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Background Mechanoreceptor activation modulates GABA neuron firing and dopamine (DA) release in the mesolimbic DA system, an area implicated in reward and substance abuse. The lateral habenula (LHb), the lateral hypothalamus (LH), and the mesolimbic DA system are not only reciprocally connected, but also involved in drug reward. We explored the effects of mechanical stimulation (MS) on cocaine addiction-like behaviors and the role of the LH-LHb circuit in the MS effects. MS was performed over ulnar nerve and the effects were evaluated by using drug seeking behaviors, optogenetics, chemogenetics, electrophysiology and immunohistochemistry. Results Mechanical stimulation attenuated locomotor activity in a nerve-dependent manner and 50-kHz ultrasonic vocalizations (USVs) and DA release in nucleus accumbens (NAc) following cocaine injection. The MS effects were ablated by electrolytic lesion or optogenetic inhibition of LHb. Optogenetic activation of LHb suppressed cocaine-enhanced 50 kHz USVs and locomotion. MS reversed cocaine suppression of neuronal activity of LHb. MS also inhibited cocaine-primed reinstatement of drug-seeking behavior, which was blocked by chemogenetic inhibition of an LH-LHb circuit. Conclusion These findings suggest that peripheral mechanical stimulation activates LH-LHb pathways to attenuate cocaine-induced psychomotor responses and seeking behaviors.
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There is a tight regulatory network between the skeletal muscle system and the immune system, and they are jointly involved in functional regulation and response of the skeletal muscle system and the immune system. Cytokines are important signaling molecules that constitute this regulatory network. The cytokines produced by skeletal muscle atrophy and the cytokines produced by mechanical stimulation of skeletal muscle have different compositions and biological effects. The normal immune system and abnormal immune function can also affect skeletal muscle through the synergistic effect of different cytokines. According to this, a complex regulatory network between the two major systems is formed. The cytokine-mediated regulatory network between the skeletal muscle system and the immune system was reviewed in order to provide the theoretical basis for prevention and treatment of the skeletal muscle atrophy and mechanical intervention of the body immune function.
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Objective To explore the role of adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy metabolism, in vascular smooth muscle cell (VSMC) migration in response to physiological cyclic stretch. Methods The Flexcell-5000T mechanical loading system was applied with a physiological cyclic stretch at 10% amplitude and 1.25 Hz frequency to primary rat VSMCs, to simulate mechanical stimulation of VSMCs in vivo. The protein expression of p-AMPK in VSMCs was detected by Western blotting, and VSMC migration was detected by wound healing test. Results Compared with the static group, physiological cyclic stretch loading for 24 h significantly decreased the area of wound healing, indicating that physiological cyclic stretch inhibited VSMC migration. The protein expression of p-AMPK in VSMCs was increased significantly after physiological cyclic stretch loading for 3 h, and was decreased significantly after 24 h. Under physiological cyclic stretch loading conditions, incubating AMPK inhibitor could significantly reduce the protein expression of p-AMPK after 3 h, and promote VSMC migration after 24 h; incubating AMPK activator AICAR under static conditions significantly increased the protein expression of p-AMPK after 3 h, and weakened VSMC migration after 24 h. Conclusions Physiological cyclic stretch inhibits VSMC migration by increasing the protein expression of p-AMPK, indicating that VSMC migration regulated by physiological cyclic stretch is of great significance for maintaining vascular homeostasis.
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Osteocytes are the main mechanical sensory and transductive cells of bone tissues. They connect with each other through many synaptic structures to form a huge regulatory network of bone steady-state cells, which are connected with osteoblasts, osteoclasts and other bone matrix surface cells. Osteocytes regulate bone metabolism and maintain bone regeneration by affecting osteoblast bone formation and osteoclast bone resorption through paracrine pathway. Aiming at the effects of some signal molecules or protein factors secreted or released by osteocytes after mechanical stimulation on the growth and differentiation of osteoblasts and osteoclasts, this paper reviews recent advances in how mechanically stimulated osteocytes communicate with osteoblasts and osteoclasts, so as to provide new ideas for the study of osteocytes biomechanics.
