Hydrophobic surface induced pro-metastatic cancer cells for in vitro extravasation models

In vitro vascularized cancer models utilizing microfluidics have emerged as a promising tool for mechanism study and drug screening. However, the lack of consideration and preparation methods for cancer cellular sources that are capable of adequately replicating the metastatic features of circulating tumor cells contributed to low relevancy with in vivo experimental results. Here, we show that the properties of cancer cellular sources have a considerable impact on the validity of the in vitro metastasis model. Notably, with a hydrophobic surface, we can create highly metastatic spheroids equipped with aggressive invasion, endothelium adhesion capabilities, and activated metabolic features. Combining these metastatic spheroids with the well-constructed microfluidic-based extravasation model, we validate that these metastatic spheroids exhibited a distinct extravasation response to epidermal growth factor (EGF) and normal human lung fibroblasts compared to the 2D cultured cancer cells, which is consistent with the previously reported results of in vivo experiments. Furthermore, the applicability of the developed model as a therapeutic screening platform for cancer extravasation is validated through profiling and inhibition of cytokines. We believe this model incorporating hydrophobic surface-cultured 3D cancer cells provides reliable experimental data in a clear and concise manner, bridging the gap between the conventional in vitro models and in vivo experiments.

A three-dimensional human adipocyte model of fatty acid-induced obesity

Obesity prevalence has reached pandemic proportions, leaving individuals at high risk for the development of diseases such as cancer and type 2 diabetes. In obesity, to accommodate excess lipid storage, adipocytes become hypertrophic, which is associated with an increased pro-inflammatory cytokine secretion and dysfunction of metabolic processes such as insulin signaling and lipolysis. Targeting adipocyte dysfunction is an important strategy to prevent the development of obesity-associated disease. However, it is unclear how accurately animal models reflect human biology, and the long-term culture of human hypertrophic adipocytes in an in vitro 2D monolayer is challenging due to the buoyant nature of adipocytes. Here we describe the development of a human 3D in vitro disease model that recapitulates hallmarks of obese adipocyte dysfunction. First, primary human adipose-derived mesenchymal stromal cells are embedded in hydrogel, and infiltrated into a thin cellulose scaffold. The thin microtissue profile allows for efficient assembly and image-based analysis. After adipocyte differentiation, the scaffold is stimulated with oleic or palmitic acid to mimic caloric overload. Using functional assays, we demonstrated that this treatment induced important obese adipocyte characteristics such as a larger lipid droplet size, increased basal lipolysis, insulin resistance and a change in macrophage gene expression through adipocyte-conditioned media. This 3D disease model mimics physiologically relevant hallmarks of obese adipocytes, to enable investigations into the mechanisms by which dysfunctional adipocytes contribute to disease.

Intestinal organoids in infants and children

Recent advances in culturing of intestinal stem cells and pluripotent stem cells have led to the development of intestinal organoids. These are self-organizing 3D structures, which recapitulate the characteristics and physiological features of in vivo intestinal epithelium. Intestinal organoids have allowed the development of novel in vitro models to study various gastrointestinal diseases expanding our understanding of the pathophysiology of diseases and leading to the development of innovative therapies. This article aims to summarize the current usage of intestinal organoids as a model of gastrointestinal diseases and the potential applications of intestinal organoids in infants and children. Intestinal organoids allow the study of intestinal epithelium responses to stress factors. Mimicking intestinal injury such as necrotizing enterocolitis, intestinal organoids increases the expression of pro-inflammatory cytokine genes and shows disruption of tight junctions after they are injured by lipopolysaccharide and hypoxia. In cystic fibrosis, intestinal organoids derived from rectal biopsies have provided benefits in genetic studies and development of novel therapeutic gene modulation. Transplantation of intestinal organoids via enema has been shown to rescue damaged colonic epithelium in mice. In addition, tissue-engineered small intestine derived from intestinal organoids have been successfully established providing a potential novel treatment and a new hope for children with short bowel syndrome.