Cell source, differentiation, functional stimulation, and potential application of human thermogenic adipocytes in vitro

Progress and obstacles in transplantation of brown adipose tissue or engineered cells with thermogenic potential for metabolic benefits

Transplantation of brown adipose tissue (BAT), engineered thermogenic progenitor cells, and adipocytes have received much attention for the improvement of obesity and metabolic disorders. However, even though the thermogenic and metabolic potential exists early after transplantation, the whitening of the brown fat graft occurs with metabolic function significantly impaired. In this review, specific experiment designs, graft outcomes, and metabolic benefits for the transplantation of BAT or engineered cells will be discussed. The current advancements will offer guidance to further investigation, and the obstacles appearing in previous studies will require innovation of BAT transplantation methods.

Adrenoceptors and SCD1 in adipocytes/adipose tissues: The expression and variation in health and obesity

Obesity, considered a metabolic disorder, is one of the most significant health issues that the community has to cope with today. A rising number of studies have been conducted to find out promising genetic targets for obese treatment. The sympathetic nervous system was proven to possess remarkable roles in energy metabolism, including the stimulation of lipolysis as well as thermogenesis, via distinct adrenoceptors appearing on the membrane of adipocyte. A decrease of β-adrenoceptor expression has been observed in obese individuals, which is related to reducing energy expenditure and developing obesity. While that the deficiency of stearoyl-CoA desaturase-1 (SCD1), which is a promising target for treatments of metabolic diseases, decreases oxidation and promotes the synthesis of fatty acids. Here, we emphasized several differences between distinct adrenoceptor subtypes, including their mRNA expression level and function in white adipose tissue and brown adipose tissue. We also highlighted SCD1's roles related to the progression of adipocytes and its changing expression under the obese condition in both rodents and humans, and furthermore, tried to figure out the interaction between adrenoceptors and SCD1 in adipose tissue.

Adipose-derived stem cells in the treatment of hepatobiliary diseases and sepsis

Determination of the mesenchymal stem cells is one of the greatest and most exciting achievements that tissue engineering and regenerative medicine have achieved. Adipose-derived mesenchymal stem cells (AD-MSC) are easily isolated and cultured for a long time before losing their stem cell characteristics, which are self-renewal and pluripotency. AD-MSC are mesenchymal stem cells that have pluripotent lineage characteristics. They are easily accessible, and the fraction of stem cells in the adipose tissue lysates is highest among all other sources of mesenchymal stem cells. It is also HLA-DR negative and can be transplanted allogenically without the need for immunosuppression. These advantages have popularized its use in many fields including plastic reconstructive surgery. However, in the field of hepatology and liver transplantation, the progress is slower. AD-MSC have the potential to modulate inflammation, ameliorate ischemia-reperfusion injury, and support liver and biliary tract regeneration. These are very important for the treatment of various hepatobiliary diseases. Furthermore, the anti-inflammatory potential of these cells has paramount importance in the treatment of sepsis. We need alternative therapeutic approaches to treat end-stage liver failure. AD-MSC can provide a means of therapy to bridge to definitive therapeutic alternatives such as liver transplantation. Here we propose to review theoretic applications of AD-MSC in the treatment of hepatobiliary diseases and sepsis.

Regulatory T cells promote adipocyte beiging in subcutaneous adipose tissue

Regulatory T cells (Tregs) play essential roles in obesity and diabetes. Here, we report a role of Tregs in enhancing β3-adrenergic receptor agonist CL316243 (CL)-stimulated thermogenic program in subcutaneous adipose tissue (SAT), but not in visceral fat. CL treatment for 7 days increased SAT adipocyte beiging and thermogenic gene expression in male or female mice. Adoptive transfer of Tregs enhanced this CL activity. Such Treg activity lost in male epididymal white adipose tissue (eWAT) and female gonadal gWAT. Adipocyte culture yielded the same conclusion. Tregs enhanced the expression of CL-induced thermogenic genes in SAT from male and female mice. This activity of Tregs reduced or disappeared in adipocytes from eWAT or gWAT. Both CL and Tregs induced much higher UCP-1 (uncoupling protein-1) expression in SAT from females than that from males. A mechanistic study demonstrated a role of Tregs in suppressing the expression of M1 macrophage markers (Tnfa, Il6, iNos, Ip10) and promoting the expression of M2 macrophage markers (Mrc1, Arg1, Il10) in bone-marrow-derived macrophages or in SAT from male or female mice. In female mice with pre-established obesity, Treg adoptive transfer reduced the gWAT weight in 2 weeks. Together with CL treatment, Treg adoptive transfer reduced the SAT weight and further improved CL-induced glucose metabolism and insulin sensitivity in female obese mice, but did not affect CL-induced body weight loss in male or female obese mice. This study revealed a predominant role of Tregs in female mice in promoting adipocyte beiging and thermogenesis in SAT, in part by slanting M2 macrophage polarization.

