A bio-artificial liver - a BAL - is used as an extra-corporeal organ designed to aid the function of the liver in patients with acute failure and University College London's team are working on one where liver cells are encapsulated in alginate. The challenge as a clinical product is related to immediate availability, because of the unpredictability of disease progression in acute liver failure.
The aim of a recent study, presented at the Society of Low Temperature Biology annual meeting by Eloy Erro, Joana da Silva (both pictured here) et al, was to achieve BAL biomass cryopreservation with different systems for post-thaw culture and recovery, aiming at an off-the-shelf product. HepG2 cells were encapsulated in 1% alginate solution, producing ~500µm beads which were encapsulated and cultured for 12-14 days in a fluidised bed bio reactor (FBB) to obtain sufficient biomass.
Cryopreservation of >1L of alginate cell beads was achieved in a cryo-bag using our controlled rate freezer Kryo 750 and DMSO was used as cryoprotectant with an ice nucleator.
The team concluded that successful cryopreservation of encapsulated liver cell spheroids on a large scale, at 16-48% of a total human liver size (the biomass of 30% liver cell numbers is the likely requirement for such a bio-artificial liver) represented the correct order of magnitude and provided sufficient post-thaw recovery. They also found the process could be easily scalable in freezing bags using the Kryo750 and the same fluidised-bed bioreactor for cell recovery. The use of micro-organoids within an alginate matrix proved an interesting choice for large-scale cryopreservation avoiding problems associated with large tissue freezing. However a more rapid recovery would be ideal, and the team is exploring improvements.
Poster - The BAL Team : http://www.ucl.ac.uk/livergroup/theteam.html
Planer's controlled rate freezer: https://planer.com/products/cryo-freezers/medium-crf/kryo-750.html
To download PDF of poster, please click here.