OOCHIP: Compartmentalized Microfluidic Perfusion System with Porous Barriers for Enhanced Cell-Cell Crosstalk in Organ-on-a-Chip

Electrospun Aligned Nanofiber Yarns Constructed Biomimetic M-Type Interface Integrated into Precise Co-Culture System as Muscle-Tendon Junction-on-a-Chip for Drug Development

The incorporation of engineered muscle-tendon junction (MTJ) with organ-on-a-chip technology provides promising in vitro models for the understanding of cell-cell interaction at the interface between muscle and tendon tissues. However, developing engineered MTJ tissue with biomimetic anatomical interface structure remains challenging, and the precise co-culture of engineered interface tissue is further regarded as a remarkable obstacle. Herein, an interwoven waving approach is presented to develop engineered MTJ tissue with a biomimetic "M-type" interface structure, and further integrated into a precise co-culture microfluidic device for functional MTJ-on-a-chip fabrication. These multiscale MTJ scaffolds based on electrospun nanofiber yarns enabled 3D cellular alignment and differentiation, and the "M-type" structure led to cellular organization and interaction at the interface zone. Crucially, a compartmentalized co-culture system is integrated into an MTJ-on-a-chip device for the precise co-culture of muscle and tendon zones using their medium at the same time. Such an MTJ-on-a-chip device is further served for drug-associated MTJ toxic or protective efficacy investigations. These results highlight that these interwoven nanofibrous scaffolds with biomimetic "M-type" interface are beneficial for engineered MTJ tissue development, and MTJ-on-a-chip with precise co-culture system indicated their promising potential as in vitro musculoskeletal models for drug development and biological mechanism studies.

Fluid flow to mimic organ function in 3D in vitro models

Many different strategies can be found in the literature to model organ physiology, tissue functionality, and disease in vitro; however, most of these models lack the physiological fluid dynamics present in vivo. Here, we highlight the importance of fluid flow for tissue homeostasis, specifically in vessels, other lumen structures, and interstitium, to point out the need of perfusion in current 3D in vitro models. Importantly, the advantages and limitations of the different current experimental fluid-flow setups are discussed. Finally, we shed light on current challenges and future focus of fluid flow models applied to the newest bioengineering state-of-the-art platforms, such as organoids and organ-on-a-chip, as the most sophisticated and physiological preclinical platforms.

Alternative Methods as Tools for Obesity Research: In Vitro and In Silico Approaches

The study of adipogenesis is essential for understanding and treating obesity, a multifactorial problem related to body fat accumulation that leads to several life-threatening diseases, becoming one of the most critical public health problems worldwide. In this review, we propose to provide the highlights of the adipogenesis study based on in vitro differentiation of human mesenchymal stem cells (hMSCs). We list in silico methods, such as molecular docking for identification of molecular targets, and in vitro approaches, from 2D, more straightforward and applied for screening large libraries of substances, to more representative physiological models, such as 3D and bioprinting models. We also describe the development of physiological models based on microfluidic systems applied to investigate adipogenesis in vitro. We intend to identify the main alternative models for adipogenesis evaluation, contributing to the direction of preclinical research in obesity. Future directions indicate the association of in silico and in vitro techniques to bring a clear picture of alternative methods based on adipogenesis as a tool for obesity research.

Microfluidic systems to study tissue barriers to immunotherapy

Immunotherapies have been heavily explored in the last decade, ranging from new treatments for cancer to allergic diseases. These therapies target the immune system, a complex organ system consisting of tissues with intricate structures and cells with a multitude of functions. To better understand immune functions and develop better therapeutics, many cellular and 2-dimensional (2D) tissue models have been developed. However, research has demonstrated that the 3-dimensional (3D) tissue structure can significantly affect cellular functions, and this is not recapitulated by more traditional 2D models. Microfluidics has been used to design 3D tissue models that allow for intricate arrangements of cells and extracellular spaces, thus allowing for more physiologically relevant in vitro model systems. Here, we summarize the multitude of microfluidic devices designed to study the immune system with the ultimate goal to improve existing and design new immunotherapies. We have included models of the different immune organs, including bone marrow and lymph node (LN), models of immunity in diseases such as cancer and inflammatory bowel disease, and therapeutic models to test or engineer new immune-modulatory treatments. We particularly emphasize research on how microfluidic devices are used to better understand different physiological states and how interactions within the immune microenvironment can influence the efficacy of immunotherapies.

Adhesive-Based Fabrication Technique for Culture of Lung Airway Epithelial Cells with Applications in Cell Patterning and Microfluidics

This work describes a versatile and cost-effective cell culture method for micropatterning and growing adherent cells on porous membranes using pressure-sensitive double-sided adhesives. This technique also allows cell culture using conventional methods and their easy integration into microfluidic chip devices. Adhesives can be used to form different patterns of cultured cells, which can be used for cell proliferation and wound-healing models. To demonstrate the viability of our system, we evaluate the toxicity effect of five different adhesives on two distinct airway epithelial cell lines and show functional applications for cell patterning and microfluidic cell culture chip fabrication. We developed a sandwiched microfluidic device that enabled us to culture cells in a submerged condition and transformed it into a dynamic platform when required. The viability of cells and their inflammatory responses to IL-1β stimulation were investigated. Our technique is applicable for conventional culturing of cells, widely available in biomedical research labs, while enabling the introduction of perfusion for an advanced dynamic cell culture model when needed.