Subtle Regulation Of Silk Scaffold Stiffness And Structures For Optimizing Vascularization Capacity

Vascularization is a key factor of facilitating tissue repair.Vascularization capacity could be improved by optimized mechanical properties,biomimetic nanostructures and sustained release of factors/small molecule drugs,resulting in better reconstruction of vascular networks.Here,various nanoscale silk elements were used to develop silk scaffolds.Kinetic factors were introduced to regulate mechanical properties subtly for optimizing vascularization capacity.Oriented cues were further provided in silk scaffolds for better vascularization.Freezing temperature as a regulating factor,was introduced to the lyophilization process.Porous scaffolds with compressive modulus of 3,4.1,5.7,6.4 and 7.4 kPa were prepared to induce better vascularization.The influence of subtly changed mechanical signal on cell behaviors was evaluated in vitro.The stem cells were cultured on the scaffolds to investigate their proliferation and endothelial differentiation behaviors.The migration of endothelial cells on the scaffolds was also studied.The in vitro cell result suggested that the cells could sense tiny changes of mechanical cues and show various vascularization behaviors.The silk scaffold with stiffness of 5.7 kPa had best vascularization capacity in our present system and facilitate improved vascular network formation and tissue ingrowth in vivo.The oriented structure was introduced into porous scaffolds based on various responsibility of different nanofiber elements.The scaffolds with suitable mechanical cues and oriented structures were developed to create better vascularization microenvironments.Finally,using beta-sheet rich silk nanofiber as the carrier,DFO-loaded silk scaffolds with oriented cues were prepared to accelerate blood vessel formation in vivo.Various regulating cues were introduced to silk-based scaffolds simultaneously,suggesting their promising future in tissue regeneration.