Directly targeting PRDM16 in thermogenic adipose tissue to treat obesity and its related metabolic diseases.

Obesity is increasing globally and is closely associated with a range of metabolic disorders, including metabolic associated fatty liver disease, diabetes, and cardiovascular diseases. An effective strategy to combat obesity involves stimulating brown and beige adipocyte thermogenesis, which significantly enhances energy expenditure. Recent research has underscored the vital role of PRDM16 in the development and functionality of thermogenic adipocytes. Consequently, PRDM16 has been identified as a potential therapeutic target for obesity and its related metabolic disorders. This review comprehensively examines various studies that focus on combating obesity by directly targeting PRDM16 in adipose tissue.

Excessive or sustained endoplasmic reticulum stress: one of the culprits of adipocyte dysfunction in obesity.

As the prevalence of obesity continues to rise globally, the research on adipocytes has attracted more and more attention. In the presence of nutrient overload, adipocytes are exposed to pressures such as hypoxia, inflammation, mechanical stress, metabolite, and oxidative stress that can lead to organelle dysfunction. Endoplasmic reticulum (ER) is a vital organelle for sensing cellular pressure, and its homeostasis is essential for maintaining adipocyte function. Under conditions of excess nutrition, ER stress (ERS) will be triggered by the gathering of abnormally folded proteins in the ER lumen, resulting in the activation of a signaling response known as the unfolded protein responses (UPRs), which is a response system to relieve ERS and restore ER homeostasis. However, if the UPRs fail to rescue ER homeostasis, ERS will activate pathways to damage cells. Studies have shown a role for disturbed activation of adipocyte ERS in the pathophysiology of obesity and its complications. Prolonged or excessive ERS in adipocytes can aggravate lipolysis, insulin resistance, and apoptosis and affect the bioactive molecule production. In addition, ERS also impacts the expression of some important genes. In view of the fact that ERS influences adipocyte function through various mechanisms, targeting ERS may be a viable strategy to treat obesity. This article summarizes the effects of ERS on adipocytes during obesity.

Effects of Environmental Noise Stress on Mouse Metabolism.

Environmental noise is associated with various health outcomes. However, the mechanisms through which these outcomes influence behavior and metabolism remain unclear. This study investigated how environmental noise affects the liver, adipose tissue, and brain metabolic functions, leading to behavioral and body weight changes. Mice were divided into a noise group exposed to construction noise and an unexposed (control) group. Behavior and body weight changes were monitored over 50 days. Early changes in response to noise exposure were assessed by measuring plasma cortisol and glial fibrillary acidic protein expression in brain tissues on days 1, 15, and 30. Chronic responses, including changes in lipoprotein and fat metabolism and neurotransmitters, were investigated by analyzing serum lipoprotein levels and body fat mass and evaluating liver, fat, and brain tissue after 50 days. The noise group showed higher locomotor activity and reduced anxiety in the open-field and Y-maze tests. Noise exposure caused an initial weight loss; however, chronic noise increased fat mass and induced adipocyte hypertrophy. Our findings underscore the role of environmental noise-induced stress in augmenting locomotor activity and reducing anxiety in mice through neurotransmitter modulation while increasing the risk of obesity by decreasing HDL cholesterol levels and promoting adipocyte hypertrophy.

Phenotypic characteristics of adipocyte-like cells generated from C2C12 myoblasts cultured with chicken serum.

