The study of osmotic reactions of cells during freezing and thawing is a crucial topic requiring detailed investigation. Understanding these processes allows for the optimization of cryopreservation protocols, thereby improving cell survival after thawing. While the literature provides information on the osmotic characteristics of various mammalian cells, data on plant cells, including microalgae, remain scarce.This article examines the osmotic behavior of microalgae cells, which are promising from a biotechnological perspective, during freezing and thawing. We obtained results on the osmotically inactive cell volume and, using a physical-mathematical model, determined the permeability coefficients of cells for water and cryoprotectants.These results will be used in further work on developing cryopreservation protocols for microalgae, enabling the optimization of the process and achieving the best possible post-thaw survival outcomes.

Cryopreservation of cell suspensions, such as testicular interstitial cells (ICs), which include cells differing in size, volume, and membrane composition, is a very challenging task. Cryobiology requires the determination of several parameters to optimize the cryopreservation procedure, such as membrane water permeability (or hydraulic conductivity) (Lp) and its activation energy (Ea0), the permeability of the cell plasma membrane to dimethyl sulfoxide (DMSO) (Ps) and its activation energy (Ea1), and the osmotically inactive cell volume. This study aims to measure these key cryopreservation parameters for ICs. Additionally, it seeks to evaluate how quickly ICs become saturated with DMSO and to determine the optimal exposure time to cryoprotective media before cooling. By analyzing cell volume changes in different DMSO-based solutions, the research intends to optimize the cryopreservation process, potentially eliminating unnecessary exposure steps while maintaining cell viability. The kinetics of ICs volume changes in cryoprotective media with different DMSO concentrations (0.7—2.8 M), which additionally included 100 mg/ml dextran 40 (0.7DMSO + D40) or 10% FBS (1.4DMSO + FBS), were analyzed using the modified Kedem–Katchalsky model to determine the membrane transport properties. The calculated parameters clearly showed that cell saturation with DMSO occurred within a few minutes after its addition and could reach equilibrium before the estimated start of water crystallization in the samples. Thus, additional exposure of cells to DMSO-containing media was unnecessary. It could potentially lower the metabolic activity of ICs. Accordingly, the cryopreservation procedure for ICs can be shortened by removing the exposure step without reducing viability of ICs in 0.7DMSO + D40 and 1.4DMSO + FBS.

The work is a fragment of the research work "Cryopreservation of three-dimensional cell structures of different degrees of heterogeneity based on physical and mathematical modelling" (state registration number 0123U102365).Introduction.Self-assembled three-dimensional cellular structures (spheroids and organoids) have recently been increasingly used in biomedical, pharmacological, and biotechnological research [1][2][3][4][5].This is due to their greater resemblance to tissues in terms of their actual characteristics (physiological, biochemical, genetic) in vivo [6,7] compared to single-layer cell models.When working with three-dimensional structures, it is important for researchers to visualize the cells within them and assess their viability and metabolic activity.

Cryopreservation of spheroids requires development of new improved methods. The plasma membranes permeability coefficients for water and cryoprotectants determine time characteristics of mass transfer through the cell membranes, and therefore the optimal modes of cells cryopreservation. Here we proposed an approach to cryopreservation of multicellular spheroids which considers their generalized characteristics as analogues of the membranes' permeability coefficients of the individual cells. We have determined such integral characteristics of spheroids from mesenchymal stromal cells (MSCs) as osmotically inactive volume; permeability coefficients for water and Me2SO molecules and the activation energy of their penetration. Based on these characteristics, we calculated the osmotic behavior of multicellular spheroids under cooling conditions to select the optimal cooling rate. We also determined the optimal cooling rate of spheroids using the probabilistic model developed based on the two-factor theory of cryodamage. From the calculation it follows that the optimal cooling rate of the MSC-based spheroids is 0.75°С/min. To verify the obtained theoretical estimates, we conducted experiments on freezing MSC-based spheroids under different modes. The obtained results of primary viability screening indicate that freezing at a constant linear cooling rate of 0.75-1.0°С/min gives a good result. Theoretical prediction of the spheroid osmotic behavior during cooling provided the basis for experimental verification of varying the temperature to which slow cooling should be carried out before immersion in liquid nitrogen. Slow freezing of spheroids to -40 °C followed by immersion in liquid nitrogen was shown to preserve cells better than slow freezing to -80 °C. Obtained data allow more effective use of MSC-based spheroids in drug screening and regenerative medicine.

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 mu g/g) of the micro (ZnOMPs) and nano (ZnONPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnONPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnOMPs only in the CS presence. Composites containing ZnONPs/MPs do not have a toxic effect on bone-forming cells -osteoblasts, preserving their ability to biomineralization. ZnOMPs and ZnONPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnONPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 -> 419 MPa (ZnOMPs), 348 -> 646 MPa (ZnONPs), and weaken the plastic (irreversible) de-formations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnONPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnONPs are more attractive.

Background: Microalgae are able to produce a significant amount of biologically significant substances. In connection with the growing popularity of microalgae, it is important to develop effective methods for storing cultures and creating strain banks. This will not only meet the needs of science and biotechnology for viable and sustainable crops, but will also solve the problem of biodiversity conservation. Objectives: study the effect of salt stress and cooling regimes on the pigment composition of microalgae Dunaliella salina cells in order to increase their safety after freezing-thawing. Materials and methods: The objects of the study were the unicellular green microalgae D. salina. Cultivation was carried out according to the standard method on nutrient media with different amounts of NaCl and trace elements. Adaptation to low temperatures was carried out by exposure of samples in the dark at temperature 4°C for 24 hours. Freezing was performed by placing 1 ml of the cell suspension in a 1.8 ml polypropylene cryogenic vial (Nunc, Sigma-Aldrich), cooled at a rate of 1 deg/min using a Mr. Frosty with following regimes: to -10°С, -40°С, -40°С followed by immersion to liquid nitrogen or direct immersion to liquid nitrogen (-196°С). Thawing was carried out in a water bath (37°С) with continuous shaking for 1–2 min. Microscopic examinations were carried out on an LSM-510 Meta laser scanning microscope (Carl Zeiss, Germany) upon excitation by a diode laser with a wavelength of 405 nm and 573 nm using a Nile Red stain. Results: It has been established that the formation of intracellular lipid globules and the synthesis of carotenoids in D. salina cells contribute to an increase in the concentration and number of motile cells after freezing-thawing. It has been shown that during rapid cooling, adaptive mechanisms do not have time to turn on in cells, and complete destruction of carotene-containing lipid globules occurs. Conclusions: Cryopreservation of D. salina cells should be carried out at a rate of 1 deg/min to -40°C, followed by immersion in liquid nitrogen and a mandatory stage of precultivation at 4°C for 24 hours. This approach allows the cells to adapt to a decrease in temperature, which contributes to the best result after freezing-thawing.

Values of cell membranes permeability coefficients for water and molecules of cryoprotective agents (CPAs) are the necessary characteristics for developing physical-mathematical models describing mass transfer processes through cell membranes in order to predict optimal cell cooling rates. We carried out a comparative analysis of the permeability coefficients of mouse oocyte membranes for molecules of water, ethylene glycol (EG), propane-1,2-diol (1,2-PD) and dimethyl sulfoxide (Me2SO), determined by applying the classical Kedem-Katchalsky model, which considers only the penetration of non-electrolyte molecules (water and CPA) through the membrane, and the model developed by us, which takes into account the transmembrane transfer of ions and the associated changes in the transmembrane electric potential. We shown that calculations based on the developed modified model provide lower values of the permeability coefficients of the oocyte membrane for water and CPA molecules. What is important that the obtained by our modified model permeability coefficients for water molecules do not depend on the type of cryoprotectant, while the application of the classical model both in our studies and works of other authors always gave different values of these coefficients in solutions with different cryoprotectants. Our modified model also makes it possible to determine the dynamics of the transmembrane electric potential of the cell under the conditions of transmembrane mass transfer and the duration of the membrane being influenced by the changes in electric potential, that is a parameter that can directly affect the viability of cells.

Ferumoxytol is a superparamagnetic iron oxide particle encapsulated by a semisynthetic carbohydrate with properties that can be used by the nephrologist for diagnosis and therapy. Ferumoxytol is approved by the US Food and Drug Administration for treating iron deficiency anemia in the setting of chronic kidney disease, but not for clinical diagnostic imaging. It has gained appeal as a magnetic resonance imaging contrast agent in patients with estimated glomerular filtration rates < 30 mL/min/1.73 m2 in whom gadolinium-based contrast magnetic resonance imaging agents are relatively contraindicated because of the association with gadolinium deposition and nephrogenic systemic fibrosis. Ferumoxytol metabolism is not dependent on kidney function, but rather is removed from the circulation by the reticuloendothelial system of the liver, spleen, and bone marrow. Additionally, the prolonged intravascular half-life (>14 hours) of ferumoxytol allows for longer image acquisition and repeat imaging, if necessary. In patients with contraindications for gadolinium contrast agents, ferumoxytol is an alternative agent for vascular assessment, including patency and course.

In this report, we have studied a cardioprotective effect of low molecular weight (below 5 kDa) fraction derived from cattle cord blood in a rat model of infarction-like cardiovasopathy. The myocardial infarction development was initiated in the animals, maintained for two months on a diet with excessive intake of fat, calcium and sodium salts, by making hypoxia-hypercapnia in them. The use of this model allowed inducing the infarction-like cardiovasopathy, comparable by many respects with the clinical picture of myocardial infarction, which was confirmed by electrocardiography, enzyme-linked immunosorbent assay and histological analysis. Preliminary administration of low molecular weight (below 5 kDa) fraction of cattle cord blood, as well as Actovegin did not prevent the heart attack, but increased the endurance of rats to hypoxia-hypercapnia and reduced the damage rate to myocardium. A preventive administration of low molecular weight fraction of cord blood was proven to mitigate the risk of hypoxia-induced damages to myocardium.