Significance of two transmembrane ion gradients for human erythrocyte volume stabilization.

Functional effectiveness of erythrocytes depends on their high deformability that allows them to pass through narrow tissue capillaries. The erythrocytes can deform easily due to discoid shape provided by the stabilization of an optimal cell volume at a given cell surface area. We used mathematical simulation to study the role of transport Na/K-ATPase and transmembrane Na+ and K+ gradients in human erythrocyte volume stabilization at non-selective increase in cell membrane permeability to cations. The model included Na/K-ATPase activated by intracellular Na+, Na+ and K+ transmembrane gradients, and took into account contribution of glycolytic metabolites and adenine nucleotides to cytoplasm osmotic pressure. We found that this model provides the best stabilization of the erythrocyte volume at non-selective increase in the permeability of the cell membrane, which can be caused by an oxidation of the membrane components or mechanical stress during circulation. The volume of the erythrocyte deviates from the optimal value by no more than 10% with a change in the non-selective permeability of the cell membrane to cations from 50 to 200% of the normal value. If only one transmembrane ion gradient is present (Na+), the cell loses the ability to stabilize volume and even small changes in membrane permeability cause dramatic changes in the cell volume. Our results reveal that the presence of two oppositely directed transmembrane ion gradients is fundamentally important for robust stabilization of cellular volume in human erythrocytes.

[Peculiarities of hemostasis in patients with COVID-19].

AIM: Analysis of the dynamics of different stages of clot formation and its lysis in patients with different COVID-19 severity. MATERIALS AND METHODS: We prospectively included 58 patients with COVID-19 (39 patients with moderate disease severity and 18 patients with severe disease) and 47 healthy volunteers as a control group. All participants underwent the assessment of flow-mediated dilation (FMD) of brachial artery, impedance aggregometry, rotational thromboelastometry and thrombodynamics. Von Willebrand factor antigen (vWF:Ag) quantification was also performed in patients with COVID-19. Measurements were repeated on the 3rd and 9th day of hospitalization. RESULTS: Compared to the control group, patients with COVID-19 showed reduced values of platelet aggregation and greater values of the clot growth rate, as well as its size and density. On the first day of hospitalization, we found no differences in the activity of plasma hemostasis and endogenous fibrinolysis between subgroups of patients. With the progression of the disease, the growth rate and size of the clot were higher in the severe subgroup, even despite higher doses of anticoagulants in this subgroup. An increase in platelet aggregation was noted during the progression of the disease, especially in the severe subgroup. There were no differences in the results of the FMD test by subgroups of patients. The vWF:Ag level was significantly higher in the severe subgroup. CONCLUSION: Thus, plasma hemostasis followed by secondary platelet activation correlates with the severity of COVID-19. Patients with moderate to severe coronavirus infection have predominantly local rather than generalized endothelial dysfunction.

[Peculiarities of blood coagulation disorders in patients with COVID-19].

AIM: To study the relationship of hemostatic disorders with inflammation and estimate their role in the course and outcomes of COVID-19. MATERIALS AND METHODS: We examined 215 consecutive patients with moderate and severe forms of acute COVID-19. The patients were on anticoagulants and immunosuppressive drugs. Hemostasis was assessed using the thrombodynamics assay, thromboelastography, fibrinogen and D-dimer levels, prothrombin time, and soluble fibrin-monomer complexes (ethanol gelation test). The hemostatic parameters were correlated with hematological and biochemical tests, including markers of inflammation (C-reactive protein, interleukins 6 and 8), as well as with the disease severity and outcomes. RESULTS: Laboratory signs of coagulopathy were revealed in the vast majority of the cases. Despite the use of low-molecular-weight heparins in the prophylactic and therapeutic doses, coagulopathy in COVID-19 manifested predominantly as hypercoagulability that correlated directly with the systemic inflammation and metabolic changes due to liver and kidney dysfunction. A direct relationship was found between the grade of coagulopathy and the severity of COVID-19, including comorbidities and the mortality. The chronometric hypocoagulability observed in about 1/4 cases was associated with a high level of C-reactive protein, which may decelerate coagulation in vitro and thereby mask the true inflammatory thrombophilia. Persistent hyperfibrinogenemia and high D-dimer in the absence of consumption coagulopathy suggest the predominance of local and/or regional microthrombosis over disseminated intravascular coagulation. CONCLUSION: The results obtained substantiate the need for laboratory monitoring of hemostasis and active prophylaxis and treatment of thrombotic complications in COVID-19.