The aim of this study was to clarify the transcriptional and metabolic characteristics of C2C12 myoblasts cultured in Dulbecco's Modified Eagle Medium (DMEM) containing 20 % chicken serum (CHS) (C2C12-CHS cells) compared with C2C12 myoblasts cultured in DMEM containing 20 % fetal bovine serum (FBS) (C2C12-FBS cells). After 3 days of culture, C2C12-CHS cells showed a marked accumulation of lipid droplets, accompanied by increased expression levels of brown adipocyte-related genes (i.e., Bmp7, Prdm16, Ucp1, Cidea, Pgc1α, Cox7a1, Cox8, and ß3-adorenoceptor). Furthermore, stimulation of ß3-adorenoceptor by its selective agonist, mirabegron, increased the mRNA expression of Ucp1 and Pgc1α in C2C12-CHS cells. Wide-targeted metabolomic analysis performed by gas chromatography-tandem mass spectrometry revealed that the metabolic profile of C2C12-CHS cells was obviously different to that of C2C12-FBS cells. Additionally, the metabolomic analysis indicated that ß3-adrenoceptor stimulation by mirabegron upregulated energy metabolism in C2C12-CHS cells as seen in brown adipocytes. These results suggest that C2C12-CHS cells may differentiate into brown adipocyte-like cells, accompanied by increased functional ß3-adrenoceptor.

Bacillus lipopeptides inhibit lipase activity and promote 3T3-L1 preadipocyte differentiation.

Bacillus lipopeptides have been reported to display anti-obesity effects. In the present study, Lipopeptides from Bacillus velezensis FJAT-45028 that consisted of iturin, fengycin and surfactin were reported. The lipopeptides exhibited a strong lipase inhibition activity in a concentration-dependent manner with a half maximal inhibitory concentration of 0.012 mg/mL, and the inhibition mechanism and type were reversible and competitive, respectively. Results of CCK8 assay showed that 3T3-L1 preadipocyte cells were completely viable under treatment of 0.050-0.2 mg/mL lipopeptides for 24 or 48 h. It was found that the lipopeptides could increase lipid droplets in the differentiated 3T3-L1 adipocytes in tested concentration and suppress the expression of peroxisome proliferator-activated receptor gamma (PPARγ). These results indicated the potential anti-obesity mechanism of the tested lipopeptides might be to inhibit lipase activity but not to suppress lipid accumulation in the adipocytes. Moreover, the lipopeptides could elevate glucose utilisation by 14.43%-33.81% in the differentiated 3T3-L1 adipocytes.

Effect of genistein supplementation on microenvironment regulation of breast tumors in obese mice.

Obesity is an important risk factor for breast cancer in women before and after menopause. Adipocytes, key mediators in the tumor microenvironment, play a pivotal role in the relationship between obesity with cancer. However, the potential of dietary components in modulating this relationship remains underexplored. Genistein, a soy-derived isoflavone, has shown promise in reducing breast cancer risk, attenuating obesity-associated inflammation, and improving insulin resistance. However, there are no reports examining whether genistein has the ability to reduce the effects of obesity on breast tumor development. In this study, we constructed a mammary tumor model in ovariectomized obese mice and examined the effects of genistein on body condition and tumor growth. Moreover, the effects of genistein on the tumor microenvironment were examined via experimental observation of peritumoral adipocytes and macrophages. In addition, we further investigated the effect of genistein on adipocyte and breast cancer cell crosstalk via coculture experiments. Our findings indicate that dietary genistein significantly alleviates obesity, systemic inflammation, and metabolic disorders induced by a high-fat diet in ovariectomized mice. Notably, it also inhibits tumor growth in vivo. The impact of genistein extends to the tumor microenvironment, where it reduces the production of cancer-associated adipocytes (CAAs) and the recruitment of M2d-subtype macrophages. In vitro, genistein mitigates the transition of adipocytes into CAAs and inhibits the expression of inflammatory factors by activating PPAR-γ pathway and degrading nuclear NF-κB. Furthermore, it impedes the acquisition of invasive properties and epithelial‒mesenchymal transition in breast cancer cells under CAA-induced inflammation, disrupting the Wnt3a/ß-catenin pathway. Intriguingly, the PPAR-γ inhibitor T0070907 counteracted the effects of genistein in the coculture system, underscoring the specificity of its action. Our study revealed that genistein can mitigate the adverse effects of obesity on breast cancer by modulating the tumor microenvironment. These findings provide new insights into how genistein intake and a soy-based diet can reduce breast cancer risk.

