Using human blood cells, researchers have succeeded in obtaining hepatic organoids (“mini-livers”) that perform all of the liver’s typical functions, such as producing vital proteins, storing vitamins, and secreting bile, among many others. The innovation permits the production of hepatic tissue in the laboratory in only 90 days and may in the future become an alternative to organ transplantation.
HUMAN HEALTH ISSUE
The liver is responsible for many metabolic, endocrine and exocrine functions. Approximately 2 million deaths per year are associated with liver failure. Brazilian researchers, based in São Paulo, claim to have bio-printed liver organoids, miniature versions of the liver, from human blood cells. These miniature organs are said to perform all the functions expected of them, namely the production of vital proteins, vitamin storage and bile secretion. Liver tissue would have been obtained in 90 days: a breakthrough that could become an alternative to organ transplantation, which often takes too long due to a lack of donor availability or compatibility.
ANIMAL FREE SCIENCE POTENTIAL
In the field of bio-imprinting, all the attention is focused on the creation of functional organs: it is worth noting the progress made this year, notably by Dr. Tal Dvir’s team, which succeeded in bio-printing in 3D a heart composed of blood vessels and tissues. The challenge now is to keep these organs alive over time – a step that has not yet been taken. One of the first companies to look at bio-printing liver tissue is Organovo, one of the first companies to look at bio-printing liver tissue. Brazilian researchers are now joining the race with their 3D-printed mini-livers.
Conducted at the Human Genome and Stem Cell research center hosted at the University of São Paulo, the study is the result of a combination of several bioengineering techniques such as pluripotent stem cell culture and cell reprogramming with 3D bio-imprinting. The researchers used the Inkredible bio-printer from Cellink, one of the industry’s leading manufacturers, to create their liver tissue. What is different from the other work done so far is that the cells were pooled in the bio-ink before being extruded. Ernesto Goulart, co-author of the study, explains: “Instead of printing individualised cells, we developed a method for grouping them before printing. These clusters of cells, or spheroids, make up the tissue and maintain its functionality much longer.” This method would have avoided the gradual loss of contact between cells and thus the functionalities of the tissues.
Researchers say it took 90 days to develop these small, bio-printed 3D livers from patient blood collection to tissue production. The first step would be to reprogram the patient’s blood cells into induced pluripotent stem cells. These are then differentiated into liver cells and their spheroids can then be integrated into the bio-ink. The printing process can now begin. The cultivation of the 3D-printed cell structures would then take 18 days. The researchers say this experiment could be done on a larger scale and on other organs.
The liver is responsible for many metabolic, endocrine and exocrine functions. Approximately 2 million deaths per year are associated with liver failure. Modern 3D bioprinting technologies allied with autologous induced pluripotent stem cells (iPS)-derived grafts could represent a relevant tissue engineering approach to treat end stage liver disease patients. However, protocols that accurately recapitulates liver’s epithelial parenchyma through bioprinting are still underdeveloped. Here we evaluated the impacts of using single cell dispersion (i.e. obtained from conventional bidimensional differentiation) of iPS-derived parenchymal (i.e. hepatocyte-like cells) versus using iPS-derived hepatocyte-like cells spheroids (i.e. three-dimensional cell culture), both in combination with non-parenchymal cells (e.g. mesenchymal and endothelial cells), into final liver tissue functionality. Single cell constructs showed reduced cell survival and hepatic function and unbalanced protein/amino acid metabolism when compared to spheroid printed constructs after 18 days in culture. In addition, single cell printed constructs revealed epithelial-mesenchymal transition, resulting in rapid loss of hepatocyte phenotype. These results indicates the advantage of using spheroid-based bioprinting, contributing to improve current liver bioprinting technology towards future regenerative medicine applications and liver physiology and disease modeling.