title: [IMMUNOGENICITY OF HUMAN UMBILICAL CORD BLOOD DERIVED MESENCHYMAL STEM CELLS AFTER OSTEOGENIC INDUCTION].
abstract: OBJECTIVE
  To study the immunological properties of osteogenically differentiated umbilical cord blood derived mesenchymal stem cells (UCB-MSCs).
  
  
  METHODS
  UCB-MSCs were isolated from the umbilical cord vein, and were expanded; the cells at passage 3 were osteogenically induced for 2 weeks in vitro. The expressions of human leukocyte antigen I (HLA-I) and HLA-II molecules were observed by flow cytometry analysis before and after osteogenic induction. Peripheral blood T lymphocytes were isolated and cultured with osteoblastic induced or non-osteoblastic induced UCB-MSCs in different cell concentrations of 1 x 10(2), 1 x 10(3), 1 x 10(4), and 1 x 10(5) cells/well. The intake value of 3H-thymidine was calculated with luminescence counter. Then T lymphocytes were pretreated with PHA, and co-cultured with osteoblastic induced and non-osteoblastic induced UCB-MSCs as described above. IL-2 was further added to test the reversed effect of T lymphocytes proliferation stimulated by UCB-MSCs. Finally, to investigate whether the immunomodulatory effects on T lymphocytes proliferation depend on direct or indirect cell contact, the Transwell chamber culture system of UCB-MSCs and T lymphocytes was established.
  
  
  RESULTS
  Flow cytometry analysis showed that non-osteoblastic induced UCB-MSCs expressed HLA-I but did not express HLA-II; the expression of HLA-II increased in osteoblastic induced UCB-MSCs. No T lymphocyte response was stimulated by non-osteoblastic induced UCB-MSCs, but osteoblastic induced UCB-MSCs could stimulate the proliferation of allogeneic T lymphocytes, especially after IFN-γ treatment. Non-osteoblastic induced UCB-MSCs of 1 x 10(4) and 1 x 10(5) cells/well could suppress the proliferation of T lymphocytes evoked by PHA, and this suppression could be reversed by the addition of IL-2. While osteoblastic induced UCB-MSCs did not have such suppressive effect. The results of the Transwell culture system also showed that non-osteoblastic induced UCB-MSCs could obviously inhibit the proliferation of T lymphocytes, but the osteoblastic induced UCB-MSCs could not.
  
  
  CONCLUSIONS
  The immunological properties of UCB-MSCs will change accordingly after osteogenic induction, so UCB-MSCs might not be suitable for the seed cells of bone tissue engineering.
authors.forename: Dawei
authors.initials: D
authors.lastname: Yang
authors.forename: Hemin
authors.initials: H
authors.lastname: Lin
authors.forename: Guangpeng
authors.initials: G
authors.lastname: Liu
mesh_terms: D002454:Cell Differentiation; D049109:Cell Proliferation; D018920:Coculture Techniques; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology*; D005434:Flow Cytometry; D006680:HLA Antigens / Q000378:metabolism*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D014470:Umbilical Cord
chemical_list: D006680:HLA Antigens