By Bella Moyer

Figure 1
A visual representation of the bioprinting process for a liver sample (Bhatt 2024).

Every day, seventeen lives are lost due to the lack of donor organs for over 100,000 people currently on the transplant waitlist (U.S. Department of Health & Human Services, 2024).  Current advances in bioprinting technology are hopeful to reduce this drastic, alarming number.  Bioprinting refers to the layer-by-layer fabrication of living tissues and organs using 3D printing techniques. Researchers have already successfully printed mini-organs, blood vessels, and tissue scaffolds. However, despite this progress, significant scientific, technical, and ethical hurdles remain before fully functional, transplantable human organs can be printed. 

Current research has found that organs can be made with a combination of bio ink and pluripotent stem cells (PSCs).  The organs are formed by a multi-step process that combines stem cell biology, tissue engineering, and 3D bioprinting technology (Figure 1).  Bio ink is a printable, gel-like material that contains living cells, and it must be biocompatible, viscous, and supportive of cell survival and growth.  PSCs are cells that can become any type of cell in the body and are either derived from embryos or created from adult cells.  Before printing, the PSCs need to become the specific type of cell required.  This is done by exposing the PSCs to specific growth factors, chemicals, and environmental cues.  Once the cells are created, they are mixed with a hydrogel to make a bio ink.  The bio ink is then printed layer by layer to a precise 3D shape of the organ based on the digital model retrieved from a CT or MRI scan (Murphy & Atala, 2014).  

The first lab-grown organ, which was a bladder, was implanted into a patient in 1999.  It was not until 2003 that scientists modified inkjet printers to print living cells.  Organovo started bioprinting in 2009 and have printed liver tissue for drug testing, and, researchers at Tel Aviv University have been able to print a tiny, beating heart using human cells (Noor et al., 2019).  Researchers have already printed tissues such as cartilage, skin, and even small vascularized tissues. While these structures are not yet suitable for transplantation, they prove that the potential for bioprinting exists to be a viable source for the future needs of organ recipients.

Despite these breakthroughs, several major barriers prevent bioprinted organs from becoming transplant-ready today.  One barrier is that of vascularization.  Human organs have a complex blood vessel network.  Researchers have been able to print basic vascular channels, but nothing near what a real organ would have (Datta et al., 2017). Another barrier is cell sourcing and differentiation.  Bioprinted organs have to use cells that match the patient’s cells to avoid rejection.  The PSCs are used for this purpose, but there are still challenges in getting them printed for proper use.  Also, even if an organ is structurally accurate, it still has to function properly, and there are challenges in getting the proper electrical and neurological signals from a bioprinted organ.  

As with most engineering advances, regulatory and ethical issues will need to be addressed.  Questions around who owns bioprinted organs, how they are tested, and how they are distributed raise important concerns in bioethics and health equity (Ventola, 2014).  But, if the challenges of bioprinting organs are met, the implications for global healthcare are enormous, not just by reducing the number of deaths in patients waiting for an organ, but also by drastically reducing the rate of rejection since the patient’s own cells would be used to print the organs.

Bioprinting could even make drug testing safer and more effective.  Instead of using animals, researchers could test new drugs and vaccines on printed human tissues and organs, leading to more accurate results and hopefully faster and safer drug development.  It could also improve global health equity by providing affordable, custom organs in regions of the world that currently do not have access to advanced medical care.

Bioprinting human organs is the future for organ donation. While current technologies can demonstrate the feasibility of printing simple tissues, the complex organ structures of human organs require further innovation in vascularization, cell behavior, and functional integration. If these hurdles are overcome, the world may see a future where organ donation is no longer a matter of life and death. 

Bibliography:

Bhatt, Supriya & Laya, Shurthi & Thakur, Goutam & Nune, Dr. Manasa. (2024). Scaffold-mediated liver regeneration: A comprehensive exploration of current advances. Journal of Tissue Engineering. 15. 10.1177/20417314241286092.

Datta, P., Ayan, B., & Ozbolat, I. T. (2017). Bioprinting for vascular and vascularized tissue biofabrication. Acta Biomaterialia, 51, 1–20. https://doi.org/10.1016/j.actbio.2017.01.035

Murphy, S. V., & Atala, A. (2014). 3D bioprinting of tissues and organs. Nature Biotechnology, 32(8), 773–785. https://doi.org/10.1038/nbt.2958

Noor, N., Shapira, A., Edri, R., Gal, I., Wertheim, L., & Dvir, T. (2019). 3D printing of personalized thick and perfusable cardiac patches and hearts. Advanced Science, 6(11), 1900344. https://doi.org/10.1002/advs.201900344

U.S. Department of Health & Human Services. (2024). Organ donation statistics. https://www.organdonor.gov/statistics-stories/statistics.html

Ventola, C. L. (2014). Medical applications for 3D printing: Current and projected uses. Pharmacy and Therapeutics, 39(10), 704–711. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4189697/