Adipose-derived mesenchymal stem/stromal cells (ADMSC) are one of the major stromal cells in the breast cancer microenvironment that promote cancer progression. Previous studies on the effects of ADMSC on breast cancer metastasis and drug resistance, using two-dimensional (2D) cultures, remained inconclusive. In the present study, we compared cocultured ADMSC and human epidermal receptor 2 positive breast primary breast cancer cells (21PT) in 2D and three-dimensional (3D) cultures and then examined their response to doxorubicin (DOX). We examined 3D bioprinted constructs with breast cancer cells in the middle and ADMSC in the edge region, which were made by using dual hydrogel-based bioinks. We found that the percentage of cleaved Caspase-3 positive cells was significantly lower in the bioprinted constructs with ADMSC and 21PT than that in the cancer cell alone constructs, in response to low DOX dose. We further increased the thickness of the ADMSC layers to mimic the status of obesity and then examined the effect of ADMSC thickness on DOX resistance and lysyl oxidase (LOX) secretion. In the moderate and thick-layered ADMSC constructs, significantly more cells were stained negative for cleaved Caspase-3, indicating less apoptosis. Both ADMSC and 21PT intrinsically expressed LOX, regardless of changes in thickness or DOX administration. Notably, treatment with a LOX inhibitor significantly decreased the stiffness in the ADMSC region but did not affect the stiffness in the 21PT region. In addition, LOX inhibitor treatment enhanced DOX sensitivity of 21PT in the bioprinted constructs, as seen by a decrease in LOX secretion and downregulation of adenosine triphosphate-binding cassette transporter gene expression. Taken together, we demonstrate that 3D bioprinted these breast cancer models faithfully reproduce in vivo conditions and should provide better models for examining breast cancer biology and for screening for drug discoveries.

The blood–brain barrier (BBB) is an active and complex diffusion barrier that separates the circulating blood from the brain and extracellular fluid, regulates nutrient transportation, and provides protection against various toxic compounds and pathogens. Creating an in vitro microphysiological BBB system, particularly with relevant human cell types, will significantly facilitate the research of neuropharmaceutical drug delivery, screening, and transport, as well as improve our understanding of pathologies that are due to BBB damage. Currently, most of the in vitro BBB models are generated by culturing rodent astrocytes and endothelial cells, using commercially available transwell membranes. Those membranes are made of plastic biopolymers that are nonbiodegradable, porous, and stiff. In addition, distinct from rodent astrocytes, human astrocytes possess unique cell complexity and physiology, which are among the few characteristics that differentiate human brains from rodent brains. In this study, we established a novel human BBB microphysiologocal system, consisting of a three-dimensionally printed holder with a electrospun poly(lactic-co-glycolic) acid (PLGA) nanofibrous mesh, a bilayer coculture of human astrocytes, and endothelial cells, derived from human induced pluripotent stem cells (hiPSCs), on the electrospun PLGA mesh. This human BBB model achieved significant barrier integrity with tight junction protein expression, an effective permeability to sodium fluorescein, and higher transendothelial electrical resistance (TEER) comparing to electrospun mesh-based counterparts. Moreover, the coculture of hiPSC-derived astrocytes and endothielial cells promoted the tight junction protein expression and the TEER value. We further verified the barrier functions of our BBB model with antibrain tumor drugs (paclitaxel and bortezomib) and a neurotoxic peptide (amyloid β 1–42). The human microphysiological system generated in this study will potentially provide a new, powerful tool for research on human BBB physiology and pathology.

No abstract