To investigate the effect and mechanism of human adipose-derived stem cells (h-ADSCs) on pulmonary inflammatory response in rats with 30% total body surface area (TBSA) third-degree scald.

A total of 72 male Sprague-Dawley rats were randomly assigned to a pure scald group and an h-ADSCs group (36 rats in each group). Using the boiling water bath method, rats in the two groups were subjected to 30% TBSA third-degree full-thickness thermal injury. Then rats in the h-ADSCs group received intravenous injection with 6 million h-ADSCs (the total injection volume is about 1 mL), and rats in the pure scald group received intravenous injection with an equal volume of saline. The tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), α7 nicotinic acetylcholine receptor (α7nAChR) messenger RNA (mRNA) and protein, nuclear factor-kappaB (NF-κB) P65 protein, hematoxylin-eosin (HE) staining score and lung injury score were compared between the two groups at 8 h, 1 week and 2 weeks after scald, and the pathological changes of lung tissue were observed under ordinary light microscope.

The TNF-α (t = 2.421, 2.626, 2.356; P = 0.035, 0.041, 0.032), IL-6 (t = 2.514, 2.751, 2.756; P = 0.029, 0.031, 0.039), HE staining score (t = 2.869, 2.631, 2.813; P = 0.028, 0.031, 0.042) and lung injury score (t = 2.172, 3.017, 2.698; P = 0.033, 0.032, 0.029) after 8 h, 1 week and 2 weeks of scald, and the NF-κB P65 protein (t = 2.639, 2.491; P = 0.028, 0.037) after 1 week and 2 weeks of scald in the h-ADSCs group were significantly lower than those in the pure scald group. After 1 week and 2 weeks of scald, the expressions of α7nAChR mRNA (t = 2.912, 2.663; P = 0.032, 0.046) and protein (t = 2.814, 2.638; P = 0.033, 0.032) in the h-ADSCs group were significantly higher than those in the pure scald group. At 8 h after injury, rats had wider alveolar septum, more stromal vascular congestion and fewer lesions in the h-ADSC group than in the pure scald group. One week after injury, rats in the h-ADSCs group showed significant thickened pulmonary septum and narrowed alveolar space with inflammatory cell infiltration. Two weeks after injury, rats in the h-ADSCs group showed significant thickened pulmonary septum and narrowed alveolar space with massive inflammatory cell infiltration.

The h-ADSCs can reduce the inflammation level of lung tissue in rats with 30% TBSA third-degree scald shock. These protective effects may be related to the increasing expressions of α7nAChR and decreasing expressions of NF-κB P65.