title: Migration of culture-expanded human mesenchymal stem cells through bone marrow endothelium is regulated by matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-3.
abstract: OBJECTIVE
  Mesenchymal stem cells (MSC) are adult stem cells that can be expanded many fold in vitro and have the therapeutic potential to restore the bone marrow microenvironment and support hematopoietic recovery after myeloablative conditioning for hematopoietic stem cell transplantation. Successful homing to the target tissue, such as bone marrow, implies that MSC are able to extravasate after systemic administration. However, the extravasation capacity of MSC and the underlying mechanisms are poorly understood to date. We studied in vitro the capacity of MSC to migrate through bone marrow endothelium.
  
  
  METHODS
  In vitro invasion and transendothelial migration assays were performed. The expression of matrix metalloproteinase (MMP) was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and zymography. Migration of cells cultured at high or low confluence was compared and differential gene expression in these conditions was analyzed with microarray and real-time RT-PCR. The functional involvement in MSC migration was assessed using neutralizing anti-MMP-2 antibody, MMP-2 short interfering RNA or recombinant tissue inhibitor of metalloproteinase (TIMP-3).
  
  
  RESULTS
  We demonstrated that MSC can invade reconstituted basement membrane and that bone marrow endothelial cells stimulate this process. We also showed that the transendothelial migration of MSC is at least partially regulated by MMP-2. High culture confluence was found to increase production of the natural MMP-inhibitor TIMP-3 and decrease transendothelial migration of MSC.
  
  
  CONCLUSIONS
  We show that MSC have the potential to migrate through bone marrow endothelium and that this process involves MMP-2. Moreover, the migration of MSC is significantly influenced by the level of culture confluence. Increased culture confluence impairs migration and is related to an upregulation of TIMP-3. The therapeutic use of MSC would benefit from a selection of culture conditions that allow optimal extravasation of these cells.
authors.affiliation: Stem Cell Laboratory, Academic Hospital Vrije Universiteit Brussel Research group, Brussels, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: De Becker
authors.forename: Paul
authors.initials: P
authors.lastname: Van Hummelen
authors.forename: Marleen
authors.initials: M
authors.lastname: Bakkus
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vande Broek
authors.forename: Joke
authors.initials: J
authors.lastname: De Wever
authors.forename: Marc
authors.initials: M
authors.lastname: De Waele
authors.forename: Ivan
authors.initials: I
authors.lastname: Van Riet
mesh_terms: D017667:Adipocytes / Q000166:cytology; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured / Q000502:physiology; D019902:Chondrocytes / Q000166:cytology; D003094:Collagen; D004338:Drug Combinations; D004727:Endothelium; D020869:Gene Expression Profiling; D006801:Humans; D007797:Laminin; D020778:Matrix Metalloproteinase 2 / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D010011:Osteocytes / Q000166:cytology; D011509:Proteoglycans; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D014162:Transfection; D015854:Up-Regulation
chemical_list: D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D034741:RNA, Small Interfering; C088390:TIMP3 protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3; C059485:matrigel; D003094:Collagen; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9