A study on the role of apoptotic human umbilical cord mesenchymal stem cells in bleomycin-induced acute lung injury in rat models

F.-B. Liu, Q. Lin, Z.-W. Liu

Department of Thoracic Surgery, Shanghai General Hospital, Shanghai Jiaotong University, Shanghai, China. zhenweiliu69@163.com

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• Pharmacology

OBJECTIVE: We sought to determine whether normal human umbilical cord mesenchymal stem cells and apoptotic human umbilical cord mesenchymal stem cells play any role in the lung repair following bleomycin-induced lung injury in rat models.

MATERIALS AND METHODS: Umbilical cord mesenchymal stem cells were obtained from the umbilical cord following caesarian section from healthy normal babies. Plasmin deprivation method was used for culture of human umbilical cord mesenchymal stem cells and flow cytometry was used to identify cell surface antigen and activity of stem cells and apoptosis. The animal model of acute lung injury was established by a one-off intratracheal instillation of bleomycin (BLM) (5 mg/kg) and then normal stem cells and apoptotic stem cells were separately injected. Alveolar lavage fluid and lung tissue were collected for further analysis prior to the injury and at days 3, 7, 14 after administration of BLM. The number of neutrophils in the broncho alveolar lavage fluid (BALF) was counted; Bicinchoninic Acid (BCA) method was used for estimation of total protein content in alveolar lavage fluid; biochemical assay was used for estimation of myeloperoxidase (MPO) activity; hematoxylin and eosin (HE) staining of lung tissue was used for histopathology analysis; reverse transcription-polymerase chain reaction (RT-PCR) assay was used for the determination of interferon-gamma (INF-γ) and mRNA changes of interleukin-4 (IL-4) in lung tissue. Enzyme-linked immunosorbent assay (ELISA) was used for the determination of cytokines TNF-α in the lung tissue.

RESULTS: Apoptotic human umbilical cord mesenchymal stem cells were more effective in reducing lung neutrophil infiltration and total protein leakage in rat models of acute lung injury (ALI). There was also an improvement in the degree of vascular permeability, reduction in the level of proinflammatory cytokines, INF-γ gene level and boost in anti-inflammatory cytokine IL-4 levels which also helps in more effectively reducing the degree of injury in ALI.

CONCLUSIONS: Human umbilical cord mesenchymal stem cell transplantation may have a bright future in the clinical setting for the treatment of ALI/acute respiratory distress syndrome (ARDS). Apoptotic human umbilical cord mesenchymal stem cells may have more effective than normal human umbilical cord mesenchymal stem cells in the treatment of acute lung injury.

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