Biocooperative Regenerative Materials by Harnessing Blood-Clotting and Peptide Self-Assembly.

The immune system has evolved to heal small ruptures and fractures with remarkable efficacy through regulation of the regenerative hematoma (RH); a rich and dynamic environment that coordinates numerous molecular and cellular processes to achieve complete repair. Here, a biocooperative approach that harnesses endogenous molecules and natural healing to engineer personalized regenerative materials is presented. Peptide amphiphiles (PAs) are co-assembled with blood components during coagulation to engineer a living material that exhibits key compositional and structural properties of the RH. By exploiting non-selective and selective PA-blood interactions, the material can be immediately manipulated, mechanically-tuned, and 3D printed. The material preserves normal platelet behavior, generates and provides a continuous source of growth factors, and promotes in vitro growth of mesenchymal stromal cells, endothelial cells, and fibroblasts. Furthermore, using a personalized autologous approach to convert whole blood into PA-blood gel implants, bone regeneration is shown in a critical-sized rat calvarial defect. This study provides proof-of-concept for a biocooperative approach that goes beyond biomimicry by using mechanisms that Nature has evolved to heal as tools to engineer accessible, personalized, and regenerative biomaterials that can be readily formed at point of use.