title: Transforming growth factor beta released from natural coral implant enhances bone growth at calvarium of mature rat.
abstract: Earlier studies have shown that transforming growth factor beta (TGF-beta) has the capability of enhancing bone formation after a single application to an orthotopic site. We investigated whether 1, 5, or 25 microg of recombinant human TGF-beta1 added to porous natural coral (NC) blocks could promote bone ingrowth in a critical size defect (CSD) model in nongrowing rats. A 6-mm CSD in the parietal bone of Wistar rats was filled with NC disks, which were retrieved at 3 and 8 weeks. We prepared undecalcified sections for microscopy and histomorphometry to study bone formation in the implants. The differences in the means of the measured variables were compared with a one-way analysis of variance and Tukey's Student range test, and p values smaller than 0.05 were considered statistically significant. Bone formation was enhanced in all the TGF-beta1-treated implants at 8 weeks in comparison with the controls, but none of the implants showed complete bridging across the defect. The number of macrophages and giant cells was reduced in the TGF-beta1 implants, which showed less resorption and more intact structure than the coral controls. Void areas without any fibrous tissue ingrowth were found only in the TGF-beta1-treated implants, which may partly explain the reduced resorption. The data suggested that TGF-beta1 induced enhanced but limited bone formation in mature rats and prevented resorption of the coral calcium carbonate matrix, possibly by hindering reactive cell formation and fibrous tissue ingrowth.
authors.affiliation: Department of Plastic Surgery, Helsinki University Central Hospital, Helsinki, Finland. jyrki.vuola@helsinki.fi
authors.forename: Jyrki
authors.initials: J
authors.lastname: Vuola
authors.forename: Tom
authors.initials: T
authors.lastname: Böhling
authors.forename: Harry
authors.initials: H
authors.lastname: Göransson
authors.forename: Pauli
authors.initials: P
authors.lastname: Puolakkainen
mesh_terms: D000818:Animals; D001846:Bone Development; D018786:Bone Substitutes; D003063:Cnidaria; D006801:Humans; D008297:Male; D008907:Mink; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D018786:Bone Substitutes; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta