The supplemental protease used for cell isolation is determined by the precedent set by the enzyme suppliers. However, it is likely that other proteases will also work but it needs to be determined by experimentation. Three different proteases have been used to isolate human islets: thermolysin, BP Protease (a Dispase equivalent enzyme), and C. histolyticum neutral protease. Substitution of one protease for another may not be a seamless transition, however, as the kinetics of digestion can be dramatically different among the various general proteases. For guidance in selecting a protease, contact VitaCyte’s technical support team.