Role of thioredoxin 1 and thioredoxin 2 on proliferation of human adipose tissue-derived mesenchymal stem cells

Thioredoxin-1 promotes the restoration of alveolar bone in periodontitis with diabetes

Treatment of periodontitis in people with diabetes remains challenging. The present study aimed to investigate the therapeutic potential of thioredoxin-1 (TRX1) in periodontitis with diabetes, as well as its role in modulating osteogenic differentiation. Our findings indicated that the production of reactive oxygen species (ROS) was elevated, while the expression of TRX1 was significantly reduced in the periodontal tissues of periodontitis mice with diabetes. Furthermore, knockdown of TRX1 in periodontal ligament stem cells (PDLSCs) resulted in the inhibition of osteogenic differentiation through disrupting Wnt/β-catenin signaling. However, this inhibition was restored upon administration of recombinant human TRX1 (rhTRX1). Importantly, rhTRX1 treatment decreased ROS generation, activated Wnt/β-catenin signal pathway and considerably promoted the alveolar bone repair of periodontitis mice with diabetes. These findings highlighted the crucial protective role of TRX1 in periodontitis with diabetes and suggested that it may serve as a potential therapeutic target for refractory periodontitis associated with oxidative stress.

Investigating The Alterations of Oxidative Stress Status, Antioxidant Defense Mechanisms, MAP Kinase and Mitochondrial Apoptotic Pathway in Adipose-Derived Mesenchymal Stem Cells from STZ Diabetic Rats

Objective

This study aimed to investigate the reliability of diabetic adipose-derived stem cells (ADSCs) for autologous cell-based therapies by exploring the functionality of signalling pathways involved in regulating oxidative stress and apoptosis.

Materials and Methods

In this experimental study, ADSCs were isolated from streptozotocin (STZ)-induced diabetic rats (dADSCs) and normal rats (nADSCs). The colonies derived from dADSCs and nADSCs were compared by colony-forming unit (CFU) assay. Reactive oxygen species (ROS) formation and total antioxidant power (TAP) were also measured. Furthermore, the expression of antioxidant enzymes, including catalase (Cat), superoxide dismutase (Sod)-1 and -3, glutathione peroxidase (Gpx)-1, -3 and -4 was measured at mRNA level by semi-quantitative reverse transcriptase polymerase chain reaction assay. The expression of Bax, Bcl2, caspase-3, total and phosphorylated c-Jun N-terminal kinase (JNK) and P38 Mitogen-Activated Protein Kinase (MAPK) at protein level was analyzed by western blotting.

Results

The results of this study indicated that viability and plating efficiency of dADSCs were significantly lower than those of nADSCs. ROS generation and TAP level were respectively higher and lower in dADSCs. The gene expression of antioxidant enzymes, including Cat, Sod-1, Gpx-3 and Gpx-4 in dADSCs was significantly greater than that in nADSCs. However, Sod-3 and Gpx-1 mRNA levels were decreased in dADSCs. Moreover, Bax/Bcl-2 protein ratio, caspase-3 protein expression and phosphorylation of JNK and P38 proteins were increased in dADSCs compared to nADSCs.

Conclusion

Taken together, diabetes might impair the cellular functions of dADSCs as candidates for autologous cell- based therapies. This impairment seems to be mediated by JNK, P38 MAPKs, and mitochondria pathway of apoptosis and partly by disruption of antioxidant capacity.

Selenium and Selenoproteins in Adipose Tissue Physiology and Obesity

Selenium (Se) homeostasis is tightly related to carbohydrate and lipid metabolism, but its possible roles in obesity development and in adipocyte metabolism are unclear. The objective of the present study is to review the current data on Se status in obesity and to discuss the interference between Se and selenoprotein metabolism in adipocyte physiology and obesity pathogenesis. The overview and meta-analysis of the studies on blood Se and selenoprotein P (SELENOP) levels, as well as glutathione peroxidase (GPX) activity in obese subjects, have yielded heterogenous and even conflicting results. Laboratory studies demonstrate that Se may modulate preadipocyte proliferation and adipogenic differentiation, and also interfere with insulin signaling, and regulate lipolysis. Knockout models have demonstrated that the selenoprotein machinery, including endoplasmic reticulum-resident selenoproteins together with GPXs and thioredoxin reductases (TXNRDs), are tightly related to adipocyte development and functioning. In conclusion, Se and selenoproteins appear to play an essential role in adipose tissue physiology, although human data are inconsistent. Taken together, these findings do not support the utility of Se supplementation to prevent or alleviate obesity in humans. Further human and laboratory studies are required to elucidate associations between Se metabolism and obesity.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

