title: Hypoxia-preconditioned mesenchymal stem cells attenuate bleomycin-induced pulmonary fibrosis.
abstract: BACKGROUND
  Idiopathic pulmonary fibrosis is a progressive diffuse parenchymal lung disorder of unknown etiology. Mesenchymal stem cell (MSC)-based therapy is a novel approach with great therapeutic potential for the treatment of lung diseases. Despite demonstration of MSC grafting, the populations of engrafted MSCs have been shown to decrease dramatically 24 hours post-transplantation due to exposure to harsh microenvironments. Hypoxia is known to induce expression of cytoprotective genes and also secretion of anti-inflammatory, anti-apoptotic and anti-fibrotic factors. Hypoxic preconditioning is thought to enhance the therapeutic potency and duration of survival of engrafted MSCs. In this work, we aimed to prolong the duration of survival of engrafted MSCs and to enhance the effectiveness of idiopathic pulmonary fibrosis transplantation therapy by the use of hypoxia-preconditioned MSCs.
  
  
  METHODS
  Hypoxic preconditioning was achieved in MSCs under an optimal hypoxic environment. The expression levels of cytoprotective factors and their biological effects on damaged alveolar epithelial cells or transforming growth factor-beta 1-treated fibroblast cells were studied in co-culture experiments in vitro. Furthermore, hypoxia-preconditioned MSCs (HP-MSCs) were intratracheally instilled into bleomycin-induced pulmonary fibrosis mice at day 3, and lung functions, cellular, molecular and pathological changes were assessed at 7 and 21 days after bleomycin administration.
  
  
  RESULTS
  The expression of genes for pro-survival, anti-apoptotic, anti-oxidant and growth factors was upregulated in MSCs under hypoxic conditions. In transforming growth factor-beta 1-treated MRC-5 fibroblast cells, hypoxia-preconditioned MSCs attenuated extracellular matrix production through paracrine effects. The pulmonary respiratory functions significantly improved for up to 18 days of hypoxia-preconditioned MSC treatment. Expression of inflammatory factors and fibrotic factor were all downregulated in the lung tissues of the hypoxia-preconditioned MSC-treated mice. Histopathologic examination observed a significant amelioration of the lung fibrosis. Several LacZ-labeled MSCs were observed within the lungs in the hypoxia-preconditioned MSC treatment groups at day 21, but no signals were detected in the normoxic MSC group. Our data further demonstrated that upregulation of hepatocyte growth factor possibly played an important role in mediating the therapeutic effects of transplanted hypoxia-preconditioned MSCs.
  
  
  CONCLUSIONS
  Transplantation of hypoxia-preconditioned MSCs exerted better therapeutic effects in bleomycin-induced pulmonary fibrotic mice and enhanced the survival rate of engrafted MSCs, partially due to the upregulation of hepatocyte growth factor.
authors.affiliation: Division of Biotechnology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. bublelanwilliam@gmail.com.
authors.forename: Ying-Wei
authors.initials: YW
authors.lastname: Lan
authors.affiliation: Department of Preclinical Sciences, Faculty of Medicine and Health Sciences and Centre for Stem Cell Research, Universiti Tunku Abdul Rahman, Selangor, Malaysia. chookb@utar.edu.my.
authors.forename: Kong-Bung
authors.initials: KB
authors.lastname: Choo
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, Republic of China. chchen1@dragon.nchu.edu.tw.|Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, Republic of China. chchen1@dragon.nchu.edu.tw.|Rong-Hsing Translational Medicine Center, National Chung Hsing University, Taichung, Taiwan, Republic of China. chchen1@dragon.nchu.edu.tw.
authors.forename: Chuan-Mu
authors.initials: CM
authors.lastname: Chen
authors.affiliation: Division of Biotechnology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. d9701407@stmail.cgu.edu.tw.
authors.forename: Tsai-Hsien
authors.initials: TH
authors.lastname: Hung
authors.affiliation: Institute of Biotechnology, National Taiwan University, Taichung, Taiwan, Republic of China. d96642009@gmail.com.
authors.forename: Young-Bin
authors.initials: YB
authors.lastname: Chen
authors.affiliation: Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. aguhsieh@gmail.com.|Department of Thoracic Medicine, St Paul's Hospital, Taoyuan, Taiwan, Republic of China. aguhsieh@gmail.com.|Department of Thoracic Medicine, Ton-Yen General Hospital, Hsinchu, Taiwan, Republic of China. aguhsieh@gmail.com.
authors.forename: Chung-Hsing
authors.initials: CH
authors.lastname: Hsieh
authors.affiliation: Department of Thoracic Medicine, Pulmonary Disease Research Center, Chang Gung Memorial Hospital, Taipei, Taiwan, Republic of China. q8828@ms11.hinet.net.|Department of Medicine, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. q8828@ms11.hinet.net.
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
authors.affiliation: Division of Biotechnology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. kchong@mail.cgu.edu.tw.|Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. kchong@mail.cgu.edu.tw.|Molecular Medicine Research Center, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China. kchong@mail.cgu.edu.tw.
authors.forename: Kowit-Yu
authors.initials: KY
authors.lastname: Chong
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001761:Bleomycin / Q000633:toxicity*; D001854:Bone Marrow Cells / Q000166:cytology; D015687:Cell Hypoxia; D002478:Cells, Cultured; D018920:Coculture Techniques; D004195:Disease Models, Animal; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000209:etiology* / Q000378:metabolism / Q000628:therapy; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; D001761:Bleomycin; D017228:Hepatocyte Growth Factor; D051057:Proto-Oncogene Proteins c-akt