Vascularized silk electrospun fiber for promoting oral mucosa regeneration

Electrospun fiber membranes have been extensively researched for tissue repair; however, fiber angiogenesis has been a difficult problem because the biomaterials used to prepare the fiber cannot promote angiogenesis by themselves. To endow the fiber with the function of promoting angiogenesis and oral mucosa regeneration, surface-aminated liposomes (NH2-LIPs) encapsulating leptin, as well as silk fiber (SF) membranes that have been immersed overnight in polydopamine (PDA) solution were synthesized. The NH2-LIPs were then grafted onto the surfaces of SF through reactions between the catechol groups of PDA and the amino groups of NH2-LIPs to induce angiogenesis on the fiber surface and thus promote oral mucosa regeneration. The PDA-modified and NH2-LIP-modified SF retained the original fibrous morphology but increased the SF tensile strength from 1.95 MPa to 2.87 MPa. PDA changed the hydrophilicity of the fibers and improved the adhesion of fibroblasts on the fibrous membranes. Leptin loaded onto SF via PDA had no significant effect on cell proliferation and formed 162.7-node tubes in human umbilical vein endothelial cells (HUVECs) within 10 h, which demonstrated that leptin loaded onto SF can promote angiogenesis. Wound closure of mucosa covered in leptin-loaded fibrous membranes reached 99% at 14 days postsurgery. Histologic analysis showed that leptin-loaded SFs exhibited clear stratification of new mucosa, as well as a strong CD34 signal that indicated the presence of new blood vessels and confirmed the successful loading of leptin on the fiber. Therefore, this work successfully showed that NH2-LIPs grafted onto the surface of SFs via PDA endow the fibers with angiogenic abilities and promote oral mucosa regeneration. Silk membranes infused with biological microparticles show promise for re-growing tissue in tricky-to-heal oral wounds. Recent studies have found that leptin, a hormone that normally regulates food intake, is also able to promote the growth of blood vessels. Wenguo Cui and Zili Ge from Soochow University in Suzhou, China, and co-workers have now developed a technique for attaching leptin to surfaces while preserving the hormone’s critical bioactivity. The team encapsulated leptin in lipid-based vesicles called liposomes, and then glued these to silk fibers using adhesives derived from mussel proteins. After cell cultures revealed the new membranes could initiate re-growth of capillary-like tissue, trials were performed on rabbits with oral injuries. The silk membrane scaffolding helped wounds to close over nearly a week faster than wounds treated with simple cotton gauze. The fiber membrane prepared from silk fibroin was modified by polydopamine and grafted the liposomes encapsulated leptin that endow the fiber with vascularization. The fiber membrane was covered with the defect of oral mucosa in rabbits, and leptin was released from the broken liposomes to promote early vascularization and accelerate the regeneration of mucous membrane.