title: Skeletal stem cell and bone implant interactions are enhanced by LASER titanium modification.
abstract: OBJECTIVE
  To evaluate the osteo-regenerative potential of Titanium (Ti) modified by Light Amplification by Stimulated Emission of Radiation (LASER) beam (Yb-YAG) upon culture with human Skeletal Stem Cells (hSSCs(1)).
  
  
  METHODS
  Human skeletal cell populations were isolated from the bone marrow of haematologically normal patients undergoing primary total hip replacement following appropriate consent. STRO-1(+) hSSC(1) function was examined for 10 days across four groups using Ti discs: i) machined Ti surface group in basal media (Mb(2)), ii) machined Ti surface group in osteogenic media (Mo(3)), iii) LASER-modified Ti group in basal media (Lb(4)) and, iv) LASER-modified Ti group in osteogenic media (Lo(5)). Molecular analysis and qRT-PCR as well as functional analysis including biochemistry (DNA, Alkaline Phosphatase (ALP(6)) specific activity), live/dead immunostaining (Cell Tracker Green (CTG(7))/Ethidium Homodimer-1 (EH-1(8))), and fluorescence staining (for vinculin and phalloidin) were undertaken. Inverted, confocal and Scanning Electron Microscopy (SEM) approaches were used to characterise cell adherence, proliferation, and phenotype.
  
  
  RESULTS
  Enhanced cell spreading and morphological rearrangement, including focal adhesions were observed following culture of hSSCs(1) on LASER surfaces in both basal and osteogenic conditions. Biochemical analysis demonstrated enhanced ALP(6) specific activity on the hSSCs(1)-seeded on LASER-modified surface in basal culture media. Molecular analysis demonstrated enhanced ALP(6) and osteopontin expression on titanium LASER treated surfaces in basal conditions. SEM, inverted microscopy and confocal laser scanning microscopy confirmed extensive proliferation and migration of human bone marrow stromal cells on all surfaces evaluated.
  
  
  CONCLUSIONS
  LASER-modified Ti surfaces modify the behaviour of hSSCs.(1) In particular, SSC(1) adhesion, osteogenic gene expression, cell morphology and cytoskeleton structure were affected. The current studies show Ti LASER modification can enhance the osseointegration between Ti and skeletal cells, with important implications for orthopaedic application.
authors.affiliation: Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, UK; Biomaterials Group, Institute of Chemistry, São Paulo State University (UNESP), Box 355, Araraquara, Brazil; Federal University of Mato Grosso do Sul (UFMS), Campo Grande, Brazil. Electronic address: karinellensisti@gmail.com.
authors.forename: Karin E
authors.initials: KE
authors.lastname: Sisti
authors.affiliation: Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, UK.
authors.forename: María C
authors.initials: MC
authors.lastname: de Andrés
authors.affiliation: Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, UK.
authors.forename: David
authors.initials: D
authors.lastname: Johnston
authors.affiliation: Biomaterials Group, Institute of Chemistry, São Paulo State University (UNESP), Box 355, Araraquara, Brazil.
authors.forename: Edson
authors.initials: E
authors.lastname: Almeida-Filho
authors.affiliation: Biomaterials Group, Institute of Chemistry, São Paulo State University (UNESP), Box 355, Araraquara, Brazil.
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Guastaldi
authors.affiliation: Bone and Joint Research Group, Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, UK.
authors.forename: Richard O C
authors.initials: RO
authors.lastname: Oreffo
mesh_terms: D018786:Bone Substitutes / Q000737:chemistry*; D001842:Bone and Bones / Q000378:metabolism*; D002448:Cell Adhesion; D049109:Cell Proliferation; D002470:Cell Survival; D003599:Cytoskeleton / Q000378:metabolism; D004996:Ethidium / Q000031:analogs & derivatives / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration; D010006:Osteoblasts / Q000378:metabolism; D010012:Osteogenesis; D019736:Prostheses and Implants; D012038:Regeneration; D014025:Titanium / Q000737:chemistry*
chemical_list: D018786:Bone Substitutes; C018533:ethidium homodimer; D014025:Titanium; D004996:Ethidium
keywords: Bone formation; LASER; Skeletal stem cell; Tissue regeneration; Titanium surface