Directly auto-transplanted mesenchymal stem cells induce bone formation in a ceramic bone substitute in an ectopic sheep model.
Bottom Line: Bone matrix proteins were up-regulated in constructs following direct auto-transplantation and in expanded MSC as well as in BMP-2 constructs.Up-regulation was detected using immunohistology methods and RT-PCR.Dense vascularization was demonstrated by CD31 immunohistology staining in all three groups.
Affiliation: Department of Plastic and Hand Surgery, University Hospital of Erlangen, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany.Show MeSH
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Mentions: Different BMP-2 concentrations were tested to determine optimal concentration for osteogenic stimulation effects (groups 4–7). In the control group using β-TCP/HA granules and a fibrinogen– thrombin matrix only, no bone formation could be detected. While using 2.5 μg/ml or 12.5 μg/ml BMP-2 early bone formation could be detected. Around the β-TCP/HA granules a small margin of osteoblast-like cells and small parts of bone matrix was found (Fig. 5A/B). Using higher concentration of BMP-2 with 60 μg/ml, trabecular, osteon-like, well-vascularized bone formation occurred within 12 weeks (Fig. 5C). The newly formed bone parts were located close to the β-TCP/HA granules. We could demonstrate the expression of collagen type I (COL1) in the newly formed bone in the 2.5, 12.5 and 60 μg/ml explants using immunohistological staining (Fig. 5D–F, D 2.5 μg/ml, E 12.5 μg/ml and F 60 μg/ml). Expression of genes specific for bone-like COL1, osteocalcin, osteonectin, osteopontin as bone matrix proteins and the osteoblast differentiation marker runt-related-transcription factor (RUNX) 2 in the 60 μg/ml explants were demonstrated using RT-PCR. Osteocalcin, osteonectin, osteopontin and COL1 were up-regulated in 60 μg/ml constructs compared to the control group using β-TCP/HA granules with fibrinogen–thrombin matrix without growth factors or cells (Fig. 6A–C).
Affiliation: Department of Plastic and Hand Surgery, University Hospital of Erlangen, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany.