Construction of functional tissue-engineered microvasculatures by using circulating fibrocytes as mural cells

Mural cells are essential to the proper function of microvasculatures. However, the feasible cell source for mural cells has not been found, which is one of the key obstacles facedin tissue engineering. Our data show that circulating fibrocytes (CFs) sheathed and stabilized the microvasculatures formed by vascular endothelial cells (VECs) in collagen gel, formed gap junctions with VECs, and induced formation of basement membrane. When transplanted into nude mice with VECs either in collagen gel or Matrigel, CFs sheathed the microvasculatures formed by VECs, induced basal membrane formation and the microvasculatures connected to the host circulation. Human brain pericytes (HBPCs) had similar function to CFs, but HBPCs often mosaic into the lumen of capillary-like structures, actively proliferate, and have lower capacity of endocytosis and migration. Based on these data, we concluded thatCFs can be used as the cell source for mural cells to generate tissue-engineered microvasculatures