Adipocyte-derived glutathione promotes obesity-related breast cancer by regulating the SCARB2-ARF1-mTORC1 complex.

Obesity is a major risk factor for poor breast cancer outcomes, but the impact of obesity-induced tumor microenvironment (TME) metabolites on breast cancer growth and metastasis remains unclear. Here, we performed TME metabolomic analysis in high-fat diet (HFD) mouse models and found that glutathione (GSH) levels were elevated in the TME of obesity-accelerated breast cancer. The deletion of glutamate-cysteine ligase catalytic subunit (GCLC), the rate-limiting enzyme in GSH biosynthesis, in adipocytes but not tumor cells reduced obesity-related tumor progression. Mechanistically, we identified that GSH entered tumor cells and directly bound to lysosomal integral membrane protein-2 (scavenger receptor class B, member 2 [SCARB2]), interfering with the interaction between its N and C termini. This, in turn, recruited mTORC1 to lysosomes through ARF1, leading to the activation of mTOR signaling. Overall, we demonstrated that GSH links obesity and breast cancer progression by acting as an activator of mTOR signaling. Targeting the GSH/SCARB2/mTOR axis could benefit breast cancer patients with obesity.

Identification of genetic polymorphisms associated with interindividual variability of vitamin A concentration in adipose tissue of healthy male adults.

BACKGROUND: Adipose tissue vitamin A (VA), i.e. mainly retinol (RET) and its esters, comes from preformed VA and proVA carotenoids present in our food. Adipose tissue VA acts as hormonal cue maintaining essential aspects of adipocyte biology which includes fat mobilization and catabolism, energy balance and glucose homeostasis, and it is thus of particular interest to study its determinants, including genetic ones. Hence, this study aimed to identify genetic variations associated with adipose tissue VA concentration. METHODS: Forty-two healthy male adults received, in a randomized crossover design, 3 test meals. Periumbilical adipose tissue samples were collected on 6 occasions, i.e. at fast and 8h after consumption of each meal. RET concentration was measured in both plasma and the adipose tissue following saponification. Participants were genotyped using whole-genome microarrays. A total of 1305 SNPs in or near 27 candidate genes were included for univariate analysis. Partial least squares regression (PLS) was carried out to find the best combination of SNPs associated with the interindividual variability in adipose tissue RET concentration. RESULTS: Adipose tissue RET concentration was not associated with plasma RET concentrations (r=-0.184, p=0.28). Interindividual variability of adipose tissue RET concentration was high (CV=62%). Twenty-nine SNPs were significantly (p<0.05) associated with adipose tissue RET concentration and a PLS regression model identified 16 SNPs as explanatory variables of this concentration. The SNPs were in or near PPARG, RXRA, STRA6, CD36, FFAR4, ALDH1A1, MGLL, DGAT2, and PKD1L2. CONCLUSION: A combination of 16 SNPs has been associated with the interindividual of adipose tissue VA concentration in humans. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov registration number NCT02100774.

Chicken Embryo Fibroblast Viability and Trans-Differentiation Potential for Cultured Meat Production Across Passages.

This study was conducted to analyze the viability of primary chicken embryo fibroblasts and the efficiency of adipogenic trans-differentiation for cultured meat production. In isolating chicken embryo fibroblasts (CEFs) from a heterogeneous cell pool containing chicken satellite cells (CSCs), over 90% of CEFs expressed CD29 and vimentin. The analysis of the proliferative capabilities of CEFs revealed no significant differences in EdU-positive cells (%), cumulative cell number, doubling time, and growth rate from passage 1 to passage 9 (p > 0.05). This indicates that CEFs can be isolated by 2 h of pre-plating and survive stably up to passage 9, and that primary fibroblasts can serve as a valuable cell source for the cultured meat industry. Adipogenic trans-differentiation was induced up to passage 9 of CEFs. As passages increased, lipid accumulation and adipocyte size significantly decreased (p < 0.05). The reduced differentiation rate of primary CEFs with increasing passages poses a major challenge to the cost and efficiency of cultured meat production. Thus, effective cell management and the maintenance of cellular characteristics for a long time are crucial for ensuring stable and efficient cultured fat production in the cultured meat industry.

