Lack of detection of COVID mRNA vaccine via in situ hybridization in human placental explants
Chorionic villi explants derived from second (n = 2) or third trimester (n = 2) human placentas were incubated with 0.1 μg/mL (not shown) or 1 μg/mL mRNA-1237 or BNT162B2 vaccines. After 0.5 h or 4 h, tissues were fixed, paraffin-embedded, sectioned and probed for mRNA vaccine using RNAscope in situ hybridization.
(A and B) Positive and (B) negative controls for RNAscope detection of mRNA vaccine. Peptidylprolyl isomerase B (PPIB) was used as a positive control. Pink dots corresponding to PPIB mRNA can be observed within the chorionic villi at 20X and 40X. DapB was used as a negative control. No signal was detected at 20 or 40X.
(C) In situ detection of mRNA vaccine in vaccine-exposed explants. No signal was evident in explants incubated with either vaccine at any of the two time points.