Berberine alleviates pulmonary hypertension through Trx1 and β-catenin signaling pathways in pulmonary artery smooth muscle cells

Pulmonary arterial hypertension (PAH) is closely associated with profound vascular remodeling, especially pulmonary arterial medial hypertrophy and muscularization, due to aberrant proliferation of pulmonary artery smooth muscle cells (PASMCs). Berberine, a drug commonly used to treat inflammation, may be a novel therapeutic option for PAH by improving pulmonary artery remodeling. The present study investigated whether berberine affected Trx1/β-catenin expression and/or activity and whether it could reduce the development of pulmonary hypertension in an experimental rat model and proliferation in human PASMCs (HPASMCs). The results showed that increased proliferation in hypoxia-induced healthy PASMCs or PAH PASMCs was associated with a significant increase in Trx1 and β-catenin expression. Treatment with the Trx1-specific inhibitor PX-12 significantly reduced pulmonary arterial pressure and vascular remodeling, as well as improved in vivo cardiac function and right ventricular hypertrophy, in Su/Hox-induced PAH rats. Berberine reversed right ventricular systolic pressure and right ventricular hypertrophy and decreased pulmonary vascular remodeling in the rats. Furthermore, berberine had an antiproliferative effect on hypoxia-induced HPASMC proliferation in a manner likely mediated by inhibiting Trx1 and its target gene β-catenin expression. Our work will help elucidate novel strategies for PAH treatment involving the traditional Chinese medicine berberine, and Trx1/β-catenin may be a promising therapeutic target.

Regional fat depot masses are influenced by protein-coding gene variants

Waist-to-hip ratio (WHR) is a prominent cardiometabolic risk factor that increases cardio-metabolic disease risk independently of BMI and for which multiple genetic loci have been identified. However, WHR is a relatively crude proxy for fat distribution and it does not capture all variation in fat distribution. We here present a study of the role of coding genetic variants on fat mass in 6 distinct regions of the body, based on dual-energy X-ray absorptiometry imaging on more than 17k participants. We find that the missense variant CCDC92_S70C, previously associated with WHR, is associated specifically increased leg fat mass and reduced visceral but not subcutaneous central fat. The minor allele-carrying transcript of CCDC92 is constitutively more highly expressed in adipose tissue samples. In addition, we identify two coding variants in SPATA20 and UQCC1 that are associated with arm fat mass. SPATA20_K422R is a low-frequency variant with a large effect on arm fat only, and UQCC1_R51Q is a common variant reaching significance for arm but showing similar trends in other subcutaneous fat depots. Our findings support the notion that different fat compartments are regulated by distinct genetic factors.

The role of the thioredoxin/thioredoxin reductase system in the metabolic syndrome: towards a possible prognostic marker?

Mammalian thioredoxin reductase (TrxR) is a selenoprotein with three existing isoenzymes (TrxR1, TrxR2, and TrxR3), which is found primarily intracellularly but also in extracellular fluids. The main substrate thioredoxin (Trx) is similarly found (as Trx1 and Trx2) in various intracellular compartments, in blood plasma, and is the cell's major disulfide reductase. Thioredoxin reductase is necessary as a NADPH-dependent reducing agent in biochemical reactions involving Trx. Genetic and environmental factors like selenium status influence the activity of TrxR. Research shows that the Trx/TrxR system plays a significant role in the physiology of the adipose tissue, in carbohydrate metabolism, insulin production and sensitivity, blood pressure regulation, inflammation, chemotactic activity of macrophages, and atherogenesis. Based on recent research, it has been reported that the modulation of the Trx/TrxR system may be considered as a new target in the management of the metabolic syndrome, insulin resistance, and type 2 diabetes, as well as in the treatment of hypertension and atherosclerosis. In this review evidence about a possible role of this system as a marker of the metabolic syndrome is reported.

