In your lifetime, dying patients could receive a 3-D printed organ made from their own cells rather than having to wait on long lists for the short supply of organ transplants. In addition, lengthy drug trials that must undergo meticulous tests could be safely sped up using bio-printed organs. That’s the goal of a San Diego-based Biotech firm, Organovo, who has created a 3-D printed liver for medical applications and research.
Organovo has not yet created a fully functional liver but has built tiny slices of liver tissue that can be used as a model and to determine the safety of a medication.
Preclinical drug trials use animal and petri dish testing before being sent to the Food and Drug Administration for review and approval for human trials. The research must effectively show that the drug is safe before moving to Stage 1 of clinical testing.
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Preclinical research often shows the drug is safe for animals, but ends up being toxic to humans in clinical trials. 3-D bio-printed livers could more effectively show human safety rather than animal and petri dish testing, as well as cut down the preclinical drug discovery process from three to six years to a matter of months.
Liver toxicity takes time to develop, and drugs can make it up to stage 3 trials (roughly a 6-10 month period) before being screened out. Liver toxicity accounts for 10% of all drug rejections in phase three trials.
3-D bio-printed livers could reduce this from occurring and could offer scientists a better understanding of what goes wrong when transitioning from animal studies to human trials.
Bioprinted livers are made by taking stem cells from an individual’s fat or bone marrow and then treated to form bioink (multicellular building blocks). The cells can then be inserted in a 3-D printer, and would take only two days before being usable for testing. Liver-like structures are then printed by inserting bio-ink, layer by layer, allowing cells to grow together into tissues. Hydrogel (a bio-inert substance) is sometimes used as a mold to stack the tissue into vertical and hollow shapes that mimic the liver’s structure. In the future, they hope to build fully functional livers that could be used in organ transplants made from the patient’s very own cells.
The 3-D printed liver lasts up to 40 days, while 2-D Petri dishes of liver tissue last only 48 hours. Bioprinted liver tissue may be a more effective liver model than Petri dishes because it more accurately models the geometry of a real liver, including cell density, multiple cell types, and key structures associated with a real liver.
Right now, the bioprinting process is expensive and not exact. Using bio-ink to form tissues is just one part of the process. Creating a fully functional organ requires mastering cell differentiation, the cell’s ability to self-organize based on its type, and building tiny blood vessel networks only hundreds of microns thick.
These issues present challenges that no lab has yet overcome. The funding and research necessary to producing fully functional organs are likely still decades away. However, Organovo’s liver tissue is 5 to 6 years away from clinical trials for surgical implementation.
In addition to Organovo’s breakthroughs, 3-D bioprinting is already being used to transplant multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures.
Although the bioprinting industry faces research and funding hurdles, the future of bio-printed livers is bright and offers a potentially great payoff.