Cryopreserved colorectal explants are somewhat less susceptible to HIV infection than fresh colorectal explants, while cryopreserved and fresh ectocervical explants are similarly susceptible.

<p><b>A</b>, HIV challenge curves for colorectal tissue showing HIV p24 concentrations (picograms/milliliter) from a single tissue donor either fresh or after cryopreservation with the indicated cryopreservation media. Each line represents a single explant and points represent supernatant collections. All three explants come from the same donor. “DMSO”, dimethylsulfoxide; “EG”, “ethylene glycol”; “mM”, “millimolar”. <b>B</b>, Summary of HIV challenge experiments for colorectal tissues. Each square represents a single explant, with each column representing a different donor (total n = 12 donors with 2–3 explants per donor per condition, as shown). Light squares indicate explants that became infected and dark squares explants that did not. Missing squares indicate cases where there was inadequate tissue available to have three explants in all conditions or where an explant was lost by experimental error. Explants are defined as infected on the first day after day 5 where the p24 concentration exceeds 250 pg/mL. <b>C</b>, Proportion of colorectal explants that became infected. Points show the proportion of all challenged explants that became infected. Lines show the 95% binomial proportion confidence intervals. <b>D</b>, Survival curves indicating cumulative HIV infection for all colorectal explants tested in each condition. Fresh explants are shown in green, cryopreserved with 10% DMSO in orange, and cryopreserved with 6% DMSO, 5% EG, and 50 mM trehalose in blue. <b>E</b>, HIV challenge curves for ectocervical tissue, as in A. <b>F</b>, Summary of HIV challenge experiments for ectocervical tissue, as in B, with a threshold of infection of 500 pg/mL (total n = 11 donors with 2–3 explants per donor per condition, as shown). <b>G</b>, Proportion of ectocervical explants that became infected, as in C. <b>H</b>, Survival curves for HIV infection of ectocervical explants, as in D.