Oxidative Stress Gene Expression Profile Correlates with Cancer Patient Poor Prognosis: Identification of Crucial Pathways Might Select Novel Therapeutic Approaches

The role of altered redox status and high reactive oxygen species (ROS) is still controversial in cancer development and progression. Intracellular levels of ROS are elevated in cancer cells suggesting a role in cancer initiation and progression; on the contrary, ROS elevated levels may induce programmed cell death and have been associated with cancer suppression. Thus, it is crucial to consider the double-face of ROS, for novel therapeutic strategies targeting redox regulatory mechanisms. In this review, in order to derive cancer-type specific oxidative stress genes' profile and their potential prognostic role, we integrated a publicly available oxidative stress gene signature with patient survival data from the Cancer Genome Atlas database. Overall, we found several genes statistically significant associated with poor prognosis in the examined six tumor types. Among them, FoxM1 and thioredoxin reductase1 expression showed the same pattern in four out of six cancers, suggesting their specific critical role in cancer-related oxidative stress adaptation. Our analysis also unveiled an enriched cellular network, highlighting specific pathways, in which many genes are strictly correlated. Finally, we discussed novel findings on the correlation between oxidative stress and cancer stem cells in order to define those pathways to be prioritized in drug development.

TIGAR knockdown radiosensitizes TrxR1-overexpressing glioma in vitro and in vivo via inhibiting Trx1 nuclear transport

The up-regulation of thioredoxin reductase-1 (TrxR1) is detected in more than half of gliomas, which is significantly associated with increased malignancy grade and recurrence rate. The biological functions of NADPH-dependent TrxR1 are mainly associated with reduced thioredoxin-1 (Trx1) which plays critical roles in cellular redox signaling and tumour radio-resistance. Our previous work has proved that TP53 induced glycolysis and apoptosis regulator (TIGAR) knockdown could notably radiosensitize glioma cells. However, whether TrxR1-overexpressing glioma cells could be re-radiosensitized by TIGAR silence is still far from clear. In the present study, TrxR1 was stably over-expressed in U-87MG and T98G glioma cells. Both in vitro and in vivo data demonstrated that the radiosensitivity of glioma cells was considerably diminished by TrxR1 overexpression. TIGAR abrogation was able to radiosensitize TrxR1-overexpressing gliomas by inhibiting IR-induced Trx1 nuclear transport. Post-radiotherapy, TIGAR low-expression predicted significant longer survival time for animals suffering from TrxR1-overexpessing xenografts, which suggested that TIGAR abrogation might be a promising strategy for radiosensitizing TrxR1-overexpressing glial tumours.

Effect of human umbilical cord blood mesenchymal stem cells administered by intravenous or intravitreal routes on cryo-induced retinal injury

Traumatic optic neuropathy is an important cause of severe vision loss. So, many attempts were performed to transplant stem cells systemically or locally to regenerate the injured retina. In this study, we investigated the effect of human umbilical cord blood mesenchymal stem cells (hUBMSCs) on histological structure, apoptotic, antiapoptotic, oxidant and antioxidant markers in an experimental model of cryo-induced retinal damage in mice. Forty-eight mice were included with 4 major groups; group I contained 18 mice as controls. The others included 30 mice exposed to cryo-induced retinal injury and were subdivided into three equal groups: group II received no treatment after injury. Group III was intravenously injected with hUCBMSCs after injury and group IV received an intravitreal injection with hUCBMSCs into both eyes. Retinal tissues were used for histopathological, immunological and gene expression studies. Real time-PCR was performed to assess B-cell lymphoma 2 (bcl2), Bcl2-associated X protein (bax), heme oxygenase-1 (hmox-1) and thioredoxin-2 (tnx-2) expression and to assess the differentiation of the stem cells into the retinal tissue. Immunohistochemical analysis was performed to assess caspase-3, 3-nitrotyrosine (3-NT) and basic fibroblast growth factor (bFGF). Disturbed retinal structure was seen in cryo-injured mice while hUCBMSCs treated groups showed nearly normal structure. By real time-PCR, significantly reduced mRNA expressions of Bax and notably enhanced mRNA expression of Bcl-2, hmox-1 and txn-2 were demonstrated in retinal injured mice with hUCBMSCs treatment compared to those without. In addition, immunohistochemical analysis confirmed downregulation of 3-NT and caspase-3 and upregulation of bFGF after hUCBMSCs injection in injured retina. Furthermore, there was no differentiation of transplanted stem cells into the retinal tissue. In conclusions, hUCBMSCs could improve the morphological retinal structure in cryo-induced retinal damage model by modulation of the oxidant-apoptotic status and by increased the expression of bFGF. © 2017 IUBMB Life, 69(3):188-201, 2017.