BMPR2 promotes fatty acid oxidation and protects white adipocytes from cell death in mice

Adipocyte cell death is pathologically involved in both obesity and lipodystrophy. Inflammation and pro-inflammatory cytokines are generally regarded as inducers for adipocyte apoptosis, but whether some innate defects affect their susceptibility to cell death has not been extensively studied. Here, we found bone morphogenetic protein receptor type 2 (BMPR2) knockout adipocytes were prone to cell death, which involved both apoptosis and pyroptosis. BMPR2 deficiency in adipocytes inhibited phosphorylation of perilipin, a lipid-droplet-coating protein, and impaired lipolysis when stimulated by tumor necrosis factor (TNFα), which lead to failure of fatty acid oxidation and oxidative phosphorylation. In addition, impaired lipolysis was associated with mitochondria-mediated apoptosis and pyroptosis as well as elevated inflammation. These results suggest that BMPR2 is important for maintaining the functional integrity of adipocytes and their ability to survive when interacting with inflammatory factors, which may explain why adipocytes among individuals show discrepancy for death responses in inflammatory settings.

Autologous Transplantation of Adipose-Derived Stem Cells to Treat Acute Spinal Cord Injury: Evaluation of Clinical Signs, Mental Signs, and Quality of Life

BACKGROUD

Spinal cord injury (SCI) is damage that can cause a temporary or permanent change in spinal cord functions.

AIM:

This work evaluates clinical signs, mental signs, and quality of life (QoL) after autologous adipose-derived stem cells (ADSCs) transplantation to treat acute spinal cord injury (SCI).

METHODS:

In this study, 47 SCI patients were recruited and divided into two groups: intervention and control. ADSCs were isolated and cultured under the cell culture quality control procedure. All patients in both groups underwent neurosurgery with or without ADSC transplantation. The recovery regarding neurological muscle, QoL, neurogenic bladder, and mental improvement was assessed after transplantation.

RESULTS:

All patients had improved in terms of motor function, bladder function, and daily living. No patients reported any side effect. MRI imaging showed significant changes in the lesion length of the spinal canal and the thickening of the spinal cord. Mental improvement was highest at six months after transplantation and lowest at one month after transplantation. The proportion of patients whose quality of life improved after treatment was 100%, while 80% of patients were satisfied with treatment outcomes.

CONCLUSIONS

Thus, our data suggested that ADSCs transplantation was safe and effective for the treatment of SCI patients. Neurological muscle and neurogenic bladder were improved significantly after transplantation.

The Effects of Adipocytes on the Regulation of Breast Cancer in the Tumor Microenvironment: An Update

Obesity is a global pandemic and it is well evident that obesity is associated with the development of many disorders including many cancer types. Breast cancer is one of that associated with a high mortality rate. Adipocytes, a major cellular component in adipose tissue, are dysfunctional during obesity and also known to promote breast cancer development both in vitro and in vivo. Dysfunctional adipocytes can release metabolic substrates, adipokines, and cytokines, which promote proliferation, progression, invasion, and migration of breast cancer cells. The secretion of adipocytes can alter gene expression profile, induce inflammation and hypoxia, as well as inhibit apoptosis. It is known that excessive free fatty acids, cholesterol, triglycerides, hormones, leptin, interleukins, and chemokines upregulate breast cancer development. Interestingly, adiponectin is the only adipokine that has anti-tumor properties. Moreover, adipocytes are also related to chemotherapeutic resistance, resulting in the poorer outcome of treatment and advanced stages in breast cancer. Evaluation of the adipocyte secretion levels in the circulation can be useful for prognosis and evaluation of the effectiveness of cancer therapy in the patients. Therefore, understanding about functions of adipocytes as well as obesity in breast cancer may reveal novel targets that support the development of new anti-tumor therapy. In this systemic review, we summarize and update the effects of secreted factors by adipocytes on the regulation of breast cancer in the tumor microenvironment.

Adipose Tissue Stem Cells for Therapy: An Update on the Progress of Isolation, Culture, Storage, and Clinical Application

Adipose tissue stem cells (ASCs), known as multipotent stem cells, are most commonly used in the clinical applications in recent years. Adipose tissues (AT) have the advantage in the harvesting, isolation, and expansion of ASCs, especially an abundant amount of stem cells compared to bone marrow. ASCs can be found in stromal vascular fractions (SVF) which are easily obtained from the dissociation of adipose tissue. Both SVFs and culture-expanded ASCs exhibit the stem cell characteristics such as differentiation into multiple cell types, regeneration, and immune regulators. Therefore, SVFs and ASCs have been researched to evaluate the safety and benefits for human use. In fact, the number of clinical trials on ASCs is going to increase by years; however, most trials are in phase I and II, and lack phase III and IV. This systemic review highlights and updates the process of the harvesting, characteristics, isolation, culture, storage, and application of ASCs, as well as provides further directions on the therapeutic use of ASCs.

The effects of green tea on lipid metabolism and its potential applications for obesity and related metabolic disorders - An existing update

Obesity is one of the top global issues, which induces several serious health consequences both physically and mentally, such as type 2 diabetes, cardiovascular diseases, dyslipidemia, eating disorders, depression and stress. However, the effective therapy to prevent and treat obesity and overweight, up to now, cannot be found nowadays. Several methods/medicines namely diet control, energy balance, environmental changes, genetic and stem cell therapies, new drugs/chemicals have been extensively studied to enhance the ability to control bodyweight and prevent obesity. Of all the aforementioned methods, green tea, used as a daily beverage, has shown beneficial impacts for the health, especially its anti-obesity effects. Available evidence shows that green tea can interrupt lipid emulsification, reduce adipocyte differentiation, increase thermogenesis, and reduce food intake, thus green tea improves the systemic metabolism and decreases fat mass. Here, we highlight and sum up the update investigations of anti-obesity effect of green tea as well as discuss the potential application of them for preventing obesity and its related metabolic disorders.