Shining a light on constructing blood supply systems for artificial tissues

Osaka, Japan—The creation of fully artificial organs is a sci-fi dream, and we may be one step closer to reality with researchers from Japan developing a new photofabrication technique (i.e., a light-controlled synthetic method) for constructing arteriole-scale tubular hydrogels.

For a synthetic tissue or organ to be fully functional in reality, not only must the artificial tissue be constructed, but a vascular network around the tissue must also be created. This network of surrounding blood vessels supplies oxygen and nutrients to tissues; without it, engineering functional artificial organs is impossible. Currently, building this network is a bottleneck in artificial tissue development, and constructing mid-sized blood vessels, or arterioles, is particularly challenging.

“While numerous methods have shown promise in the synthesis of smaller capillaries and larger arteries, the ability to construct arterioles that provide the link between these systems is an unresolved problem in the development of artificial vascular networks” says senior author Keisuke Morishima. “However, our team has recently developed a method to bridge this critical gap by continuously forming ring structures at meniscus interfaces.”

This technique uses an innovative strategy leveraging the surface tension that forms a meniscus at an oil–hydrogel interface in a small channel. The meniscus effect creates a curve in the liquid, similar to the surface of a glass of water. Shining UV light onto this curved surface causes the hydrogel to form a ring-like structure at the channel wall. Repeating this process at precise points along the channel builds up a series of rings, gradually forming a hollow tubular hydrogel structure. This approach was successfully used to construct hydrogel structures similar in size and shape to natural arterioles.

Hydrogel tubular structures could be created with controlled lumen sizes and complex geometries, including curved and branched configurations, and multiple materials could be combined in one structure, reducing the material-switching steps and waste of conventional fabrication. “Such complex architecture would be necessary in the successful creation of a synthetic vascular network” explains Morishima. In addition, lack of stability has been an issue in the development of softer tubular hydrogels, but the team was able to form tubular structures using biologically relevant softer hydrogels that had good stability. The process could also be automated by combining image processing and synchronized UV irradiation, which created smoother surfaces than the previous discrete layer-by-layer fabrication.

“Integrating these hydrogel fabrication systems with precise microfluidic flow control components has strong potential for the facile production of vascular models of living systems—a key step toward the development of fully synthetic tissues,” says lead author Yuki Kamiya.

While the creation of fully functioning artificial tissues is still a long way off, this research paves the way for creating vascular models to investigate how the dream of artificial tissues and organs may one day become a reality. Beyond artificial organs, potential applications include drug discovery, disease modeling, food technology, soft robotics, and biohybrid systems.

The article “Meniscus-Guided Interfacial Ring-by-Ring Assembly for In Situ Fabrication of Tubular Hydrogel Structures” was published in Advanced Materials at DOI:

About The University of Osaka

The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan’s leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.

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