RESUMO
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 4×10~9/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, PaO_2 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.
RESUMO
BACKGROUND:Recently,application of stem cells and growth factor to promoting lung regeneration in repair of emphysema lesion has been a hot focus in study.Thus,it is worth to pay attention on whether stem cells carrying relevant foreign growth factor gene can repair emphysema lesion.OBJECTIVE:To evaluate the effidency of adenovirus vector mediated green fluorescence protein(Ad-GFP)transfecting bone marrow mesenchymal stem cells(BMSCs)and its effect on the cell proliferation,to explore oriented migration of intravenously administrated BMSCs transfected with Ad-GFP in the lung tissues of pulmonary emphysema rats.METHODS:MSCs were separated and purified from the bone marrow of rats by density gradient centrifugation and by adherence.At different multiplicity of infection(MOI),transfection efficiency was observed by laser confocal microscopy.At 48 hours of transfection,MTT method was used to evaluate the proliferation of MSCs.A total of 16 Wistar rats were randomly divided into emphysema model group and control group(n=8).Model rats were established by exposure to cigarette smoke.MSCs,transfected with Ad-GFP,were grafted into the body of rats via tail vein.Lungs derived at 24 hours after implantation,and frozen sections were made.Migration and survival of MSCs in the lung tissues were observed by fluorescence microscopy.RESULTS AND CONCLUSION:MSCs from Wistar rats were successfully cultured,grew well and infected by Ad-GFP.The highest transfection effincincy(88.42 %)could be achieved at MOI of 200.Green fluorescent protein labeling had little effect on proliferation of MSCs by different MOI(P＞0.05).At 24 hours posttransplantation,the green fluorescence-positive tissue was Found in the lung tissues of emphysema model group and control group.Compared with control group,the expression of GFP in lung tissues was higher in emphysema model group(P＜0.05).These suggested that introduction of target gene cannot affect proliferation and homing property of BMSCs.
RESUMO
BACKGROUND: Pathological changes of pulmonary emphysema are not reversible according to the existent pathogenesis of pulmonary emphysema. Research over many years report that injury of pulmonary blood capillary may take part in new pathogenesis of pulmonary emphysema based on lung volume reduction operation and bronchial lumen occlusion. Mesenchymal stem cells (MSCs) have multi-directional differentiation potencies, such as the differentiation into vascular endothelial cells. Therefore, MSCs may promote pulmonary vascularization and repair pulmonary tissue.OBJECTIVE: To observe the effect of MSCs transplantation on pathological changes of arterial blood gas and pulmonary tissue in model rats with pulmonary emphysema, and investigate the therapeutic effects on MSCs on pulmonary emphysema and the pathogenesis of pulmonary emphysema.DESIGN: Randomized controlled animal study.SETTING: The Second Hospital of Shanxi Medical University.MATERIALS: Thirty healthy Wistar rats, 6 weeks old, of either gender, weighing 180-200 g. They were provided by Physiological Experiment Animal Center, Shanxi Medical University. All rats were randomly divided into MSCs treatment group, model group and control group with 10 rats each.METHODS: The experiment was carried out in the Physiological Laboratory of Shanxi Medical University from April 2005 to April 2006. Rats in the MSCs treatment group and in the model group were anesthetized and intratracheally perfused with 250 U/kg Porcine pancreatic elastase (PPE) to establish pulmonary emphysema models; while, rats in the control group were perfused with saline. The models were successfully established 4 weeks later. All rats were anesthetized and then femur and tibia were obtained to separate and culture MSCs in vitro. Immunocytochemistry was used to detect the expression of CD71 in order to evaluate MSCs. Bromium azacytidine-labeled MSCs were inserted along caudal vein into rats in the MSCs treatment group; while, rats in the model group and control group were inserted with the same volume of PBS solution.MAIN OUTCOME MEASURES: ① Changes of arterial blood gas in the three groups; ② Pulmonary tissue was used for pathological sections in order to calculate mean alveolar number, mean alveolar area and mean linear intercept; ③Immunocytochemical staining was used to measure numbers of CD34+ cells so as to determine proliferation of alveolar blood capillary.RESULTS: Three rats in all died during the model establishment, while another 3 rats were supplied. Therefore, an overall number of 30 rats were involved in the final analysis. ① Culture and evaluation of MSCs: At 3 days after inoculation, MSCs were generally adherent to walls and fusiformly shaped. In the third generation, the expression of CD71 was observed on the surface of MSCs.② Comparisons of arterial blood gas in the three groups: There were no significant differences in pH value, PO2, PCO2 and SaO2 in the three groups (P ＞ 0.05). ③ Pathological changes of pulmonary tissue: Pathological changes in the MSCs treatment group were milder than those in the model group;meanwhile, mean alveolar number in the MSCs treatment group was more than that in the model group, and there was significant difference between them (F=80.201, P＜ 0.05). While mean alveolar area and mean linear intercept in the MSCs treatment group were smaller than those in the model group, and there were significant differences (F =26.755,26.875, P ＜ 0.05). ④ Comparisons of CD34+ expression in pulmonary tissue: Relative positive area of CD34+ in the MSCs treatment group and model group was smaller than that in the control group (F =20.411, P ＜ 0.05), but that in the MSCs treatment group was larger than that in the model group, and there was significant difference between them (F=20.411, P＜ 0.05).CONCLUSION: MSCs can reverse the pathological changes of pulmonary emphysema; on the other hand, the decrease of the number of pulmonary capillary maybe one of the important pathogeneses of pulmonary emphysema.