Adaptable Fabrication of Vascularized Milliscale Tissues in Membrane-Free Organ Chips Manufactured with 3D Printed Molds
Inexpensive stereolithography (SLA) 3D printing enables rapid prototyping of resin molds for polydimethylsiloxane (PDMS) soft lithography and organ chip fabrication, but geometric distortion and surface roughness of SLA resins can impede the development of adaptable manufacturing workflows. This study reports post-processing procedures for manufacturing SLA-printed molds built with a Formlabs F3 printer that produce fully cured, flat, patently bonded, and optically clear PDMS organ chips. User injection loading tests with iterated guide structure designs were conducted to achieve engineering reduction to practice of milliscale membrane-free organ chips (MFOC), defined as reproducible loading of aqueous solutions without failure of surface tension-based liquid patterning. The optimized manufacturing workflow was applied to further engineer milliscale MFOC for specific applications in modeling vascular physiology and pathobiology. The open lateral interfaces of bulk tissues seeded in MFOC facilitate the formation of anastomoses with internal vasculature to create milliscale perfusable vascular beds. After optimizing bulk tissue vasculogenesis in MFOC, we developed a method for seeding the bulk tissue interfaces with a confluent endothelium to stimulate self-assembly of perfusable anastomoses with the internal vasculature. Rocker- and pump-based flow-conditioning protocols were tested to engineer enhanced barrier function of the perfusable internal vasculature. Modularity of the MFOC design enabled creation of a multi-organ device that was used to model decaying gradients of cancer-associated vascular inflammation in organ compartments positioned at increasing distances from a tumor compartment. These easily adaptable methods for designing and fabricating vascularized microphysiological systems can accelerate their adoption in a diverse range of preclinical laboratory settings.