Lung-on-a-chip devices could provide new strategies for a biomimetic lung cell microenvironment and construction of lung disease models in vitro, and are expected to greatly promote the development of drug evaluation, toxicological detection, and disease model building. In this study, we developed a novel poly (lactic-co-glycolic acid) (PLGA) nanofiber/polydimethylsiloxane (PDMS) microporous composite membrane-sandwiched lung-on-a-chip to perform anti-tumor drug testing. The composite membrane was characterized, and the results showed that it was permeable to molecules and thus could be used to study small-molecule drug diffusion. In addition, the microchip could apply perfusion fluids to simulate blood flow under extremely low fluid shear stress, and could also simulate the spherical-like shape of the alveoli by deformation of the composite membrane. Using this chip, we evaluated the anti-tumor drug efficacy of gefitinib in two kinds of non-small cell lung cancer cells, the lung adenocarcinoma NCI-H1650 cell line and the large cell lung cancer NCI-H460 cell line. We further probed the resistance of NCI-H460 cells to gefitinib under normoxic and hypoxic conditions. The established composite membrane-sandwiched lung chip can simulate more biochemical and biophysical factors in the lung physiological and pathological microenvironment, and it has important applications in the personalized treatment of lung tumors. It is expected to play a potential role in clinical diagnosis and drug screening.

In this study, we designed and manufactured a series of different microstructure topographical cues for inducing neuronal differentiation of cells in vitro, with different topography, sizes, and structural complexities. We cultured PC12 cells in these microstructure cues and then induced neural differentiation using nerve growth factor (NGF). The pheochromocytoma cell line PC12 is a validated neuronal cell model that is widely used to study neuronal differentiation. Relevant markers of neural differentiation and cytoskeletal F-actin were characterized. Cellular immunofluorescence detection and axon length analysis showed that the differentiation of PC12 cells was significantly different under different isotropic and anisotropic topographic cues. The expression differences of the growth cone marker growth-associated protein 43 (GAP-43) and sympathetic nerve marker tyrosine hydroxylase (TH) genes were also studied in different topographic cues. Our results revealed that the physical environment has an important influence on the differentiation of neuronal cells, and 3D constraints could be used to guide axon extension. In addition, the neurotoxin 6-hydroxydopamine (6-OHDA) was used to detect the differentiation and injury of PC12 cells under different topographic cues. Finally, we discussed the feasibility of combining the topographic cues and the microfluidic chip for neural differentiation research.

Microfluidic spinning, which has recently emerged as an important approach to processing hydrogels, can handle the flow in the fluid channel and generate microfibers in a controlled and mild manner, and therefore, it is suitable for cell loading, long-term culture, and tissue engineering. In this study, we utilized three-dimensional (3D) printing technology to prepare microfluidic chip templates with different microchannel heights in a one-step manner and obtained microfluidic spinning and microfiber assembly microchips. Hollow calcium alginate (CaA)/gelatin methacrylate (GelMA) composite microfibers were successfully prepared using a microfluidic spinning microchip combined with different fluid-injection strategies. The obtained hollow microfibers had one, two, or three lumens, and different inclusions could be added to the fiber walls. Hollow microfibers with a single lumen were used to load human umbilical vein endothelial cells (HUVECs) and exhibited good cell compatibility and barrier functions. We constructed a neural model based on the HUVEC-loaded hollow microfibers using a customized 3D printer. Using this established neural model, we induced the neural differentiation of rat adrenal medullary pheochromocytoma cells (PC12) using nerve growth factor. Axonal length, tubulin expression, and related gene (GAP-43 and TH) expression in PC12 cells were assessed. The current findings underscore the potential of utilizing microfluidic spinning in in vitro blood–brain barrier simulation, neuropharmaceutical and toxin evaluation, and brain-on-a-chip construction.