e object of the paper is to show the heterogeneity of 300 cord samples processed in the current research. e differences in effectiveness of mesenchymal stem cell (MSC) isolation are shown. Moreover, the recommendations for choosing the method of MSC isolation depending on the value of stromal-vascular rate are given. e data can be useful for selecting the optimal conditions to obtain MSC and for further cryopreservation of umbilical cord tissue.

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HBD-2-a member of β-defensin family of antimicrobial peptides-is known to permeabilize cell membranes of susceptible cells, but the mechanism of such interactions is poorly understood. In our study, we used a hemolytic model to explore the kinetic properties of HBD-2 interactions with membranes of human erythrocytes. We ran hemolytic assays with a wide range of both HBD-2 and erythrocyte concentrations, as well as varying pH values, incubation times, and osmotic strengths; each in the presence or the absence of inhibitory substances such as proteins and salts. The results show that HBD-2 cell membrane permeabilization is both dose-and time-dependent (with plateau effect observed in each case), and inversely dependent on erythrocyte concentration. HBD-2 interactions with cell membranes highly depend on pH value and the presen ce of inhibitors but are not affected by tested osmotic strength range. Our findings suggest that interactions of HBD-2 with cell membranes are mainly electrostatic in nature and are limited by released cell content. We developed a speculative model of such interaction based on our results. K e y w o r d s: human beta-defensin 2, hemolytic activity, membrane permeabilization.