314
Cell Growth in Microgravity
5
The Experience in Microgravity
Microgravity
and
randomized
gravity
facilitate spatial colocalization and three-
dimensional assembly of cells into large
aggregates. It is believed that diminu-
tion or nulliFcation of gravity results in
other forces displaying dominance. More
than 25 types of cells have been flown
in space. ±or 20 years, flight experiments
have shown that single cells respond to
space conditions with changes in cellu-
lar morphology and function. Cytoskeletal
reorganization occurs early after achieving
orbit. Human dermal Fbroblasts displayed
a signiFcant increase in collagen synthe-
sis aboard Space lab. This might facilitate
larger or more differentiated organoids by
cell aggregation. Space flight decreases
the amounts of osteocalcin and pre-pro-
alpha 2 chain of type 1 precollagen mRNA
in long bone and calvarial periosteum of
rats. Hence, cell types adversely affected
in microgravity (such as muscle, bone,
and cartilage) may yield inferior types of
tissue morphogenesis. Space bioreactors
were used for a 137-day cell culture on Mir
to generate three-dimensional cartilagi-
nous constructs from chondrocytes, which
were preaggregated on resorbable poly-
glycolic acid scaffolds. In parallel control
experiments, the constructs were main-
tained in analog culture for the same
period. In both flight and control cul-
tures, chondrogenesis occurred, yielding
many of the histochemical characteristics
of native collagen. ±light constructs were
mechanically inferior to constructs grown
on earth, largely due to a disproportionate
loss of one of the matrix components, gly-
cosaminoglycan. Cartilaginous constructs
obtained
in
the
modeled
microgravity
Tab. 1
Partial list of cells and tissues cultivated in microgravity in space and on the ground.
Cell/tissue
Environment
Observation
Lymphocytes
Several shuttle missions,
Maser sounding rockets
Inhibited locomotion, Impaired
immunocompetence, impaired
mitogenicity, changes in cytokine
production, altered cellular signaling
Chondrocytes
RWV in space (MIR/STS-79 for
4months)
In space culturing of pre-assembled 3-D
aggregates results in constructs which are
mechanically inferior to similar
aggregates grown in RWV on the ground.
Effect might mimic microgravity-induced
loss of cartilage
PC12 cells
Six weeks serial passaging of
cells in culture bags on MIR
Space Station (STS-86)
Establishes feasibility of long term, serial
passaging of cells in space, formation of
large aggregates with epitheloid
morphology
MIP 101 colon
carcinoma cells
EDU-1 on STS-70
Increased proliferation, enhanced
carcinoembryonic antigen (CEA)
production
Osteoblasts
Four days on STS-56 in
Materials Dispersion
Apparatus minilabs (MDA)
Inhibition of growth, reduction in serum
growth activation, changes in
micro±lament structure
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