title: Human palatine tonsil: a new potential tissue source of multipotent mesenchymal progenitor cells.
abstract: BACKGROUND
  Mesenchymal progenitor cells (MPCs) are multipotent progenitor cells in adult tissues, for example, bone marrow (BM). Current challenges of clinical application of BM-derived MPCs include donor site morbidity and pain as well as low cell yields associated with an age-related decrease in cell number and differentiation potential, underscoring the need to identify alternative sources of MPCs. Recently, MPC sources have diversified; examples include adipose, placenta, umbilicus, trabecular bone, cartilage, and synovial tissue. In the present work, we report the presence of MPCs in human tonsillar tissue.
  
  
  METHODS
  We performed comparative and quantitative analyses of BM-MPCs with a subpopulation of adherent cells isolated from this lymphoid tissue, termed tonsil-derived MPCs (T-MPCs). The expression of surface markers was assessed by fluorescent-activated cell sorting analysis. Differentiation potential of T-MPCs was analyzed histochemically and by reverse transcription-polymerase chain reaction for the expression of lineage-related marker genes. The immunosuppressive properties of MPCs were determined in vitro in mixed lymphocyte reactions.
  
  
  RESULTS
  Surface epitope analysis revealed that T-MPCs were negative for CD14, CD31, CD34, and CD45 expression and positive for CD29, CD44, CD90, and CD105 expression, a characteristic phenotype of BM-MPCs. Similar to BM-MPCs, T-MPCs could be induced to undergo adipogenic differentiation and, to a lesser extent, osteogenic and chondrogenic differentiation. T-MPCs did not express class II major histocompatibility (MHC) antigens, and in a similar but less pronounced manner compared with BM-MPCs, T-MPCs were immunosuppressive, inhibiting the proliferation of T cells stimulated by allogeneic T cells or by non-specific mitogenic stimuli via an indoleamine 2,3-dioxygenase-dependent mechanism.
  
  
  CONCLUSIONS
  Human palatine T-MPCs represent a new source of progenitor cells, potentially applicable for cell-based therapies.
authors.affiliation: Department of Health and Human Services, Cartilage Biology and Orthopaedics Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Sasa
authors.initials: S
authors.lastname: Janjanin
authors.forename: Farida
authors.initials: F
authors.lastname: Djouad
authors.forename: Rabie M
authors.initials: RM
authors.lastname: Shanti
authors.forename: Dolores
authors.initials: D
authors.lastname: Baksh
authors.forename: Kiran
authors.initials: K
authors.lastname: Gollapudi
authors.forename: Drago
authors.initials: D
authors.lastname: Prgomet
authors.forename: Lars
authors.initials: L
authors.lastname: Rackwitz
authors.forename: Arjun S
authors.initials: AS
authors.lastname: Joshi
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007165:Immunosuppression Therapy; D007371:Interferon-gamma / Q000494:pharmacology; D007959:Lymphocyte Culture Test, Mixed; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D039902:Multipotent Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D014066:Palatine Tonsil / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D017471:Receptors, Interferon / Q000378:metabolism; D000096743:Interferon gamma Receptor
chemical_list: D007371:Interferon-gamma; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor