Theory-based cryopreservation mode of mesenchymal stromal cell spheroids.

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.

Determination of cell membrane permeability coefficients: Comparison of models in the case of oocytes.

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 (MeSO), 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.

Theoretical Estimation of the Optimum Cooling Rate of a Cell Suspension at Linear Freezing Modes Based on a Two Factor Theory of Cryodamage.

Background: According to the two-factor theory cryodamage arises from intracellular crystallization and solution effects due to freeze concentration.

Objective: The study aims to evaluate the contribution of two types of cryodamages that are related to extra- and intracellular crystallization.

Methods: The probability of intracellular crystal formation during cooling of cell suspension in cryoprotective solution has been determined based on general thermodynamics theory.

DEVELOPMENT OF A MODEL TO INVESTIGATE RED BLOOD CELL SURFACE CHARACTERISTICS AFTER CRYOPRESERVATION.

Background: Maintaining cell surface properties after freezing and thawing, characterized in particular by the surface potential and associated with it cell ability to intercellular adhesion, could be used as a characteristic of successful cryopreservation.

Objective: This study was conducted to research applying different erythrocytes freezing modes and analyses the regimes cryopreservation effect on the cell surface charge and adhesion to microorganisms.

Materials And Methods: Human erythrocytes frozen by three modes.

Permeability of rat and rabbit erythrocyte membranes for a series of amides.

Permeability coefficients of rat and rabbit erythrocyte membranes for a series of amides, as well as for erythrocytes treated with p-chloromercuribenzenesulfonic acid monosodium salt (pCMBS) have been determined at 25 and 37 degrees C. Directly proportional dependence of the pCMBS treated erythrocyte permeability for investigated substances and their partition coefficients between the hydrophobic phase and water as well as the values of activation energy of this process indicate that penetration of small hydrophilic molecules is realized by passive diffusion through the lipid bilayer. The results obtained indicate that penetration of small hydrophilic molecules of formamide through lipids is determined by the existence of a free space between hydrocarbon chains that arises from kink formation.