Stem cell transplantation in the context of HIV--how can we cure HIV infection?

All HIV target cells are derived from hematopoietic stem cells. More than two decades ago, a hypothesis was postulated that a cure for HIV may be possible by performing a transplant with HIV-resistant hematopoietic stem cells that would allow for an HIV-resistant immune system to arise. HIV-resistant stem cells could be generated by genetically modifying them with gene therapy vectors transferring anti-HIV genes. First attempts of stem cell gene therapy for HIV were carried out in the USA in the 1990s demonstrating safety, but also little efficacy at that time. The first demonstration that the postulated hypothesis was correct was the cure of an HIV-infected individual in Berlin in 2009 who received an allogeneic bone marrow transplant from a donor who lacked the CCR5 chemokine receptor, a naturally arising mutation rendering HIV target cells resistant to infection with macrophage tropic strains of HIV. In 2013, reports were published about a possible cure of HIV-infected individuals who received allogeneic bone marrow transplants with cells not resistant to HIV. We will review these stem cell transplant procedures and discuss their utility to provide a cure for HIV infection, including efficacious future stem cell gene therapy applications.