Cell Culture Company’s bioreactors are not sampled for cell density throughout the run, as this is not a key process parameter like it is for batch and fed-batch processes. Unlike tank systems, protein production in HFBR is not limited by cell viability. Cell Culture Company has data showing long-term protein production in an HFBR that can last up to 100 days. Throughout these long-term runs, parameters like pH, glucose, and lactate remain consistent after the initial growth curve and allow us to indirectly assess the health of the cells.