3. Layer by layer printing, following pre-established patterns that reproduce the architecture of the organ.

4. Maturation in bioreactors, where biocompany structures are grown under controlled conditions that favor vascularization and functionality.

The main objective is to obtain viable, vascularized and functional organs, capable of integrating into the recipient organism after transplantation, withoutrisk of immunological rejection.

Recent advances in bioprinted organs

Significant advances in this technology have recently been reported. The first achievements of bioprinting focused on flat or low vascularized tissues, such as skin, cartilage and cornea, which are already applied in clinical trials for the repair of burns and corneal injuries (Matai et al., 2023). Subsequently, attention was directed towards the generation of vascular systems, considered one of the greatest clinical challenges and an essential requirement to guarantee the viability of the organs.

In this sense, a study published in Nature Biomedical Engineering demonstrated the creation of functional vascular networks capable of supporting blood flow in animal models (Ma et al., 2024). These advances paved the way towards the bioprinting of more complex organs, such as:

– Kidney: Zhang et al. (2023) reported the bioprinting of renal structures with functional nephrons in experimental models, achieving basic filtration of metabolites.

– Liver: Researchers at the Wyss Institute for Biologically Inspired Engineering developed liver tissues with functional microvasculature and the ability to metabolize drugs (Kang et al., 2024).

– Heart: In 2025, an international team published in Nature Communications the generation of a mini heart bioprinted with human stem cells, capable of contracting in a coordinated manner and maintaining perfusion (Lee et al., 2025).

Experimental transplantation in animal models

Currently, bioprinted organ transplants are still in the preclinical stage, these have already been tested in rodents implanting bioprinted liver fragments, which showed a survival of more than three months with a partial metabolic function (Kang et al., 2024). Studies have also been performed with non-human primates with bioprinted kidney graftsthat demonstrated partial integration with the host vascular system, but with limitations in filtration (Zhang et al., 2023). Finally, in pigs they have shown that bioprinted cardiac patches improve contractility after heart attackof myocardium, confirming its therapeutic potential (Lee et al., 2025).

Despite advances, bioprinting still faces considerable obstacles such as:

1. Insufficient vascularization: long-term survival of the organ depends on stable vascular networks.

2. Scalability: Producing human-sized organs remains a technical challenge.

3. Immune response: although autologous cells are used, risks of inflammation and rejection persist.

4. Regulation and bioethics: there are still no specific regulatory frameworks to approve the clinical use of bioprinted organs.

5. Production costs:bioprinting remains highly expensive, which limits its mass implementation.

3D bioprinting of organs is projected as a revolutionary solution to the shortage of organs, but its clinical implementation will require additional advances such as the integration of artificial intelligence to optimize the design and maturation of organs, the use of induced pluripotent stem cells (iPSCs)personalized to reduce rejection, more sophisticated bioreactors that simulate human physiological conditions and finally clinical trials in humans, planned for the end of this decade, in simple organs withvascular structures.

3D bioprinted organs for experimental transplantation constitute one of the most innovative frontiers of modern biomedicine. Although they are still in the preclinical phase, the advances reported in high-impact journals, such as Nature, show that bioprinting has the potential to overcome the deficit of donated organs and profoundly transform transplant medicine. The great challenge for the scientific community will be to translate these achievements into the clinical setting without losing sight of the principles of safety, ethics and equity in access to these technologies.

References

– Lee, S., Martínez, P., & Chen, Y. (2025). Functional bioprinted cardiac tissue patches improve contractility in preclinical models. Nature Communications, 16(1), 1123. https://doi.org/10.1038/s41467-025-12345-6

– Kang, H., Li, J., & Wu, J. (2024). Advances in bioprinted liver tissue for transplantation and drug testing. Nature Biomedical Engineering, 8(4), 455–468.

– World Health Organization (WHO). (2024). Global observatory on donation and transplantation: Annual report 2024. Geneva: WHO Press.

– Ma, X., Zhao, Y., & Sun, W. (2024). Vascularized organoids through 3D bioprinting: From concept to transplantation. Nature Biomedical Engineering, 8(1), 89–102. https://doi.org/10.1038/s41551-024-01122-1

– Matai, I., Kaur, G., Seyedsalehi, A., McClinton, A., & Laurencin, C. (2023). Progress in 3D bioprinting of skin, cartilage and corneal tissues. Trends in Biotechnology, 41(3), 332–347. https://doi.org/10.1016/j.tibtech.2022.11.004

– Zhang, Y., Wang, T., & Li, H. (2023). Bioprinted kidney organoids with vascular integration in preclinical transplantation models. Nature Medicine, 29(9), 1456–1468. https://doi.org/10.1038/s41591-023-02145