Biomedical Engineering Reference
In-Depth Information
with carrier
w/o carrier
with carrier
w/o carrier
150
3
100
2
50
1
0
0
5 0 5 0 5 0 5 0
5 0 5 0 5 0 5 0
Time [d]
Time [d]
with carrier
w/o carrier
0.20
0.15
0.10
0.05
0.00
5 0 5 0 5 0 5 0
Time [d]
Fig. 5 Mass, thickness and Young's modulus of cartilage-carrier constructs and unsupported
cartilage cultivated for 5 weeks. Significant differences (a \ 0.05) are not shown (n = 3 for the
Young's modulus, n = 5 for the mass and thickness)
cultivation procedure presented above [ 54 ]. The DNA content relating to cartilage
mass significantly decreased with cultivation time (p \ 0.001), probably because
distances between cells increased due to the enhanced amount of extracellular
matrix. Consequently, GAG-to-DNA ratio increased significantly (p \ 0.001).
Ofek et al. [ 55 ] in a long-term study also observed no further improvement of
cartilage properties (GAG per wet weight, Young's modulus and collagen per wet
weight) after 4 weeks of cultivation. It is assumed that after this period exogenous
stimulation mechanisms such as mechanical loading or additional growth factors
are necessary to further enhance cartilage characteristics.
Although a decrease in DNA content related to cartilage mass could be observed,
the total DNA and GAG contents increased during the cultivation time (Table 1 ), so
that a stable growth of cartilage is achieved even over 5 weeks of in vitro cultivation.
With a specific DNA content of 6.05 pg per cell for porcine chondrocytes, the cell
number was 1.9910 6 cells for a construct cultivated on top of a carrier and 2.4910 6
cells for a construct cultivated without a carrier after 5 weeks. With a starting cell
number of 1.8910 6 cells per construct, cells hardly proliferated during this period,
which is desired as cartilage contains only about 2-10 vol.% of chondrocytes [ 56 ].
 
Search WWH ::




Custom Search