title: Enhanced integrin-mediated human osteoblastic adhesion to porous amorphous calcium phosphate/poly (L-lactic acid) composite.
abstract: BACKGROUND
  The initial osteoblastic adhesion to materials characterizes the first phase of cell-material interactions and influences all the events leading to the formation of new bone. In a previous work, we developed a novel amorphous calcium phosphate (ACP)/poly(L-lactic acid) (PLLA) material that demonstrated morphologic variations in its microstructure. The aim of this study was to investigate the initial interaction between this material and osteoblastic cells. Cellular attachment and the corresponding signal transduction pathways were investigated.
  
  
  METHODS
  A porous ACP/PLLA composite and PLLA scaffold (as a control) were incubated in fetal bovine serum (FBS) containing phosphate-buffered saline (PBS), and the protein adsorption was determined. Osteoblastic MG63 cells were seeded on the materials and cultured for 1, 4, 8, or 24 hours. Cell attachment was evaluated using the MTS method. Cell morphology was examined using scanning electron microscopy (SEM). The expression levels of the genes encoding integrin subunits α1, α5, αv, β1, focal adhesion kinase (FAK), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were determined using real-time reverse transcription polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  The ACP/PLLA material significantly increased the protein adsorption by 6.4-fold at 1 hour and 2.4-fold at 24 hours, compared with the pure PLLA scaffold. The attachment of osteoblastic cells to the ACP/PLLA was significantly higher than that on the PLLA scaffold. The SEM observation revealed a polygonal spread shape of cells on the ACP/ PLLA, with the filopodia adhered to the scaffold surface. In contrast, the cells on the PLLA scaffold exhibited a spherical or polygonal morphology. Additionally, real-time RT-PCR showed that the genes encoding the integrin subunits α1, αv, β1, and FAK were expressed at higher levels on the ACP/PLLA composite.
  
  
  CONCLUSIONS
  The ACP/PLLA composite promoted protein adsorption and osteoblastic adhesion. The enhanced cell adhesion may be mediated by the binding of integrin subunits α1, αv, and β1, and subsequently may be regulated through the FAK signal transduction pathways.
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, Zhejiang 310009, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, Zhejiang 310009, China.
authors.forename: Yiying
authors.initials: Y
authors.lastname: Qi
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, Zhejiang 310009, China.
authors.forename: Weixu
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, Zhejiang 310009, China.
authors.forename: Zhongli
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
authors.forename: Wenjian
authors.initials: W
authors.lastname: Weng
authors.affiliation: Department of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
authors.forename: Kui
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, Zhejiang 310009, China. Email: herongxin2005@yahoo.com.cn.
authors.forename: Rongxin
authors.initials: R
authors.lastname: He
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D006801:Humans; D039423:Integrin alpha1 / Q000378:metabolism; D039482:Integrin alpha5 / Q000378:metabolism; D039564:Integrin alphaV / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D016023:Integrins / Q000235:genetics / Q000378:metabolism*; D019344:Lactic Acid / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology*; D016062:Porosity; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D039423:Integrin alpha1; D039482:Integrin alpha5; D039564:Integrin alphaV; D019012:Integrin beta1; D016023:Integrins; C519480:amorphous calcium phosphate; D019344:Lactic Acid; D051416:Focal Adhesion Protein-Tyrosine Kinases