Effects of the traditional Chinese medicine baicalein on the viability of random pattern skin flaps in rats

Abstract

Background: Random skin flaps are routinely placed during plastic and reconstructive surgery, but the distal areas often develop ischemia and necrosis. Baicalein, a major flavonoid extracted from the traditional Chinese herbal medicine huangqin, Scutellaria baicalensis Georgi, may improve flap viability.

Materials and methods: Rats were randomly divided into baicalein and control groups and they underwent placement of modified McFarlane flaps after intraperitoneal administration of baicalein or vehicle. Flap survival and water content were measured 7 days later, as were angiogenesis, apoptosis, and oxidative stress in ischemic flaps.

Results: Baicalein promoted flap survival, reduced edema, increased mean vessel density, and enhanced vascular endothelial growth factor production at both the translational and transcriptional levels. Baicalein reduced caspase 3 cleavage, increased superoxidase dismutase and glutathione levels, and decreased the malondialdehyde level.

Conclusion: Baicalein promoted flap viability by stimulating angiogenesis and inhibiting apoptosis and oxidation.

Keywords: angiogenesis; apoptosis; baicalein; oxidation; random skin flap.

Figure 1

Baicalein improved flap survival and reduced edema. Notes: (A) Digital photographs of the flaps taken on Days 3 and 7. (B) Digital photographs of the inner sides of the flaps taken on Day 7 to measure edema. (C) Survival percentages. (D) Tissue water content. Values are mean±SD, n=6 per group. Significant differences between the groups are indicated by *P<0.05 and **P<0.01.

Figure 2

Baicalein promoted angiogenesis in flap ischemic areas. Notes: (A) On Day 7, angiogenesis in the ischemic flap areas (Areas II) was evident by H&E staining (original magnification, ×100 and ×200; scale bars, 50 and 100 μm). (B) Immunochemical detection of CD34, which is a marker of angiogenesis (original magnification, ×200; scale bar, 50 μm). (C) MVDs assessed by H&E staining. (D) The numbers of CD34-positive vessels. Values are mean±SD, n=6 per group. Significant differences between the groups are indicated by *P<0.05 and **P<0.01.

Figure 3

Baicalein increased VEGF mRNA/protein levels in ischemic flap regions. Notes: (A) In situ hybridization of VEGF mRNA on Day 7 (original magnification, ×400). (B) ODs indicative of VEGF transcription levels. (C) Immunohistochemical VEGF expression on Day 7 (original magnification, ×200; scale bar, 50 μm). (D) ODs indicative of VEGF mRNA level. (E) Western blotting for VEGF on Day 7. Gels were run under the same experimental conditions, and cropped images of the blots are presented. (F) ODs indicative of VEGF protein expression. Values are expressed as mean±SD, n=6 per group. Significant differences between the groups are indicated by *P<0.05 and **P<0.01.

Figure 4

Baicalein reduced apoptosis in ischemic flap regions. Notes: (A) Immunohistochemical evaluation of cleaved CASP3 levels on Day 7 (original magnification, ×200; scale bar, 50 μm). (B) Western blotting for cleaved CASP3 on Day 7. Gels were run under the same experimental conditions, and cropped blots are presented. (C) ODs indicative of VEGF protein expression. (D) ODs were quantified and analyzed. Values are expressed as mean±SD; n=6 per group. Significant differences between the groups are indicated by *P<0.05.

Figure 5

Baicalein reduced oxidative stress in ischemic flap regions. Notes: (A) Immunohistochemical evaluation of SOD expression in ischemic flaps (original magnification, ×200; scale bar, 50 μm). (B) ODs indicative of SOD expression. (C) Western blotting for SOD on Day 7. All gels were run under the same experimental conditions, and cropped images of the blots are presented. (D) ODs indicative of SOD expression are shown. (E–G) The levels of SOD, GSH, and MDA in ischemic flaps were measured using the xanthine oxidase, modified dithiobisnitrobenzoic acid, and modified thiobarbituric acid methods, respectively. Values are mean±SD; n=6 per group. Significant differences are indicated by *P<0.05, **P<0.01. Abbreviations: GSH, glutathione; MDA, malondialdehyde; SOD, superoxide dismutase.