New stilbenes from Cajanus cajan inhibit adipogenesis in 3T3-L1 adipocytes through down-regulation of PPARγ.

Two new stilbenes, denominated Cajanotone B (CAB) and Cajanotone C (CAC), were isolated from the leaves of Cajanus cajan. In this study, the structures of CAB and CAC were unambiguously elucidated by a combination of various spectral methods. Both compounds significantly inhibited the adipogenesis in 3T3-L1 adipocytes by reducing the lipid accumulation, triglyceride content and FFA secretion. CAB and CAC also substantially inhibit the mRNA expression of HSL, ATGL, C/EBPα and PPARγ as deciphered based by RT-PCR assay. Down-regulation of PPAR is believed to be the primary mechanism underlying which CAB and CAC inhibited adipogenic differentiation because the lipid-promoting activity of PPAR agonists can be counteracted by these compounds. The molecular interaction between CAB/CAC and PPARγ was revealed with the help of molecular docking. Taken together, CAB and CAC could serve as new lead compounds with the potential to speed up the development of novel lipid-lowering and weight-control therapies.

Bioprospection of rattlesnake venom peptide fractions with anti-adipose and anti-insulin resistance activity in vitro.

Animal venoms are natural products that have served as a source of novel molecules that have inspired novel drugs for several diseases, including for metabolic diseases such as type-2 diabetes and obesity. From venoms, toxins such as exendin-4 (Heloderma suspectum) and crotamine (Crotalus durissus terrificus) have demonstrated their potential as treatments for obesity. Moreover, other toxins such as Phospholipases A2 and Disintegrins have shown their potential to modulate insulin secretion in vitro. This suggests an unexplored diversity of venom peptides with a potential anti-obesogenic in Mexican rattlesnake venoms. For that reason, this study explored the in vitro effect of Crotalus venom peptide-rich fractions on models for insulin resistance, adipocyte lipid accumulation, antioxidant activity, and inflammation process through nitric oxide production inhibition. Our results demonstrated that the peptide-rich fractions of C. aquilus, C. ravus, and C. scutulatus scutulatus were capable of reverting insulin resistance, enhancing glucose consumption to normal control; C. culminatus, C. molossus oaxacus, and C. polystictus diminished the lipid accumulation on adipocytes by 20%; C. aquilus, C. ravus, and C. s. salvini had the most significant cellular antioxidant activity, having nearly 80% of ROS inhibition. C. aquilus, C. pyrrhus, and C. s. salvini inhibited nitric oxide production by about 85%. We demonstrated the potential of these peptides from Crotalus venoms to develop novel drugs to treat type-2 diabetes and obesity. Moreover, we described for the first time that Crotalus venom peptide fractions have antioxidant and inflammatory properties in vitro models.

Transcriptome analysis reveals selectively high expression of beige adipocyte marker genes in mouse perinephric fat.

To reveal the differences in the properties of visceral adipose tissue in healthy unstimulated mice, we performed transcriptome analysis using RNA sequencing. Among visceral adipose tissues, perinephric adipose tissue was found to exclusively express beige adipocyte markers while expressing white adipocyte markers. These results imply potential specific roles of perinephric adipose tissue in both physiological and pathological conditions.

Enrichment of Fat Graft with Association of ASC and Nanofat in an Animal Model.

