| Purposes:Blood vessel repair and angiogenesis are the basic conditions for the restoration of the lung tissues and the recovery of the pulmonary functions after the pulmonary injuries. The cellular factors which play a crucial role in the repair and regeneration of the blood vessels may also have a critical function in the initiation and development of the fibrosis. The vascular endothelial growth factor (VEGF), which is the specific mitogen of the blood vessel endothelial cells, promotes the proliferation and differentiation of the endothelial cells, therefore, induces mass angiogenesis. The transforming growth factor- bata1 (TGF-bata1) is also very important in the angiogenesis by accelerating the maturation of the para-cells and stimulating the formation of the new blood vessels. The purposes of this study which applied the immunohistochemical approaches, the in situ hybridization techniques, and the transmission electron microscope (TEM) and the light-microscope observations were to explore the role of TGF- bata1 and VEGF in the occurrence and development of thepulmonary fibrosis as well as the synthesis and distribution of these two factors in relation to the angiogenesis process of the pulmonary tissues.Methods:Eighty (80) healthy SD rats, which weighed 170~220g, were randomly assigned to the control group (CG) and the bleomycin group (BLM) with 40 in each group. The rats in the BLM group were stabilized in supine and were then performed abdominal anesthesia with 0.5ml sodium pentobarbital 10.L-1 (50mg.kg-1). The bleomycin-As (Tianjin Taihe Pharmaceuticals, Inc., 8mg, batch number 001014) was introduced to the lung tissues of the rats through the trachea with #7 needle syringe. The rat was then erected and spun during above procedure for the fully distribution of the bleomycin in the lungs. The rats in the CG were injected saline to their lungs with the same procedures. 8 rats from each group were randomly chosen on day 3, 7, 14, 21, and 28 to be prepared for the samples. After abdominal anesthesia, the carotid artery was opened to execute the rat. The left whole lung was then surgically removed and stabilized with 4% 0.1PBS paraformaldehyde and 1/1000 DEPC. The 6 u m paraffin slices were cut from the samples starting from the hilum to the pulmonary membrane after routine dehydration and paraffin envelopment. The immunohistochemical analysis was conducted with the SABC approach using the VEGF/ TGF- P i lab kit (Boster, Inc., Wuhan, China) and following its instructions. The pathological changes of the samples were also observed and recorded using both the light-microscope and TEM on the same dates.Results:1. The BLM group had demonstrated great significance in both of the VEGF/TGF-bata1 presentation which was mainly in the alveolar macrophagocytes and the pathological changes in the pulmonary tissues since day 3 comparing to the CG group. In the BLM group, VEGF and TGF- bata1 presented dramatically in the early stages of the fibrosis and this phenomenon lasted with the parallel increases of both the factors. This presentation of VEGF and TGF- bata1 showed the greatest distribution on day 28 in the lung interstitial cells and the areas of the presentation corresponded to that of the new angiogenesis and the fibrohyperplacia of the pulmonary tissues. And starting on day 7, the cells with these two factors began to transform to the interstitial cells.2. In the BLM group, the endothelial cells of the lung capillaries were observed to demonstrate early necrosis, separation from the base, and increased penetrance followed by a great amount of angiogenesis. The pulmonary capillaries were mostly repaired with no erythrocytes in the alveoli under the light-microscope observation; however, twisted new blood capillaries and hyper-penetration were observed with TEM by which the blood embolism formation and inconsistence of the endothelial membrane of the alveolar capillaries were also observed, even on day 28 in the BLM group.3. The angiogenesis was corresponding greatly... |
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