Use of Thrombodynamics for revealing the participation of platelet, erythrocyte, endothelial, and monocyte microparticles in coagulation activation and propagation.

BACKGROUND AND OBJECTIVE: For many pathological states, microparticles are supposed to be one of the causes of hypercoagulation. Although there are some indirect data about microparticles participation in coagulation activation and propagation, the integral hemostasis test Thrombodynamics allows to measure micropaticles participation in these two coagulation phases directly. Demonstrates microparticles participation in coagulation activation by influence on the appearance of coagulation centres in the plasma volume and the rate of clot growth from the surface with immobilized tissue factor.Methods: Microparticles were obtained from platelets and erythrocytes by stimulation with thrombin receptor-activating peptide (SFLLRN) and calcium ionophore (A23187), respectively, from monocytes, endothelial HUVEC culture and monocytic THP cell culture by stimulation with lipopolysaccharides. Microparticles were counted by flow cytometry and titrated in microparticle-depleted normal plasma in the Thrombodynamics test. RESULTS: Monocyte microparticles induced the appearance of clotting centres through the TF pathway at concentrations approximately 100-fold lower than platelet and erythrocyte microparticles, which activated plasma by the contact pathway. For endothelial microparticles, both activation pathways were essential, and their activity was intermediate. Monocyte microparticles induced plasma clotting by the appearance of hundreds of clots with an extremely slow growth rate, while erythrocyte microparticles induced the appearance of a few clots with a growth rate similar to that from surface covered with high-density tissue factor. Patterns of clotting induced by platelet and endothelial microparticles were intermediate. Platelet, erythrocyte and endothelial microparticles impacts on the rate of clot growth from the surface with tissue factor did not differ significantly within the 0-200·103/ul range of microparticles concentrations. However, at concentrations greater than 500·103/ul, erythrocyte microparticles increased the stationary clot growth rate to significantly higher levels than do platelet microparticles or artificial phospholipid vesicles consisting of phosphatidylcholine and phosphatidylserine. CONCLUSION: Microparticles of different origins demonstrated qualitatively different characteristics related to coagulation activation and propagation.

Computer Design of Low-Molecular-Weight Inhibitors of Coagulation Factors.

The review discusses main approaches to searching for new low-molecular-weight inhibitors of coagulation factors IIa, Xa, IXa, and XIa and the results of such studies conducted from 2015 to 2018. For each of these factors, several inhibitors with IC50 < 10 nM have been found, some of which are now tested in clinical trials. However, none of the identified inhibitors meets the requirements for an "ideal" anticoagulant, so further studies are required.

An enhanced clot growth rate before in vitro fertilization decreases the probability of pregnancy.

BACKGROUND: The shift towards hypercoagulation during in vitro fertilization (IVF) can lead to the impairment of embryo implantation and placental blood circulation, which is believed to be a factor in an unsuccessful IVF cycle. OBJECTIVES: To assess coagulation in women with infertility before the start of an IVF cycle and during treatment to reveal the association between coagulation imbalance and IVF outcome. PATIENTS/METHODS: We conducted a prospective cohort observational study including 125 participants who underwent fresh IVF cycles. Blood samples were collected at five time points: before IVF, one week after the start of controlled ovarian stimulation (COS), on the day of follicular puncture, on the day of embryo transfer (ET) and one week after ET. Coagulation tests (clotting times: activated partial thromboplastin time (APTT) and prothrombin; fibrinogen and D-dimer concentrations; thrombodynamics) were performed. RESULTS: Women with an elevated clot growth velocity (>32.3 µm/min, detected by thrombodynamics) before IVF demonstrated a higher risk of negative IVF outcomes (adjusted RR = 1.38; 95% CI 1.28-1.49; P<0.001). During the procedure, we observed increases in prothrombin, fibrinogen and D-dimer concentrations, a slight shortening of APTT and a hypercoagulation shift in the thrombodynamics parameters. The hemostasis assay values during COS and after ET had no associations with IVF outcomes. CONCLUSIONS: Hypercoagulation in the thrombodynamics before the start of IVF treatment was associated with negative IVF outcomes. After the start of COS, all tests demonstrated a hypercoagulation trend, but the hypercoagulation did not influence IVF outcome. This research is potentially beneficial for the application of thrombodynamics assay for monitoring hemostasis in infertile women prior to an IVF procedure with the goal of selecting a group requiring hemostasis correction to increase the chances of pregnancy.

