Latent TB bacteria can hide in marrow cells

Infectious disease and stem cell researchers recently found evidence that tuberculosis bacteria may hide in bone- and cartilage-forming stem cells in bone marrow to protect themselves from drugs and the immune system.

The study was conducted by researchers from India, the Forsyth Institute in Cambridge and the Stanford University School of Medicine and was published on Wednesday in the journal Science Translational Medicine. The study determined that it was possible to infect a particular subset of bone marrow stem cells grown with TB bacteria in laboratory dishes, the Boston Globe reports.

The team then infected mice with an engineered strain of the bacteria that would not grow unless activated by a drug. The researchers found that the TB bacteria grew in the lungs and in the same subset of bone marrow stem cells.

"Anybody, it seems to me, who has any insight into how a bug can hang out for that period of time and remain viable is doing good things," Barry Bloom, an infectious disease and global health specialist at the Harvard School of Public Health, said, according to the Boston Globe. "This paper offers one such bit of evidence, that it could hide in a relatively privileged part of the bone marrow."

Previous studies showed that bone marrow stem cells from TB patients that were deemed cured were still able to grow TB bacteria in some cases. The finding demonstrated that current TB medication may not kill bacteria hiding in the stem cells.

Continued research will be needed to better understand how the infection could be reactivated from the stem cells and how the bacteria got into the cells in the first place, the Boston Globe reports.

"For understanding tuberculosis vaccine development, diagnostic development, and treatment development, it's very, very important we understand what are the situations that distinguish these two different phases of the disease," Antonio Campos-Neto, one of the leaders of the work, said, according to the Boston Globe. "In some cases, the infection just moves to an active pathology, and in other cases, it stays latent forever."