INTRODUCTION: Fat graft (FG) absorption rate varies from 20 to 80% in two years. Recently, several bioengineering techniques were applied to improve FG retention rate. Numerous studies investigated the use of adipocyte-derived stem cells (ASC) as FG enrichment. However, ASC production is costly, complex, and time-consuming. In contrast, Nanofat, a combination of lipids, stem cells and growth factors, offers a faster, simpler, and more cost-effective alternative for FG enrichment. OBJECTIVE: This study aims to compare the effects of ASC with those of Nanofat, as a viable option in FG enrichment. MATERIAL AND METHODS: Animals were allocated in three groups: Control group (1 mL fat), ASC group (1 mL fat +1x106 ASC), and NnF group (1 mL of fat + 0.3mL NnF). These groups were subdivided in three subgroups (4, 8, and 12 weeks, n = 6/group). We performed ultrasound and macroscopic measurements for FG volume, histology and expression of healing and inflammation genes. RESULTS: At week 12, ASC and NnF groups showed a higher retention of FG when compared to the Control group (51%, 46%, 12% respectively, p < 0.01). Fibrosis was similar in ASC and Nanofat groups. The Nanofat group showed a higher vascular density then the Control group (p < 0.05). Il-10 gene expression was higher, and Mmp9 was lower in the Nanofat group when compared to the ASC and Control groups. CONCLUSION: This study indicates that enriching FG with both ASC and Nanofat led to an increased retention rate of the FG, suggesting that Nanofat might be a promising alternative for FG enrichment. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Lipid Droplets Big and Small: Basic Mechanisms That Make Them All.

Lipid droplets (LDs) are dynamic storage organelles with central roles in lipid and energy metabolism. They consist of a core of neutral lipids, such as triacylglycerol, which is surrounded by a monolayer of phospholipids and specialized surface proteins. The surface composition determines many of the LD properties, such as size, subcellular distribution, and interaction with partner organelles. Considering the diverse energetic and metabolic demands of various cell types, it is not surprising that LDs are highly heterogeneous within and between cell types. Despite their diversity, all LDs share a common biogenesis mechanism. However, adipocytes have evolved specific adaptations of these basic mechanisms, enabling the regulation of lipid and energy metabolism at both the cellular and organismal levels. Here, we discuss recent advances in the understanding of both the general mechanisms of LD biogenesis and the adipocyte-specific adaptations controlling these fascinating organelles.

Nervonic acid improves fat transplantation by promoting adipogenesis and angiogenesis.

Adipose tissue engraftment has become a promising strategy in the field of regenerative surgery; however, there are notable challenges associated with it, such as resorption of 50­90% of the transplanted fat or cyst formation due to fat necrosis after fat transplantation. Therefore, identifying novel materials or methods to improve the engraftment efficiency is crucial. The present study investigated the effects of nervonic acid (NA), a monounsaturated very long­chain fatty acid, on adipogenesis and fat transplantation, as well as its underlying mechanisms. To assess this, NA was used to treat cells during adipogenesis in vitro, and the expression levels of markers, including PPARγ and CEBPα, and signaling molecules were detected through reverse transcription­quantitative PCR and western blotting. In addition, NA was mixed with fat grafts in in vivo fat transplantation, followed by analysis through Oil Red O staining, hematoxylin & eosin staining and immunohistochemistry. It was demonstrated that NA treatment accelerated adipogenesis through activation of the Akt/mTOR pathway and inhibition of Wnt signaling. NA treatment enriched the expression of Akt/mTOR signaling­related genes, and increased the expression of genes involved in angiogenesis and fat differentiation in human mesenchymal stem cells (MSCs). Additionally, NA effectively improved the outcome of adipose tissue engraftment in mice. Treatment of grafts with NA at transplantation reduced the resorption of transplanted fat and increased the proportion of perilipin­1+ adipocytes with a lower portion of vacuoles in mice. Moreover, the NA­treated group exhibited a reduced pro­inflammatory response and had more CD31+ vessel structures, which were relatively evenly distributed among viable adipocytes, facilitating successful engraftment. In conclusion, the present study demonstrated that NA may not only stimulate adipogenesis by regulating signaling pathways in human MSCs, but could improve the outcome of fat transplantation by reducing inflammation and stimulating angiogenesis. It was thus hypothesized that NA could serve as an adjuvant strategy to enhance fat engraftment in regenerative surgery.

