Quantitative measurement of the splice variants 120 and 164 of the angiogenic peptide vascular endothelial growth factor in the time flow of fracture healing: a study in the rat.
Formation of new blood vessels is essential for the process of wound and fracture healing. Little is known about the time-dependent expression and the involved splice variants of the vascular endothelial growth factor (VEGF). We therefore quantified and differentiated the angiogenic factor VEGF and its receptors (VEGFR) in a rat fracture model by immunohistochemical, biochemical and molecular biological methods. VEGF could be immunostained in chondrocytes and osteoblasts of the callus, but not in fibrous callus. In the capillaries, VEGFR-1 (flt-1) and VEGFR-2 (flk-1/KDR) were also visualized. Both receptors were also detectable in some chondrocytes and in osteoclasts. Enzyme-linked immunosorbent assay (ELISA) measurements showed high levels of VEGF in fractured tibiae and negligible ones in non-injured bone. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed expression of the rat splice variants VEGF(120) and VEGF(164) during the course of fracture healing, which corresponds to human VEGF121 and VEGF165 splice variants. VEGF plays the most important role during the early phase of fracture healing, but VEGF concentrations decrease further after day 5.
Department of Anatomy, Christian Albrechts University, 24098 Kiel, Germany. t.pufe@anat.uni-kiel.de
Thomas
T
Pufe
Britt
B
Wildemann
Wolf
W
Petersen
Rolf
R
Mentlein
Michael
M
Raschke
Gerhard
G
Schmidmaier
D017398:Alternative Splicing; D000818:Animals; D002146:Bony Callus / Q000166:cytology / Q000502:physiology; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology; D016228:Endothelial Growth Factors / Q000235:genetics*; D005260:Female; D050723:Fractures, Bone / Q000473:pathology*; D014644:Genetic Variation; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008222:Lymphokines / Q000235:genetics*; D009928:Organ Specificity; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D040262:Receptors, Vascular Endothelial Growth Factor / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014945:Wound Healing / Q000235:genetics*
D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D040262:Receptors, Vascular Endothelial Growth Factor