Fine structure and dynamics of EB3 binding zones on microtubules in fibroblast cells.

End-binding (EB) proteins associate with the growing tips of microtubules (MTs)and modulate their dynamics directly and indirectly, by recruiting essential factors to fine-tune MTs for their many essential roles in cells. Previously EB proteins have been shown to recognize a stabilizing GTP/GDP-Pi cap at the tip of growing MTs, but information about additional EB-binding zones on MTs has been limited. In this work, we studied fluorescence intensity profiles of one of the three mammalian EB-proteins, EB3, fused with red fluorescent protein (RFP). The distribution of EB3 on MTs in mouse fibroblasts frequently deviated from single exponential decay and exhibited secondary peaks. Those secondary peaks, which we refer to as EB3-islands, were detected on 56% comets of growing MTs and were encountered once per 44 s of EB3-RFP comet growth time with about 5 s half-lifetime. The majority of EB3-islands in the vicinity of MT tips was stationary and originated from EB3 comets moving with the growing MT tips. Computational modeling of the decoration of dynamic MT tips by EB3 suggested that the EB3-islands could not be explained simply by a stochastic first-order GTP hydrolysis/phosphate release. We speculate that additional protein factors contribute to EB3 residence time on MTs in cells, likely affecting MT dynamics.

The hemostasis system in children with hereditary spherocytosis.

INTRODUCTION: Patients with hereditary spherocytosis (HS) are characterized by having an increased risk for thrombosis. An early manifestation of thrombotic complications can occur even in childhood, especially after surgery. Hypercoagulability can be associated with hemolytic crises. AIM: The aim of this study was to investigate the hemostatic state in children with HS using global hemostasis assays. METHODS: The hemostatic status of 62 children (38 boys and 24 girls; age range: 0.5 to 17 years) with HS during and without hemolytic crisis was assessed using clotting times (APTT, TT, and PR), fibrinogen and D-dimer levels, and global hemostasis, thromboelastography (TEG) and thrombodynamics (TD) assays. One hundred and two healthy children undergoing annual medical examination were enrolled as a control group. RESULTS: TEG and TD parameters were increased in the children with HS compared to the control group (60 ±â€¯5 mm vs. 53 ±â€¯4 mm, p < 0.05 for TEG maximum amplitude; 28 ±â€¯3 µm/min vs. 24 ±â€¯2 µm/min, p < 0.05 for TD clot growth rate), while APTT, TT and PR were not significantly different between the two groups. Patients with HS were divided into 2 groups: those during hemolytic crisis (28 patients) and those without hemolytic crisis (34 patients). TEG and TD parameters were increased in those during hemolytic crisis compared to the steady state HS group (62 ±â€¯5 mm vs. 57 ±â€¯4 mm, p < 0.05 for TEG maximum amplitude; 31 ±â€¯4 µm/min vs. 26 ±â€¯3 µm/min, p < 0.05 for TD clot growth rate). The D-dimer levels were increased in 4 HS patients, for whom the activation of blood clotting was noted. Fibrinogen levels were decreased in patients with HS compared to the control group (2.1 ±â€¯0.4 mg/ml vs. 2.6 ±â€¯0.4 mg/ml, p < 0.05). Other tests were within the reference ranges for both groups. CONCLUSIONS: The global hemostasis tests TEG and TD revealed hypercoagulability in patients with HS. More dramatic changes were observed in patients experiencing a hemolytic crisis.

EB-Family Proteins: Functions and Microtubule Interaction Mechanisms.

Microtubules are polymers of tubulin protein, one of the key components of cytoskeleton. They are polar filaments whose plus-ends usually oriented toward the cell periphery are more dynamic than their minus-ends, which face the center of the cell. In cells, microtubules are organized into a network that is being constantly rebuilt and renovated due to stochastic switching of its individual filaments from growth to shrinkage and back. Because of these dynamics and their mechanical properties, microtubules take part in various essential processes, from intracellular transport to search and capture of chromosomes during mitosis. Microtubule dynamics are regulated by many proteins that are located on the plus-ends of these filaments. One of the most important and abundant groups of plus-end-interacting proteins are EB-family proteins, which autonomously recognize structures of the microtubule growing plus-ends, modulate their dynamics, and recruit multiple partner proteins with diverse functions onto the microtubule plus-ends. In this review, we summarize the published data about the properties and functions of EB-proteins, focusing on analysis of their mechanism of interaction with the microtubule growing ends.

Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling.

Essentials Roles of the two thrombin receptors in platelet signaling are poorly understood. Computational systems biology modeling was used together with continuous flow cytometry. Dual-receptor system has wide-range sensitivity to thrombin and optimal response dynamics. Procoagulant platelet formation is determined by donor-specific activities of the two receptors. SUMMARY: Background Activation of human platelets with thrombin proceeds via two protease-activated receptors (PARs), PAR1 and PAR4, that have identical main intracellular signaling responses. Although there is evidence that they have different cleavage/inactivation kinetics (and some secondary variations in signaling), the reason for such redundancy is not clear. Methods We developed a multicompartmental stochastic computational systems biology model of dual-receptor thrombin signaling in platelets to gain insight into the mechanisms and roles of PAR1 and PAR4 functioning. Experiments employing continuous flow cytometry of washed human platelets were used to validate the model and test its predictions. Activity of PAR receptors in donors was evaluated by mRNA measurement and by polymorphism sequencing. Results Although PAR1 activation produced rapid and short-lived response, signaling via PAR4 developed slowly and propagated in time. Response of the dual-receptor system was both rapid and prolonged in time. Inclusion of PAR1/PAR4 heterodimer formation promoted PAR4 signaling in the medium range of thrombin concentration (about 10 nm), with little contribution at high and low thrombin. Different dynamics and dose-dependence of procoagulant platelet formation in healthy donors was associated with individual variations in PAR1 and PAR4 activities and particularly by the Ala120Thr polymorphism in the F2RL3 gene encoding PAR4. Conclusions The dual-receptor combination is critical to produce a response combining three critical advantages: sensitivity to thrombin concentration, rapid onset and steady propagation; specific features of the protease-activated receptors do not allow combination of all three in a single receptor.

Effect of Hematocrit and Erythrocyte Density on Intraoperative Blood Loss in Hemophilia A Patients During Total Knee Arthroplasty.

Intraoperative blood loss during total knee arthroplasty in patients with hemophilia varies over a wide range (from 300 to 3000 ml). The reasons have not been clarified yet. We studied the dependence of intraoperative blood loss during total knee arthroplasty in patients with hemophilia A on hematocrit and mean erythrocyte density. Intraoperational blood loss ≥1000 ml was observed in patients with hematocrit <38.5%. In patients with hematocrit >38.5% this parameter depended on the mean erythrocyte density: in patients with increased erythrocyte density, the risk of intraoperational blood loss ≥1000 ml was higher. The increase in erythrocyte density can serve as an indicator of pathological processes, including the processes modulating hemostasis. It can also be assumed that erythrocytes with higher density change blood flow, which affects platelet adhesion to the damaged endothelium. Hematocrit below the threshold level and mean density of erythrocytes above the normal level can be regarded as risk factor for increased intraoperational blood loss.

Dynamics of calcium spiking, mitochondrial collapse and phosphatidylserine exposure in platelet subpopulations during activation.

UNLABELLED: Essentials The sequence and logic of events leading to platelet procoagulant activity are poorly understood. Confocal time-lapse microscopy was used to investigate activation of single adherent platelets. Platelet transition to the procoagulant state followed cytosolic calcium oscillations. Mitochondria did not collapse simultaneously and membrane potential loss could be reversible. SUMMARY: Background Activated platelets form two subpopulations, one of which is able to efficiently aggregate, and another that externalizes phosphatidylserine (PS) and thus accelerates membrane-dependent reactions of blood coagulation. The latter, procoagulant subpopulation is characterized by a high cytosolic calcium level and the loss of inner mitochondrial membrane potential, and there are conflicting opinions on their roles in its formation. Methods We used confocal microscopy to investigate the dynamics of subpopulation formation by imaging single, fibrinogen-bound platelets with individual mitochondria in them upon loading with calcium-sensitive and mitochondrial potential-sensitive dyes. Stimulation was performed with thrombin or the protease-activated receptor (PAR) 1 agonist SFLLRN. Stochastic simulations with a computational systems biology model of PAR1 calcium signaling were employed for analysis. Results Platelet activation resulted in a series of cytosolic calcium spikes and mitochondrial calcium uptake in all platelets. The frequency of spikes decreased with time for SFLLRN stimulation, but remained high for a long period of time for thrombin. In some platelets, uptake of calcium by mitochondria led to the mitochondrial permeability transition pore opening and inner mitochondrial membrane potential loss, which could be either reversible or irreversible. The latter resulted in an increase in the cytosolic calcium level and PS exposure. These platelets had higher cytosolic calcium levels before activation, and their mitochondria collapsed not simultaneously but one after another. Conclusions These results support a model of procoagulant subpopulation development following a series of stochastic cytosolic calcium spikes that are accumulated by mitochondria, leading to a collapse, and suggest important roles of individual platelet reactivity and signal exchange between different mitochondria of a platelet.

