Abstract:

BACKGROUND: Preliminary study has proved that the bone marrow-derived mesenchymal stem cells (MSCs) in a rat emphysema model produced by use of trypsin alone can "homing" to the lesioned lung tissues, and participate in the formation of pulmonary arteries to promote lung tissue repair. Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) play equally a powerful role in promoting angiogenesis.
OBJECTIVE: To observe the influence of bFGF, VEGF and MSCs in regeneration of pulmonary capillary and pathological repair of pulmonary emphysema rats.
METHODS: Except normal control group, the remaining 5 groups of rats were exposed to tobacco smoke and received a single intratracheally instillation of porcine pancreatic elastase to induce emphysema models. Following successful modeling, rats of bFGF group were intratracheally injected with 400 U bFGF and rats of VEGF group with 2 μg VEGF, once a week for three times. MSCs group was injected 1 mL suspension of 4×10⁹/L MSCs into tail vein. MSCs+VEGF group was injected MSCs into tail vein and intratracheally injected VEGF (2 ug, three times) at the same time. Model control and normal control groups were intratracheally injected with equal volume of sodium chloride. Four weeks after treatment, arterial blood gas analysis was performed to observe pathological and morphological changes of lung tissues. CD34⁺ expression in lung tissues was determined using immunohistochemistry method.
RESULTS AND CONCLUSION: Compared with model control group, PaO2 values dramatically increased in VEGF group (P < 0.05), while other indices remained unchanged (P > 0.05); there were no obvious changes in each index in other groups (P > 0.05). Gross and microscopic observations showed that, lung was smooth, pale pink, and elastic in normal control group, with uniform size of pulmonary alveoli on cross-section; pathological changes of chronic obstructive pulmonary emphysema existed in model control group, but improved in other 4 groups. Compared with model control group, mean pulmonary alveoli number and CD34⁺ relative positive area dramatically increased in bFGF, VEGF, MSCs, MSCs+VEGF groups (P < 0.05), mean linear intercept and mean alveoli area were significantly reduced (P < 0.05). No significant difference was observed in each index among these 4 groups (P > 0.05). bFGF, VEGF and MSCs could improved the pathology of pulmonary emphysema models produced by tobacco smoking and intratracheally instillation of porcine pancreatic elastase. The possible mechanism of recovering the pulmonary emphysema is the proliferation of pulmonary capillary and enlargement of pulmonary artery, improved blood flow in the lung, improved ventilation/perfusion shunt, reduced pulmonary alveolus size and volume of the lung through self-compensation.