Fabrication of a bioreactor combining soft lithography and vat photopolymerisation to study tissues and multicellular organisms under dynamic culture conditions.

Despite its capability to create much more realistic microenvironments for culturing of animal or human biological models, the spread of microfluidic tools in the world of biology and medicine has still not reached the predicted scale. Major obstacles to their widespread acceptance by end-users are manufacturing cost and operational complexity. 3D printing is a technology that is now widely democratised, thanks to its ease of use and very attractive cost/performance ratio. In particular, photopolymerisation through a liquid crystal screen is experiencing a very significant growth. Here, we describe the methodology we developed to evaluate this microfabrication technique and selected a photoprintable resin to manufacture a fluidic microsystem dedicated to tissue or micro-organism culture. The first originality of our approach lies in the architecture of the microsystem, which is made up of an elementary culture chamber in two parts, making it very easy to open after the culture period to carry out biochemical analyses. The second one is the nature of the materials used to make up the culture chamber, which consists of polydimethylsiloxane and a photoprinted resin. This hybrid assembly, combining an elastomer and a rigid plastic material, ensures a better seal and better dimensional control once the assembly is complete. We demonstrate the ability of our protocol to flexibly fabricate different culture chambers with dimensions down to 100 microns and we show for one of them three applications: a 2D layer of cell lines, a parasitic worm and a 3D microtissue from a pancreatic cancer patient.