A bistable inhibitory OptoGPCR for multiplexed optogenetic control of neural circuits

Information is transmitted between brain regions through the release of neurotransmitters from long-range projecting axons. Understanding how the activity of such long-range connections contributes to behavior requires efficient methods for reversibly manipulating their function. Chemogenetic and optogenetic tools, acting through endogenous G-protein coupled receptor (GPCRs) pathways, can be used to modulate synaptic transmission, but existing tools are limited in sensitivity, spatiotemporal precision, or spectral multiplexing capabilities. Here we systematically evaluated multiple bistable opsins for optogenetic applications and found that the Platynereis dumerilii ciliary opsin (PdCO) is an efficient, versatile, light-activated bistable GPCR that can suppress synaptic transmission in mammalian neurons with high temporal precision in-vivo. PdCO has superior biophysical properties that enable spectral multiplexing with other optogenetic actuators and reporters. We demonstrate that PdCO can be used to conduct reversible loss-of-function experiments in long-range projections of behaving animals, thereby enabling detailed synapse-specific functional circuit mapping.

P-020 PERFORMANCE OF AN ATRAUMATIC AND VERSATILE LIGHT-ACTIVATED ADHESIVE FOR HERNIA MESH FIXATION

Aim

This study evaluates the versatility and performance of a novel adhesive for atraumatic hernia mesh fixation. The TISSIUM adhesive is a biodegradable and biocompatible viscous liquid that can be precisely applied to different tissue and mesh.1 Once in place, the surgeon utilizes a light probe to polymerize the adhesive, creating a flexible elastomeric connection that provides strong, durable and atraumatic mesh fixation.

Materials and Methods

The performance of the TISSIUM adhesive when used with a range of marketed mesh and against peritoneum (n=7) and muscle (n=3) was evaluated using a standardized lap-shear bench method using porcine tissues. The shear strength was compared to resorbable tacks (n=8) (against peritoneum as standard of care in IPOM) and self-adhesive meshes (n=4) and fibrin glue (n=3) (against muscle as classically used in the retromuscular approach).

Results

Lap-shear data revealed that the TISSIUM adhesive performance was equivalent to resorbable tacks when fixing meshes to the peritoneum. Similar testing protocol demonstrated that the TISSIUM adhesive shear strength was 6 to 13 times superior to non- penetrating fixation devices such as fibrin glue or self-adhesive mesh.

Conclusions

The use of the TISSIUM Adhesive for hernia mesh fixation is compatible with various mesh materials used in hernia repair and, in a bench model, outperforms existing non-penetrating methods in diverse tissue planes demonstrating the potential to help the surgeon achieve more effective and efficient atraumatic repair in a range of hernia procedures.