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The important function of the endplate is to transmit stress and supply nutrition. Endplate degeneration might induce or promote degeneration of the intervertebral disc, causing a series of spine diseases that seriously impair people’s health and life quality. Endplate chondrocytes can respond to mechanical stimulation, which is an important factor affecting endplate degeneration. Inappropriate mechanical stimulation will accelerate endplate degeneration. This review summarized the effects of mechanical stimulation on vertebral endplate chondrocyte apoptosis, synthesis inhibition, calcification, and extracellular matrix degradation. The endplate degeneration induced by mechanical stimulation is regulated by a complex network of signal pathways composed of various signal transduction factors. The signal pathways involved in this review included NF-κB, Wnt, Hedgehog, MAPK, RhoA/Rock-1, AKT/mTOR, TGF-β signaling pathway and miRNA related signals. The interconnection of these pathways was highlighted and summarized. Multiple signaling pathways work together to regulate endplate chondrocyte metabolism, which ultimately leads to the endplate degeneration. This review might shed light on early diagnosis and precise treatment of cartilage endplate degeneration.
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BACKGROUND: Cartilage tissue repair is an important field of tissue engineering. How to use engineering technology to effectively differentiate seed cells into chondrocytes is a focus and difficulty in the field of tissue engineering. At present, it is difficult to make seed cells differentiate into mature and stable chondrocytes by simple orientation-inducing culture. Thereafter, the authors preliminarily studied the induced directional differentiation using intermittent hydrostatic pressure stimulation based on the characteristics of ATDC5 chondrocytes, in addition to the use of effective culture solution. OBJECTIVE: To investigate the effects of intermittent hydrostatic pressure on the earlyterm chondrocyte differentiation of ATDC5 cells. METHODS: ATDC5 cell lines were cultured in multilayer. Cells adhered well with multiple-layer formation after 3 days, and were then sealed to maintain sterility. Intermittent hydrostatic pressure was applied to the cultures (10 MPa, 1 Hz, 4 h/d). Cells cultured with no intermittent hydrostatic pressure served as control group. Morphological changes of the cells were observed under microscope at 4, 7, 11, 14, and 17 days. Expression levels of Aggrecan, COL-2 and SOX-9 mRNA were detected by real-time PCR. RESULTS AND CONCLUSION: After application of intermittent hydrostatic pressure, ATDC5 cells aggregated and appeared with obvious patchy changes. The mRNA expression levels of Aggrecan and COL-2 were significantly increased. SOX-9 mRNA expression level showed no significant difference compared with the control group, but presented with fall-rise pattern. Intermittent hydrostatic pressure influences the mRNA expression related to chondrocyte differentiation and promotes the secretion of chondrogenic matrix. This method is contributive to the mature cartilage differentiation.
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Objective:To evaluate the effects of noise, bright light and mechanical stimulation on sleep, blood-brain barrier and cognitive function in septic rats.Methods:Forty male Sprague-Dawley (SD) rats were selected and intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS) was used to establish sepsis model. 0, 30, 45, 60, 75 dB noise stimulation or 0, 50, 100, 200, 400 Lux light stimulation were given to rats (all n = 4). The serum levels of cortisol and melatonin, and the cerebral content of Evans blue (EB) were measured 96 hours after the stimulation to determine the optimal intensity of intervention. The other 40 SD rats were randomly divided into control group (Con group), LPS group, noise intervention group (LPS+60 dB group), 200 Lux light intervention group (LPS+200 Lux group) and mechanical stimulation group (LPS+MS group), with 8 rats in each group. The open fields test and fear conditioning test were used to evaluate the exploratory behavior and cognitive function 96 hours after corresponding stimulation. The enzyme linked immunosorbent assay (ELISA) was used to detect cerebral level of interleukin-6 (IL-6) and serum levels of cortisol and melatonin. The blood-brain barrier integrity was assessed by EB staining. The protein levels of ZO-1, Claudin-5 and caspase-3 in the hippocampus were detected by Western blotting to assess the blood-brain barrier integrity and neuronal apoptosis. Results:Compared with 0 dB group or 0 Lux group, the serum melatonin concentration in 60 dB group and 200 Lux group were significantly reduced, while the serum cortisol concentration and cerebral EB content were significantly increased. Therefore, 60 dB noise and 200 Lux light were selected in the subsequent experiments. Compared with Con group, the horizontal score and vertical score in the open field test in LPS group were significantly decreased. There were no significant differences in the proportion of freezing time, the cerebral contents of EB and IL-6, the serum levels of melatonin and cortisol, and the hippocampal expressions of ZO-1, Claudin-5 and caspase-3. Compared with LPS group, the horizontal score, vertical score and the percentage of freezing time in LPS+60 dB group, LPS+200 Lux group and LPS+MS group were significantly reduced [horizontal score: 73.8±9.7, 80.3±9.4, 64.5±8.3 vs. 103.6±15.5; vertical score: 9.4±1.7, 11.2±1.9, 6.8±0.9 vs. 15.9±2.8; the percentage of freezing time: (45.3±4.7)%, (53.3±5.8)%, (42.1±5.1)% vs. (66.1±6.3)%], the serum level of melatonin was significantly decreased (ng/L: 53.62±6.20, 44.25±6.41, 45.33±5.84 vs. 74.39±7.54), the serum level of cortisol was significantly increased (nmol/L: 818.34±95.53, 710.04±65.41, 989.73±91.63 vs. 398.82±72.59), the levels of EB, IL-6 in the brain tissue were significantly increased [EB (μg/g): 2.80±0.35, 2.38±0.31, 3.24±0.42 vs. 1.59±0.26; IL-6 (ng/g): 31.56±4.11, 26.69±3.75, 37.47±4.56 vs. 16.28±2.69], the expressions of ZO-1 and Claudin-5 were significantly decreased (ZO-1/β-actin: 0.37±0.04, 0.32±0.05, 0.24±0.04 vs. 0.80±0.09; Claudin-5/β-actin: 0.62±0.08, 0.47±0.06, 0.35±0.05 vs. 0.97±0.20), and the expression of cleaved caspase-3 was significantly increased (caspase-3/β-actin: 0.56±0.06, 0.39±0.04, 0.72±0.12 vs. 0.20±0.03), with statistically significant differences (all P < 0.05). Conclusion:60 dB noise, 200 Lux light or mechanical stimulation for 96 hours could inhibit the secretion of serum melatonin, promote the secretion of cortisol, and activate neuroinflammation in septic rats, and lead to neuronal apoptosis in hippocampus and hyper-permeability of blood-brain barrier, which in turn could cause sleep disturbance and cognitive impairment.
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Objective@#To observe the efficacy and safety of postural modified Valsalval manoeuvre in terminating paroxysmal supraventricular tachycardia (PSVT).@*Methods@#From January 2017 to June 2018, a total of 98 patients with PSVT were selected in the Affiliated Hospital of Xuzhou Medical University.They were randomly allocated to standard Valsalval manoeuvre group(48 cases) and postural modified Valsalval manoeuvre group(50 cases) according to sealed envelope method.The patients in standard Valsalval manoeuvre group carried out standard semi-recumbent Valsalva manoeuvre, while the other group received semi-recumbent with supine repositioning and passive leg raise immediately after the Valsalva strain.The general clinical data, total cardioversion success rate, first-time cardioversion success rate and the incidence of adverse reactions were compared between the two groups.@*Results@#There were no statistically significant differences in male proportion, age, history of PSVT or coronary heart disease, incidence of hypertension, diabetes and heart rate, systolic and diastolic blood pressure at attack between the two groups(all P>0.05). The total cardioversion success rate [40.0%(20/50)], first-time cardioversion success rate [28.0%(14/50)] in the modified group were significantly higher than those in the standard group [16.7%(8/48), 12.5%(6/48)](χ2=27.924, 16.308, all P<0.05). The incidence of adverse reactions was low in both two groups, and there was no statistically significant difference(P>0.05).@*Conclusion@#Postural modified Valsalval manoeuvre can effectively improve the cardioversion success rate of PSVT, and has high safety, which is worthy of clinical promotion.
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As the most important tissues of the motor system, skeleton and skeletal muscles are closely related to each other. The concept of bone-muscle units has been proposed for a long time, and they are linked closely by mechanical loading generated by exercise. Skeleton provides mechanical support attachments for skeletal muscle force, and contraction of skeletal muscle drives body movement. During the process of body movement, acting as an intermediate medium between the mechanical load and bone, skeletal muscles regulate metabolic activity of the bone through endocrine factors and mechanical stimulation, which is closely related to continuous bone remodeling and maintains good structure and function of the bone. This review focuses on recent research progress of skeletal muscle affecting bone remodeling by applying mechanical stimulation to the bone, which will provide some new ideas for prevention and treatment of bone metabolism diseases.
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Objective To explore the effect of mechanical stimulation on polarity of macrophages. Methods RAW264.7 cells were stimulated with tensile stretch at various amplitude and time, then cell viability was assessed with cell count kit-8 (CCK-8) for determining the stimulation parameters. RAW264.7 cells were induced to M1 type, then tensile stretch at 10% amplitude and 2 Hz was applied to M1 cells. CCK-8 and flow cytometry were used to detect the effects of tensile stretch on cell activity and apoptosis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the effect of tensile stretch on M1 type macrophage related gene expression. Results After stimulation for 3 hours, tensile stretch at 15% or 20% amplitude and 2 Hz significantly inhibited cell viability (P0.05). Tensile stretch at 10% amplitude and 2 Hz neither inhibited viability nor cause apoptosis of M1 type macrophages. The expression of inflammation-related genes including interleukin-1β(IL-1β) and tumor necrosis factor-α (TNF-α) of M1 type macrophages was significantly down-regulated with tensile stretch at 10% amplitude and 2 Hz (P＜0.05). Conclusions Mechanical stimulation at 10% amplitude and 2 Hz can inhibit M1 type macrophages and promote the polarization from M1 to M2. Mechanical stimulation may become a method for treating inflammation-related diseases.
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Ligament tissue engineering is currently a novel approach to the treatment of ligament injury, which can replace the deficiency of autografts. Ligament tissue engineering consists of four basic elements:seed cells, nanoscaffolds, growth factors, and mechanical stimulation. At present, the main problem in ligament tissue engineering is how to control seed cells to ligament cells more controllly. The study found that each physical property of the natural bio ligament and mechanical stimulation (uniaxial stretching) plays an important role in the differentiation of stem cells into ligament cells. Therefore, the design of nanofiber scaffolds must consider the elastic modulus of the material and the material. Structure(material arrangement, porosity and diameter, etc.), elastic modulus and material structure in different ranges will guide cells to differentiate into different lineages. Considering that the ligament is the main force-bearing tissue of the human body, mechanical stimulation is also essential for stem cell differentiation, especially uniaxial stretching, which best meets the stress of the ligament in the body. A large number of studies have found the frequency and amplitude of stretching. And time will also lead the cells to differentiate in different directions. RhoA/ROCK plays a regulatory role in cytoskeletal remodeling and cell differentiation. It is also found that RhoA/ROCK protein participates in the process of nanofiber arrangement and uniaxial stretching to guide stem cells to differentiate into ligament cells, specifically how to influence stem cell differentiation. It is not clear at present that understanding the effects of physical properties on stem cell differentiation and understanding the mechanism of action of RhoA/ROCK protein will provide a new theoretical basis for further optimization of ligament tissue engineering.
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Humans , Cell Differentiation , Environment , Ligaments , Research , Tissue Engineering , Tissue ScaffoldsABSTRACT
As a kind of mechanical effector cells, chondrocytes can produce a variety of physical and chemical signals under the stimulation of multiaxial load
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Apoptosis , Cells, Cultured , Chondrocytes , Stress, MechanicalABSTRACT
Vibration represents a micro reciprocating motion of a particle or object along a line or arc relative to a reference position, while the effect of low-magnitude high-frequency vibration (LMHFV) on skeletal system cells is similar to the mechanical stimulation of muscle movement. Bone mesenchymal stem cells (BMSCs), which have been identified as force-sensitive cells, exist in the bone marrows and have the potential of multi-lineage differentiation. Their biological characteristics can change functionally according to the appropriate stimulation in vitro, in order to reach the optimal demand of the stimulation. LMHFV can promote the osteogenic differentiation of BMSCs, therefore, the research on its mechanism can contribute to the application of vibration in the treatment of diseases such as osteoporosis, fracture, osteogenesis imperfecta, obesity as well as the promotion of orthodontic tooth movement. This paper summarizes the recent progress about the effects of vibration on BMSCs stem cells in osteogenesis and the possible mechanisms, so as to provide research ideas and methods for studying the mechanical as well as biological changes of BMSCs under vibration stimulation.
