Ex vivo culture of human colorectal tissue for the evaluation of candidate microbicides

AIDS. 2006 Jun 12;20(9):1237-45. doi: 10.1097/01.aids.0000232230.96134.80.


Objectives: Establishment of an in vitro model to evaluate rectal safety and the efficacy of microbicide candidates.

Design: An investigation and characterization of human colorectal explant culture for screening candidate microbicides to prevent rectal transmission of HIV-1 infection.

Methods: Human colorectal explants were cultured at the liquid-air interface on gelfoam rafts. Phenotypic characterization of HIV-1 target cells was performed by fluorescence-activated cell sorter analysis. HIV-1 infection was determined by the measurement of p24 antigen release, viral RNA, and proviral DNA accumulation.

Results: Colorectal explant CD4 T cells expressed higher CCR5 and CXCR4 levels compared with blood. Minor differences between the rectal and sigmoid colon were observed with a trend for slightly higher CCR5 and HLA-DR expression in cells from the sigmoid colon. Favourable culture conditions were established for colorectal tissue. Although tissue structure degenerated with time, CD4: CD8 cell ratios remained constant, and tissue supported productive HIV-1 infection. The ability of candidate microbicides to inhibit R5 HIV-1 infection was evaluated. Polyanion candidates, PRO2000 and dextrin sulphate, provided 99% protection at 1 microg/ml and 1 mg/ml, respectively, equivalent to 1/5000 and 1/40 of the vaginal formulations. The nucleotide reverse transcriptase inhibitor (NRTI) 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) provided protection at concentrations 1000-fold lower (10 microg/ml) than the proposed vaginal formulation (1%). Furthermore, non-NRTI UC-781 and TMC-120 provided greater than 99% inhibition at 3.3 or 0.33 microg/ml, respectively. No products demonstrated toxicity to rectal mucosa at inhibitory concentrations.

Conclusion: Colorectal explant culture was shown to be a useful tool for the preclinical evaluation of potential microbicides. The data suggest that rectally applied microbicides might provide protection from HIV-1 transmission.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Topical
  • Antiviral Agents / administration & dosage
  • Antiviral Agents / therapeutic use*
  • Cell Separation
  • Colon / virology*
  • Drug Evaluation / methods*
  • Flow Cytometry
  • Gels
  • HIV Infections / drug therapy*
  • HIV Infections / immunology
  • HIV-1*
  • Humans
  • Leukocytes / immunology
  • Phenotype
  • Rectum / virology*
  • Tissue Culture Techniques
  • Virus Replication


  • Antiviral Agents
  • Gels