title: Downregulation of Melanoma Cell Adhesion Molecule (MCAM/CD146) Accelerates Cellular Senescence in Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells.
abstract: Therapeutic applications of mesenchymal stem cells (MSCs) for treating various diseases have increased in recent years. To ensure that treatment is effective, an adequate MSC dosage should be determined before these cells are used for therapeutic purposes. To obtain a sufficient number of cells for therapeutic applications, MSCs must be expanded in long-term cell culture, which inevitably triggers cellular senescence. In this study, we investigated the surface markers of human umbilical cord blood-derived MSCs (hUCB-MSCs) associated with cellular senescence using fluorescence-activated cell sorting analysis and 242 cell surface-marker antibodies. Among these surface proteins, we selected the melanoma cell adhesion molecule (MCAM/CD146) for further study with the aim of validating observed expression differences and investigating the associated implications in hUCB-MSCs during cellular senescence. We observed that CD146 expression markedly decreased in hUCB-MSCs following prolonged in vitro expansion. Using preparative sorting, we found that hUCB-MSCs with high CD146 expression displayed high growth rates, multilineage differentiation, expression of stemness markers, and telomerase activity, as well as significantly lower expression of the senescence markers p16, p21, p53, and senescence-associated β-galactosidase, compared with that observed in hUCB-MSCs with low-level CD146 expression. In contrast, CD146 downregulation with small interfering RNAs enhanced the senescence phenotype. In addition, CD146 suppression in hUCB-MSCs caused downregulation of other cellular senescence regulators, including Bmi-1, Id1, and Twist1. Collectively, our results suggest that CD146 regulates cellular senescence; thus, it could be used as a therapeutic marker to identify senescent hUCB-MSCs.
  
  
  CONCLUSIONS
  One of the fundamental requirements for mesenchymal stem cell (MSC)-based therapies is the expansion of MSCs during long-term culture because a sufficient number of functional cells is required. However, long-term growth inevitably induces cellular senescence, which potentially causes poor clinical outcomes by inducing growth arrest and the loss of stem cell properties. Thus, the identification of markers for evaluating the status of MSC senescence during long-term culture may enhance the success of MSC-based therapy. This study provides strong evidence that CD146 is a novel and useful marker for predicting senescence in human umbilical cord blood-derived MSCs (hUCB-MSCs), and CD146 can potentially be applied in quality-control assessments of hUCB-MSC-based therapy.
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Jin
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Kwon
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Miyeon
authors.initials: M
authors.lastname: Kim
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Yun Kyung
authors.initials: YK
authors.lastname: Bae
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Choi
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Wonil
authors.initials: W
authors.lastname: Oh
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea.
authors.forename: Yoon Sun
authors.initials: YS
authors.lastname: Yang
authors.affiliation: Biomedical Research Institute, R&D Center, MEDIPOST Co., Ltd., Gyeonggi-do, Republic of Korea jhb@medi-post.co.kr.
authors.forename: Hong Bae
authors.initials: HB
authors.lastname: Jeon
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D051929:CD146 Antigen / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation; D005312:Fetal Blood / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D045164:Mesenchymal Stem Cell Transplantation / Q000592:standards; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011786:Quality Control; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D051929:CD146 Antigen; C497902:MCAM protein, human; D034741:RNA, Small Interfering
keywords: Bmi-1; Cell surface marker; Cellular senescence; Human umbilical cord blood-derived mesenchymal stem cells; Id1; Melanoma cell adhesion molecule (CD146); Mesenchymal stem cell-based therapy; Twist1