Objective:To explore the healing mechanism of porcine small intestinal submucosa decorated with nano-silver (NS-PSIS) in the treatment of a model of fistula-in-ano.Methods:NS-PSIS was constructed. Animal models of fistula-in-ano were established using New Zealand rabbits and randomly divided into two groups according to random number table ( n=12 in each group). Rabbits in the experimental group were treated with NS-PSIS for anal fistulas, and those in the control group were treated with PSIS. The treated anal fistula tissue samples were obtained at 12, 24, 48 h and 14 d after surgery ( n=3 in each group). Hematoxylin-eosin staining was performed to observe the pathomorphological changes of the marginal tissues of the anal fistula. Masson staining was performed to assess collagen deposition in the marginal tissue of the anal fistula and quantitative analysis was performed. Immunohistochemical staining was performed to detect the expression of CD34 in the marginal tissue of the anal fistula and calculate the microvessel density (MVD). The expression of transforming growth factor (TGF)-β1, Smad2, collagen type Ⅰ (COL Ⅰ) and collagen type Ⅲ (COL Ⅲ) was detected. Real-time polymerase chain reaction (RT-qPCR) was performed to detect the mRNA expression of TGF-β1, Smad2, COL Ⅰ and COL Ⅲ. For measurement data meeting normal distribution, independent sample t-test was used for comparison between two groups; otherwise, Wilcoxon rank sum test was used. Results:NS-PSIS was successfully constructed. A New Zealand rabbit model of fistula-in-ano was successfully established. In the early stage of treatment (12-48 h after surgery), significant inflammatory cell infiltration, fibroblast proliferation, collagen synthesis and neovascularization were observed around the fistula tract in both groups. Masson staining showed that collagen synthesis in the NS-PSIS group was significantly more than that in the PSIS group at 48 h after surgery [(29.40±2.80)% vs. (20.97±1.68)%, t=-7.752, P<0.01]. Immunohistochemistry showed that at 48 h after surgery, the MVD in NS-PSIS group was significantly higher than that in PSIS group [6.8 (5.2, 7.8) vs. 5 (4, 6.8), Z=-2.969, P<0.01]. At 24 h after surgery, the expression levels of COL Ⅰ [(22.06±2.83)% vs. (13.5±2.88)%, t=-6.342, P<0.01] and COL Ⅲ [(25.70±3.44)% vs. (20.02±2.45)%, t=-4.038, P<0.001] in NS-PSIS group were significantly higher than those in PSIS group. At 48 h after surgery, the expression levels of COL Ⅰ [(28.71±3.81)% vs. (20.09±3.07)%, t=-5.284, P<0.01] and COL Ⅲ [(30.59±1.41)% vs. (24.01±1.77)%, t=-710, P<0.01] in NS-PSIS group were significantly higher than those in PSIS group. In addition, the expression levels of TGF-β1 [19.71 (18.56, 20.90)% vs. (18.56±2.57)%, Z=-3.621, P<0.01] and Smad2 [(18.56±2.57)% vs. (12.22±2.55)%, t=-5.249, P<0.01] in the NS-PSIS group were significantly higher than those in the PSIS group at 48 h after surgery. RT-qPCR showed that the mRNA expression levels of TGF-β1 [8.62 (8.57, 9.05) vs. 6.87 (6.51, 7.14), Z=-3.621, P<0.01], Smad2 [13.44 (11.25, 13.59) vs. 10.05 (9.05, 10.37), Z=-3.616, P<0.01], COL Ⅰ [4.02 (3.84, 5.82) vs. 2.58 (2.08, 4.08), Z=-2.012, P<0.01] and COL Ⅲ [12.12 (11.60, 14.60) vs. 9.24 (7.25, 9.52), Z=-3.064, P<0.01] in the NS-PSIS group were significantly higher than those in the PSIS group at 48 h after surgery. Conclusion:The ability of NS-PSIS to promote neovascularization and collagen synthesis might be superior to PSIS in the early stage of therapy (48 h after surgery), and the mechanism might be related to the activation of TGF-β1/Smad2/COL Ⅰ/COL Ⅲ signaling pathway.

微小RNA-21、微小RNA-320c、微小RNA-1225-5p对胃癌患者腹膜转移的评价效能