Protective Effects of Different Doses of Human Umbilical Cord Mesenchymal Stem Cell on the Acute Lung Injury in Rats with Severe Burn / 现代生物医学进展

ABSTRACT

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 groupsSham(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.