Microfabrication technology for the engineering of 3D cell laden microgels for cell culture and tissue engineering

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• Professor Marcel Karperien, University of Twente, Enschede, Netherlands
• Wednesday 08 February 2017, 08:00-08:30
• Online.

If you have a question about this talk, please contact Ilana Spilka.

It is increasingly recognized that cells respond differently in 2D and in 3D cell culture. To address this fundamental issue, my laboratory has developed various microfabrication technologies for the on-chip production of microgels in a size range of 30 to 100µM either laden with a single cell or with multiple cells in a 3D environment. These platforms can be used for the on-chip production of cell laden microgels using a variety of hydrogel materials cross linking in stable macromolecular networks either by photo crosslinking, ionic crosslinking or enzymatic crosslinking. In a side-by-side comparison of these 3 crosslinking methods we demonstrate that on chip crosslinking of PEGDA with UV-light has detrimental effects on cell survival and cell function. More than 50% of cells died after 1 day. The remaining cells became metabolically arrested and stopped functioning after 3 days. This is due to the relatively high dosage of UV light that is needed for on chip cross linking of the polymers in stable macromolecular networks due to the short retention time of the microgel droplets on chip. Much more favourable cell survival of approximately 80% cell survival after 1 day was observed when cells were embedded in alginate microgels hydrogels by on chip ionic cross linking. Long term cell survival was excellent. However, these microgels disintegrated within 14 days of culture due to leakage of Ca++ ions out of the gel resulting in escape of cells. On chip enzymatic cross linking of tyramine-polymer conjugates proved most favourable: Cell survival after 1 day was >95% and the microgels remained stable also in long term cultures of more than 4 weeks with neglectable cell escape. Cells remained metabolically active. When human Mesenchymal Stem Cells were encapsulated in these microgels either as single cell or as multiple cells, the cells efficiently differentiated into adipocytes and into osteoblasts depending on the culture conditions. Differentiation can be tuned by modifying the mechanical properties of the microgels and by varying the composition of the polymers.

By introducing small variations in these microfluidic platforms, we are also able to produce cell laden hollow microgels with a fully crosslinked shell. When MSCs were captured in the centre of these microgels they spontaneously started to aggregate. The speed of aggregation was tightly and inversely controlled by the crosslinking density of the core of the microgel. Cell aggregation was achieved both in vitro and in ex vivo organ culture models suggesting that these hollow microgels can be used as in vivo microbioreactors whereby the cross-linked shell separates the gel’s inside from the body.

In conclusion, using microfluidics in combination with enzymatically cross linkable polymer conjugates it is possible to efficiently develop cell laden microgels in various configurations. This new technology enables to study cell behaviour in a 3D environment as a function of mechanical properties and gel composition at the single cell level. Furthermore, it enables the formation of micro bioreactors for long term culture of cells. Finally, these cell laden microgels can be used as building blocks for more complex tissue structures by combining the cell laden microgels with other materials. This opens the possibility to develop complex and modular bio-inks for biofabrication processes.

This talk is part of the Three-dimensional cell culture: Innovations in tissue scaffolds and biomimetic systems series.

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• Online
• Three-dimensional cell culture: Innovations in tissue scaffolds and biomimetic systems

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