ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

There was no correlation between the flow rate and the magnitude of the over prediction.
The experimental results (figure 2) indicated that the OTR in 13FIF module was not
significantly different from that in the 19FIF module. The OTRs predicted by the model
clearly support this finding, where for each flow rate, the theoretical OTRs were the same
irrespective of the number of fiber in fiber sets in the bioreactor.
This part of the paper illustrates the model predictions. OTR will be influenced by the
number and the density of cells in the annulus. Using the model one may predict the effect
on OTR of increased cell density. To study this, OTRs were calculated when Vmax was
10nmol/(cm 3 s) and doubled to 20nmol/(cm 3 s) with three different gas phase oxygen
concentrations and two different plasma flow rates. The results show an increase in OTR as
Vmax is decreased. Results also show the highest OTR was 1874nmol/s and that was with
lower Vmax and higher flow rate.
Figure 3 models the effect of oxygen diffusion coefficient in silicone rubber membrane Dm
and different oxygen partial pressure (pG) in Comp C. Effect of Dm on the axial profile of
PO2 in the annulus with Vmax of 25 nmol/(cm 3 s) is shown in figure 3. The change in the
axial profile of PO2 is notable, when Dm is 16x10 -7 cm 2 /s compared to different Dm (not
shown). When Vmax was increased to about fivefold in magnitude, no changes can be
seen in the PO2 when Dm is 16x10 -5 . However, there is rapid initial fall in PO2 to below
2mmHg and remaining below this level for about 60% of the axial length of the annulus
when Dm was 16x10 -7 . Sharper drop in PO2 was found when the inlet pG was 40mmHg.
Figure 3: The effect of oxygen diffusion coefficient in silicone rubber membrane Dm and different oxygen
partial pressure (pG) in Comp C.
6. DISCCUSSION
A novel FIF bioreactor was developed and tested to assess its potential for liver cell culture.
A mathematical model of flow and oxygen transport in the FIF bioreactor has been
described. This model provides a means of altering certain physical and operational
parameters to calculate the expected oxygen transfer rates of hollow fibre bioreactors
operating in the fibre in fibre configuration. The model showed ability to predict the effect
of the inner and outer membrane permeabilities on the flow and axial profile of PO2 in the
annulus, respectively. The model showed very good agreement with experimental results.
Human liver normally has an oxygen partial pressure of 50 mmHg (ranging from 70mmHg
to 30 mmHg), and hepatocytes in vivo are supplied with mixed venous and arterial blood