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Vibration represents a micro reciprocating motion of a particle or object along a line or arc relative to a reference position, while the effect of low-magnitude high-frequency vibration (LMHFV) on skeletal system cells is similar to the mechanical stimulation of muscle movement. Bone mesenchymal stem cells (BMSCs), which have been identified as force-sensitive cells, exist in the bone marrows and have the potential of multi-lineage differentiation. Their biological characteristics can change functionally according to the appropriate stimulation in vitro, in order to reach the optimal demand of the stimulation. LMHFV can promote the osteogenic differentiation of BMSCs, therefore, the research on its mechanism can contribute to the application of vibration in the treatment of diseases such as osteoporosis, fracture, osteogenesis imperfecta, obesity as well as the promotion of orthodontic tooth movement. This paper summarizes the recent progress about the effects of vibration on BMSCs stem cells in osteogenesis and the possible mechanisms, so as to provide research ideas and methods for studying the mechanical as well as biological changes of BMSCs under vibration stimulation.
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OBJECTIVE@#The aim of this study was to induce oral submucous fibrosis (OSF) in Sprague-Dawley(SD) rat models by arecoline and mechanical stimulation.@*METHODS@#Two factors factorial design was used to divide 48 rats into 8 groups (n=6). Different concentrations of arecoline (0, 0.5, 2, and 8 mg·mL⁻¹) and mechanical stimulation (with or without brush) were treated. After 16 weeks of treatment, the mouth opening was measured, the pathological changes of the buccal mucosa were observed, and the expressions of type Ⅲ collagen, transforming growth factor β1 (TGF-β1), and interferon-γ (IFN-γ) were detected.@*RESULTS@#In rats with moderate and high concentrations of arecoline, typical OSF pathological features were observed in the buccal mucosa, the mouth openings were significantly reduced, and the expression levels of type Ⅲ colla-gen and TGF-β1 were significantly increased (P0.05).@*CONCLUSIONS@#Moderate and high concentrations of arecoline can induce OSF in SD rats, but mechanical stimulation cannot induce OSF.
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Animals , Rats , Arecoline , Pharmacology , Fibroblasts , Mouth Mucosa , Oral Submucous Fibrosis , Rats, Sprague-DawleyABSTRACT
Objective @#To provide an experimental basis for predicting the sample size needed for animal experiments by studying the survival of SD rats after buccal mucosal biopsy with arecoline administered at different concentrations with different methods.@*Methods @#In all, 48 rats were divided into 8 groups, with 6 in each group, as follows: rats in groups A-D were treated with arecoline at different concentrations (0, 0.5, 2, 8 mg/mL); rats in groups E-H were treated with arecoline at different concentrations (0, 0.5, 2, 8 mg/mL), followed by stimulation of the buccal mucosa by mechanical rubbing. After 16 weeks, a 6-mm-diameter sample of the buccal mucosa was collected, and the wound was closed with interrupted sutures. The survival time of the rats was recorded, and the relationship between the survival time and the concentration of arecoline and mechanical stimulation was analyzed. @*Results@#No rats died during the first 16 weeks after treatment or after biopsy. The success rate of the arecoline stimulation model was 66.7%. The average observation time of all SD rats after biopsy was 42.5 days. Up to 120 days after biopsy, the cumulative survival rate in the eight groups was 50%, 33%, 17%, 0%, 33%, 17%, 0% and 0%, respectively (in alphabetical order). The cumulative survival rate in the groups administered 0 mg/mL (groups A and E), 0.5 mg/mL (groups B and F), 2 mg/mL (groups C and G), and 8 mg/mL (groups D and H) was 42%, 25%, 8% and 0%, respectively. Cox survival analysis showed that moderate and high concentrations of arecoline (2, 8 mg/mL) significantly affected the survival duration (P < 0.05), while mechanical stimulation had no significant effect on the survival duration (P > 0.05). The chi-squared test showed that the survival rate of rats showing wound healing (33.3%) was significantly higher than that of rats showing incomplete wound healing (0.0%) (P=0.003). @*Conclusion @#The success rate of the rat buccal submucosal fibrosis model was higher than moderate and high concentrations of arecoline, but the survival duration was significantly reduced after biopsy. Mechanical stimulation did not lead to a significant decrease in the survival duration, and impaired wound healing may be a cause of death in this model.
