Cell Culture
Figure 16: Hamilton Company’s BioLevitator™ 3D cell culture system
Glycosan BioSystems (
www.glyconsan.com) man- ufactures and sells Extracel™ and HyStem™ hyaluronic acid-based hydrogels for 3D and stem cell culture. As 3D cell culture increases in popu- larity, a key need for researchers is to gently and rapidly recover encapsulated cells for either nucle- ic acid or protein extraction. Glycosan has recent- ly launched Extracel-SS and HyStem-CSS hydro- gels which dissolve within two hours. The key improvement is the novel crosslinker, PEGSSDA, which has an internal disulfide bond which breaks upon exposure to reducing agents (Figure 15).
Hamilton Company (
www.hamiltoncompany.com) and Global Cell Solutions (
www.globalcellsolu-
tions.com) have joined forces to develop the BioLevitator™, a unique 3D cell culture system. The instrument is a self-contained incubator and
bioreactor with temperature and CO2 control. The BioLevitator is used to culture adherent cell types
on a unique 3D magnetic substrate called the Global Eukaryotic Microcarrier or GEM™, devel- oped by Global Cell Solutions. The GEM is com- posed of an alginate core with covalently bound proteins, which allows the cells to grow on the 3D curved surface. Multiple protein coatings are avail- able to support established, cancer, primary, and stem cell lines. Cells cultured on the GEM, includ- ing primary and stem cells, are healthier and have shown an improved in vivo phenotype. The GEM is non-autofluorescent and optically clear making cell-based assays much more user friendly. Cells can be easily assayed via fluorescence, luminescence, or absorbance detection methods. Additional down- stream applications, including electroporation and cryopreservation, have shown enhanced efficiency when the cells are attached to the GEM. The cell culture parameters of the BioLevitator are directly scalable to the 3D-CellHOST. The 3D-CellHOST integrates up to four BioLevitators on Hamilton’s MICROLAB STAR automated liquid handling platform and has the ability to produce two billion cells per week. The automated platform eliminates user error and variation between cell lines and users. The latest advancement in the BioLevitator technology is the addition of a pH reader, for online monitoring of the quality of the cell culture medium and automated medium change (Figure 16)
Figure 17: Automated generation of hanging drops to produce microtissues using the InSphero GravityPlus technology
34
Microscale organotypic cell-culture technologies are currently shifting from the academic environ- ment to an industry setting enabling better model systems to test for drug efficacy and toxicology in vitro. Over the past few years, the hanging drop technology has shown its versatility to recreate embryonic, tumour and primary tissues in vitro. However, the conventional hanging drop technol- ogy – placing drops of cell suspension on a surface which is cultivated upside down – did not allow for high-throughput production of microtissues. The GravityPlus technology from InSphero (
www.insphero.com) allows for generating hang- ing drops as well as medium exchange from the top enabled by a special well-design where the inlet and the culture compartment are connected via a vertical microchannel. The capillary and cohesion forces lead to highly stabilised hanging drops which can be handled either manually or in an automated fashion. This system enables InSphero to produce microtissues with a number of substantial advantages: a) low cell numbers required for one tissue depending on the required size (100-25,000); b) no adverse effects of artifi- cial materials on biochemical assays; c) standard- ised tissue size and one tissue per drop enables
Drug Discovery World Summer 2010
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