Micropatterned composite membrane guides oriented cell growth and vascularization for accelerating wound healing

Skin defect is common in daily life,but repairing large skin defects remains a challenge.Using biomaterials to deliver biochemical or physical factors to promote skin tissue regeneration is of great significance for accelerating wound healing.Specific surface micropatterns on biomaterials could affect cell behavior and tissue regeneration.However,few studies have focused on the construction of wound healing biomaterials with surface micropatterns and their role in skin tissue regeneration.In the present study,gelatin-polycaprolactone/silk fibroin composite membranes with different micropatterns were fabricated by photolithography,including line,grid and plane micropatterns.In vitro cell experiments demonstrated that the line micropattern on the composite membrane could guide cell-oriented growth,and more importantly,promote the expression of angiogenesis-related markers andα-smooth muscle actin(α-SMA)at both gene level and protein level.In the rat full-thickness skin defect model,the composite membrane with line micropatterns increasedα-SMA production and neovascularization in wounds,leading to accelerated wound contraction and healing.The current study not only suggests that composite membranes with specific micropatterns can be promising wound repair materials but also provides new insights into the importance of biomaterial surface topology for tissue regeneration.

Zn/Sr dual ions-collagen co-assembly hydroxyapatite enhances bone regeneration through procedural osteo-immunomodulation and osteogenesis

The immune microenvironment induced by biomaterials played vital roles in bone regeneration.Hydroxyapatite(HA)and its ion-substituted derivates represent a large class of core inorganic materials for bone tissue engineering.Although ion substitution was proved to be a potent way to grant HA more biological functions,few studies focused on the immunomodulatory properties of ion-doped HA.Herein,to explore the potential osteoimmunomodulatory effects of ion-doped HA,zinc and strontium co-assembled into HA through a collagen template biomimetic way(ZnSr-Col-HA)was successfully achieved.It was found that ZnSr-Col-HA could induce a favorable osteo-immune microenvironment by stimulating macrophages.Furthermore,ZnSr-Col-HA demonstrated a procedural promoting effect on osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)in vitro.Specifically,the osteo-immune microenvironment acted as a dominant factor in promoting osteogenic gene expressions at the early stage through OSM signal pathway.Whereas the direct stimulating effects on BMSCs by Zn^(2+)/Sr^(2+) were more effectively at the later stage with Nfatc1/Maf and Wnt signals activated.In vivo study confirmed strong promoting effects of ZnSr-Col-HA on critical-sized cranial defect repair.The current study indicated that such a combined biomaterial design philosophy of dual ion-doping and biomimetic molecular co-assembly to endow HA applicable osteoimmunomodulatory characteristics might bring up a new cutting-edge concept for bone regeneration study.