The standard practice for healing sudden wounds in the field – bandaging up a wound using a piece of semi-permeable, antimicrobial fabric – has barely changed for generations now, but several pioneering groups are trying to fix that. One, based out of Texas A&M University, has been showcasing their latest attempt to put the tech in bandages. Instead of bandaging the wound externally, they’ve developed proof-of-concept “injectable bandages” that can infill fresh wounds and prevent bleeding. As the team note, blood loss (hemorrhage) is a leading cause of death in battlefield wounds, and the current healing tech is not up to the task. Serious injuries simply cannot be patched up by gauze. Instead, materials that not only stop bleeding quickly but also imbue the wound with active biological treatment are desperately needed. Other teams around the world have come up with a few other prototypes in this regard, including one that injects the wound with tiny sponges. That group used an antimicrobial coating, a coagulating substance named chitosan, found in shrimp shells. The team behind this latest study, published in Acta Biomaterialia, took their inspiration from a different source, but one that’s equally as aquatic: seaweed, along with a little bit of engineering ingenuity. What the team were aiming for was an injectable gelatin, a gelling agent that is usually derived from the water-based chemical breakdown of collagen. Used in plenty of foodstuffs, it generally increases the viscosity of the overall mixture – a property that is clearly ideal for stopping blood loss. The team’s gelatin was derived from kappa-carrageenan, which is found in seaweed. When combined with extremely small fragments of clay known as nanosilicates, you get yourself a special type of injectable, strong, self-hardening gelatin. In fact, it’s a type of hydrogel, a water-loving, highly absorbent structure. Importantly, gelatin hydrogels can mimic the properties of the “scaffolding” between cells – the extracellular matrix – which also provides vital biochemical support. This makes them perfectly compatible with the wounds in which they are injected. Additionally, a test compound that played the role of a therapeutic was encapsulated within some gelatin hydrogel, and experiments show that it was slowly released post-injection. This team’s specific use of electrically charged nanosilicates also confers a novel function: Their presence physically encourages plasma protein and platelets to gather on the surface of the gel, which initiates a mass coagulation feedback cycle. This accelerates the natural clotting ability of the blood. At the same time, the injectable bandages also allow for the release of vascular endothelial growth factor (VEGF), a protein used by the body to encourage the proliferation of blood vessels. If your tissues aren’t getting proper oxygenation, then the growth of new blood vessels can fix that. The team reasoned, correctly, that an effusion of VEGF through their hydrogels would enhance wound healing. So far, only isolated laboratory experiments – in vitro – have been performed on layers of cells with simulated wounds; in vivo live testing, as it were, is still to come. At the same time, it's not specifically clear how quickly these materials would clot and heal bona fide wounds. So far, blood clotting appears to be accelerated by several minutes, but wound healing overall isn't. Nevertheless, these nanoengineered, injectable hydrogels are another exciting addition to a growing catalogue of techniques that could save countless lives in both operating theaters and the theater of war. Source
