0616 GMT February 29, 2020
"From our previous research, we learned that cancer stem cells reside in the hypoxic zones to maintain self-renewal property, and escape from the immune system," said Bikul Das, MBBS, PhD, Associate Research Investigator at the Forsyth Institute, and the honorary director of the KaviKrishna laboratory, Guwahati, India. "So, we hypothesized that Mtb, like cancer, may also have figured out the advantage of hiding in the hypoxic area," Science Daily reported.
To test this hypothesis, Dr. Das and his collaborators at Jawarharlal Nehru University (JNU), New Delhi, and KaviKrishna Laboratory, Indian Institute of Technology, Guwahati, utilized a well-known mouse model of Mtb infection, where months after drug treatment, Mtb remain dormant for future reactivation. Using this mouse model of dormancy, scientists isolated the special bone marrow stem cell type, the CD271+ mesenchymal stem cells, from the drug treated mice.
Prior to isolation of the stem cells, mice were injected with pimonidazole, a chemical that binds specifically to hypoxic cells. Pimonidazole binding of these cells was visualized under confocal microscope and via flow cytometry. The scientists found that despite months of drug treatment, Mtb could be recovered from the CD271+ stem cells. Most importantly, these stem cells exhibit strong binding to pimonidazole, indicating the hypoxic localization of the stem cells. Experiments also confirmed that these stem cells express a hypoxia activated gene, the hypoxia inducible factor 1 alpha (HIF-1 alpha).