Tissue Engineering Part C, Methods vol:21 issue:6 pages:519-29
As the fields of tissue engineering and regenerative medicine mature towards clinical applications the need for on-line monitoring, both for quantitative and qualitative use, becomes essential. Resazurin based metabolic assays are frequently applied for determining cytotoxicity and have shown great potential for monitoring 3D bioreactor facilitated cell culture. However, no quantitative correlation between the metabolic conversion rate of resazurin and cell number has been defined yet. In this work we determined conversion rates of Presto Blue™, a resazurin based metabolic assay, for human periosteal cells during 2D and 3D static and 3D perfusion culture. Our results showed that for the evaluated culture systems there is a quantitative correlation between the Presto Blue™ conversion rate and the cell number during the expansion phase, with no influence of the perfusion related parameters i.e. flow rate and shear stress. The correlation between cell number and Presto Blue™ conversion subsequently enabled the definition of operating windows for optimal signal readouts. In conclusion, our data showed that the conversion of the resazurin based Presto Blue™ metabolic assay can be used as a quantitative read-out for on-line monitoring of cell proliferation in a 3D perfusion bioreactor system although a system specific validation is required.