title: Characterization of intercellular communication and mitochondrial donation by mesenchymal stromal cells derived from the human lung.
abstract: BACKGROUND
  Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are capable of repairing wounded lung epithelial cells by donating cytoplasmic material and mitochondria. Recently, we characterized two populations of human lung-derived mesenchymal stromal cells isolated from digested parenchymal lung tissue (LT-MSCs) from healthy individuals or from lung transplant recipients' bronchoalveolar lavage fluid (BAL-MSCs). The aim of this study was to determine whether LT-MSCs and BAL-MSCs are also capable of donating cytoplasmic content and mitochondria to lung epithelial cells.
  
  
  METHODS
  Cytoplasmic and mitochondrial transfer was assessed by co-culturing BEAS2B epithelial cells with Calcein AM or Mitotracker Green FM-labelled MSCs. Transfer was then measured by flow cytometry and validated by fluorescent microscopy. Molecular inhibitors were used to determine the contribution of microtubules/tunnelling nanotubes (TNTs, cytochalasin D), gap junctions (carbenoxolone), connexin-43 (gap26) and microvesicles (dynasore).
  
  
  RESULTS
  F-actin microtubules/TNTs extending from BM-MSCs, LT-MSCs and BAL-MSCs to bronchial epithelial cells formed within 45 minutes of co-culturing cells. Each MSC population transferred a similar volume of cytoplasmic content to epithelial cells. Inhibiting microtubule/TNTs, gap junction formation and microvesicle endocytosis abrogated the transfer of cytoplasmic material from BM-MSCs, LT-MSCs and BAL-MSCs to epithelial cells. In contrast, blocking connexin-43 gap junction formation had no effect on cytoplasmic transfer. All MSC populations donated mitochondria to bronchial epithelial cells with similar efficiency. Mitochondrial transfer was reduced in all co-cultures after microtubule/TNT or endocytosis inhibition. Gap junction formation inhibition reduced mitochondrial transfer in BM-MSC and BAL-MSC co-cultures but had no effect on transfer in LT-MSC co-cultures. Connexin-43 inhibition did not impact mitochondrial transfer. Finally, bronchial epithelial cells were incapable of donating cytoplasmic content or mitochondria to any MSC population.
  
  
  CONCLUSIONS
  Similar to their bone marrow counterparts, LT-MSCs and BAL-MSCs can donate cytoplasmic content and mitochondria to bronchial epithelial cells via multiple mechanisms. Given that BM-MSCs utilize these mechanisms to mediate the repair of damaged bronchial epithelial cells, both LT-MSCs and BAL-MSCs will probably function similarly.
authors.affiliation: School of Medicine, University of Queensland, Brisbane, QLD, Australia. Kenneth.Sinclair@uqconnect.edu.au.|Queensland Lung Transplant Service, Ground Floor, Clinical Sciences Building, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD, 4032, Australia. Kenneth.Sinclair@uqconnect.edu.au.
authors.forename: Kenneth Andrew
authors.initials: KA
authors.lastname: Sinclair
authors.affiliation: School of Medicine, University of Queensland, Brisbane, QLD, Australia.|Queensland Lung Transplant Service, Ground Floor, Clinical Sciences Building, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD, 4032, Australia.
authors.forename: Stephanie Terase
authors.initials: ST
authors.lastname: Yerkovich
authors.affiliation: School of Medicine, University of Queensland, Brisbane, QLD, Australia.|Queensland Lung Transplant Service, Ground Floor, Clinical Sciences Building, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD, 4032, Australia.
authors.forename: Peter Mark-Anthony
authors.initials: PM
authors.lastname: Hopkins
authors.affiliation: School of Medicine, University of Queensland, Brisbane, QLD, Australia.|Queensland Lung Transplant Service, Ground Floor, Clinical Sciences Building, The Prince Charles Hospital, Rode Road, Chermside, Brisbane, QLD, 4032, Australia.
authors.forename: Daniel Charles
authors.initials: DC
authors.lastname: Chambers
mesh_terms: D000328:Adult; D001692:Biological Transport; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000648:ultrastructure; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002450:Cell Communication; D002460:Cell Line; D018920:Coculture Techniques; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D017629:Gap Junctions / Q000378:metabolism / Q000648:ultrastructure; D015870:Gene Expression; D006801:Humans; D008168:Lung / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000648:ultrastructure; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D061251:Primary Cell Culture
chemical_list: D018031:Connexin 43; C500216:GJA1 protein, human
keywords: Bronchoalveolar lavage; Intercellular communication; Mesenchymal stem cells; Mesenchymal stromal cells; Mitochondrial donation