The influence and mechanism of fish collagen peptide and egg yolk lecithin on proliferation and lipid composition in feline adipocytes.

The influences of fish collagen peptide (FCP) and egg yolk lecithin (EYL) on the proliferation, fat accumulation and triglyceride content in feline adipocytes were investigated in this work, aiming at unveiling the mechanism of fat accumulation for cheek of feline animals. The lipogenic changes of adipocytes in the presence of FCP and EYL were determined by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The results demonstrated that FCP of 10 mg/mL had the strongest cell activity, with a relative increment rate of 156 ± 0.23%, and the triglyceride content reached 215.9 ± 3.86 mmol/L. By comparison, it was observed that an EYL concentration of 5 mg/mL elicited the highest cell activity, exhibiting a relative increment rate of 152 ± 0.60%, and the level of triglyceride content was noted to reached 256.56 ± 25.68 mmol/L. After the feline adipocytes were treated with different concentrations of two active substances, fat formation and lipid droplets were found by oil red O staining. Liposome analyses confirmed that the formation of lipid compounds was regulated by FCP and EYL through pathways involved in lipid metabolism, notably including inositol phosphate insulin resistance, and phosphatidylinositol signaling pathways. This regulation was found to enhance cell vitality and facilitate fat accumulation. These findings provide a new strategy for the development of nutritional and healthy products or foods that promote feline cheek.

Adipocyte-Targeted Nanotechnology and Cell-Based Therapy for Obesity Treatment.

Obesity is a critical risk factor for the development of metabolic diseases and is often associated with dysfunctional adipocytes. Prevalent treatments such as lifestyle intervention, pharmacotherapy, and bariatric surgery are often accompanied by adverse side effects and poor patient compliance. Nanotechnology and cell-based therapy offer innovative approaches for targeted obesity treatments, as they can directly target adipocytes, regulate lipid metabolism, and minimize off-target effects. Here, we provide an overview of the intricate relationship between adipocytes and obesity, highlighting the potential of nanotechnology and cell-based therapy in obesity treatment. Additionally, we discuss the advancements of adipose-derived mesenchymal stem cells (ADMSCs) in obesity progression, including the latest challenges and considerations for developing adipose-targeted treatments for obesity. The objective is to provide a perspective on the design and development of nanotechnology and cell-based therapy for treating obesity and related comorbidities.

An improved in vitro 3T3-L1 adipocyte model of inflammation and insulin resistance.

Tumor necrosis factor alpha (TNF-α)/hypoxia-treated 3T3-L1 adipocytes have been used to model inflamed and insulin-resistant adipose tissue: this study examines gaps in the model. We tested whether modulating TNF-α/hypoxia treatment time could reduce cell death while still inducing inflammation and insulin resistance. Adipocytes were treated with TNF-α (12 h or 24 h) and incubated in a hypoxic chamber for 24 h. To examine maintenance of the phenotype over time, glucose and FBS were added at 24 h post initiation of treatment, and the cells were maintained for an additional 48 h. Untreated adipocytes were used as a control. Viability, insulin resistance, and inflammation were assessed using Live/Dead staining, RT-qPCR, ELISA, and glucose uptake assays. Treatment for 12 h with TNF-α in the presence of hypoxia resulted in an increase in the percentage of live cells compared to 24 h treated cells. Importantly, insulin resistance and inflammation were still induced in the 12 h treated adipocytes: the expression of the insulin sensitive and inflammatory genes was decreased and increased, respectively. In 72 h treated adipocytes, no significant differences were found in the viability, glucose uptake or insulin-sensitive and inflammatory gene expression. This study provides a modified approach to in vitro odeling adipocyte inflammation and insulin resistance. .

