Composable microfluidic spinning platforms for facile production of biomimetic perfusable hydrogel microtubes

Microtissues with specific structures and integrated vessels play a key role in maintaining organ functions. To recapitulate the in vivo environment for tissue engineering and organ-on-a-chip purposes, it is essential to develop perfusable biomimetic microscaffolds. We developed facile all-aqueous microfluidic approaches for producing perfusable hydrogel microtubes with diverse biomimetic sizes and shapes. Here, we provide a detailed protocol describing the construction of the microtube spinning platforms, the assembly of microfluidic devices, and the fabrication and characterization of various perfusable hydrogel microtubes. The hydrogel microtubes can be continuously generated from microfluidic devices due to the crosslinking of alginate by calcium in the coaxial flows and collecting bath. Owing to the mild all-aqueous spinning process, cells can be loaded into the alginate prepolymer for microtube spinning, which enables the direct production of cell-laden hydrogel microtubes. By manipulating the fluid dynamics at the microscale, the composable microfluidic devices and platforms can be used for the facile generation of six types of biomimetic perfusable microtubes. The microfluidic platforms and devices can be set up within 3 h from commonly available and inexpensive materials. After 10-20 min required to adjust the platform and fluids, perfusable hydrogel microtubes can be generated continuously. We describe how to characterize the microtubes using scanning electron or confocal microscopy. As an example application, we describe how the microtubes can be used for the preparation of a vascular lumen and how to perform barrier permeability tests of the vascular lumen.