To date, there have been several experimental studies to assess tissue viability of transverse rectus abdominis myocutaneous (TRAM) flaps. Botulinum toxin A (BoTA) has gained popularity in many clinical fields, for a variety of therapeutic and aesthetic purposes. In addition, there have been reports regarding the positive effect of BoTA on flap survival by various mechanisms. In this study, we hypothesized that pretreatment with BoTA could augment the survival of TRAM flaps via increased hypoxia-inducible factor (HIF)1α/vascular endothelial growth factor (VEGF)–dependent angiogenesis.
Twenty-four Sprague-Dawley rats were randomly divided into 2 groups: a control group and a BoTA group. Five days before superiorly based TRAM flap elevation, the BoTA group was pretreated with BoTA, whereas the control group was pretreated with normal saline. Gross flap survival rates were assessed, and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blotting were performed for the evaluation of angiogenesis-related factors (CD34, HIF-1α, and VEGF).
In the BoTA group, the gross flap survival rate was significantly higher than that in the control group on both ipsilateral (92.78.3 ± 5.05% vs 86.8 ± 3.88%, P = 0.009) and contralateral (91.57 ± 5.79% vs 74.28 ± 11.83%, P < 0.001) sides.
The relative mRNA expression of CD34 and VEGF was significantly higher in the BoTA group than that in the control group in every zone, whereas the relative mRNA expression of HIF-1α was significantly higher in the BoTA group than that in the control group on contralateral sides. The relative protein expression of CD34, VEGF, and HIF-1α was significantly higher in the BoTA group than that in the control group in every zone.
In conclusion, we demonstrate that presurgical BoTA treatment might increase angiogenesis by HIF-1α/VEGF, subsequently increase superiorly based TRAM flap survival in a rat model.