Promotive efficacy of macrophage and granulocyte macrophage colony-stimulating factor on the survival of deep epigastric perforator flap in rats and the mechanism

Abstract

Objective To study the promotive effect of macrophage and granulocyte macrophage colony-stimulating factor (GM-CSF) on the survival of deep epigastric perforator (DEP) in rats and the mechanism. Methods A stable animal model of DEP flap in Sprague-Dawley rats was established for human deep inferior epigastric perforator flap breast reconstruction. The flaps were treated respectively by the method of subcutaneous injection of recombinant rat GM-CSF ( group Ⅰ ) , rat peritoneal macrophages (group Ⅱ ), GM-CSF combined with macrophages ( group Ⅲ ), and saline as parallel negative control ( group Ⅳ). The rats were sacrified and flap specimens were harvested on the 7th day after operation. The survival rate of flaps and micro-vesscle density (MVD) were measured. Sirius Red staining was done to analyze collagen deposition, and the mRNA expression of collagen I , collagen Ⅲ, extracellular matrix matalloproteinase inducer (EMMPRIN) , matrix metalloproteinase 2 ( MMP-2), vascular endothelial growth factor (VEGF) and VEGFR was detected by reverse transcription-polymerase chain reaction (RT-PCR).Results Survival rate of the flaps in both group Ⅰ [(53.08 ±8. 76)%] and group Ⅱ [(47.95 ±4. 92)%] was significantly higher than in control group [(43.28 ±5. 27)%], but significantly lower than in group Ⅲ [(61.68±6.60)%]. Collagen deposition in groups Ⅰ [(16. 34 ±2.47)%] and Ⅲ [(19.41 ±2.01)%] was significantly higher than in control group [(13. 19 ±2.91)%]. But collagen deposition in group Ⅱ [(12. 50 ± 2. 66)%] was lower than in control group, though there was no significant difference (P＞0.05). MVD in groups Ⅰ,Ⅱ and Ⅲ (24. 82 ±4. 18, 24.30 ±3.02, 29. 82 ±4.74 respectively) was significantly higher than in control group (21. 37 ± 2. 65 ) , and that in group Ⅲ was significantly higher than the others. The results of RT-PCR showed collagen Ⅰ, EMMPRIN, MMP2 and VEGFR expression levels were significantly higher in group Ⅰ than in control group ( P ＜ 0. 05 ) ; EMMPRIN expression was significantly higher in group Ⅱ than in control group (P ＜0.05); Collagen Ⅰ, Collagen Ⅲ, EMMPRIN, MMP2 and VEGFR expression levels in group Ⅲ were significantly higher than in control group ( P ＜ 0. 05 ). There was no significant difference between groups ⅠⅢ and control group (P＞0.05). Conclusion By promoting the expression of collagen synthesis (collagen Ⅰ, collagen Ⅲ) and degradation (EMMPRIN, MMP2) related genes,and expression of angiogenesis related gene (VEGFR), recombinant rat GM-CSF and macrophages enhanced collagen remodeling and angiogenesis, and ultimately promoted the survival of DEP flaps in rats. Key words: Macrophage; Granulocyte-macrophage colony-stimulating factor; Deep inferior epigastric perforator flap