Heritability of in vitro phenotypes exhibited by murine adipose-derived stromal cells

Adipose-derived stromal cells (ADSCs) exhibit significant potential as therapeutic agents to promote tissue regeneration. Success of ADSC-based therapies is dependent upon efficient cell expansion in vitro as well as postinjection survival in the caustic milieu of damaged tissue. Genetic background regulates ADSC proliferative capacity and stress resistance, but the extent of the genetic effect size is not completely defined. The present study aimed to quantify phenotypic ranges and heritability of in vitro ADSC characteristics. ADSCs were isolated from mice representing 16 genetically diverse inbred mouse strains, including 12 classical inbred strains and four wild-derived strains. Cells were grown in vitro, and proliferative capacity and oxidative stress resistance were assessed. The fold change for ADSC growth ranged from 0.87 (BALB/cByJ) to 23.60 (POHN/DehJ), relative to original seeding density. The heritability of proliferative capacity was estimated to be 0.6462 (p = 9.967 × 10(-15)), and this phenotype was not associated with other ADSC traits. Cell viability following H2O2 treatment ranged from 39.81 % (CAST/EiJ) to 91.60 % (DBA/2 J), and the heritability of this phenotype was calculated as 0.6146 (p = 1.22 × 10(-12)). Relationships between cell viability and weight of the donor fat pad were also discovered. Donor genetic background is a major determinant of in vitro ADSC phenotypes. This study supports the development of forward genetics strategies to identify genes that underlie ADSC phenotypic diversity, which will inform efforts to improve cell-based therapies.

Vitamin C promotes the proliferation of human adipose-derived stem cells via p53-p21 pathway

Although adipose-derived stem cells (ADSCs) have demonstrated a promising potential for the applications of cell-based therapy and regenerative medicine, excessive reactive oxygen species (ROS) are harmful to ADSCs cell survival and proliferation. Vitamin C is an important antioxidant, and is often added into culture media as an essential micronutrient. However, its roles on the proliferation of human ADSCs have not been studied. Therefore, in this study, human ADSCs were isolated, and detected by flow cytometry for the analysis of their cell surface antigens. Cell proliferation and cell cycle progression were measured with cell counting kit-8 assay and flow cytometry, respectively. Western blotting was used to detect the expression levels of cyclin E1, p53, p21, and CDK2 proteins. The effect of vitamin C pretreatment on the production of hydrogen peroxide (H₂O₂)-mediated ROS in the ADSCs was evaluated by flow cytometry. Our results indicated that vitamin C treatment significantly increased cell proliferation, and changed the cell cycle distribution of ADSCs by decreasing the percentage of G₁ phase, and concurrently increased the percentage of S and G₂/M phase. Western blot analysis indicated that vitamin C treatment up-regulated the expression levels of cyclin E1 and CDK2, but down-regulated p53 and p21 proteins expression, which contributed to cell proliferation and cell cycle progression. Vitamin C pretreatment significantly reduced the production of H₂O₂-induced ROS in the ADSCs. These findings suggest that vitamin C can promote the proliferation and cell cycle progression in the ADSCs possibly through regulation of p53-p21 signal pathway.

Stem cells and the impact of ROS signaling

An appropriate balance between self-renewal and differentiation is crucial for stem cell function during both early development and tissue homeostasis throughout life. Recent evidence from both pluripotent embryonic and adult stem cell studies suggests that this balance is partly regulated by reactive oxygen species (ROS), which, in synchrony with metabolism, mediate the cellular redox state. In this Primer, we summarize what ROS are and how they are generated in the cell, as well as their downstream molecular targets. We then review recent findings that provide molecular insights into how ROS signaling can influence stem cell homeostasis and lineage commitment, and discuss the implications of this for reprogramming and stem cell ageing. We conclude that ROS signaling is an emerging key regulator of multiple stem cell populations.

Recombinant human thioredoxin-1 promotes neurogenesis and facilitates cognitive recovery following cerebral ischemia in mice

Cerebral ischemia (CI) can induce loss of hippocampal neurons, causing cognitive dysfunction such as learning and memory deficits. In adult mammals, the hippocampal dentate gyrus contains neural stem cells (NSCs) that continuously generate newborn neurons and integrate into the pre-existing networks throughout life, which may ameliorate cognitive dysfunction following CI. Recent studies have demonstrated that recombinant human thioredoxin-1 (rhTrx-1) could promote proliferation of human adipose tissue-derived mesenchymal stem cells and angiogenesis. To investigate whether rhTrx-1 also regulates hippocampal neurogenesis following CI and its underlying mechanisms, adult mice were subjected to bilateral common carotid arteries occlusion (BCCAO) to induce CI and treated with rhTrx-1 before reperfusion. Mice treated with rhTrx-1 showed shortened escape latencies in Morris water maze by 30 days and improvements in spatial memory demonstrated by probe trial test. Enhanced NSCs proliferation was observed at day 14, indicated by BrdU and Ki67 immunostaining. Doublecortin (DCX)(+) cells were also significantly increased following rhTrx-1 treatment. Despite increases in BrdU(+)/NeuN(+) cells by day 30, the double-labeling to total BrdU(+) ratio was not affected by rhTrx-1 treatment. The promotive effects of rhTrx-1 on NSCs proliferation and differentiation were further confirmed in in vitro assays. Western blot revealed increased ERK1/2 phosphorylation after rhTrx-1 treatment, and the ERK inhibitor U0126 abrogated the effects of rhTrx-1 on NSCs proliferation. These results provide initial evidence that rhTrx-1 effects neurogenesis through the ERK signaling pathway and are beneficial for improving spatial learning and memory in adult mice following global CI.

Thioredoxins, glutaredoxins, and peroxiredoxins--molecular mechanisms and health significance: from cofactors to antioxidants to redox signaling

Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and "antioxidants". Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions.

Thymosin beta-4 promotes mesenchymal stem cell proliferation via an interleukin-8-dependent mechanism

Mesenchymal stem cells (MSCs) hold great promise for the field of tissue regeneration. Because only a limited number of MSCs can be obtained from each donor site, it is important to establish standard methods for MSC expansion using growth and trophic factors. Thymosin β4 (Tβ4) is a novel trophic factor that has antimicrobial effects and the potential to promote tissue repair. Tβ4 is a ubiquitous, naturally-occurring peptide in the wound bed. Therefore, the relationship between Tβ4 and MSCs, especially adjacent adipose tissue-derived stem cells (ASCs), merits consideration. Exogenous Tβ4 treatment enhanced the proliferation of human ASCs, resulting in prominent nuclear localization of PCNA immunoreactivity. In addition, exogenous Tβ4 also increased IL-8 secretion and blocking of IL-8 with neutralizing antibodies decreased Tβ4-induced ASC proliferation, suggesting that IL-8 is a critical mediator of Tβ4-enhanced proliferation. Moreover, Tβ4 activated phosphorylation of ERK1/2 and increased the nuclear translocation of NF-κB. These observation provide that Tβ4 promotes the expansion of human ASCs via an IL-8-dependent mechanism that involves the ERK and NF-κB pathways. Therefore, Tβ4 could be used as a tool for MSC expansion in cell therapeutics.

Murine adipose tissue-derived stromal cell apoptosis and susceptibility to oxidative stress in vitro are regulated by genetic background

Adipose tissue-derived stromal cells (ADSCs) are of interest for regenerative medicine as they are isolated easily and can differentiate into multiple cell lineages. Studies of their in vitro proliferation, survival, and differentiation are common; however, genetic effects on these phenotypes remain unknown. To test if these phenotypes are genetically regulated, ADSCs were isolated from three genetically diverse inbred mouse strains- C57BL/6J (B6), BALB/cByJ (BALB), and DBA/2J (D2)- in which genetic regulation of hematopoietic stem function is well known. ADSCs from all three strains differentiated into osteogenic and chondrogenic lineages in vitro. ADSCs from BALB grew least well in vitro, probably due to apoptotic cell death after several days in culture. BALB ADSCs were also the most susceptible to the free radical inducers menadione and H₂O₂. ADSCs from the three possible F1 hybrids were employed to further define genetic regulation of ADSC phenotypes. D2, but not B6, alleles stimulated ADSC expansion in BALB cells. In contrast, B6, but not D2, alleles rescued BALB H₂O₂ resistance. We conclude that low oxidative stress resistance does not limit BALB ADSC growth in vitro, as these phenotypes are genetically regulated independently. In addition, ADSCs from these strains are an appropriate model system to investigate genetic regulation of ADSC apoptosis and stress resistance in future studies. Such investigations are essential to optimize cell expansion and differentiation and thus, potential for regenerative medicine.

