title: Cell proliferation and differentiation during fracture healing are influenced by locally applied IGF-I and TGF-beta1: comparison of two proliferation markers, PCNA and BrdU.
abstract: Growth factors IGF-I and TGF-beta1 are known to stimulate fracture healing. The purpose of this study was to investigate the role of locally applied IGF-I and TGF-beta1 during the early phase of fracture healing (Days 5, 10, and 15 after fracture) on cellular processes like proliferation and differentiation in a rat model. Two different immunohistochemical markers were used to analyze cell proliferation: (1) injection of the thymidine analogue BrdU and subsequent immunohistochemical staining for BrdU-positive nuclei, and (2) the antibody against the "proliferating cell nuclear antigen" (PCNA). In comparison, both methods revealed similar results concerning the types of proliferating cells at the different time points and the two groups. Labeling indices of both methods showed very good correlation (e.g., r(s): 0.887 and p < 0.001 at day 10 in the control group without growth factors). Comparison of the callus morphology and the proliferation rate showed differences during fracture healing due to the local application of IGF-I and TGF-beta1 from coated implants. At Day 5 the callus of the group treated with growth factors displayed an earlier appearance of cartilage compared to the control group. This was accompanied by an onset of cell proliferation in chondrocytes. Likewise, at the later time points an enhanced maturation of the callus tissue and the proliferation pattern were detectable in the growth-factor group. These results indicate that local application of IGF-I and TGF-beta1 accelerates early cellular processes during fracture healing.
authors.affiliation: Department of Trauma and Reconstructive Surgery, Charité, Campus Virchow, Humboldt-University of Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany. britt.wildemann@charite.de
authors.forename: B
authors.initials: B
authors.lastname: Wildemann
authors.forename: G
authors.initials: G
authors.lastname: Schmidmaier
authors.forename: S
authors.initials: S
authors.lastname: Ordel
authors.forename: R
authors.initials: R
authors.lastname: Stange
authors.forename: N P
authors.initials: NP
authors.lastname: Haas
authors.forename: M
authors.initials: M
authors.lastname: Raschke
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002146:Bony Callus / Q000187:drug effects; D001973:Bromodeoxyuridine / Q000032:analysis; D002356:Cartilage / Q000254:growth & development; D002454:Cell Differentiation; D002455:Cell Division; D019902:Chondrocytes / Q000166:cytology*; D020099:Coated Materials, Biocompatible / Q000627:therapeutic use; D005260:Female; D017102:Fracture Healing / Q000187:drug effects*; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000494:pharmacology; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000008:administration & dosage* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1
chemical_list: D015415:Biomarkers; D020099:Coated Materials, Biocompatible; D018809:Proliferating Cell Nuclear Antigen; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D007334:Insulin-Like Growth Factor I; D001973:Bromodeoxyuridine