Maram Mohammed: Biotechnology Master Program
Title of Master's thesis: Investigation of 3D Bioprinted Co-cultures as liver tissue models.
Thesis work performed at CELLINK AB,Göteborg
Liver fibrosis is a strong risk factor for liver cancer and has become a major concern worldwide. All chronic liver diseases (CLD) can lead to liver fibrosis. Nonalcoholic fatty liver disease (NAFLD) and its more severe form nonalcoholic steatohepatitis (NASH) are of particular interest to pharmaceutical companies. One obstacle in the development of efficient therapies is the lack of robust, representative, and biologically relevant in vitro models of human liver fibrosis to aid the development phase of pharmaceuticals. This is due to the fact that most invitro models used today are 2D mono layer cultures of stellate cells. These models ignore the importance of the interplay between hepatocytes and stellate cells in liver fibrosis as well as the role played by spatial organization of different cells.
Bioprinting allows the production of tissue-like structures that mimic the 3D architecture and complexity of native tissue. In this project two different hepatocyte/ stellate cell ratios (4:1 and 2:1) were bioprinted to produce a liver tissue model. Fibrosis was then induced by addition of the growth factor TGF-β resulting in a fibrotic liver tissue model. Auxiliary proteins supporting liver specific cells were incorporated in the bioink used. The produced fibrotic liver tissue model’s viability and functionality were then assessed using different assays. Namely, Live/Dead analysis, Celltiter-Blue viability assay, LDH cytotoxicity assay, Bicinchoninic acid protein assay and Actin/DAPI staining. These assays were originally designed to be used on cells in 2D and not on cells imbedded in a bioink/hydrogel. These assays’ applicability for use on cells bioprinted in 3D was therefore evaluated before they were used to analyze the produced bioprinted fibrotic liver tissue models.
It was possible to adapt the mentioned assays to be used with 3D bioprinted constructs. Viability, cytotoxicity and protein deposition results indicated that 2 HepG2:1 LX-2 coculture ratio was superior to 4 HepG2:1 LX-2 in simulating liver fibrosis. There did not seem to be a significant difference between the group in which fibrosis was induced by TGF- β compared to the control group in any of the conditions investigated. This indicates that fibrosis was in fact not induced despite the addition of TGF- β as both groups were behaving in a similar manner. Further investigation is needed in this regard.
Supervisor: Itedale Namro Redwan and Duong Nguyen, Bioink and Tissue Engineering Team, CELLINK AB
Examiner: Julie Gold
Opponent: Alexander Back and Axel Norberg
Student project presentation
5th floor conferece room, Biotech Center, Arvid Walgrens Backe 20, Göteborg
18 February, 2019, 10:00
18 February, 2019, 11:00