Biodegradable, thermosensitive implant for approximating cylindrical structures: A preliminary study

Abstract

A new invention, i.e., a biodegradable, thermosensitive hybrid gel composite in the form of a thin sheet, was used as an implant inside the rat and guinea pig to test its tissue reactions, degradation, and function as a bridging agent. Tissue tractions in subcutaneous tissue, in muscle, around a peripheral nerve, and around an artery were mild. Degradation made rapid progress, starting on the third day and completed in 2-3 weeks. The hybrid gel, when wrapped around the cut ends of a peripheral nerve or an artery, functioned well as a bridging tube. In the case of the cut nerve, regenerating fascicles crept through the tube which protected them from fibrosis. In the case of the cut artery, patency of flow was maintained, and arterial wall healing was complete in 2-3 weeks. The hybrid gel composite contracted at body temperature, thus holding well to body tissues. Its biodegradable and inert nature offers the potential for future use as a tissue wrap and bridging agent.

Effects of pH and thermally sensitive hybrid gels on osteogenic differentiation of mesenchymal stem cells

“…[22][23][24] Namely, above 32 C, PNIPAM becomes insoluble in water so that the gel network made of such a polymer expels water and collapses. Upon lowering the temperature, individual microgels can swell up to 10 times in their size.…”

“…Among environmentally sensitive polymers, thermally sensitive poly( N -isopropylacrylamide) (PNIPAM) with a lower critical solution temperature (LCST ∼32℃) is the mostly studied. 22–24 Namely, above 32℃, PNIPAM becomes insoluble in water so that the gel network made of such a polymer expels water and collapses. Upon lowering the temperature, individual microgels can swell up to 10 times in their size.…”

A Reversible Thermosensitive Adhesive for Retinal Implants

“…16 Another in vivo study showed that pNIPAM is safe and effective in approximating cylindrical structures such as peripheral nerve and artery without any toxic effects. 17 Our in vivo study showed that ppNIPAM-coated implants may stay attached to the retina for at least 6 weeks. It is often difficult but critical to remove the posterior vitreous totally from the retinal surface, especially in rabbits, because when we leave a residual vitreous the ppNIPAM coated implant may loosen from the retinal surface.…”