For years, scientists have been trying to develop a topical vaginal microbicide for preventing transmission of HIV, the virus that causes AIDS.
Several microbicide gels have been assessed in clinical trials after passing laboratory and animal safety tests.
However, all the microbicides were found to be ineffective against HIV, and two of the gels - nonoxynol-9 and cellulose sulfate - actually increased the risk of HIV infection in women.
"Our goal was to develop assays that are predictive of safety before proceeding to clinical trials that typically cost millions of dollars, involve thousands of women, and take many years," said study leader Dr Betsy C. Herold, a professor at Einstein.
While evaluating a microbicide's safety, the researchers look primarily for signs that the chemical inflames cells of the vaginal lining, or epithelium.
Tight junctions between genital tract epithelial cells provide an anatomic barrier, and prevent HIV from reaching submucosal targets.
Microbicides that disrupt the barrier increase the risk for HIV infection.
According to the Dr. Herold, this assay may help in predicting the safety of microbicides.
"Our findings strongly suggest that microbicides can increase the risk of HIV infection through a mechanism other that inflammation - namely, by disrupting the protective epithelial cell barrier," said Herold.
"If confirmed by further study, this assay should be used early on to screen for microbicide safety before advancing a product to clinical trials involving thousands of women," she added.
The study has been published in the Journal of Infectious Diseases.