Pore size-mediated macrophage M1-to-M2 transition influences new vessel formation within the compartment of a scaffold. (March 2020)

• Record Type: Journal Article
• Authors: Yin, Yuan; He, Xiao-Tao; Wang, Jia; Wu, Rui-Xin; Xu, Xin-Yue; Hong, Yong-Long; Tian, Bei-Min; Chen, Fa-Ming
• Is Part Of: Applied materials today. Volume 18(2020)
• Publication Date: 2020-03
• Subjects: Vascularization -- Angiogenesis -- Macrophage polarization -- Scaffold pores -- Immunomodulation; Materials science -- Periodicals; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1016/j.apmt.2019.100466
• Languages: English
• ISSNs: 2352-9407

Abstract

Graphical abstract: Highlights: The pore size of a scaffold influences the phenotypes of resident macrophages. Macrophage polarization contributes to angiogenesis and vascularization. A scaffold with a relatively larger size promotes the angiogenesis responses in vitro . A scaffold with a relatively larger size leads to more vessel formation in vivo . Pore size-mediated macrophage M1-to-M2 transition facilitates vessel regeneration. Abstract: Increasing evidence indicates that material pore size can affect both macrophage (Mφ) polarization and new vessel formation within the compartment of a transplant. Using genipin cross-linked collagen/chitosan (Col-Ch) scaffolds with average pore sizes of 160 and 360 μm (Col-Ch-160 and Col-Ch-360, respectively) as material vascularization models, this study examined the influence of pore size-mediated M1-to-M2 transition of Mφs penetrating the scaffold on subsequent angiogenesis and vascularization. Following seeding in scaffolds, Mφs (M0 or M1) on both scaffolds tended to exhibit the M1 phenotype at day 1 and the M2 phenotype at day 3 and day 7. Col-Ch-360 exhibited a greater potential to encourage M1-to-M2 transition and to promote Mφ secretion of anti-inflammatory and pro-angiogenic cytokines. When supernatants derived from Mφ-scaffold cultures were used to incubate human umbilical vein endothelial cells (HUVECs), cells incubated with Col-Ch-360-derived supernatants displayed a great angiogenic response in terms of tube formation and cell migration. Compared with Col-Ch-160, subcutaneous transplantation of Col-Ch-360 scaffolds resulted in more blood vessel formation, along with more VEGF + cells and fewer pro-inflammatory (M1) Mφs across the pores of the material. Our data suggest that compared to Col-Ch-160, Col-Ch-360 scaffolds promote angiogenesis in vitro and vascularization in vivo, most likely because Mφs residing in materials with larger pores undergo a higher degree of M1-to-M2 transition.