| Objective To establish an animal model of the Multiple Growth Factors-Releasing Fibrin Gel Delivery System(hereafter referred to as gel delivery system), and discuss the effect of the gel delivery system on the repair and proliferation of lung in vivo.Methods Nine New Zealand rabbits were randomly divided into three groups, with three rabbits in each group. A variety of growth factors, including platelet derived growth factor, vascular endothelial growth factor, transforming growth factor and epidermal growth factor, were added to fibrinogen solution. Growth factors group was received injection of 7ml fiber protein solution containing varieties of growth factors and 0.7ml thrombin solution to right middle lobe via flexible bronchoscopy. The gel delivery system was established in the area of injection, releasing various growth factors slowly. Non-growth factors group was received injection of 7ml fiber protein solution and 0.7ml thrombin solution to right middle lobe. Control group was received bronchoscopy to right middle lobe. In 14 d after operation, animals were sacrificed by anesthesia, and right middle lobe specimens were collected and determined. Total collagen protein level(containing type I-V collagen) was measured by Sircol collagen assay. The expression of type I collagen protein was assayed by immunohistochemistry, and measured by area sum, AOD sum and IOD sum. The expression of type II collagen protein was measured by Western blot. Alveolar septum thickness and pulmonary interstitial microvessel count was measured by pathological examination. The m RNA expression of SPA was measured by real-time RT-PCR method.Result(1) In alveolar septum thickness, control group was 38.389±9.160 nm, non-growth factors group was 41.267±11.845 nm, growth factors group was59.500±13.904 nm. Growth factors group was significantly more thickness than non-growth factors group(P=0.000) and control group(P=0.000). There was no significant difference between non-growth factors group and control group(P=0.462).(2) In total collagen protein level, control group was 41.563±8.255, non-growth factors group was 45.349±19.039,growth factors group was 89.261±24.837. Growth factors group was significantly higher than non-growth factors group(P=0.001,t=4.070) and control group(P=0.000, t=4.421). There was no significant difference between non-growth factors group and control group(P=0.731,t=0.351).(3) In area sum, control group was 3.970×104±5.137×104, non-growth factors group was 7.636×104±5.101×104, growth factors group was 16.025×104±6.483×104. Growth factors group was significantly higher than non-growth factors group(P=0.000) and control group(P=0.000). There was no significant difference between non-growth factors group and control group(P=0.052). In AOD sum, control group was 101.118±99.448, non-growth factors group was 170.274±82.221, growth factors group was 249.875±75.725. Growth factors group was significantly higher than non-growth factors group(P=0.007) and control group(P=0.000). Non-growth factors group was significantly higher than control group(P=0.047). In IOD sum, control group was 2.030×104±2.622×104, non-growth factors group was 3.910×104±2.621×104, growth factors group was 8.256×104±3.316×104. Growth factors group was significantly higher than non-growth factors group(P=0.000) and control group(P=0.000). There was no significant difference between non-growth factors group and control group(P=0.052).(4) No expression of type II collagen protein was observed in the sample.(5) In pulmonary interstitial MVD, control group was 2.667±1.155, non-growth factors group was 3.417±1.379, growth factors group was 3.750±1.055. Growth factors group was significantly greater than control group(P=0.035,t=30.952). There was no significant difference not only between growth factors group and non-growth factors group(P=0.502,t=0.664), but also between non-growth factors group and control group(P=0.137,t=5.474).(5) In the m RNA level of SPA, non-growth factors group was 1.87±2.09, growth factors group was 7.53±6.64. There was no significant differencebetween growth factors group and non-growth factors group(P=0.232,F=1.986).Conclusion We established the Multiple Growth Factors-Releasing Fibrin Gel Delivery System in the lung of New Zealand rabbits. The system could promote the repair of lung in the following aspects. It could promote the synthesis and release of collagen, improve the proliferation of pulmonary interstitium fibrocytes and the capillary hyperplasia, induce pulmonary interstitium inflammatory exudates and neutrophils infiltration in vivo. |
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