title: Fetal cells in the maternal appendix: a marker of inflammation or fetal tissue repair?
abstract: BACKGROUND
  Fetal microchimeric cells that have trafficked into the maternal circulation persist in maternal tissues for years after pregnancy, but their biological role is unclear. We investigated whether fetal cells participate in maternal tissue repair during human pregnancy.
  
  
  METHODS
  Appendix specimens were acquired from women undergoing appendicectomy during (n = 8) or after (n = 1) pregnancy. Fluorescence in situ hybridization (FISH) determined the presence of male presumed-fetal cells, and immunostaining indicated the fetal cell phenotype.
  
  
  RESULTS
  Male cells were identified in appendiceal tissues from all women with known present or past male pregnancies (n = 7) and from a woman with a previous spontaneous abortion of undetermined gender (n = 1), but not in one woman with three daughters. One woman was only 6 weeks pregnant at appendicectomy. Male cells were evenly distributed through appendix tissues, in larger numbers where there was a greater degree of inflammation and when the current pregnancy was male. Combined immunostaining and Y-FISH demonstrated male desmin+ muscle cells and CD3+ lymphocytes, suggesting fetal cells had differentiated.
  
  
  CONCLUSIONS
  Male-presumed fetal cells of haematopoietic and mesenchymal origin were identified in the appendix of all pregnant women who had sons. We suggest that fetal cells are present at sites of maternal tissue injury during pregnancy, and may participate in tissue repair.
authors.affiliation: Division of Surgery, Faculty of Medicine, Institute of Reproductive and Developmental Biology, Imperial College London, UK. m.daavoribeirodossantos@umcutrecht.nl
authors.forename: Margarida Avo
authors.initials: MA
authors.lastname: Santos
authors.forename: Keelin
authors.initials: K
authors.lastname: O'Donoghue
authors.forename: Josephine
authors.initials: J
authors.lastname: Wyatt-Ashmead
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Fisk
mesh_terms: D000328:Adult; D001065:Appendix / Q000473:pathology*; D015415:Biomarkers / Q000032:analysis; D002678:Chimera; D015331:Cohort Studies; D005260:Female; D053686:Fetal Stem Cells / Q000166:cytology*; D005333:Fetus / Q000166:cytology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D014945:Wound Healing / Q000502:physiology*
chemical_list: D015415:Biomarkers