Differential regulation of blood vessel formation between standard and delayed bone healing.
Blood vessel formation is a prerequisite for bone healing. In this study, we tested the hypothesis that a delay in bone healing is associated with an altered regulation of blood vessel formation. A tibial osteotomy was performed in two groups of sheep and stabilized with either a rigid external fixator leading to standard healing or with a highly rotationally unstable one leading to delayed healing. At days 4, 7, 9, 11, 14, 21, and 42 after surgery, total RNA was extracted from the callus. Gene expressions of vWF, an endothelial cell marker, and of several molecules related to blood vessel formation were studied by qPCR. Furthermore, histology was performed on fracture hematoma and callus sections. Histologically, the first blood vessels were detected at day 7 in both groups. mRNA expression levels of vWF, Ang1, Ang2, VEGF, CYR61, FGF2, MMP2, and TIMP1 were distinctly lower in the delayed compared to the standard healing group at several time points. Based on differential expression patterns, days 7 and 21 postoperatively were revealed to be essential time points for vascularization of the ovine fracture callus. This work demonstrates for the first time a differential regulation of blood vessel formation between standard and mechanically induced delayed healing in a sheep osteotomy model.
Lienau
Jasmin
J
Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Schmidt-Bleek
Katharina
K
Peters
Anja
A
Haschke
Franek
F
Duda
Georg N
GN
Perka
Carsten
C
Bail
Hermann J
HJ
Schütze
Norbert
N
Jakob
Franz
F
Schell
Hanna
H
D000809:Angiotensins / Q000235:genetics; D000818:Animals; D002146:Bony Callus / Q000473:pathology / Q000502:physiology*; D055515:Cysteine-Rich Protein 61 / Q000235:genetics; D016267:External Fixators; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000235:genetics; D017102:Fracture Healing / Q000502:physiology*; D006406:Hematoma / Q000473:pathology / Q000503:physiopathology; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D018919:Neovascularization, Physiologic / Q000502:physiology*; D010027:Osteotomy; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012756:Sheep; D013977:Tibia / Q000098:blood supply / Q000293:injuries / Q000502:physiology; D013978:Tibial Fractures / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D014841:von Willebrand Factor / Q000235:genetics
D000809:Angiotensins; D055515:Cysteine-Rich Protein 61; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D042461:Vascular Endothelial Growth Factor A; D014841:von Willebrand Factor; D016222:Fibroblast Growth Factor 2; D020778:Matrix Metalloproteinase 2