[Application of the organ-on-a-chip technology in experimental ophthalmology]

Lymph Node-on-Chip Technology: Cutting-Edge Advances in Immune Microenvironment Simulation

Organ-on-a-chip technology is attracting growing interest across various domains as a crucial platform for drug screening and testing and is set to play a significant role in precision medicine research. Lymph nodes, being intricately structured organs essential for the body's adaptive immune responses to antigens and foreign particles, are pivotal in assessing the immunotoxicity of novel pharmaceuticals. Significant progress has been made in research on the structure and function of the lymphatic system. However, there is still an urgent need to develop prospective tools and techniques to delve deeper into its role in various diseases' pathological and physiological processes and to develop corresponding immunotherapeutic therapies. Organ chips can accurately reproduce the specific functional areas in lymph nodes to better simulate the complex microstructure of lymph nodes and the interactions between different immune cells, which is convenient for studying specific biological processes. This paper reviews existing lymph node chips and their design approaches. It discusses the applications of the above systems in modeling immune cell motility, cell-cell interactions, vaccine responses, drug testing, and cancer research. Finally, we summarize the challenges that current research faces in terms of structure, cell source, and extracellular matrix simulation of lymph nodes, and we provide an outlook on the future direction of integrated immune system chips.

Retinal Organoids: A Next-Generation Platform for High-Throughput Drug Discovery

Retinal diseases are leading causes of blindness globally. Developing new drugs is of great significance for preventing vision loss. Current drug discovery relies mainly on two-dimensional in vitro models and animal models, but translation to human efficacy and safety is biased. In recent years, the emergence of retinal organoid technology platforms, utilizing three-dimensional microenvironments to better mimic retinal structure and function, has provided new platforms for exploring pathogenic mechanisms and drug screening. This review summarizes the latest advances in retinal organoid technology, emphasizing its application advantages in high-throughput drug screening, efficacy and toxicity evaluation, and translational medicine research. The review also prospects the combination of emerging technologies such as organ-on-a-chip, 3D bioprinting, single cell sequencing, gene editing with retinal organoid technology, which is expected to further optimize retinal organoid models and advance the diagnosis and treatment of retinal diseases.

[Bioprinting technologies in ophthalmology]

Bioprinting allows additive fabrication of bioengineered constructs with defined two- or three-dimensional organization using live cells, biopolymers and other materials. This article reviews main bioprinting technologies and their capabilities in clinical and experimental ophthalmology. Analysis of literature sources helped reveal and describe the main types of bioprinting technologies: inkjet, laser-assisted, and extrusion. Extrusion bioprinting is the most widely used method, providing the ability to use various types of bioinks and a wide range of cell concentrations. The following materials can be used as the base for bioinks: alginate, collagen, gelatin, hyaluronic acid, chitosan, fibrin, as well as their different combinations. These materials can be modified for best bioprinting properties by adding various functional groups. The major directions of application of bioprinting technologies in ophthalmology are tissue engineering for regenerative medicine and fabrication of model systems for fundamental and preclinical studies. Experiments in creating a bioprinted cornea are being conducted in the field of regenerative medicine. Furthermore, there are studies on fabricating retinal tissue equivalents, although tissue engineering of this structure is a task of great complexity. Model systems, which can be fabricated by bioprinting, are represented by tissue equivalents of ocular structures and the appendages of the eye, as well as by microphysiological organ-on-a-chip systems. Another promising application of bioprinting is fabrication of biocompatible implantable electrode arrays for visual neuroprostheses.