不同浓度hUCMSCs对重度烧伤大鼠急性肺损伤的保护作用初探

Protective Effects of Different Doses of Human Umbilical Cord Mesenchymal Stem Cell on the Acute Lung Injury in Rats with Severe Burn

目的:通过气管内给药的方法比较不同浓度人脐带间充质干细胞气管内移植对重度烧伤致急性肺损伤大鼠的保护作用。方法:建立50%面积全层烫伤大鼠模型,将75只成熟雄性Wistar大鼠随机分为正常对照组(A组)、生理盐水组(B组)、1×10~5HUCMSCs移植组(C)、5×10~5HUCMSCs移植组(D)、1×10~6HUCMSCs移植组(E),每组15只,B组及移植组(C、D、E组)烫伤后立即液体复苏,B组烫伤后气管内滴注0.2 m L生理盐水,移植组气管内滴注不同浓度h UCMSCs,分别在移植后的天第1、3、7天留取大鼠肺组织标本,HE染色观察肺组织病理变化,MPO、CD68免疫组化染色观察肺组织中性粒细胞及肺巨噬细胞阳性表达情况。结果:肺组织病理切片可见:A组各时间点肺泡腔清晰,肺泡结构完整,偶见少量炎性细胞。烫伤后第1天,B组及移植组(C、D、E组)肺泡间隔增厚,大量红细胞漏出及炎性细胞浸润。烫伤后第3天,各组肺泡结构较前清晰,炎性细胞浸润及红细胞漏出较第一天减少,与B组相比移植组肺泡结构清晰,间隔变薄,移植组各组间改变不明显。烫伤后第7天,移植组肺组织损伤较B组明显减轻,E组损伤肺组织恢复最为明显。MPO染色显示:与A组相比,阳性细胞数在烫伤后第1天明显增加(P<0.05),但各组之间无明显差异。在烫伤后第3天,与B组相比,移植组阳性细胞数减少明显(P<0.05),E组阳性细胞减少明显(P<0.05);在烫伤后第7天E组阳性细胞数量较其他组显著减少(P<0.05)。CD68染色显示在烫伤后第1天各组阳性细胞显著增多(P>0.05),在烫伤后第3天移植组阳性细胞数减少(P<0.05),但各移植组间无明显差异,烫伤后第7天移植组阳性细胞数量较B组明显减少(P<0.05),E组较C、D组阳性细胞减少有显著差异(P<0.05)。结论:气管内移植HUCMSCs能修复重度烧伤后损伤的肺组织,减少肺组织中性粒细胞及巨噬细胞的浸润,且1×10~6HUCMSCs移植效果更明显。

Objective：To investigate the protective effect of intratracheal transplantation of different dose of human umbilical cord mesenchymal stem cells （MSCs） in rats with acute lung injury induced by severe burns.Methods：Seventy-five male Wistar rats were randomly divided into five groups：Sham（group A）,Saline group（group B） and different doses of hUMSCs transplantation groups（C,D and E）.The dosage ofhUMSCs was 1 × 105,5 × 105 and 1 × 106 respectively.Rats inflicted by 50 ％TBSA Ⅲ degree scalding employed as the model.After modeling,rats in group B and transplantation groups were immediately fluid resuscitated.Transplantation groups were intratracheally administered different dose hUCMSCs （0.2 mL）,and group B were given normal saline in the same dose intratracheally.The lung tissue samples were collected on day 1,day 3 and day 7 after administration.HE staining was used to observe the pathological changes of lung tissue.MPO and CD68 immunohistochemical staining were used to observe the positive expression of neutrophils and macrophages in lung tissue.Results：Lung pathology showed that alveolar cavity was clear,alveolar structure integrity,occasionally a small amount of inflammatory cells of group A at each time point.At 1 day after scald,group B and the transplantation group （group C,D,E）the alveolar septum was thickened,and there was visible pulmonary capillary hyperemia,as well as a large amount of inflammatory cell infiltrations in the pulmonary capillaries and alveolar space.At 3 day,group B and the transplantation group alveolar structural damage,pulmonary hemorrhage and inflammatory cell infiltrations were better than those in 1 day.Compared with group B,the alveolar structure was clear and the septum was thinner,but there was no significant difference between the transplantation groups.On the 7 day after scald,the lung injury in the transplanted group was significantly less than group B,and the recovery of the injured lung tissue in E group was the most obvious.The number of the MPO positive cells increased significantly on the first day after scald （P ＜0.05） compared with group A,but there was no significant difference between the two groups.Compared with B group,the number of positive cells in transplantation group was significantly reduced at 3 and 7 day after scald,（P＜0.05）,and the number of positive cells in group E was significantly lower than other groups （P＜0.05）.CD68 staining showed a significant increase in positive cells in each group on day 1 （P＞ 0.05）.The number of positive cells decreased in 3 day after transplantation （P＜0.05）,but there was no significant difference between the transplantation groups.The number of positive cells in transplantation group was significantly lower than group B （P＜0.05） after 7 day.Compared with group C and D,there was significant difference in group E （P＜0.05）.Conclusions：Intratracheal transplantation of different dose hUCMSCs have protective on severe burns induced acute lung injury models;the protection mechanisms may be that the hUCMSCs transplantation can inhibit the invasion of the inflammatory cells in lung tissues,and the optimal dosage is 1 × 106.