A study published this week in Science Translational Medicine showed that genetically modified blood stem cells transplanted into HIV patients successfully produced antiviral material, which could theoretically suppress the virus long-term without antiretroviral drugs.

However, the amounts were too low to actually show anti-HIV activity.

Scientists believe that stem cell-based gene therapy is a promising prospect to eventually replace highly active antiretroviral therapy (HAART) (see related AIDS Beacon news).

“We hope to provide patients with long term protection from immunodeficiency and free them from a life long dependence on antiviral drugs with this treatment,” said Dr. David DiGiusto, lead author of the study in email correspondence with The AIDS Beacon.

The advantage to gene therapy is that treatments would be one-time or periodic, rather than having to take a daily pill.

This study in particular focused on RNA-based gene therapy. RNA is genetic material that is similar to DNA. RNA can affect which proteins are produced by a cell, and could offer a way to prevent infected cells from making the proteins HIV needs to survive and replicate.

The current study was small, with only seven participants. All of the participants had HIV- and AIDS-related lymphoma and were scheduled to undergo blood stem cell transplants, a common treatment for lymphoma.

For the trial, the scientists slightly modified the transplant. After collecting blood stem cells from the participants, the cells were mixed with antiviral RNA pieces, which block HIV by preventing the virus from infecting new cells and keep it from replicating.

The patients then received a transplant of their genetically modified blood stem cells containing the antiviral RNA.

Unfortunately, the transplanted stem cells did not produce enough disease-resistant blood cells to effectively suppress HIV in the participants.

However, the modified cells survived and produced the antiviral RNA for up to two years, indicated the possibility for long-term therapy for HIV patients.

The authors also stated that the results of the transplant were encouraging because the procedure was accomplished safely with minimal side effects in the participants. There had been concern that the antiviral RNA would be toxic to the patients, or that they could develop cancer, which is sometimes associated with antiviral genetic material.

The researchers found the results a promising step toward gene therapy for HIV. Dr. John Rossi, an author on the paper, told The AIDS Beacon in email correspondence that they are in the process of designing a new, improved clinical trial.

“We are planning to modify the conditions for another stem cell trial to get better numbers of gene modified cells,” said Dr. Rossi.

Improving the transplant procedure could generate more HIV resistant stem cells, resulting in more effective disease treatment.

For more information, please see the study in Science Translational Medicine (abstract).