ASGSB 2003 Annual Meeting Abstracts


[14]

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 wholemount staining.

(Supported by: NIAC/USRA grants)

 

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