[Pathogenesis of chronic obstructive pulmonary disease]

Therapeutic effects of amniotic fluid-derived mesenchymal stromal cells on lung injury in rats with emphysema

Background

In chronic obstructive pulmonary disease (COPD), two major pathological changes that occur are the loss of alveolar structure and airspace enlargement. To treat COPD, it is crucial to repair damaged lung tissue and regenerate the lost alveoli. Type II alveolar epithelial cells (AECII) play a vital role in maintaining lung tissue repair, and amniotic fluid-derived mesenchymal stromal cells (AFMSCs) possess the characteristics of regular mesenchymal stromal cells. However, it remains untested whether transplantation of rat AFMSCs (rAFMSCs) might alleviate lung injury caused by emphysema by increasing the expression of surfactant protein (SP)A and SPC and inhibiting AECII apoptosis.

Methods

We analyzed the phenotypic characteristics, differentiation potential, and karyotype of rAFMSCs, which were isolated from pregnant Sprague–Dawley rats. Moreover, we examined the lung morphology and the expression levels of SPA and SPC in rats with emphysema after cigarette-smoke exposure and intratracheal lipopolysaccharide instillation and rAFMSC transplantation. The ability of rAFMSCs to differentiate was measured, and the apoptosis of AECII was evaluated.

Results

In rAFMSCs, the surface antigens CD29, CD44, CD73, CD90, CD105, and CD166 were expressed, but CD14, CD19, CD34, and CD45 were not detected; rAFMSCs also strongly expressed the mRNA of octamer-binding transcription factor 4, and the cells could be induced to differentiate into adipocytes and osteocytes. Furthermore, rAFMSC treatment up-regulated the levels of SPA, SPC, and thyroid transcription factor 1 and inhibited AECII apoptosis, and rAFMSCs appeared to be capable of differentiating into AECII-like cells. Lung injury caused by emphysema was alleviated after rAFMSC treatment.

Conclusions

rAFMSCs might differentiate into AECII-like cells or induce local regeneration of the lung alveolar epithelium in vivo after transplantation and thus could be used in COPD treatment and lung regenerative therapy.

[Structural abnormalities and inflammation in COPD: a focus on small airways]

Chronic obstructive pulmonary disease (COPD) is characterized by poorly reversible airflow limitation associated with airway remodelling and inflammation of both large and small airways. The site of airflow obstruction in COPD is located in the small airways, justifying a focus on this compartment. The structural abnormalities that are found in bronchioles with a diameter less than 2mm are characterized by increased airway wall thickness with peribronchial fibrosis, and by luminal obstruction by mucous exudates. Destruction of alveolar walls, the hallmark of emphysema, may be related to protease-antiprotease imbalance, and to mechanisms involving apoptosis, senescence, and autoimmunity. Cigarette smoke inhalation triggers the recruitment of innate immune cells (neutrophils and macrophages) and putatively adaptive immunity mediated via T and B lymphocytes and lymphoid follicles in the small airways. These data suggest a potential role for therapies that can target remodelling and inflammation in the small airways of patients with COPD.