Fabrication of organ-on-a-chip using a dynamic photomask

Approximately 90% of drugs evaluated through preclinical models fail after entering human trials. The underlying reason is that traditional models struggle to accurately mimic the physiological structure and functions of the human body, significantly reducing the accuracy of drug safety, efficacy, and toxicity assessments.

Organ-on-a-Chip (OoC) technology, an advanced in vitro platform that mimics human organ functions, is a miniature physiological modeling tool well-suited for biomedical research. It can be used to study the pathophysiology of both single organs and multiple organs. Moreover, the U.S. FDA Modernization Act 2.0 stipulates that, in addition to animal experiments, five alternative methods—including organ-on-a-chip and microphysiological systems—can also be employed for Investigational New Drug (IND) submissions. This means that by leveraging this technology, researchers can more rapidly identify and advance more effective drug candidates into clinical trials.

Over the past two decades, despite the continuous advancement of organ-on-chip (OoC) technology, the human body remains a highly complex organism composed of various organs, and OoC still faces significant challenges in accurately recreating the in vivo microenvironment and structural features. In addition to the need to transition organ cell cultures from 2D to 3D, cultivating multicellular spheroids—such as tumor spheroids and organoids—is also essential for further enhancing the physiological relevance of OoC systems. However, conventional OoC fabrication methods rely on PDMS soft lithography; devices based on PDMS may not be well-suited for toxicology and drug-screening studies. On one hand, this approach is inconvenient for modifications and lacks adaptability for dynamic cell culture; on the other hand, the fabrication process is lengthy, thereby reducing its manufacturability.

This study aims to develop a highly adaptable OoC manufacturing system that can rapidly fabricate OoCs with flexible designs, tailored to the requirements of the tissue models of interest.

The system relies on two key components: (1) a customizable microfluidic chamber and (2) a digital light mask display. Stereolithography is employed to photo-pattern hydrogels directly within the chamber, enabling the fabrication of intricate internal microfluidic channel architectures. The customizability of the microfluidic chamber allows us to precisely control critical OoC parameters, including the number, height, shape, and dimensions of the inlet and outlet ports. Our approach utilizes pre-defined microfluidic chambers customized via Xurography, as well as cell-laden microfluidic channels patterned by digital light masks; the entire process—from design to prototype—can be completed in under two hours. The versatility of our method endows OoC fabrication with previously unattainable key features, such as gradual variation in microchannel height and real-time modification of channel designs to accommodate live tissues (e.g., spheroids).

Schematic Diagram of the Dynamic Photomask OoC Manufacturing System ：

(A)

Assembly of polymer coverslips and Xerography Then, use double-sided tape (purple) to form a predefined microfluidic chamber.
It will be made of a photocrosslinkable hydrogel. LunaGel ^TM (Australia Gelomics The precursor solution (orange), composed of the company, is injected into the microfluidic chamber;
Use a digital light mask to pattern microfluidic channels in the chamber. Go Light patterning ；
The uncured precursor is discharged from the microfluidic chamber, forming the microfluidic chip.
By connecting via laser cutting PMMA The fabricated media storage device is used to set up the perfusion system (green) for re- Force The perfusion drive or silicone tubing (blue) is used for pump-assisted perfusion.

(B) The schematic diagram shows a red light-emitting diode ( LED ) Predefined microfluidic chambers, liquid crystal displays ( LCD ), xy The position of the stage and the microscope lithography instrument.

(C) Schematic diagram of the mask alignment mode on an optical measurement instrument, where (1) Red LED Used to illuminate the boundaries of a predefined microfluidic chamber, (2) Visualization and (3) At xy With the aid of a stage, align the digital photomask with the chamber.

(D) Schematic diagram of the photo-crosslinking mode, in which (1) Blue LED Repositioned to take the place of the microscope, (2) Photo-crosslink the precursor solution before activation.

(E) The photograph shows the overall structure of the developed photometric instrument.

(F) Highlight the fine-tuning stage for precise positioning of the microfluidic chamber (brown).

(G) Highlight in blue LED (Blue) and microscope (pink) in LCD The position below.

(H) shows the control box for the light measurement instrument, including the positions of the control buttons and joystick.

Article summary:

This article introduces the advantages of OoC and some of the current limitations that hinder its further development. To address these limitations, we have developed a highly dynamic system capable of meeting the diverse design requirements of specific organ-tissue microenvironments while keeping the design-to-prototype cycle within two hours. In this work, we utilize an in-house OoC photo-crosslinking instrument composed of an improved liquid-crystal display (LCD) that can function normally as a digital light mask display. The digital light mask display enables real-time observation of OoC fabrication and allows for real-time modification of the light mask to accommodate changes in shape and size. Living tissues—such as spheroids and organoids—are captured within the device.

Using this system, we have developed a simple workflow for fabricating Organ-on-a-Chip (OoC) devices, featuring the following key functionalities: (1) Easy customization of microfluidic chip architectures—such as inlet and outlet designs, device height, and internal channel configurations—to shorten the design-to-prototype cycle; (2) The ability to modify channel designs during OoC fabrication to accommodate live tissues of varying shapes and sizes. We demonstrated the successful use of our system to engineer tissue endothelialization on OoC platforms, where a functional endothelial barrier was established around a cell-laden hydrogel. The system we have developed will help accelerate the innovation of more physiologically relevant OoC devices, thereby meeting the growing demand for OoC technology in both the scientific community and the pharmaceutical industry.

Introduction to Gelomics Hydrogels

Gelomics, based in Australia, boasts advantages in bio-material supply across multiple dimensions—including natural conditions, technology, quality, environmental friendliness, and safety. After years of research and development, Gelomics has introduced LunaGel, a ready-to-use, batch-stable product solution that eliminates the need for “on-ice operations.” ^TM — A methacrylated gelatin hydrogel with both photo- and thermo-responsive properties, whose colloidal stiffness can be regulated by light exposure. It finds applications in 3D cell culture, organoids, bioprinting, animal studies, angiogenesis, and cell invasion. We offer high-quality products at affordable prices, supporting research and development in the biomedical field.

LunaGel with box PNG

Source: https://doi.org/10.1101/2023.11.22.568385

Keywords:

The 23rd China Biologics Annual Conference of CBioPC

Bai Xiaobai delivers its first GMP-compliant, high-capacity vial-specific cleaning machine.