Myricetin and myricitrin indirectly and directly increases uncoupling protein-1 mRNA expression in C3H10T1/2 beige adipocytes.

In thermogenic brown and beige adipocytes, the proton gradient formed by energy derived from nutrients such as lipids and carbohydrates is consumed by uncoupling protein-1 (UCP-1), resulting in thermogenesis without ATP production in the mitochondria. Accordingly, increased UCP-1 expression represents a crucial aspect of dietary management for individuals with overweight and obesity. Myricetin and its glycoside, myricitrin, are food-derived flavonoids that possess various beneficial effects. This is the first study to examine the effects of myricetin and myricitrin on the inflammation-inhibited expression of Ucp-1 using a modified cell-based assay with conditioned medium (CM). The CM derived from lipopolysaccharide (LPS)-activated RAW264.7 macrophages was observed to inhibit the Ucp-1 expression induced by adrenergic stimulation in 10T1/2 adipocytes. Conversely, the CM derived from activated macrophages treated with myricetin or myricitrin reversed this inhibition of Ucp-1 expression. Subsequently, the direct effects of both the compounds on basal and adrenaline-induced expression of Ucp-1 were investigated. In contrast to a previous report, myricetin and myricitrin did not increase the basal Ucp-1 mRNA expression in 10T1/2 adipocytes when treated during the differentiation-promoting period. However, we have found for the first time that both compounds enhanced the adrenergic sensitivity of 10T1/2 adipocytes when treated during the differentiation-inducing period. These results indicate that myricetin and myricitrin have indirect effects on inflammation-induced suppression and direct effects on adrenergic sensitivity, suggesting a novel mechanism that both compounds increase Ucp-1 expression in vivo by both indirect and direct effects, rather than by affecting basal expression.

Combined Effects of Cyclic Hypoxic and Mechanical Stimuli on Human Bone Marrow Mesenchymal Stem Cell Differentiation: A New Approach to the Treatment of Bone Loss.

Background: The prevention and treatment of bone loss and osteoporotic fractures is a public health challenge. Combined with normobaric hypoxia, whole-body vibration has a high clinic potential in bone health and body composition. The effect of this therapy may be mediated by its action on bone marrow mesenchymal stem cells (MSCs). Objectives: Evaluate the effects of cyclic low-vibration stimuli and/or hypoxia on bone marrow-derived human MSC differentiation. Methods: MSCs were exposed four days per week, two hours/day, to hypoxia (3% O2) and/or vibration before they were induced to differentiate or during differentiation into osteoblasts or adipocytes. Gene and protein expression of osteoblastic, adipogenic, and cytoskeletal markers were studied, as well as extracellular matrix mineralization and lipid accumulation. Results: early osteoblastic markers increased in undifferentiated MSCs, pretreated in hypoxia and vibration. This pretreatment also increased mRNA levels of osteoblastic genes and beta-catenin protein in the early stages of differentiation into osteoblasts without increasing mineralization. When MSCs were exposed to vibration under hypoxia or normoxia during osteoblastic differentiation, mineralization increased with respect to cultures without vibrational stimuli. In MSCs differentiated into adipocytes, both in those pretreated as well as exposed to different conditions during differentiation, lipid formation decreased. Changes in adipogenic gene expression and increased beta-catenin protein were observed in cultures treated during differentiation. Conclusions: Exposure to cyclic hypoxia in combination with low-intensity vibratory stimuli had positive effects on osteoblastic differentiation and negative ones on adipogenesis of bone marrow-derived MSCs. These results suggest that in elderly or frail people with difficulty performing physical activity, exposure to normobaric cyclic hypoxia and low-density vibratory stimuli could improve bone metabolism and health.