A High-Throughput Automated Microfluidic Platform for Calcium Imaging of Taste Sensing

Evaluating chemical effects on human neural cells through calcium imaging and deep learning

New substances intended for human consumption must undergo extensive preclinical safety pharmacology testing prior to approval. These tests encompass the evaluation of effects on the central nervous system, which is highly sensitive to chemical substances. With the growing understanding of the species-specific characteristics of human neural cells and advancements in machine learning technology, the development of effective and efficient methods for the initial screening of chemical effects on human neural function using machine learning platforms is anticipated. In this study, we employed a deep learning model to analyze calcium dynamics in human-induced pluripotent stem cell-derived neural progenitor cells, which were exposed to various concentrations of four representative chemicals. We report that this approach offers a reliable and concise method for quantitatively classifying the effects of chemical exposures and predicting potential harm to human neural cells.

The impacts and mechanisms of dietary proteins on glucose homeostasis and food intake: a pivotal role of gut hormones

Glucose and energy metabolism disorders are the main reasons induced type 2 diabetes (T2D) and obesity. Besides providing energy, dietary nutrients could regulate glucose homeostasis and food intake via intestinal nutrient sensing induced gut hormone secretion. However, reviews regarding intestinal protein sensing are very limited, and no accurate information is available on their underlying mechanisms. Through intestinal protein sensing, dietary proteins regulate glucose homeostasis and food intake by secreting gut hormones, such as glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and glucose-dependent insulinotropic polypeptide (GIP). After activating the sensory receptors, such as calcium-sensing receptor (CaSR), peptide transporter-1 (PepT1), and taste 1 receptors (T1Rs), protein digests induced Ca2+ influx and thus triggered gut hormone release. Additionally, research models used to study intestinal protein sensing have been emphasized, especially several innovative models with excellent physiological relevance, such as co-culture cell models, intestinal organoids, and gut-on-a-chips. Lastly, protein-based dietary strategies that stimulate gut hormone secretion and inhibit gut hormone degradation are proposed for regulating glucose homeostasis and food intake.

Selective Trapping and Retrieval of Single Cells Using Microwell Array Devices Combined with Dielectrophoresis

We proposed selective manipulation techniques for retrieving and retaining target cells arrayed in microwells based on dielectrophoresis (DEP). The upper substrate with microband electrodes was mounted on the lower substrate with microwells based on the same design of microband electrodes by 90 degree relative to the lower substrate. A repulsive force of negative dielectrophoresis (n-DEP) was employed to retrieve the target cells from the microwell array selectively. Furthermore, the target cells were retained in the microwells after other cells were removed by n-DEP. Thus, the system described in this study could make it possible to retrieve and recover single target cells from a microwell array after determining the function of cells trapped in each microwell.

Matrine, as a CaSR agonist promotes intestinal GLP-1 secretion and improves insulin resistance in diabetes mellitus

BACKGROUND

Matrine (Mat), a bitter tastes compounds of derived from leguminosae such as Sophora flavescens and S. subprostrata, commonly used to improve obesity and diabetes.

PURPOSE

Our study to demonstrate bitter substances can stimulate the Bitter taste receptors (TAS2Rs) or Calcium-sensing receptor (CaSR) to stimulate the secretion of GLP-1 to promote blood glucose regulation.

METHODS

The diabetic mice and intestinal secretory cell model were established to evaluate the Mat on glucose metabolism, intestinal insulin secretion and GLP-1 secretion related substances. To clarify the mechanism of Mat in regulating GLP-1 secretion by immunofluorescence, calcium labeling, siRNA, and molecular docking.

RESULTS

The results showed that Mat could significantly improve glucose metabolism and increased insulin and GLP-1 secretion in diabetic mice and increased trisphosphate inositol (IP3) levels by affecting the expression of phospholipase C β2 (PLCβ2) and promote an increase in intracellular Ca2+ levels in STC-1 cells to subsequently stimulate the secretion of GLP-1. Knockdown of the bitter taste receptors mTas2r108, mTas2r137, and mTas2r138 in STC-1 cells by siRNA did could not affect the role of Mat in regulating GLP-1. However, the secretion of GLP-1 by Mat could be significantly inhibited by administration of a CaSR inhibitor or siRNA CaSR. Molecular docking analysis showed that Mat could embed CaSR protein and bind to the original ligand of the egg white at the same amino acid site to play the role of an agonist.

CONCLUSION

Matrine is a typical bitter alkaloid could be used as an agonist of CaSR to stimulate the secretion of GLP-1 in the intestine, and it may be used as a potential drug for diabetes treatment.

Development of innovative tools for investigation of nutrient-gut interaction

The gastrointestinal tract is the key interface between the ingesta and the human body. There is wide recognition that the gastrointestinal response to nutrients or bioactive compounds, particularly the secretion of numerous hormones, is critical to the regulation of appetite, body weight and blood glucose. This concept has led to an increasing focus on "gut-based" strategies for the management of metabolic disorders, including type 2 diabetes and obesity. Understanding the underlying mechanisms and downstream effects of nutrient-gut interactions is fundamental to effective translation of this knowledge to clinical practice. To this end, an array of research tools and platforms have been developed to better understand the mechanisms of gut hormone secretion from enteroendocrine cells. This review discusses the evolution of in vitro and in vivo models and the integration of innovative techniques that will ultimately enable the development of novel therapies for metabolic diseases.

An Automated Perifusion System for Modifying Cell Culture Conditions over Time

BACKGROUND

Cells are continuously exposed to changes in their environment. Endocrine systems, in particular, communicate by rhythms and feedback loops. In this study, we developed an automated system to produce such conditions for cultured cells in a precisely timed manner. We utilized a programmable pair of syringe pumps for inflow and a peristaltic pump for outflow to create rhythmic pulses at 5-min intervals in solutions that mimic the endogenous patterns of insulin produced by pancreatic islets as a test case.

RESULTS

This perifusion system was first tested by measuring trypan blue absorbance, which was intermittently added and washed out at 3:3 and 2:3 min (in:out). Absorbance corresponded with patterns of trypan blue delivery. We then created patterns of forced oscillations in islets by intermittently switching between solutions containing 28 millimolar (mM) glucose (producing high levels of intracellular calcium ([Ca²⁺]_i) and insulin secretion) and 28 mM glucose + calcium-channel blocker nifedipine (producing low levels of [Ca²⁺]_i and insulin secretion). Forced perifusion effects were monitored by fura-2 AM fluorescence measurements of [Ca²⁺]_i. Islets showed uniform oscillations in [Ca²⁺]_i at time intervals consistent with the perifusion pattern, mimicking endogenous pulsatility.

CONCLUSIONS

This study highlights a valuable method to modify the environment of the cell culture over a period of hours to days.