title: In vitro effects of low-level laser irradiation for bone marrow mesenchymal stem cells: proliferation, growth factors secretion and myogenic differentiation.
abstract: OBJECTIVE
  Bone marrow derived mesenchymal stem cells (BMSCs) have shown to be an appealing source for cell therapy and tissue engineering. Previous studies have confirmed that the application of low-level laser irradiation (LLLI) could affect the cellular process. However, little is known about the effects of LLLI on BMSCs. The aim of this study was designed to investigate the influence of LLLI at different energy densities on BMSCs proliferation, secretion and myogenic differentiation.
  
  
  METHODS
  BMSCs were harvested from rat fresh bone marrow and exposed to a 635 nm diode laser (60 mW; 0, 0.5, 1.0, 2.0, or 5.0 J/cm(2)). The lactate dehydrogenase (LDH) release was used to assess the cytotoxicity of LLLI at different energy densities. Cell proliferation was evaluated by using 3-(4, 5-dimethylithiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) and 5-bromo-2'-deoxyuridine (BrdU) assay. Production of vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) were measured by enzyme-linked immunosorbent assay (ELISA). Myogenic differentiation, induced by 5-azacytidine (5-aza), was assessed by using immunocytochemical staining for the expression of sarcomeric alpha-actin and desmin.
  
  
  RESULTS
  Cytotoxicity assay showed no significant difference between the non-irradiated group and irradiated groups. LLLI significantly stimulated BMSCs proliferation and 0.5 J/cm(2) was found to be an optimal energy density. VEGF and NGF were identified and LLLI at 5.0 J/cm(2) significantly stimulated the secretion. After 5-aza induction, myogenic differentiation was observed in all groups and LLLI at 5.0 J/cm(2) dramatically facilitated the differentiation.
  
  
  CONCLUSIONS
  LLLI stimulates proliferation, increases growth factors secretion and facilitates myogenic differentiation of BMSCs. Therefore, LLLI may provide a novel approach for the preconditioning of BMSCs in vitro prior to transplantation.
authors.affiliation: Department of Surgery, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China.
authors.forename: Jian-feng
authors.initials: JF
authors.lastname: Hou
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Yuan
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Ying-jie
authors.initials: YJ
authors.lastname: Wei
authors.forename: Sheng-shou
authors.initials: SS
authors.lastname: Hu
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000166:cytology*; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D028022:Low-Level Light Therapy; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000528:radiation effects*; D020932:Nerve Growth Factor / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D042461:Vascular Endothelial Growth Factor A; D020932:Nerve Growth Factor; D007770:L-Lactate Dehydrogenase; D001374:Azacitidine