MicroCT based angiography for studying neovascularization of long bone fracture repair in a rat model

Abstract

Objective To explore microcomputed tomography (MicroCT) based angiography for exhibiting the neovascularization/angiogenesis of a callus on a rat femoral fracture model.Methods After a closed fracture establishment,60 nale SD rats were randomized into2 groups (30 in each group)and killed at the time point of 1,2,3,4 and 8 weeks The callus in experimental group were scanned by MieroCT and 3-D vasculature images were reconstructed.Vessel size distribution,total vessel volume and volume fraction were quantified.The callus in control group were assessed by using immunohistochemisty for observing the expression of vascular endothelial growth factor (VEGF) and VEGF receptor 2 ( VEGFR-2 ).Results MicroCT based angiography provided native 3-D vasculature images to iconicly reveal the states of neovascularization.And the total vessel volume and volume fraction peaked at 3 weeks ( P ＜ 0.05 ):( 196.00 ± 20.33 ) mm3 and ( 6.70 ± 0.74 ) ％ respectively ; Immunohistochemistry of callus sections showed the expression of VEGF and VEGFR-2 occurred in the early stage of fracture healing and peaked at 2 weeks,the number of positive cells were ( 113.40 ± 9.17 ) and ( 51.80 ± 4.24 ) respectively ( P ＜0.05).Conclusion MicroCT based angiography atraumaticly provided high-resolution,quantitative,3-dimention,and objective data analysis.MicroCT based angiography is a robust methodology for evaluation of vascular networks in the callus of a small animal. Key words: MicroCT; Perfusion; Angiogenesis; Fracture; Immunohistochemistry