Disease Focus Series: Stem cells for HIV/AIDS

2020 update: This post from almost 10 years ago on the HIV pandemic and particularly the first paragraph ring differently in the context of the COVID-19 novel coronavirus pandemic.

HIV virus lymphocyte
HIV virus (green) budding from a lymphocyte. Colored EM.

Over the last several years, there has been great concern about a possible flu pandemic around the world, but meanwhile the great pandemic of modern history, HIV/AIDS, continues. There are now more than 33 million HIV infected individuals. More than 2 million people have died from HIV infection in 2008 alone, approximately 1 out of 6 of these deaths were children younger than 15. Thus, HIV/AIDS is one of the most serious health issues in the world.

There remains a troubling misconception amongst the public that with the advent of anti-viral therapy involving protease inhibitors and different types of reverse transcriptase inhibitors, that AIDS has become less of a concern. However, anti-viral therapy is not widely available across the globe, up to half of patients with HIV do not respond optimally to this therapy, drug-resistant strains of HIV exist as HIV rapidly evolves, and other serious effects of HIV are becoming more evident that shorten the life spans of people infected with HIV even with effective anti-viral treatments. Therefore, research into new treatments for HIV/AIDS is critically important.

One possible, relatively new avenue for AIDS treatment involves cutting edge stem cell approaches. Much of this exciting research is going on here in California funded by CIRM. There is a powerful video produced by CIRM and featuring CIRM Director Jeff Sheehy, discussing the need for more research and these exciting, new potential areas of regenerative medicine that offer hope. You can watch it here.

CIRM is funding research by two disease teams (UCLA and City of Hope) into potential therapies whereby patients could receive treatments of their own hematopoietic stem cells that have been modified in such a way that the virus cannot infect them or their progeny blood cells.  Cells that are resistant to HIV infection would have an advantage over others that don’t and would gradually come to constitute the vast majority of cells within the person’s immune system. While not every HIV virus would disappear from the body, many patients treated in this way could be for all intents and purposes be cured permanently.

This stem cell-based approach was inspired by the finding that a leukemia patient who also happened to be infected by HIV, appears to have been cured of both leukemia and the virus by a bone marrow transplant. The cure is thought to be due to the fact that the marrow donor from whom the leukemia patient received the transplant was naturally resistant. The donor was homozygous for a mutation in the CCR5 gene. The CCR5 protein is a cellular receptor exploited by the virus to get into cells. This naturally occurring mutation appears to in effect ‘change the locks’ on cell membranes so the virus cannot enter cells, rendering the blood cells immune to the virus.

Other possible stem cell-based approaches to attacking this virus include efforts to teach the immune system to hone in on the HIV virus and kill it more effectively. For the vast majority of people, the immune system is not very effective at battling HIV so such an immune-enhancing treatment could be extremely beneficial.

HIV is not going away, the number of people infected continues to grow, and its propensity to evolve rapidly could mean the emergence of more drug resistant strains. According to the WHO (see graph #2), the number of people dying from AIDS has not significantly decreased around the world in recent years even with the advent of anti-viral therapies.

The bottom line is that it is critically important that we continue to fight this disease and stem cell-based approaches to treating AIDS bring hope to millions of people.