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Microfluidic organs-on-chips aim to realize more biorelevant in vitro experiments compared to traditional two-dimensional (2D) static cell culture. Often such devices are fabricated via poly(dimethylsiloxane) (PDMS) soft lithography, which offers benefits (e.g., high feature resolution) along with drawbacks (e.g., prototyping time/costs). Here, we report benchtop fabrication of multilayer, PDMS-free, thermoplastic organs-on-chips via laser cut and assembly with double-sided adhesives that overcome some limitations of traditional PDMS lithography. Cut and assembled chips are economical to prototype ($2 per chip), can be fabricated in parallel within hours, and are Luer compatible. Biocompatibility was demonstrated with epithelial line Caco-2 cells and primary human small intestinal organoids. Comparable to control static Transwell cultures, Caco-2 and organoids cultured on chips formed confluent monolayers expressing tight junctions with low permeability. Caco-2 cells-on-chip differentiated ∼4 times faster, including increased mucus, compared to controls. To demonstrate the robustness of cut and assemble, we fabricated a dual membrane, trilayer chip integrating 2D and 3D compartments with accessible apical and basolateral flow chambers. As proof of concept, we cocultured a human, differentiated monolayer and intact 3D organoids within multilayered contacting compartments. The epithelium exhibited 3D tissue structure and organoids expanded close to the adjacent monolayer, retaining proliferative stem cells over 10 days. Taken together, cut and assemble offers the capability to rapidly and economically manufacture microfluidic devices, thereby presenting a compelling fabrication technique for developing organs-on-chips of various geometries to study multicellular tissues.

Tissue-engineered models continue to experience challenges in delivering structural specificity, nutrient delivery, and heterogenous cellular components, especially for organ-systems that require functional inputs/outputs and have high metabolic requirements, such as the heart. While soft lithography has provided a means to recapitulate complex architectures in the dish, it is plagued with a number of prohibitive shortcomings. Here, concepts from microfluidics, tissue engineering, and layer-by-layer fabrication are applied to develop reconfigurable, inexpensive microphysiological systems that facilitate discrete, 3D cell compartmentalization, and improved nutrient transport. This fabrication technique includes the use of the meniscus pinning effect, photocrosslinkable hydrogels, and a commercially available laser engraver to cut flow paths. The approach is low cost and robust in capabilities to design complex, multilayered systems with the inclusion of instrumentation for real-time manipulation or measures of cell function. In a demonstration of the technology, the hierarchal 3D microenvironment of the cardiac sympathetic nervous system is replicated. Beat rate and neurite ingrowth are assessed on-chip and quantification demonstrates that sympathetic-cardiac coculture increases spontaneous beat rate, while drug-induced increases in beating lead to greater sympathetic innervation. Importantly, these methods may be applied to other organ-systems and have promise for future applications in drug screening, discovery, and personal medicine.

Suturing peripheral nerve transections is the predominant therapeutic strategy for nerve repair. However, the use of sutures leads to scar tissue formation, hinders nerve regeneration, and prevents functional recovery. Fibrin-based adhesives have been widely used for nerve reconstruction, but their limited adhesive and mechanical strength and inability to promote nerve regeneration hamper their utility as a stand-alone intervention. To overcome these challenges, we engineered composite hydrogels that are neurosupportive and possess strong tissue adhesion. These composites were synthesized by photocrosslinking two naturally derived polymers, gelatin-methacryloyl (GelMA) and methacryloyl-substituted tropoelastin (MeTro). The engineered materials exhibited tunable mechanical properties by varying the GelMA/MeTro ratio. In addition, GelMA/MeTro hydrogels exhibited 15-fold higher adhesive strength to nerve tissue ex vivo compared to fibrin control. Furthermore, the composites were shown to support Schwann cell (SC) viability and proliferation, as well as neurite extension and glial cell participation in vitro, which are essential cellular components for nerve regeneration. Finally, subcutaneously implanted GelMA/MeTro hydrogels exhibited slower degradation in vivo compared with pure GelMA, indicating its potential to support the growth of slowly regenerating nerves. Thus, GelMA/MeTro composites may be used as clinically relevant biomaterials to regenerate nerves and reduce the need for microsurgical suturing during nerve reconstruction.