CAMBRIDGE, Mass., June 19 (UPI) -- Researchers have discovered that Mycobacterium tuberculosis, or Mtb, the bacteria that causes tuberculosis, can hide in bone marrow stem cells in low oxygen areas called hypoxia zones out of reach of the immune system or toxic chemicals.
This, researchers said, is the reason tuberculosis can lay dormant in a patient and strike seemingly out of nowhere.
"These findings now explain why it is difficult to develop vaccines against tuberculosis," said Bikul Das, MBBS, Ph.D., an associate research investigator at the Forsyth Institute in India, in a press release. "The immune cells activated by the vaccine agent may not be able to reach the hypoxic site of bone marrow to target these 'wolfs-in-stem-cell-clothing.'"
Based on previous research, cancer stem cells were already known to reside in hypoxic zones and escape from the immune system. Researchers thought Mtb may have "figured out the advantage of hiding" in the same areas.
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Researchers used a mouse model of Mtb infection that, after months of treatment, remained in CD271+ stem cells. Before isolating the cells for testing, researchers injected them with pimonidazole, a chemical that binds to hypoxic cells. Researchers were then able to see that the mouse stem cells had bonded to pimonidazole, as well as that they were able to recover Mtb despite previous drug treatment.
Researchers then confirmed the finding by isolating the same stem cell in the bone marrow of a human tuberculosis patient who had undergone extensive treatment, finding viable Mtb just as they did in the mouse model.
The study is published in the American Journal of Pathology.
