Cell culturing experiments are ubiquitous to the study of biology, development of new medical treatments, and the biomanufacturing industry. However, there are still major technological barriers limiting the advancement of knowledge and ballooning the experimental costs associated with these systems. For example, currently, it is difficult to perform nondisruptive monitoring and control of the cells in the cultured samples. This often necessitates the use of sacrificial assays and results in product inconsistency. To resolve these bottlenecks, we present a prototype "addressable" microfluidic technology capable of spatiotemporal fluid and cell manipulations within living cultures. As a proof-of-concept, we demonstrate its ability to perform additive manufacturing by seeding cells in spatial patterns (including co-culturing multiple cell types) and subtractive manufacturing by removing surface adherent cells via the focused flow of trypsin. Additionally, we show that the device can sample fluids and perform cell "biopsies" (which can be subsequently sent for ex situ analysis), from any location within its culture chamber. Finally, the on-chip plumbing is completely automated using external electronics. This opens the possibility of performing long-term computer-driven experiments, where the cell behavior is modulated in response to the minimally disruptive observations (e.g., fluid sampling and cell biopsies) throughout the entire duration of the cultures. A limitation of the presented α prototype is that it is only two-dimensional (2D). However, technology serves as a foundation for ultimately extending the concept to three-dimensional (3D). Another limitation of the device is that it is currently made from poly(dimethylsiloxane) (PDMS), while more work needs to be done to manufacture from a material that degrades away or allow the cells to lay down the tissue matrix. Unfortunately, the existing biodegradable materials are typically not strong enough for the fabrication of microfluidic valves. Hence, new ones need to be developed before this technology can become mainstream. Yet, it is the hope of the authors that this will be achieved soon, and the microfluidic plumbing technology will eventually be scaled up to 3D, to overcome the limitations of the conventional cell culturing platforms.
Keywords: additive manufacturing; automation; biopsy; cell culturing; cell manipulation; control; fluid manipulation; microfluidics; nondestructive; nondisruptive; noninvasive; patterning; scaffolds; subtractive manufacturing; tissue engineering; wound healing.