title: Calcium phosphate surfaces promote osteogenic differentiation of mesenchymal stem cells.
abstract: Although studies in vivo revealed promising results in bone regeneration after implantation of scaffolds together with osteogenic progenitor cells, basic questions remain how material surfaces control the biology of mesenchymal stem cells (MSC). We used human MSC derived from bone marrow and studied the osteogenic differentiation on calcium phosphate surfaces. In osteogenic differentiation medium MSC differentiated to osteoblasts on hydroxyapatite and BONITmatrix, a degradable xerogel composite, within 14 days. Cells revealed a higher alkaline phosphatase (ALP) activity and increased RNA expression of collagen I and osteocalcin using real-time RTPCR compared with cells on tissue culture plastic. To test whether material surface characteristics alone are able to stimulate osteogenic differentiation, MSC were cultured on the materials in expansion medium without soluble additives for osteogenic differentiation. Indeed, cells on calcium phosphate without osteogenic differentiation additives developed to osteoblasts as shown by increased ALP activity and expression of osteogenic genes, which was not the case on tissue culture plastic. Because we reasoned that the stimulating effect on osteogenesis by calcium phosphate surfaces depends on an altered cell-extracellular matrix interaction we studied the dynamic behaviour of focal adhesions using cells transfected with GFP labelled vinculin. On BONITmatrix, an increased mobility of focal adhesions was observed compared with cells on tissue culture plastic. In conclusion, calcium phosphate surfaces are able to drive MSC to osteoblasts in the absence of osteogenic differentiation supplements in the medium. An altered dynamic behaviour of focal adhesions on calcium phosphate surfaces might be involved in the molecular mechanisms which promote osteogenic differentiation.
authors: Cell Biology Laboratory, Medical Faculty, University of Rostock, Rostock, Germany.
authors: Petra
authors: P
authors: Müller
authors: Ulrike
authors: U
authors: Bulnheim
authors: Annette
authors: A
authors: Diener
authors: Frank
authors: F
authors: Lüthen
authors: Marianne
authors: M
authors: Teller
authors: Ernst-Dieter
authors: ED
authors: Klinkenberg
authors: Hans-Georg
authors: HG
authors: Neumann
authors: Barbara
authors: B
authors: Nebe
authors: Andreas
authors: A
authors: Liebold
authors: Gustav
authors: G
authors: Steinhoff
authors: Joachim
authors: J
authors: Rychly
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism; D002130:Calcium Phosphates / Q000737:chemistry*; D002448:Cell Adhesion / Q000502:physiology; D002454:Cell Differentiation; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D017886:Durapatite / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology*; D012822:Silicon Dioxide / Q000737:chemistry*; D016596:Vinculin / Q000378:metabolism
chemical_list: C519914:BONITmatrix; D002130:Calcium Phosphates; C488955:VCL protein, human; C485184:enhanced green fluorescent protein; D015675:Osteocalcin; D016596:Vinculin; D049452:Green Fluorescent Proteins; D012822:Silicon Dioxide; D017886:Durapatite; D000469:Alkaline Phosphatase