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02598 HUMAN CERVICAL AND COLORECTAL EXPLANTS FOR TOXICITY AND EFFICACY TESTING OF TOPICAL MICROBICIDES Cummins, Jr., J.E.* In this study, we investigated the value of human cervical and colorectal explants in the preclinical assessment of microbicides with anti-HIV activity. Normal tissues were obtained 2-4 hours after surgery. Colorectal explants (placed on gelfoam and embedded in Matrigel) and cervical explants (embedded in 2% agarose) were cultured in transwells with the epithelium oriented on top. After tissue activation, HIV-1Ba-L with or without product (diluted 1:10) was applied and incubated overnight. Residual virus and microbicide were removed, and the explants were cultured for 2 weeks. HIV replication was determined by p24gag levels in the basolateral medium and by immuno-histochemical (IHC) analysis. Products tested were cellulose acetate phthalate (CAP), CarraguardTM, PRO 2000 (0.5% and 4%), K-Y plus nonoxynol-9 (KY-N9), UC781 (0.1% and 1%), and Vena GelTM along with their placebos. In both models, CAP, 0.5% and 4% PRO 2000, and 0.1% and 1% UC781 blocked HIV infection. IHC analysis demonstrated an absence of p24+ cells in cervical explants treated with these products. With the exception of KY-N9 and 4% PRO 2000, histological analysis showed minimal damage to the epithelium and submucosa. The low toxicity and anti-HIV activity of CAP, 0.5% PRO 2000, and 0.1% and 1% UC781 suggest further testing in human trials. These explant models may be useful for preclinical toxicity and efficacy testing of microbicides. Dr. James E. Cummins, Jr. |
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