Introduction. In modern medicine, the transplantation of mesenchymal stem cells (MSC) is utilized as a universal system for organism’s protection and renewal under normal and pathological conditions. However, there are only a few studies concerning the use of mesenchymal stem cells to treat respiratory viral infections. This study aimed to estimate the morphological direction of MSC action in lung tissues of the experimental animals infected with influenza А(Н1N1).
Methodology. Forty non-inbred mice (14-18 g) were used in experiments. An influenza virus strain A/FM/1/47/H1N1 was used to develop an experimental model. The strain was adapted to infect the lungs of white mice. Primary cultures of MSC from Wharton jelly were isolated from umbilical cords after obtaining informed consent. All animals were separated into eight groups (including the control group), depending on the concentration and route of administration (intravenous or intranasal) of MSC preparations. We performed pathohistological and morphometric studies of lung tissues for comparative morphological characterization of the effects of MSCs administration in experimental influenza virus-induced pneumonia.
Results. Transplantation of MSCs in experimental animals infected with the influenza A(H1N1) virus stimulated the body’s immune system and led to the development of a powerful local cell-mediated reaction in the lungs. A pronounced cellular lymphoid-macrophage response developed in the foci of viral pneumonia and the lungs respiratory sections with preserved ventilation on the third day of the disease.
Subsequently, the processes of cell infiltration in the foci of serous-hemorrhagic viral pneumonia progressed. Cellular infiltration was observed mainly in the interalveolar septa, the lumen of the alveoli, bronchioles, and bronchi. The morphometric indicators of the prevalence and intensity of hyperplasia in broncho-associated lymphoid tissue (2.42±0.26), infiltration by lymphoid cells of the connective tissue of the lungs (2.75±0.31), the presence of lymphoid cells in the alveoli (4.00±0.65) exceed the indicators of the control group by 2.42; 2.07 and 3.01 times, respectively (p<0.05) regardless of the concentration and method of administration of MSCs into infected animals.
Thus, the therapeutic potential of MSCs in animals infected with the influenza A (H1N1) virus was aimed at stopping the development of acute diffuse exudative serous hemorrhagic inflammation of the lungs. At the same time, the form of inflammation changes. A pronounced diffuse proliferation of cells of broncho-associated lymphoid tissue was the main morphological feature of the inflammatory process.