Optimization of Factor Combinations for Stem Cell Differentiations on a Design-of-Experiment Microfluidic Chip

Recent advances in liver-on-chips: Design, fabrication, and applications

The liver is a multifunctional organ and the metabolic center of the human body. Most drugs and toxins are metabolized in the liver, resulting in varying degrees of hepatotoxicity. The damage of liver will seriously affect human health, so it is very important to study the prevention and treatment of liver diseases. At present, there are many research studies in this field. However, most of them are based on animal models, which are limited by the time-consuming processes and species difference between human and animals. In recent years, liver-on-chips have emerged and developed rapidly and are expected to replace animal models. Liver-on-chips refer to the use of a small number of liver cells on the chips to simulate the liver microenvironment and ultrastructure in vivo. They hold extensive applications in multiple fields by reproducing the unique physiological functions of the liver in vitro. In this review, we first introduced the physiology and pathology of liver and then described the cell system of liver-on-chips, the chip-based liver models, and the applications of liver-on-chips in liver transplantation, drug screening, and metabolic evaluation. Finally, we discussed the currently encountered challenges and future trends in liver-on-chips.

Optoplasmonic Modulation of Cell Metabolic State Promotes Rapid Cell Differentiation

Cell differentiation plays a vital role in mediating organ formation and tissue repair and regeneration. Although rapid and effective methods to stimulate cell differentiation for clinical purposes are highly desired, it remains a great challenge in the medical fields. Herein, a highly effective and conceptual optical method was developed based on a plasmonic chip platform (made of 2D AuNPs nanomembranes). through effective light-augmented plasmonic regulation of cellular bioenergetics (CBE) and an entropy effect at bionano interfaces, to promote rapid cell differentiation. Compared with traditional methods, the developed optoplasmonic method greatly shortens cell differentiation time from usually more than 10 days to only about 3 days. Upon the optoplasmonic treatment of cells, the conformational and vibration entropy changes of cell membranes were clearly revealed through theoretical simulation and fingerprint spectra of cell membranes. Meanwhile, during the treatment process, bioenergetics levels of cells were elevated with increasing mitochondrial membrane potential (Δψ_m), which accelerates cell differentiation and proliferation. The developed optoplasmonic method is highly efficient and easy to implement, provides a new perspective and avenue for cell differentiation and proliferation, and has potential application prospects in accelerating tissue repair and regeneration.

Clever Experimental Designs: Shortcuts for Better iPSC Differentiation

For practical use of pluripotent stem cells (PSCs) for disease modelling, drug screening, and regenerative medicine, the cell differentiation process needs to be properly refined to generate end products with consistent and high quality. To construct and optimize a robust cell-induction process, a myriad of cell culture conditions should be considered. In contrast to inefficient brute-force screening, statistical design of experiments (DOE) approaches, such as factorial design, orthogonal array design, response surface methodology (RSM), definitive screening design (DSD), and mixture design, enable efficient and strategic screening of conditions in smaller experimental runs through multifactorial screening and/or quantitative modeling. Although DOE has become routinely utilized in the bioengineering and pharmaceutical fields, the imminent need of more detailed cell-lineage specification, complex organoid construction, and a stable supply of qualified cell-derived material requires expedition of DOE utilization in stem cell bioprocessing. This review summarizes DOE-based cell culture optimizations of PSCs, mesenchymal stem cells (MSCs), hematopoietic stem cells (HSCs), and Chinese hamster ovary (CHO) cells, which guide effective research and development of PSC-derived materials for academic and industrial applications.

A high-throughput, open-space and reusable microfluidic chip for combinational drug screening on tumor spheroids

Screening drug combinations using tumor spheroids can play a vital role in the development of disease treatment and personalized medicine. However, current studies focus on drug gradients or combinations of two drugs in most cases, and it is difficult to find complex therapeutic combinations involving more drugs. The use of design-of-experiment (DOE) microfluidics is a potential strategy to study this area systematically. Here we develop a high-throughput, open-space multilayered PMMA microfluidic chip for combinational drug screening on tumor spheroids. This microchip is straightforward to fabricate, compatible with standard spheroid cultures, and friendly for end-users. The device consists of an inlet layer and multiple dispersing layers. In the inlet layer, different samples can be loaded into the chip simultaneously. The sample solutions flow into the dispersing layers to generate various combinations based on the specific DOE principle. We demonstrated that the chip performance is in quantitative agreement with the design, using water and doxycycline combinations as models. As a proof-of-concept study, we constructed a HeLa reporter cell line to quantify the autophagy of tumor spheroids and used the chip to identify critical factors relating to the growth of the spheroids. Specifically, we used L-glutamine, D-glucose, FBS, and cisplatin as the factors and studied the autophagy, growth curves, and spheroid sizes in response to different combinations of the four factors. We found that D-glucose can inhibit the effects of cisplatin on tumor spheroids, and cisplatin caused severe autophagy in 3D tumor spheroids compared to 2D monoculture cells. Our method has the potential to allow more drug combinations to be examined, and it can be extended to DOE approaches with seven or more inputs.