In drug discovery, the emergence of unexpected toxicity is often a problem resulting from a poor understanding of the pharmacokinetics of drug–drug interactions (DDI). Organ-on-a-chip (OoC) has been proposed as an in vitro model to evaluate drug efficacy and toxicity in pharmacology, but it has not been applied to DDI studies yet. In this study, we aim to evaluate whether organ-on-a-chip technologies can be applied to DDI studies. To assess the usefulness of OoC for DDI studies, we proposed a multi-organ-on-a-chip (MOoC) with a liver part as the metabolic model and a cancer part as the drug target model, and a pharmacokinetic–pharmacodynamic (PK–PD) model describing the MOoC. An anticancer prodrug, CPT-11, was used to evaluate the drug efficacy of the metabolite in the liver part of the MOoC. To evaluate DDI using the MOoC, the inhibitory effect of simvastatin and ritonavir on the metabolism of CPT-11 was tested. The DDI estimation method was evaluated by comparing the results of the concomitant administration experiment using the MOoC and the results of simulation using the proposed PK–PD model with the estimated parameters. The results were similar, suggesting that the combination of the PK–PD model and the MOoC is a useful way to predict DDI. We conclude that OoC technologies could facilitate a better understanding of pharmacokinetic mechanisms with DDI.

Microphysiological systems (MPSs), including organ-on-a-chip (OoC), have attracted attention as a novel method for estimating the effects and side effects of drugs in drug discovery. To reproduce the dynamic in vivo environment, previous MPSs were connected to pump systems to perfuse culture medium. Therefore, most MPSs are not user-friendly and have poor throughput. We aimed to develop a kinetic pump integrated microfluidic plate (KIM-Plate) by applying the stirrer-based micropump to an open access culture plate to improve the usability of MPSs. The KIM-Plate integrates six multiorgan MPS (MO-MPS) units and meets the ANSI/SBS microplate standards. We evaluated the perfusion function of the kinetic pump and found that the KIM-Plate had sufficient agitation effect. Coculture experiments with PXB cells and hiPS intestinal cells showed that the TEER of hiPS intestinal cells and gene expression levels related to the metabolism of PXB cells were increased. Hence, the KIM-Plate is an innovative tool for the easy coculture of highly conditioned cells that is expected to facilitate cell-based assays in the fields of drug discovery and biology because of its usability and high throughput nature.

Increased low-density lipoprotein levels are risk factors for diabetic neuropathy. Diabetes mellitus is associated with elevated metabolic stress, leading to oxidised low-density lipoprotein formation. Therefore, it is important to investigate the mechanisms underlying the pathogenesis of diabetic neuropathy in diabetes complicated by dyslipidaemia with increased levels of oxidised low-density lipoprotein. Here, we examined the effects of hyperglycaemia and oxidised low-density lipoprotein treatment on Schwann cell death and its underlying mechanisms. Immortalised mouse Schwann cells were treated with oxidised low-density lipoprotein under normo- or hyperglycaemic conditions. We observed that oxidised low-density lipoprotein-induced cell death increased under hyperglycaemic conditions compared with normoglycaemic conditions. Moreover, hyperglycaemia and oxidised low-density lipoprotein treatment synergistically upregulated the gene and protein expression of toll-like receptor 4. Pre-treatment with TAK-242, a selective toll-like receptor 4 signalling inhibitor, attenuated hyperglycaemia- and oxidised low-density lipoprotein-induced cell death and apoptotic caspase-3 pathway. Our findings suggest that the hyperactivation of toll-like receptor 4 signalling by hyperglycaemia and elevated oxidised low-density lipoprotein levels synergistically exacerbated diabetic neuropathy; thus, it can be a potential therapeutic target for diabetic neuropathy.

Numerous in vitro studies have been conducted in conventional static cell culture systems. However, most of the results represent an average response from a population of cells regardless of their local microenvironment. A microfluidic probe is a non-contact technology that has been widely used to perform local chemical stimulation within a restricted space, providing elaborated modulation and analysis of cellular responses within the microenvironment. Although microfluidic probes developed earlier have various potential applications, the two-dimensional structure can compromise their functionality and flexibility for practical use. In this study, we developed a three-dimensional microfluidic probe integrated device equipped with vertically oriented microchannels to overcome crucial challenges and tested the potential utility of the device in biological research. We demonstrated that the device tightly regulated spatial diffusion of a fluorescent molecule, and the flow profile predicted by simulation replicated the experimental results. Additionally, the device modulated the physiological Ca²⁺ response of cells within the restricted area by altering the local and temporal concentrations of biomolecules such as ATP. The novel device developed in this study may provide various applications for biological studies and contribute to further understanding of molecular mechanisms underlying cellular physiology.

Aims/Introduction: As a common chronic complication, diabetic neuropathy affects a substantial number of individuals with diabetes mellitus, with limited therapeutic options addressing the underlying pathogenesis. The glucose‐lowering action of imeglimin is mediated through improved insulin sensitivity in peripheral organs, including the skeletal muscle and liver, along with augmented insulin release from β‐cells. Imeglimin exerts its effects in part by modulating mitochondrial complex I, leading to the reduced production of reactive oxygen species and protection against metabolic stress. Despite these beneficial effects, the effect of imeglimin on diabetic neuropathy remains unclear. In this study, we evaluated whether imeglimin ameliorated peripheral nerve dysfunction in streptozotocin (STZ)‐induced diabetic rats. Materials and Methods: The rats received imeglimin (200 mg/kg twice daily) or vehicle for 4 weeks, and the sensory nerve conduction velocity (SNCV), motor nerve conduction velocity (MNCV), sciatic nerve blood flow (SNBF), and intraepidermal nerve fiber density (IENFD) were assessed. Neurite outgrowth was examined in ND7/23 cells derived from the dorsal root ganglion. Results: Imeglimin treatment significantly improved SNCV, SNBF, and IENFD without affecting blood glucose levels, indicating neuroprotective effects, independent of glycemic control. Furthermore, imeglimin enhanced neurite outgrowth in ND7/23 cells, demonstrating its direct neurotrophic effect. These findings indicate that imeglimin protects against diabetic neuropathy by enhancing nerve blood flow and promoting neurite growth independent of the systemic control of glycemia. Conclusions: This study provides supporting evidence for the potential therapeutic application of imeglimin in diabetic neuropathy.