title: Nonreproducibility of "snap-frozen" rectal biopsies for later use in ex vivo explant infectibility studies.
abstract: Sexual transmission accounts for the majority of new HIV infections worldwide with sexually exposed cervicovaginal and colorectal mucosae being primary sites of infection. Two recent Phase 1 rectal microbicide trials included, as an ancillary endpoint, suppression of ex vivo HIV infection of in vivo microbicide-exposed rectal mucosal tissue biopsies. Both trials demonstrated significant suppression of biopsy infectibility in drug-exposed versus placebo-exposed tissue. This potential early biomarker of efficacy has raised the feasibility of utilizing "snap-frozen" tissue samples, acquired at multiple trial sites to be shipped for central processing, providing a mechanism to correlate tissue drug concentrations with a functional index of HIV prevention. While previous reports have indicated acceptable comparability of fresh versus freeze-thawed cervicovaginal tissue samples, no similar evaluations with colorectal tissue biopsies have been done. In this study, rectal biopsies from healthy, HIV-seronegative participants were assessed for structural integrity (histology), viability (MTT assays), and tissue infectibility to compare results from fresh versus combinations of freeze/thaw protocols. Results indicated that while all protocols showed equivalent viability with fresh samples (MTT), histology documented poor preservation of tissue integrity following freezing. Infectibility results from freeze-thawed colorectal tissue were markedly lower (usually<25% of fresh samples) and varied greatly and unpredictably. Centralized colorectal tissue infectibility assays using biopsies from remote trial sites cannot currently be supported under these protocols.
authors: Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Ian
authors: I
authors: McGowan
authors: Karen
authors: K
authors: Tanner
authors: Julie
authors: J
authors: Elliott
authors: Javier
authors: J
authors: Ibarrondo
authors: Elena
authors: E
authors: Khanukhova
authors: Charina
authors: C
authors: McDonald
authors: Terry
authors: T
authors: Saunders
authors: Ying
authors: Y
authors: Zhou
authors: Peter A
authors: PA
authors: Anton
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D015925:Cryopreservation; D004724:Endoscopy; D005260:Female; D018023:HIV Seronegativity / Q000187:drug effects*; D006801:Humans; D008297:Male; D012007:Rectum / Q000187:drug effects / Q000473:pathology*; D015203:Reproducibility of Results
chemical_list: D000890:Anti-Infective Agents