 Hi, my name is Laura Suggs. I'm here at the University of Texas at Austin in the Department of Biomedical Engineering. This is my co-author, David Hammers, who's in the Department of Kinesiology and Health Education, also here at UT Austin. And we recently published a manuscript in the Journal of Biotechnology and Bioengineering. This work was funded by the National Science Foundation as a result of the American Recovery and Reinvestment Act, and that allowed us to hire David on to complete this work. So in particular, we're interested in ischemic injury as a result of either permanent injury or in our case transient injury. In particular, we're interested in tourniquet use. Tourniquet use is widespread over the globe. It can be a result of trauma to provide to reduce blood loss or to provide a bloodless surgical field. Published estimates are that over 20,000 tourniquets are used every day, and what we've established via our colleague in the Department of Kinesiology, Roger Ferrer, in a rat model is that tourniquet use can provide long-term or produces long-term functional deficits in rats, so we can demonstrate measurable function loss in rats out to two weeks. We've employed this injury model to try to evaluate different therapeutic modalities. In particular, we're interested in the growth factor, insulin-like growth factor 1. This is a growth factor that's important in skeletal muscle repair. It has a number of different functions, including myoblasts, differentiation promotion, promoting proliferation of myoblasts, survival of affected cells, and other therapeutic benefits. So because of its regenerative potential, we were interested in delivering this growth factor in a focal way using a delivery system that we've developed in my lab. This delivery system is based on fibrin, so fibrin is the result of the coagulation cascade. It's cross-linked with an enzyme thrombin. In our lab, we peggulate this material, so we covalently bind it to polyethylene glycol. Polyethylene glycol is di-functional and serves as an additional cross-linking site. The polyethylene glycol can also bind IGF-1 and serve to localize it to the site of delivery. Because it's based on fibrin, it can be cross-linked in situ and injected into the site of injury. And so what my colleague David is going to do is demonstrate how that injection system works. In order to make the peggulate fibrin gel, we react fibrinogen by functional polyethylene glycol molecule and IGF-1 and what this does, it causes covalent binding of a fibrinogen to IGF-1 and when we mix it with thrombin, it causes polymerization through the normal clotting reaction and that's how we make our peggulate fibrin gel. So in order to load this for injectable use, we load our thrombin to the syringe, then we load our peggulated fibrinogen into the same syringe, still fluid at this site. We mix it up, then we inject it and the animal will be injected into the injured lateral gastrocnemius muscle as still liquid and soon after injection, it polymerizes and we have a polymerized peggulate fibrin gel. We've demonstrated that IGF-1 can be loaded into peggulated fibrin and we evaluated release of this growth factor in vitro using ELISA and western blotting techniques and demonstrated that the free peptide can be released at physiologic concentrations up to 96 hours after incorporation. And so at that point we looked at administering this IGF-loaded peggulated fibrin 24 hours after a tourniquet injury in rats. And what we were able to demonstrate when we measured force production in the hind limb of rats, at two weeks following administration of this treatment, we were able to improve functional recovery of the rat. So in controls where we just inject saline, what we see is that we get about just under 50% of maximum force production recovered at two weeks. When we deliver the IGF-loaded peggulated fibrin, we see just under 73% maximum force production. And that is statistically significant. And it's also greater than either a bolus injection of IGF at the same concentration or the vehicle, the unloaded vehicle alone. So what we have here is a system that can be injected directly into the hind limb following injury and improve cell survival, limit some of the detrimental phases that result from ischemia reperfusion and enhance functional recovery of the injury.