ASGSB 2003 Annual Meeting Abstracts
The Hematopoietic Stem Cell Therapy for Astronauts' Immunodeficiency in Space.
A.N. Roach, B.C.
Kim, and S. Ohi.
Howard University and Hospital, Washington, DC.
It is well established
that astronauts develop immunodeficiency in 0/microgravity (mG) environment.
One explanation could be inhibition of hematopoietic stem cell growth and
hematopoiesis in mG environments, resulting in less or abnormal immune cells.
Exploiting the capability of hematopoietic stem cells to differentiate into
all types of blood cells, including immune cells, we have tested whether the
hematopoietic stem cell therapy (HSCT) could mitigate the immunodeficiency.
Since hindlimb suspended mice (HLS), a space flight model, reportedly show
decreased immunity, the ability to eliminate bacterial infection by the host
immune system may be compromised. The HLS mice are thus expected to be less
efficient in eliminating reporter gene-marked Escherichia coli. To
prove this, we transformed E. coli with a plasmid harboring b-galactosidase
(LacZ) gene, pCMV.SPORT-b-gal, to be used as the reporter gene-marked
bacteria. To test the X-Gal staining procedure for b-galactosidase, we stained
various tissues from b-gal transgenic mice and observed uniform and intense
blue stains. When corresponding tissues from control free roaming mice were
stained after E. coli infection, the tissues were stained less blue
than those of the LacZ mice. Next, we stained similar tissues from 2- week HLS
mice that were infected with b-gal-E. coli, we observed increased
tissue staining compared to control mice, thereby confirming the
immunodeficiency. Note that the intensity of X-gal stain inversely correlates
with the degree of immunity. Importantly, the whole mount staining indicates
that HSCT could restore immunity of the HLS mice, thereby helping to eliminate
reporter gene-marked E. coli. To quantitate these results further, we
have established procedures to measure the number of LacZ-E. coli in
the host blood. Preliminary results are concurrent with that observed in
(Supported by: NIAC/USRA
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