New research, in HIV positive patients being treated for blood cancer, has identified a critical time window after donor stem cell transplantation, during which the expanding donor cells are particularly vulnerable to being infected with HIV.
Patients with HIV who develop blood cancer may require treatment by allogeneic stem cell transplant, using bone marrow stem cells provided by a healthy donor. During a transplant, most of the patient's original immune cells are destroyed, and the immune system and blood cells are restored from the new donor stem cells.
'These results show a weak point that may explain why allogeneic stem cell transplants may not completely remove the virus from the body, despite a drastic reduction in the number of infected cells' said senior author Dr Julian Schulze zur Wiesch from the German Centre for Infection Research.
Stem cell transplantation in HIV positive patients has been the only medical intervention found to cure HIV (see BioNews 1039), however in nearly all cases HIV infection persists after transplantation.
In a new study it was discovered that immune cells generated from the donor stem cells are at risk of being infected with HIV during the first few weeks after transplantation.
In this study of 16 HIV positive participants with blood cancer, the researchers show that stem cell transplantation promotes reactivation of the virus within the patient's remaining original immune cells. This leads to some of the new immune cells becoming infected, thus 're-seeding' HIV within the host.
'Additional immunotherapy or gene therapy may be required to achieve ongoing, spontaneous control of HIV infection in people with HIV after allogeneic stem cell transplantation,' said Dr Schulze zur Wiesch.
This research was published in Science Translational Medicine.