[THROMBIN-MEDIATED EFFECTS OF BLOOD MICROPARTICLES ON FORMATION, STRUCTURE, AND STABILITY OF FIBRIN CLOTS].

The effects of blood microparticles (MPs) on the dynamics of fibrin polymerization, clot structure and susceptibility to fibrinolysis were studied. Kinetics of fibrin polymerization, fibrinolysis, thrombin generation in platelet-free, microparticle-depleted and microparticle-depleted plasma replenished with cephalin, from healthy donors were analyzed in parallel. MPs have profound effects on all stages of fibrin formation, decrease its turbidity. All parameters obtained in the absence of MPs were recovered after reconstitution of phospholipids. Thrombin generation rates were reduced in the absence of MPs. In the presence of MPs the fibrin networks had less poro us structures with thinner fibers, while clots formed in the absence of MPs had larger pores and were built of thicker fibers. Clots formed in the presence of MPs were significantly more resistant to fibrinolysis. Results show that normally circulating MPs can support the formation of stable clots at the sites of vascular injury.

[Regulation of Membrane-Dependent Reactions of Blood Coagulation].

All major coagulation reactions do not occurs in blood plasma itself, these processes are actually two-dimensional reactions localized to thephospholipid membranes. Almost all blood cells, lipoproteins, and microparticles provide assembly of protein complexes. A central role among them are played by platelets and platelet-derived microparticles. On their membranes occurs the most important coagulation reactions such as activation of prothrombin by prothrombin complex, activation of factor X by complexes intrinsic and extrinsic tenase. This reactions are important for processes activation of the contact path coagulation, activation factor XI by thrombin, appearance of enzymatic activity of factor VIIa etc. This review is focused on the membrane-dependent reactions, here are discussed mechanisms and regulation these reactions and the possible prospects of the study.

Eculizumab effect on the hemostatic state in patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by a hypercoagulable state associated with acute hemolysis. Eculizumab is used to reduce the intensity of intravascular hemolysis in PNH patients. The hemostatic status of three patients with PNH was assessed during eculizumab treatment by D-dimer assay and the global assays: thromboelastography (TEG), thrombin generation test (TGТ), and thrombodynamics (TD). In the state of hemolytic crisis before the therapy D-dimer concentration was increased in two patients accompanied by hypercoagulation changes in TEG parameter angle (α). TD parameter the clot growth velocity (V) revealed hypercoagulability while TGT parameter ETP was within the normal range in all patients. The lactate dehydrogenase (LDH) activity decreased during the 8months of eculizumab therapy. The physical health was improved, the frequency of hemolytic crisis decreased. Patients periodically exhibited hypercoagulable state: the mean values α=38±11° (with normal range 20-40°), ETP=1311±442nM·min (with normal range 800-1560nM·min), V=31±4µm/min (with normal range 20-29µm/min). During the eculizumab therapy two patients had the repeated clinical manifestation of acute hemolytic crisis, the parameters of the global tests were increased compared to the previous measurement. The global hemostasis tests TEG, TGT and TD revealed hypercoagulability in patients with PNH during eculizumab therapy.

[The method of analysis of distribution of erythrocytes by density: practical guidelines].

