Human pluripotent stem cell (hPSC)-derived islet cells provide promising resources for diabetes studies, cell replacement treatment and drug screening. Recently, hPSC-derived organoids have represented a new class of in vitro organ models for disease modeling and regenerative medicine. However, rebuilding biomimetic human islet organoids from hPSCs remains challenging. Here, we present a new strategy to engineer human islet organoids derived from human induced pluripotent stem cells (hiPSCs) using an organ-on-a-chip platform combined with stem cell developmental principles. The microsystem contains a multi-layer microfluidic device that allows controllable aggregation of embryoid bodies (EBs), in situ pancreatic differentiation and generation of heterogeneous islet organoids in parallel under perfused 3D culture in a single device. The generated islet organoids contain heterogeneous islet-specific α and β-like cells that exhibit favorable growth and cell viability. They also show enhanced expression of pancreatic β-cell specific genes and proteins (PDX1 and NKX6.1) and increased β-cell hormone specific INS gene and C-peptide protein expressions under perfused 3D culture conditions compared to static cultures. In addition, the islet organoids exhibit more sensitive glucose-stimulated insulin secretion (GSIS) and higher Ca²⁺ flux, indicating the role of biomimetic mechanical flow in promoting endocrine cell differentiation and maturation of islet organoids. This islet-on-a-chip system is robust and amenable to real-time imaging and in situ tracking of islet organoid growth, which may provide a promising platform for organoid engineering, disease modeling, drug testing and regenerative medicine.

The blood-brain barrier (BBB) restricts the uptake of many neuro-therapeutic molecules, presenting a formidable hurdle to drug development in brain diseases. We proposed a new and dynamicin vivo-like three-dimensional microfluidic system that replicates the key structural, functional and mechanical properties of the blood-brain barrierin vivo. Multiple factors in this system work synergistically to accentuate BBB-specific attributes–permitting the analysis of complex organ-level responses in both normal and pathological microenvironments in brain tumors. The complex BBB microenvironment is reproduced in this system via physical cell-cell interaction, vascular mechanical cues and cell migration. This model possesses the unique capability to examine brain metastasis of human lung, breast and melanoma cells and their therapeutic responses to chemotherapy. The results suggest that the interactions between cancer cells and astrocytes in BBB microenvironment might affect the ability of malignant brain tumors to traverse between brain and vascular compartments. Furthermore, quantification of spatially resolved barrier functions exists within a single assay, providing a versatile and valuable platform for pharmaceutical development, drug testing and neuroscientific research.

Drug absorption in the intestine is tightly related to drug-induced nephrotoxicity, which is a relatively common side effect in clinical practice. It highlights a great need to develop predictive models with high accuracy in the early stage during new drug discovery and development. Herein, we presented a novel intestine-kidney chip, which recapitulated drug absorption in the intestine and its resultant drug toxicity on the kidney. This work aims to provide an integrated tool for accurate assessment of drug absorption-related nephrotoxicity in vitro. A microfluidic device with multi-interfaces was designed, which facilitated the co-culture of the intestinal and glomerular endothelial cells in compartmentalized micro-chambers. Thus, drug absorption and following nephrotoxicity could be explored in a single assay based on the formation of the intact intestine function on the chip. Specifically, we adopt digoxin (DIG) as a model drug combined with colestyramine (COL) or Verapamil (VER), which significantly influence DIG absorption in the intestine. Different degrees of nephrotoxicity under drug combinations were further observed on the chip, including cell apoptosis, cell viability, and lactate dehydrogenase leakage. These features were consistent with the variance of DIG absorption by the intestinal cells. In agreement with clinical observations, our data demonstrated that DIG-induced nephrotoxicity was enhanced combined with VER but weakened with COL. All of these findings suggest that the established microdevice might provide a useful and cost-effective platform in vitro for testing drug absorption and nephrotoxicity in preclinical trials during new drug development.

Cadmium (Cd) is a common environmental pollutant.