Investigation of endothelial and stem cell biochemical response in biomimetic 3D printed blood vessel scaffolds*

In vitro investigation of human umbilical vein endothelial cell (HUVEC) and adipose-derived stem cell (ADSC) responses in a biomimetic 3D bioprinted blood vessel model under complex physiological flows was performed.  The goal is to characterize the dynamic flow conditions which drive endothelial cell mechanotransduction, cellular growth, and morphological maturation, as well as the differentiation of ADSCs into endothelial-like phenotypes. Cylindrical vessel scaffolds were 3D printed using polylactic acid (PLA) material and the vessel lumen were inoculated with a co-culture of HUVEC and ADSC in a custom-built bioreactor system using cell growth medium ((DMEM, Corning®) and (ECM, Cell Applications Inc)). The vessels were installed in a sterile experimental flow loop facility capable of providing physiological flow forcing conditions. Cellular co-culture was subjected to wall shear stresses from physiological flow forcing for up to 8 hours each day and then followed by steady flow. Real-time flow conditions were monitored using disposable blood pressure transducers and an ultrasonic flow rate sensor. Post-facto analysis was performed on dissected vessels using confocal microscopy techniques, live/dead staining, and polymerase chain reaction (PCR) testing to probe cellular growth and proliferation indicators.