Functioning liver units in less than a minute

Researchers at the UMC Utrecht are working towards on-demand production of cell structures or human body parts. Recent research published in Advanced Materials, described the process of bioprinting to create functioning liver units, organoids. The so-called volumetric 3D printing is a technology which can produce a gelatin hydrogel containing working liver cells within 20 seconds. These hydrogel structures open up new possibilities for regenerative medicine and personalized drug testing.

Compared to more ‘conventional’ 3D printing concepts, the unlayered and nozzleless approach of the volumetric 3D printing minimalized the mechanical stress on the vulnerable liver organoids. In general, organoids are difficult to use because it is hard to structure them without damaging the cell structures. Due to the contactless approach, the organoids are handled more gently. Traditional 3D printing techniques could have damaged the organoids during the printing process.  

The technique, derived from a company from Switzerland, is based on the chemical properties of a special gelatin, bio resin. The bio resin is cured with a specific UV light. Cell-friendly light doses are used, these are beneficial for preserving cell functions after the printing process. The treatment  causes the cured spots to polymerize, harden and become more heat resistant compared to its uncured and therefore unpolymerized form. After the light treatment, the uncured spots can be melted away, leaving the hardened structure. The pre-treated hydrogel can be filled with liver organoids, resulting in a cell-laden structure at the end.

The research team mentioned that the bio printed organoids demonstrated key functions of the human liver. Demonstrated key functions include liver-specific enzyme activity, toxin filtration and the production of albumin, an important liver protein.

Additionally, the authors tested different architectures of the gelatin gels. Observing that the detoxification of chemicals could be improved by changing the structure of the gel and different porous networks could act as blood vessels. This offers the option to perfuse the organoids with nutrients, one major lack in nowadays organoid assays.

The volumetric 3D printing technique may lead to new possibilities for regenerative medicine and personalized drug testing. These 3D printed organ structures could eventually replace transplant organs or cell structures. By using patient’s own cells, these organ structures could avoid immune response of the patient. This could result in a reduction in the prevalence of rejection of the newly implemented cell structure. Which is a risk of high concern in conventional organ transplantation. Next to this, hydrogel structures could be loaded with the cells of a patient, opening up the possibility to test personalized drugs on a personalized structure.

Overall, the combination of volumetric 3D printing and organoids holds great potential. However, currently, the elaborated version of the technique is still a prospect for the future. Additional research is necessary to improve and adjust this innovative technology.