A simple method to generate adipose stem cell-derived neurons for screening purposes

Strategies involved in mesenchymal stem cell (MSC) differentiation toward neuronal cells for screening purposes are characterized by quality and quantity issues. Differentiated cells are often scarce with respect to starting undifferentiated population, and the differentiation process is usually quite long, with high risk of contamination and low yield efficiency. Here, we describe a novel simple method to induce direct differentiation of MSCs into neuronal cells, without neurosphere formation. Differentiated cells are characterized by clear morphological changes, expression of neuronal specific markers, showing functional response to depolarizing stimuli and electrophysiological properties similar to those of developing neurons. The method described here represents a valuable tool for future strategies aimed at personalized screening of therapeutic agents in vitro.

MicroRNA-193 pro-proliferation effects for bone mesenchymal stem cells after low-level laser irradiation treatment through inhibitor of growth family, member 5

The enhanced proliferation of mesenchymal stem cells (MSCs) can be helpful for the clinical translation of cell therapy. Low-level laser irradiation (LLLI) has been demonstrated as regulating MSC proliferation. MicroRNAs (miRNAs) are involved in various pathophysiologic processes in stem cells, but the role of miRNAs in the LLLI-based promotion of MSC proliferation remains unclear. We found that the proliferation level and cell cycle-associated genes in MSCs were increased after LLLI treatment in a time-dependent manner. Microarray assays revealed subsets of miRNAs to be differentially regulated, and these dynamic changes were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) after LLLI. miR-193 was the most highly up-regulated miRNA, and the change in it was related with the proliferation level. Gain-loss function experiments demonstrated that miR-193 could regulate the proliferation of MSCs, including human's and rat's, but could not affect the apoptosis and differentiation level. Blockade of miR-193 repressed the MSC proliferation induced by LLLI. By qRT-PCR, we found that miR-193, in particular, regulated cyclin-dependent kinase 2 (CDK2) expression. Bioinformatic analyses and luciferase reporter assays revealed that inhibitor of growth family, member 5 (ING5) could be the best target of miR-193 to functionally regulate proliferation and CDK2 activity, and the mRNA and protein level of ING5 was regulated by miR-193. Furthermore, the ING5 inhibited by small interfering RNA (siRNA) could up-regulate the proliferation of MSCs and the expression of CDK2. Taken together, these results strongly suggest that miR-193 plays a critical part in MSC proliferation in response to LLLI stimulation, which is potentially amenable to therapeutic manipulation for clinical application.

Generation of reactive oxygen species in adipose-derived stem cells: friend or foe?

INTRODUCTION

Reactive oxygen species (ROS) participate in cellular apoptosis and are involved in pathophysiological etiology of degenerative diseases. However, recent studies suggest that ROS at low levels may play a pivotal role as second messengers and activate normal cellular processes. Intracellular ROS increase the proliferation, migration, and regenerative potential of adipose-derived stem cells (ASCs). In contrast, manipulations that diminish intracellular ROS levels interfere with normal ASC function. ROS generation therefore acts like a double-edged sword.

AREAS COVERED

This review discusses the following research questions: i) Do ROS stimulate or suppress ASCs? ii) How are ROS generated from ASCs? iii) Which function(s) is/are regulated by intracellular ROS generation? In addition, the antioxidant/antiapoptotic effect of ASCs is briefly introduced.

EXPERT OPINION

Whether ROS is harmful or beneficial is primarily a question of dosage. Low or moderate ROS generation increases the proliferation, migration and regenerative potential of ASCs. Therefore, it is beneficial to expose ASCs to moderate oxidative stress during manipulation. The addition of a ROS donor in culture can reduce the cost for the expansion of ASCs and a ROS preconditioning can enhance the regenerative potential of ASCs.