cell transplantation. The injectable meta-biomaterial therefore provides new perspectives in soft tissue engineering and regenerative medicine.

Characterization of Polyethylene Glycol-Reinforced Alginate Microcapsules for Mechanically Stable Cell Immunoisolation

Islet transplantation within mechanically stable microcapsules offers the promise of long-term diabetes reversal without chronic immunosuppression. Reinforcing the ionically gelled network of alginate (ALG) hydrogels with covalently linked polyethylene glycol (PEG) may create hybrid structures with desirable mechanical properties. This report describes the fabrication of hybrid PEG-ALG interpenetrating polymer networks and the investigation of microcapsule swelling, surface modulus, rheology, compression, and permeability. It is demonstrated that hybrid networks are more resistant to bulk swelling and compressive deformation and display improved shape recovery and long-term resilience. Interestingly, it is shown that PEG-ALG networks behave like ALG during microscale surface deformation and small amplitude shear while exhibiting similar permeability properties. The results from this report's in vitro characterization are interpreted according to viscoelastic polymer theory and provide new insight into hybrid hydrogel mechanical behavior. This new understanding of PEG-ALG mechanical performance is then linked to previous work that demonstrated the success of hybrid polymer immunoisolation devices in vivo.