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In December researchers announced they had used a modified form of the human immunodeficiency virus to successfully treat Sickle Cell Anemia in a mouse model. Future studies of the technique in mice and non-human primates will determine if and when human trials of this advance might begin.
Sickle cell anemia is a genetic disease which affects 70,000 Americans and is most prevalent in African Americans and Hispanics (it is an unfortunate side effect of genetic protection against diseases such as malaria). The disease causes the production of an abnormal hemoglobin which often forms into a sickle shape. These abnormal hemoglobins clog capillaries and cause a number of problems from anemia and stroke to bouts of severe pain and organ damage. Although there have been a lot of advances in treatment of the disease, the life expectancy of those afflicted with the disease is still only 43 years.
Researchers from the Massachusetts Institute of Technology, the Albert Einstein College of Medicine, and the Hospital for Sick Children in Toronto collaborated in an extremely sophisticated effort to cure mice of the disease.
First, they removed bone marrow from mice afflicted with the disease. They then ablated the marrow -- treating it to remove the disease. After this was accomplished, they injected the tissue with a modified version of HIV which carried a gene designed to prevent the disease.
The bone marrow was then injected back into mice, who were free of sickle cell anemia for 10 weeks. Ongoing monitoring of the mice will continue to see how long the protection lasts and as a springboard for developing future studies of the technique.
The process of ablating bone marrow used by the researchers it too toxic to be attempted with humans, but research is underway in several other laboratories to find method of ablating that human beings could tolerate.
Similarly, there are concerns about the possibility that the modified HIV virus might cause untoward side effects in human beings. "There's a very small possibility of that [HIV-related problems] occurring and it hasn't been demonstrated to date," researcher Robert Pawliuk told Wired.
Source:
Sickle cell therapy shows promise. Kristen Philipkoski, Wired, December 13, 2001.
Sickle cell anemia cured in lab mice. Associated Press, December 13, 2001.