The article describes the phthalate method of analysis of distribution of erythrocytes by density and demonstrates its possibility. The distribution of erythrocytes by density is implemented using centrifugation of blood in micro-hematocrit capillaries in presence of compounds of dimethyl- and dibuthylphthalates of known density. The acquisition of such clinically reliable parameters of distribution of erythrocytes by density as mean density of erythrocytes, width of distribution of erythrocytes by density, light and heavy fraction of erythrocytes and maximum of curve of distribution of erythrocytes by density is described. The causes of deviation of distribution of erythrocytes by density from standard values under various pathological conditions are considered. The syndrome of dehydration of erythrocytes is described in details. The simple and accessible method of acquisition of distribution of erythrocytes by density is described. It is demonstrated that analysis of distribution of erythrocytes by density makes it possible to determine character of changes occurring with erythrocytes. The monitoring of parameters of distribution of erythrocytes by density allows evaluating dynamics of pathological process and effectiveness of therapy.

[Influence of temperature on spatial fibrin clot formation process in thrombodynamics].

In this study we have investigated the process of spatial fibrin clot formation in non-steered platelet-free plasma at the temperatures from 20°C to 43°C using thrombodynamics - the novel in vitro hemostasis assay, which imitates the process of hemostatic clot growth in vivo. During data processing the following parameters were calculated: initial (V i ) and stationary (V st ) rates of clot growth which characterize initiation and propagation phases of clotting process, and clot size on the 30 th minute. The temperature dependence of extrinsic and intrinsic tenase activities, which determine values of the initial and stationary clot growth rates, respectively, have been also measured. It was established that the temperature lowering from 37°C to 24°C extends mainly on the initiation phase of clot growth, while the stationary rate of clot growth changes insignificantly. Meanwhile none of the thrombodynamics parameters shows the dramatic change of plasma coagulation system condition at the temperature of 24°C (acute hypothermia). Using the thrombodynamics assay an assumption, that the temperature lowering does not change the state of plasma hemostasis system significantly has been confirmed.

[Role of spatio-temporal non uniformities in blood coagulation regulation].

This paper reviews some contemporary researches of thrombosis and hemostasis process that consider its spatio-temporal dynamics. Among them, there are platelet distribution in the blood vessel and the dependence of the platelet plug growth on the hematocrit level; influence of the tissue factor density on the blood coagulation onset and on the efficacy of some drugs, designed for the hemostasis improvement; regulation of blood coagulation by the flow rate. Mechanisms controlling the mentioned processes are described. Clinical significance and novel diagnostic and therapeutic approaches are discussed from the position of the spatio-temporal non uniformities of thrombosis and hemosatsis.

[Investigation of molecular machine that integrates microtubules depolymerization and chromosomes movement in mitosis].

The main goal of a dividing cell is to distribute its genetic material equally between two daughter cells. Each of the two sister chromatids comprising each chromosome should go into one of the daughter cells. This is possible thanks to polar protein polymers called microtubules, which form a structure called "spindle" during mitosis. Microtubules are one of the basic elements of the cytoskeleton, but at the same time they are highly dynamic. Minus ends of the microtubules attach to the two poles of the spindle, while their plus ends are constantly growing or shrinking, and are also able to attach to the chromosomes and to move them. Chromosomes attach to the microtubule ends with a special protein super-complex called kinetochore. Each sister chromatid in a pair attaches to the microtubules emanating from a corresponding spindle pole. Kinetochores are attached to the dynamic plus ends of the microtubules, but tubulin subunits are still able to attach and detach to these attached ends. One of the most important questions in mitosis is understanding of the mechanism that allows such attachment to be stable (since unstable attachments lead to chromosome loss and aneuploidy) yet dynamic (arrest of the microtubule dynamics stops mitosis). More than 100 proteins comprising the kinetochore are known today, but there is no clear mechanical view on the molecular machine that forms kinetochore-microtubule attachment. The difficulties in understanding this mechanism are due to the variety of theoretical views on the principle of such machine, as well as limited number of biochemically isolated candidates to test these hypotheses experimentally. Therefore, investigation of the properties of putative couplers of microtubule depolymerization and chromosome movement is an important task.

[Molecular self-organization and multiple equilibrium systems].

We have compared different types of natural self-organizing systems: crystal-like formation of multi molecular systems were conferred with self-organization in active media and dissipative structure formation. The comparison revealed a common feature of all such systems. They all have bi-(multi-)stable states. We propose a hypothesis that self-organization is impossible in systems that could not have bi-(multi-) stable states.