Proportional-Integral-Derivative (PID) Control of Secreted Factors for Blood Stem Cell Culture
Fig 2
Empirical correlations were used to develop the model.
[A] (i) Cell numbers for each phenotype group are converted to (ii) growth rates, as % change per day. (iii) Average TGF-β1 concentrations are calculated from the time course data. (iv) These midpoints (day 2, 6, 10) are combined for all three media dilution rates and correlated to give growth rates (%/day) as a function of TGF-β1 concentration (pg/mL). [B] (i) Total cell numbers are categorized into phenotype groups and (ii) adjusted by TGF-β1 gene expression values to reflect each phenotype’s relative contribution to TGF-β1 accumulation. (iii) The new adjusted cell numbers are summed to give a total ‘adjusted’ cell number. Separately, (iv) TGF-β1 concentrations (pg/mL) are converted to (v) TGF-β1 amounts (pg) using the culture volume (mL). (vi) This is converted to secretion rates, in pg/day. (vii) These midpoints (day 2, 6, 10) are combined for all three dilution rates and correlated to give TGF-β1 secretion (pg/day) as a function of total ‘adjusted’ cell number.