Photocurable extracellular matrix sealant for cessation of venous hemorrhage.

Hemorrhage is the second leading cause of death in patients under 46 years of age in the United States. Cessation of hemorrhage prevents hemorrhagic shock and tissue hypoxia. Controlling the bleed via direct pressure or tourniquet is often the first line of defense, but long-term care requires staples, hemostatic agents, or sealants that seal the vessel and restore blood flow. Here, we compare a new photocurable extracellular matrix sealant (pcECM) with low, medium, and high crosslink density formulations to a commercially available fibrin-based sealant, TISSEEL®. pcECM has potential uses in surgical and remote settings due to room temperature storage conditions and fast preparation time. Here, we determine if pcECM sealant can stop venous hemorrhage in a murine model, adhere to the wound site in vivo throughout the wound-healing process, and has the mechanical properties necessary for stopping hemorrhage. Adjusting pcECM crosslinking density significantly affected viscosity, swelling, burst strength, tensile strength, and elasticity of the sealant. 3-Dimensional ultrasound volume segmentations showed pcECM degrades to 17 ± 8% of its initial implant volume by day 28. Initially, local hemodynamic changes were observed, but returned close to baseline levels by day 28. Acute inflammation was observed near the puncture site in pcECM implanted mice, and we observed inflammatory markers at the 14-day explant for both sealants. pcECM and fibrin sealant successfully sealed the vessel in all cases, and consistently degraded over 14-28 days. pcECM is a durable sealant with tunable mechanical properties and possible uses in hemorrhage control and other surgical procedures.

Critical factors for the bulk adhesion of engineered elastomeric proteins.

Many protein-based materials, such as soy and mussel adhesive proteins, have been the subject of scientific and commercial interest. Recently, a variety of protein adhesives have been isolated from diverse sources such as insects, frogs and squid ring teeth. Many of these adhesives have similar amino acid compositions to elastomeric proteins such as elastin. Although elastin is widely investigated for a structural biomaterial, little work has been done to assess its adhesive potential. In this study, recombinant elastin-like polypeptides were created to probe the factors affecting adhesion strength. Lap shear adhesion was used to examine the effects of both extrinsic factors (pH, concentration, cross-linker, humidity, cure time and cure temperature) and intrinsic factors (protein sequence, structure and molecular weight). Of the extrinsic factors tested, only humidity, cure time and cure temperature had a significant effect on adhesion strength. As water content was reduced, adhesion strength increased. Of the intrinsic factors tested, amino acid sequence did not significantly affect adhesion strength, but less protein structure and higher molecular weights increased adhesion strength directly. The strengths of proteins in this study (greater than 2 MPa) were comparable to or higher than those of two commercially available protein-based adhesives, hide glue and a fibrin sealant. These results may provide general rules for the design of adhesives from elastomeric proteins.

Effect of localizing fruit and vegetable consumption on greenhouse gas emissions and nutrition, Santa Barbara County.

The US agrifood system is very productive, but highly centralized and resource intensive with very weak links between production and consumption. This contributes to high levels of malnutrition and greenhouse gas emissions (GHGE). A popular approach to improvement is localization-reducing direct transport (farm to retail distance, or "food miles"). We examined Santa Barbara County (SBC) California, which mirrors the high production, nutritional and environmental problems, and growing localization movement of California. SBC ranks in the top 1% of US counties in value of agricultural products, and >80% of this value is produce (fruits and vegetables). We calculated the amount of produce grown in and consumed in SBC and estimated that >99% of produce grown in SBC is exported from the county, and >95% of produce consumed in SBC is imported. If all produce consumed in SBC was grown in the county (100% localization), it would reduce GHGE from the agrifood system <1%, and not necessarily affect nutrition. While food miles capture only a portion of the environmental impact of agrifood systems, localization could be done in ways that promote synergies between improving nutrition and reducing GHGE, and many such efforts exist in SBC.