An Automated Microfluidics Technology for Minimally Disruptive Analysis of Cells and Fluids within Living 3D Cultures

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SUMMARY Cell experiments are ubiquitous to the studies of biology, tissue engineering and drug testing. However, 3D cultures are notoriously difficult to analyze nondestructively. Instead, they are typically evaluated using sacrificial means: such as histology sectioning, or by crushing the sample for chemical plate-reader assays. This is inefficient, costly and results in data discontinuity because each new experiment only provides a single time point (which is further averaged over the whole construct, if crushed). Likewise, delivering new cells or chemicals (e.g., nutrients, drugs, dyes, etc.) to custom locations without disturbing an on-going experiment is also difficult: only invasive injections would ensure that the deep portions of a 3D culture are reached. This limits the type of experiments that are feasible; and, the inability to deliver nutrients results in cell death in the deep portions of the thick cultures (i.e., it is currently not possible to grow them to physiologically relevant sizes). Therefore, there is a need to be able to perform fluid and cell manipulations (i.e., delivering, probing, removing, and sampling) within the living 3D cultures, continuously and with minimal effects to the studied biology. To that end, the broad goal of the proposed project is to resolve all these bottlenecks simultaneously, and additionally create a breadth of new experimental possibilities, by interlacing the 3D cultures with automated microscopic channels and ports. The feasibility of the idea has been demonstrated via a proof-of-concept prototype capable of XY fluid and cell manipulations within a living 2D culture. Therefore, the proposed R15 program takes the next logical steps by scaling up this invention to 3D scaffolds (Aim 1) and demonstrating its first practical application - a continuous nondestructive spatiotemporal culture analysis (Aim 2). Specifically, Aim 1 designs a novel plumbing architecture capable of performing thousands of XYZ fluid/cell manipulations using minimal external hardware (Task 1). It also devises a fabrication recipe for a hands-free manufacturing of the microfluidic scaffolds using commercially available 3D printers (Task 2). Simultaneously, Aim 2 uses the existing 2D prototype (until the 3D scaffold from Aim 1 is ready) to determine how to use conventional end-point (i.e., toxic) chemical assays ex-situ in order to obtain a continuous stream of information about the cell behavior occurring at different points in a living culture. A successful outcome of this aim will enable circumventing the reliance on sacrificial analysis (e.g., histology), which will speed up experiments, save costs and yield troves of continuous spatiotemporal biological data. Ultimately, this technology will facilitate the future development of closed-loop controls of basic cell behavior in organ-sized 3D scaffolds, which will generally benefit multiple fields of research and industries that involve microorganism cultures: such as biology, regenerative medicine, production of biological molecules, drug testing, toxicology, cosmetics, etc. Chem/Bio/Electr/Comp Eng undergrads (~10 total) will be exposed to multidisciplinary 3D printing, microfluidics, microscopy, and cell culturing research over the course of the 3 yr project.