3D bioprinted liver tissue models can become an essential platform for drug development by providing drug metabolism. The liver is responsible for metabolizing various compounds for distribution and activation. 3D bioprinting technologies – bioprinters and bioinks –can advance mimicry of the complex architecture of the cellular organization, vascular branches, and bile canaliculi network.
The aim of the following project was to investigate two different liver models by 3D bioprinting liver cells in HEP X. The first includes co-culture of HepG2 and LX2 and the second includes printing HEP X with primary hepatocytes or primary stellate cells.
In our labs we can demonstrate that HepG2 (hepatocyte cell line) and LX2 (stellate-like cell line) can be bioprinted as single culture or co-culture constructs. We have bioprinted various ratios and cell densities to demonstrate various liver tissue models.
Fluorescent microscopy images demonstrate higher viable cells (green) than dead cells (red). LX2 cells cluster within the HEP X bioink while HepG2 cells remains single cells after 14 days. In co-culture at 2:1 and 4:1 (hepatocytes:stellate cells) ratios, small cluster formation was observed. Scale bars 100µm.
For clinical relevancy, we have also demonstrated 3D bioprinting of primary human hepatocytes or stellate cells as in vitro assay models for drug development.
Human primary hepatocytes are sensitive cells; however, within the HEP X bioink, the cells can survive 3D bioprinting (live-green, dead-red). Hepatocyte (yellow) clustering was observed for up to 21 days of culture with multiphoton imaging. Scale bars 100µm or 25µm as indicated.
Human primary stellate cells are essential for understanding liver matrix production. After 3D bioprinting within HEP X, the stellate cells maintain their morphological characteristics (as seen in bright field). Even only after 4 days, tunnel formation was observed with viable cells (live-green, dead-red). Scale bars 100µm.
At CELLINK, we demonstrate that co-culture or single culture of major liver cells such as hepatocytes and stellate cells can be bioprinted into 3D constructs using our human liver ECM based HEP X bioink. Since liver cells are niche within their liver lobule unit, the liver ECM components will provide the environmental cues to maintain and improve specific cell functions.
HEP X will also provide an favourable environment of primary hepatocytes, stellate cells, and non-parenchymal cells as a drug development platform.