title: Bone marrow-derived stem-cell repopulation contributes minimally to the Type II pneumocyte pool in transplanted human lungs.
abstract: BACKGROUND
  Lung transplant recipients are vulnerable to immunologic, infectious, ischemic, and toxic pulmonary injuries. The authors investigated whether type II pneumocytes in the lungs of cross-gender lung transplant patients show genotypic evidence to support repopulation of the lung by stem cells of bone marrow origin, and whether the degree of repopulation was related to rejection history.
  
  
  METHODS
  Recut sections were obtained from lung biopsy specimens from seven male recipients of transplanted lungs from female donors. Sequential immunohistochemistry and fluorescence in situ hybridization was performed on each section to evaluate for Y-chromosome-containing type II pneumocytes.
  
  
  RESULTS
  Y-chromosome-containing type II pneumocytes were found in 9 of 25 biopsy specimens from 5 of 7 gender-mismatched male lung transplant recipients, and accounted for 0% to 0.553% of type II pneumocytes. There was no evidence of polyploidy to suggest cell-cell fusion. The number of type II pneumocytes of male karyotype showed a statistically significant relationship to the cumulative number of episodes of acute cellular rejection.
  
  
  CONCLUSIONS
  Lung transplant recipients develop low levels of pneumocyte repopulation by bone marrow-derived stem cells or their progeny. These cells contribute minimally to the type II pneumocyte proliferation that is often present in these patients as a sequela to alveolar injury.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston Medical School, Houston, TX 77030, USA. dani.s.zander@uth.tmc.edu
authors.forename: Dani S
authors.initials: DS
authors.lastname: Zander
authors.forename: Maher A
authors.initials: MA
authors.lastname: Baz
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Cogle
authors.forename: Gary A
authors.initials: GA
authors.lastname: Visner
authors.forename: Neil D
authors.initials: ND
authors.lastname: Theise
authors.forename: James M
authors.initials: JM
authors.lastname: Crawford
mesh_terms: D000293:Adolescent; D000328:Adult; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D016040:Lung Transplantation / Q000473:pathology / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D033581:Stem Cell Transplantation; D014019:Tissue Donors; D018183:Transplantation Chimera