title: Secreted galectin-3 as a possible biomarker for the immunomodulatory potential of human umbilical cord mesenchymal stromal cells.
abstract: OBJECTIVE
  Human umbilical cord-derived mesenchymal stromal cells (UC-MSCs) possess broad and potent immunomodulatory activities and have shown great potential in anti-inflammatory therapies. However, a biomarker that can be used to assess quickly and efficiently the immunomodulatory function of UC-MSCs has not been identified. Several studies have revealed that galectin-3 (Gal-3), a member of the human galectin family, is involved in the immunosuppressive function of MSCs.
  
  
  METHODS
  Gal-3 gene expression in UC-MSCs was analyzed using quantitative reverse transcriptase polymerase chain reaction and Western blotting. Blocking of Gal-3 expression in UC-MSCs with small interfering RNA was employed to analyze whether the immunosuppressive function of UC-MSCs was affected.
  
  
  RESULTS
  We found that UC-MSCs expressed Gal-3 both on the cell surface and in secreted form, and the expression levels of Gal-3 did not show significant variation after cell passaging. We further showed that Gal-3 expression correlated with the immunosuppressive function of UC-MSCs because knock-down of Gal-3 expression with small interfering RNA significantly abrogated the inhibitory effects of UC-MSCs on mitogen-stimulated and alloantigen-stimulated proliferation of human peripheral blood mononuclear cells; meanwhile, the inhibitory effect of UC-MSCs was reversed by adding back recombinant Gal-3 to the co-culture systems. The inhibitory activities of human UC-MSCs were not reduced even when they were separated from human peripheral blood mononuclear cells in a transwell co-culture system, indicating that the soluble form of Gal-3 was the major effector.
  
  
  CONCLUSIONS
  The Gal-3 protein secreted by UC-MSCs shows good correlation with immunosuppressive potential and may serve as a possible biomarker for the potency test of UC-MSCs.
authors.affiliation: Key Laboratory of Systems Bioengineering, Ministry of Education and Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
authors.forename: Guang-Yang
authors.initials: GY
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Wang
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Liu
authors.forename: Delin
authors.initials: D
authors.lastname: Zhu
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D037502:Galectin 3 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D056747:Immunomodulation / Q000187:drug effects / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014470:Umbilical Cord / Q000166:cytology
chemical_list: D015415:Biomarkers; D037502:Galectin 3; D034741:RNA, Small Interfering; D011994:Recombinant Proteins
keywords: biomarker; galectin-3; immunomodulatory; umbilical cord-derived mesenchymal stromal cells