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As the human population ages and the life expectancy increases,tendon injuries will become more prevalent,especially among young individuals.Though the traditional operative therapy for tendon lesion can relieve the suffering of patients,the functional reconstruction is usually not optimistic.Tissue engineering is an advancing field,as the technology of construction in vitro and application in vivo matures,that can provide a more promising approach for tendon repair without tendon autograft.Challenges and future directions in the field of tendon tissue engineering focusing on four key parameters:seed cells,novel scaffolds,and mechanical stimulation.Recently,the discovery of TDSCs (tendon-derived stem cells) provides new ideas for the selection of seed cells and effect of mechanical stimulation on the tendon tissue engineering has become a hot spot.This article provides a review of recent progress in research about seed cells,scaffolds and mechanical stimulation for tendon engineering,and also speculates on the development in the future.
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Objective To explore the clinical application of two endometrial mechanical stimulation methods in patients with repeated implantation failure (RIF) in frozen-thawed embryo transfer (FET) cycle. Methods A total of 127 women with RIF who planned to perform FET again were included. They were separated into 3 groups: Group A (45 cases) with endometrial scratching and group B (42 cycles) with endometrial sucking within menstrual period in FET cycle, while in control group C (40 cases), no endometrial mechanical stimulation was performed. The outcomes of pregnancy were compared. Results The endometrial types of endometrial scratching group were mainly type A. The embryo implantation rate and clinical pregnancy rate in group A (27.27%, 46.67%) were significantly higher than those in group B (12.75 %, 21.43%) and group C (11.46%, 20.0%) (P <0.05). Conclusion The endometrial mechanical stimulation can improve the endometrial receptivity, compare with endometrial sucking, endometrial scratching can improve the clinical pregnancy rate of RIF patients more obviously.
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Cells in the body are exposed to physiological and pathophysiological stimuli that encompass both chemical and mechanical factors. It is important to understand how these factors modulate functions at cellular and organ levels. Compared to the large amount of information on cellular or organ responses to chemical factors, there is a paucity of knowledge on the effects of mechanical factors. Recent advances of fluorescence proteins and microscopy make it a very useful tool for elucidating the mechanotransduction processes; the state-of-the-art technologies for live-cell imaging of signaling is particularly valuable for investigating the spatial and temporal aspects of molecular mechanisms in mechanobiology. This review will cover the basic knowledge of fluorescence proteins and their application for biological research. In particular, the development and characterization of biosensors based on fluorescent resonance energy transfer (FRET) will be discussed. Genetically encoded FRET biosensors, which allows the imaging and quantification of tempo-spatial activation of molecules, will be introduced to demonstrate how the initiation and transmission of biochemical signals in response to local mechanical stimulation can be visualized in live cells. Specific emphasis will be on the elucidation of molecule hierarchy of signaling transduction in live cells upon the mechanical stimulation.
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Objective To study mechanical responses from mesenchymal stem cells (MSCs) under different mechanical stimulus duration, by measuring its elastic modulus and characterizing its stress fibers. Methods High resolution images of MSCs cytoskeleton in vitro were acquired by using atomic force microscope (AFM) and laser scanning confocal microscope (LSCM). AFM cantilever with micro-bead attached probe was used to perform force-distance curve experiment on MSCs at the approaching time of 0.1，0.5, 1, 5,10 s, respectively. The elastic modulus of MSCs at 300 nm indentation depth were measured and compared. Results The rat MSCs cytoskeleton presented an intensely organized network structure. The elastic modulus of rat MSCs varied obviously for different mechanical stimulus duration. The median and quartile (QR) of MSCs elastic modulus were 10.02 (QR=9.66),1.94 (QR=7.71),3.63 (QR=19.33),17.15(QR=35.13), 23.52 kPa(QR=34.87), with probe approaching time at 0.1，0.5, 1, 5,10 s, respectively. The MSCs elastic modulus showed the tendency of increasing with stimulus duration increasing, except for the extremely short stimulus (0.1 s). Conclusions Unlike inorganic elastomer, rat MSCs possess complete and flexible mechanical load-bearing structure and can respond actively to a relatively longer mechanical stimulation, with an increase of elastic modulus. These results may provide basic data for further tissue engineering researches on mechanical regulation of MSCs behavior.