Background. Late seeking medical advice, limited number of cardiac surgery hospitals and conservative treatment, which does not seem to be always efficacious, trigger the search for new, more effective mode therapy of acute myocardial infarction (MI). Recently, mesenchymal stromal cells (MSCs) have come into sharp focus of scientists due to the prospects for clinical use. On the other hand, multicenter studies have proved that therapeutic hypothermia (TH) has neuro- and cardioprotective effects, and it is administered as one of the urgent methods in providing primary health care. Purpose. Providing and analyzing ultrasonography (US) of rat hearts with experimental MI in order to determine the nature of heart remodelling under combined use of TH and introducing allogeneic MSCs. Materials and methods. The study involved 90 outbred white rats weighing 240–270 g. Myocardial infarction was reproduced by ligating the descending branch of the left coronary artery on the border of the upper and middle third of the vessel. Therapeutic hypothermia was performed in a cold chamber, 60 minutes long. The local skin temperature of the neck area was maintained at +4 оC, while the rectal and tympanic temperature decreased to + 25 оC. A suspension of allogeneic cryopreserved MSCs of the placenta with a concentration of 1.2 × × 106 cells/ml was administered once intravenously through v. saphena magna. Heart sonography was carried out by means of «Сономед 500» («СПЕКТРОМЕД», Russia) ultrasound scanner in B- and M-mode using a linear sensor 7.5L38 with frequency of 7.5 MHz. Results and discussion. The control group with experimental MI showed significantly suppressed function of the left ventricle (LV). It resulted in decreasing stroke volume (SV) and cardiac output (CO) and on the whole indicated reduced ejection fraction (EF) to 46.04 %, that was 35 % less than the corresponding normal range. According to the values of relative wall thickness (RWT) and left ventricular mass (LVM) on day 7 and day 30 after ligating the left coronary artery, LV remodelling was proceeding via eccentric mode of LV alteration. Therapeutic hypothermia was not able to completely stop the pathophysiological processes associated with coronary ligation. EF was not significantly different from the control group, and was 51.08 ± ± 2.68 %. On day 7 of the experiment, heart remodelling in this group was proceeding according to the normal geometry model, and on day 30 – according to the eccentric model. In spite of the volume overload causing post-infarction extension of the left ventricular cavity, in the group with applying MSCs, on day 7 there was a compensatory increase of the stroke volume, 1.8 times over compared to the group with normal range values and 2.3 over compared to the control group. The ejection fraction was 17 % less than the normal range, but statistically significantly higher than the corresponding indicator of the control group of this observation period. Heart remodelling after applying allogeneic MSCs associated with MI at all stages of observation was proceeding by eccentric LV hypertrophy. Аfter therapeutic hypothermia and applying MSCs associated with experimental myocardial infarction on day 7 and day 30, the group recorded the best values of echo params of LV anatomical structures, indicating no dilatation along with occuring moderate myocardial hypertrophy. The ejection fraction showed the best outcome, i. e. 58.78 %, while LV remodelling was minimal, occurring according to normal heart geometry. Conclusions. Applying echocardiography in rats is a very informative diagnosis method which makes it possible to describe the type of structural and functional remodelling of the myocardium associated infarction at early and late observation stages. The ultrasound study showed that the closest to the normal range was the group of animals exposed to therapeutic hypothermia and MSC transplantation. According to LVM and RWT values, in the rats of that group on day 7 and day 30 of the experiment, LV remodelling was characterized by normal geometry.

Background. At present, there are attempts aimed at repairing the myocardium affected by acute myocardial infarction (MI) via biologically sourced drugs, which are able to stimulate reparative regeneration, including the use of mesenchymal stromal cells (MSCs). On the other hand, therapeutic hypothermia initially after the occurrence of impaired blood flow in the coronary arteries aids in reducing the level of metabolism in cardiomyocytes and, accordingly, suppressing the formation of free radicals and inhibiting apoptosis. Purpose – рerforming and analysing Doppler sonography of the ascending aorta in rats with experimental MI in order to assess the systolic function of the left ventricular myocardium influenced by the combined use of therapeutic hypothermia and administering allogeneic MSCs. Materials and methods. The study involved 90 outbred white rats weighing 240–270 g. Myocardial infarction was reproduced by ligating the left coronary artery. Therapeutic hypothermia was performed in a cold chamber, 60 minutes long. The local skin temperature of the neck area was maintained at +4 оС. A suspension of allogeneic cryopreserved MSCs of the placenta was administered once intravenously. Sonography of the ascending aorta on day 7 and day 30 after ligating the coronary artery was carried out by means of «Сономед 500» ultrasound scanner in B-mode with the Doppler (PW-mode). Results. Studying the aortic blood flow showed that on day 7 after ligating the coronary artery, rats had a decrease in max systolic velocity and a tendency to increase diastolic blood flow velocity. Those changes influenced the pulsatility index and systolic-diastolic ratio. A 19 % decrease in the Stewart index confirmed the development of systolic dysfunction in the control group, the severity of which did not decrease until day 30 of the experiment. The impact of allogeneic MSCs on the process of remodeling the heart of rats after ligating the left coronary artery was evident on day 7 (acute stage of myocardial infarction) via abnormally low (below control) blood flow in the aorta with complete hemodynamics restoring on day 30 of the experiment. The combination of therapeutic hypothermia and administering allogeneic MSCs aided in the minimal deviation of hemodynamic parameters from the normal range. On day 7, there was only an increase in the average aortic blood flow rate by 29%, and a decrease in systolic-diastolic ratio by 12% compared to the corresponding normal range, suggesting compensation of the pumping function of the myocardium. Conclusions. Doppler assessment of systolic and diastolic blood flow velocities in the ascending aorta of rats makes it possible to indirectly record the presence and severity of systolic dysfunction of the left ventricle and follow up myocardial contractile function affected by MI. The combination of therapeutic hypothermia and administering allogeneic MSCs after ligating the left coronary artery helps to maintain hemodynamic parameters in the aorta at a level close to normal range during the acute phase of myocardial infarction as well as at the stage of scarring.