Effect of Intratracheal Administration of Adipose-derived Stromal Cells on Bleomycin-induced Lung Injury in a Rat Model.

BACKGROUND Mesenchymal stromal cells (MSCs) have been intensively investigated in regenerative medicine. Among the different types of MSCs, adipose tissue-derived stromal cells (ASCs) can be obtained with relatively less invasive techniques. Since ASC administration is a candidate strategy for the treatment of refractory diseases including pulmonary fibrosis, we investigated whether intratracheal injection of ASCs had therapeutic potential against bleomycin (BLM)-induced lung injury in rats. METHODS BLM was intratracheally administered to rats, and 1 week later ASCs were harvested. Two weeks after BLM treatment, ASCs or phosphate-buffered saline (PBS) were injected autologously into the rats via the trachea A semi-quantitative histological evaluation was conducted to assess the injured lungs, followed by cell tracing at 3 or 6 weeks after BLM instillation. RESULTS ASC administration did not affect the severity of lung damage on the third week after BLM exposure, but prevented further aggravation of the lung injury, as apparent on the sixth week. A fluorescent cell tracer revealed that the majority of ASCs did not appear to have penetrated inside the lung region injured by BLM on the third week after BLM instillation, but some of these cells sprouted deep into the thick distorted architecture of the injured lung on the sixth week after the BLM instillation. CONCLUSIONS The results of the present study suggest that ASCs may play a role in the prevention of ongoing aggravation of lung injury in the long term.