Hydrocortisone Promotes Differentiation of Mouse Embryonic Stem Cell-Derived Definitive Endoderm toward Lung Alveolar Epithelial Cells

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.

Intrapulmonary autologous transplant of bone marrow-derived mesenchymal stromal cells improves lipopolysaccharide-induced acute respiratory distress syndrome in rabbit

Background

Lung diseases such as acute respiratory distress syndrome (ARDS) have a high incidence worldwide. The current drug therapies for ARDS have supportive effects, making them inefficient. New methods such as stromal cell therapy are needed for this problem.

Methods

This research was performed with ten New Zealand rabbits in two groups. Bone marrow aspiration was performed on the treated group, and mesenchymal stem cells were isolated and cultured. The experimental model of ARDS was induced using LPS from Escherichia coli strain O55:B5. Then, 10¹⁰ bone marrow mesenchymal stem cells (BM-MSCs) were autologously transplanted intrapulmonary in the treatment group, and 1–2 ml of PBS in the control group. The clinical signs, computed tomographic (CT) scans, echocardiography, blood gas analysis, complete blood count, and cytokine levels were measured before and at 3, 6, 12, 24, 48, 72, and 168 h after BM-MSC transplant. Finally, the rabbits were killed, and histopathological examination was performed.

Results

The results showed that BM-MSCs decreased the severity of clinical symptoms, the number of white blood cells and heterophils in the blood, the total cell count, and number of heterophils and macrophages in bronchoalveolar lavage, and balanced the values of arterial blood gases (increase in partial pressure of oxygen and O₂ saturation and decrease in the partial pressure of carbon dioxide). They also downregulated the tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations and increased the IL-10 concentrations at different times compared with time 0 and in the control group, significantly. In the CT scan, a significant decrease in the Hounsfield units and total lung volume was found by echocardiography, and in comparing the two groups, a significant difference in the parameters was noticed. The histopathology demonstrated that the BM-MSCs were able to reduce the infiltration of inflammatory cells and pulmonary hemorrhage and edema.

Conclusions

This study indicated that BM-MSCs play a significant role in the repair of lung injury.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2272-x) contains supplementary material, which is available to authorized users.