Polymer fibers as contact guidance to orient microvascularization in a 3D environment

Abstract

We describe an in vitro culture process that uses 100-microm diameter poly(ethylene terephthalate) monofilaments as contact guidance of human umbilical vein endothelial cells (HUVECs) to orient the development of microvessels in a 3D environment. Untreated fibers, distanced either by 0.05, 0.1, 0.15, or 0.2 mm were first covered with HUVECs and then sandwiched between two layers of fibrin gel containing HUVECs. After 2 and 4 days of culture, cell connections and microvessels were evaluated. Cell connections formed massively along and in between adjacent fibers that were distanced by 0.05 and 0.1 mm, whereas with fibers separated by larger distances, connections were rare. After 4 days of culture, the optimum fiber-to-fiber distance to form microvessels was 0.1 mm. This study reveals that polymer fibers embedded in gel can be used as guides to direct the microvascularization process, with potential applications in cancer and cardiovascular research and tissue engineering.

Development of fibrin gel-microgroove model for microvascularization by endothelial cells

“…Moreover, in 100-μm microgrooves, it was frequently observed that cell branches connected with each other and formed networks. As such networks would subsequently lead to the formation of lumens in a vascularization process, the present finding that the formation of multicellular network was predominant in 100-μm microgrooves may suggest that 100-μm microgrooves were a preferred condition among the four types, which is consistent with the findings of previous studies [5,10]. Therefore, this agreement proves that the microgroove structure can be an alternative experimental model to polymer fibers in the study of microvascularization.…”

“…PET fibers which had been used as a geometrical guidance to endothelial cells for microvascularization in previous studies [5,10], were replaced with a micrometer-scale structure, microgrooves. Using MEMS techniques, microgrooves with different sizes (groove width) can be patterned in a small area.…”

“…2(b)). The 100-μm-wide spacing mimicked the diameter of PET fibers used in the studies of Sukmana and Vermette [5,10].…”

“…In a previous study, Sukmana and Vermette cultured ECs for several days with paralleled fibers, which was made from polyethylene terephthalate (PET) and sandwiched by two layers of fibrin gel, for stimulating microvascularization [5]. It was demonstrated that the PET fibers served as a geometrical guidance to restrict and align the cells towards the formation of tube-like structure between two adjacent fibers.…”

“…It was demonstrated that the PET fibers served as a geometrical guidance to restrict and align the cells towards the formation of tube-like structure between two adjacent fibers. It was also concluded that in the range of 50 μm to 200 μm, fibers spaced at a distance of 100 μm were an optimal condition for tube-like structure formation [5]. However, only one condition for fiber spacing could be examined in one device, which would impair the efficiency of examining further variations of fiber spacing distance as well as fiber diameter.…”