flask types had comparable geometrical ratios, the hydrodynamic stresses in the
SP100 were higher at the suspension criteria. In fact, the absolute hydrodynamic
stresses over time were higher due to the lower circulation times, which increase the
risk that the cells on the MCs are more frequently exposed to detrimental stresses. At
the same time, the residence times, and therefore also the exposure times, of the MCs
to the hydrodynamic stresses were shorter, as the multi-phase simulations have
indicated. In both cases, the peak cell densities were in the same range as cell
densities measured in planar static cultures at maximum confluency (% 2.9 Â 10
5
cells/cm
2 ), in which the cells were expanded in parallel. This result indicates that the
cells cultivated at N s1u
N
N s1 are mainly restricted by the available growth
surface. In contrast, significant lower cell densities were achieved at lower and
higher impeller speeds. A peak living cell density of 1.05 Æ 0.06 Â 10
5 cells/cm
2
(¼ 4.49 Æ 0.06 Â 10
5 cells/mL, EF 35) and 1.36 Æ 0.57 Â 10
5 cells/cm
2 (¼ 4.48 Æ
0.57 Â 10
5 cells/mL, EF 45) was determined for the SP100 and SP300 at 25 rpm and
20 rpm, respectively. These peak cell densities are up to 84% lower than those at
N s1u N N s1 . This observation may have been caused by the higher amount of
sedimented MCs and the increased MC-cell aggregate formation (see also [12]). The
viability of the cells on the MCs was always >99%. This was not surprising as dead
cells detach from the MC surface. Thus, the increase in dead cells in the supernatant
depends on the cell detachment from the MC surface and the die-off of cell in the
supernatant.
Table 8 Summary of cultivation results with hMSCs from the adipose tissue in the SP100 and
SP300
N
[rpm]
Living X max [10
5
cells/cm
2
]
EF
μ
[d
À1
]
t d [d]
q Glc [pmol/
cell/d]
q Lac [pmol/
cell/d]
q Amn [pmol/
cell/d]
Corning 125 mL spinner (SP100)
25
1.05 Æ 0.06
35.0 0.6 Æ
0.0
1.1 Æ
0.1
13.2 Æ 2.3 20.7 Æ 2.7
8.8 Æ 0.3
49
N s1u
1.67 Æ 0.12
55.6 0.7 Æ
0.0
1.0 Æ
0.0
10.6 Æ 1.6 35.2 Æ 1.9
6.1 Æ 0.4
60
N s1
1.68 Æ 0.36
56.0 0.7 Æ
0.1
0.9 Æ
0.1
9.8 Æ 0.8
30.3 Æ 1.0
6.2 Æ 0.3
120
0.60 Æ 0.04
20.1 0.5 Æ
0.1
1.5 Æ
0.4
35.0 Æ 1.6 88.8 Æ 5.2
16.5 Æ 0.3
Corning 500 mL spinner (SP300)
20
1.36 Æ 0.57
45.2 0.5 Æ
0.1
1.3 Æ
0.1
21.0 Æ 0.9 28.6 Æ 9.9
14.7 Æ 0.2
41
N s1u
2.46 Æ 0.16
81.9 0.7 Æ
0.0
1.0 Æ
0.0
15.5 Æ 0.6 40.6 Æ 1.8
10.6 Æ 0.5
52
N s1
2.43 Æ 0.66
81.1 0.7 Æ
0.0
1.0 Æ
0.0
11.8 Æ 1.2 35.3 Æ 3.3
9.7 Æ 0.4
100
1.25 Æ 0.29
41.8 0.5 Æ
0.1
1.3 Æ
0.0
20.8 Æ 9.8 88.6 Æ 2.1
19.0 Æ 1.4
214
V. Jossen et al.
SP100 were higher at the suspension criteria. In fact, the absolute hydrodynamic
stresses over time were higher due to the lower circulation times, which increase the
risk that the cells on the MCs are more frequently exposed to detrimental stresses. At
the same time, the residence times, and therefore also the exposure times, of the MCs
to the hydrodynamic stresses were shorter, as the multi-phase simulations have
indicated. In both cases, the peak cell densities were in the same range as cell
densities measured in planar static cultures at maximum confluency (% 2.9 Â 10
5
cells/cm
2 ), in which the cells were expanded in parallel. This result indicates that the
cells cultivated at N s1u
N
N s1 are mainly restricted by the available growth
surface. In contrast, significant lower cell densities were achieved at lower and
higher impeller speeds. A peak living cell density of 1.05 Æ 0.06 Â 10
5 cells/cm
2
(¼ 4.49 Æ 0.06 Â 10
5 cells/mL, EF 35) and 1.36 Æ 0.57 Â 10
5 cells/cm
2 (¼ 4.48 Æ
0.57 Â 10
5 cells/mL, EF 45) was determined for the SP100 and SP300 at 25 rpm and
20 rpm, respectively. These peak cell densities are up to 84% lower than those at
N s1u N N s1 . This observation may have been caused by the higher amount of
sedimented MCs and the increased MC-cell aggregate formation (see also [12]). The
viability of the cells on the MCs was always >99%. This was not surprising as dead
cells detach from the MC surface. Thus, the increase in dead cells in the supernatant
depends on the cell detachment from the MC surface and the die-off of cell in the
supernatant.
Table 8 Summary of cultivation results with hMSCs from the adipose tissue in the SP100 and
SP300
N
[rpm]
Living X max [10
5
cells/cm
2
]
EF
μ
[d
À1
]
t d [d]
q Glc [pmol/
cell/d]
q Lac [pmol/
cell/d]
q Amn [pmol/
cell/d]
Corning 125 mL spinner (SP100)
25
1.05 Æ 0.06
35.0 0.6 Æ
0.0
1.1 Æ
0.1
13.2 Æ 2.3 20.7 Æ 2.7
8.8 Æ 0.3
49
N s1u
1.67 Æ 0.12
55.6 0.7 Æ
0.0
1.0 Æ
0.0
10.6 Æ 1.6 35.2 Æ 1.9
6.1 Æ 0.4
60
N s1
1.68 Æ 0.36
56.0 0.7 Æ
0.1
0.9 Æ
0.1
9.8 Æ 0.8
30.3 Æ 1.0
6.2 Æ 0.3
120
0.60 Æ 0.04
20.1 0.5 Æ
0.1
1.5 Æ
0.4
35.0 Æ 1.6 88.8 Æ 5.2
16.5 Æ 0.3
Corning 500 mL spinner (SP300)
20
1.36 Æ 0.57
45.2 0.5 Æ
0.1
1.3 Æ
0.1
21.0 Æ 0.9 28.6 Æ 9.9
14.7 Æ 0.2
41
N s1u
2.46 Æ 0.16
81.9 0.7 Æ
0.0
1.0 Æ
0.0
15.5 Æ 0.6 40.6 Æ 1.8
10.6 Æ 0.5
52
N s1
2.43 Æ 0.66
81.1 0.7 Æ
0.0
1.0 Æ
0.0
11.8 Æ 1.2 35.3 Æ 3.3
9.7 Æ 0.4
100
1.25 Æ 0.29
41.8 0.5 Æ
0.1
1.3 Æ
0.0
20.8 Æ 9.8 88.6 Æ 2.1
19.0 Æ 1.4
214
V. Jossen et al.