Humanized cerebral organoids-based ischemic stroke model for discovering of potential anti-stroke agents.

Establishing a stoke experimental model, which is better in line with the physiology and function of human brain, is the bottleneck for the development of effective anti-stroke drugs. A three-dimensional cerebral organoids (COs) from human pluripotent stem cells can mimic cell composition, cortical structure, brain neural connectivity and epigenetic genomics of in-vivo human brain, which provides a promising application in establishing humanized ischemic stroke model. COs have been used for modeling low oxygen condition-induced hypoxic injury, but there is no report on the changes of COs in response to in vitro oxygen-glucose deprivation (OGD)-induced damage of ischemic stroke as well as its application in testing anti-stroke drugs. In this study we compared the cell composition of COs at different culture time and explored the cell types, cell ratios and volume size of COs at 85 days (85 d-CO). The 85 d-CO with diameter more than 2 mm was chosen for establishing humanized ischemic stroke model of OGD. By determining the time-injury relationship of the model, we observed aggravated ischemic injury of COs with OGD exposure time, obtaining first-hand evidence for the damage degree of COs under different OGD condition. The sensitivity of the model to ischemic injury and related treatment was validated by the proven pan-Caspase inhibitor Z-VAD-FMK (20 µM) and Bcl-2 inhibitor navitoclax (0.5 µM). Neuroprotective agents edaravone, butylphthalide, P7C3-A20 and ZL006 (10 µM for each) exerted similar beneficial effects in this model. Taken together, this study establishes a humanized ischemic stroke model based on COs, and provides evidence as a new research platform for anti-stroke drug development.

Metrnl deficiency retards skin wound healing in mice by inhibiting AKT/eNOS signaling and angiogenesis.

Meteorin-like (Metrnl) is a novel secreted protein with various biological activities. In this study, we investigated whether and how Metrnl regulated skin wound healing in mice. Global Metrnl gene knockout mice (Metrnl-/-) and endothelial cell-specific Metrnl gene knockout mice (EC-Metrnl-/-) were generated. Eight-mm-diameter full-thickness excisional wound was made on the dorsum of each mouse. The skin wounds were photographed and analyzed. In C57BL/6 mice, we observed that Metrnl expression levels were markedly increased in skin wound tissues. We found that both global and endothelial cell-specific Metrnl gene knockout significantly retarded mouse skin wound healing, and endothelial Metrnl was the key factor affecting wound healing and angiogenesis. The proliferation, migration and tube formation ability of primary human umbilical vein endothelial cells (HUVECs) were inhibited by Metrnl knockdown, but significantly promoted by addition of recombinant Metrnl (10 ng/mL). Metrnl knockdown abolished the proliferation of endothelial cells stimulated by recombinant VEGFA (10 ng/mL) but not by recombinant bFGF (10 ng/mL). We further revealed that Metrnl deficiency impaired VEGFA downstream AKT/eNOS activation in vitro and in vivo. The damaged angiogenetic activity in Metrnl knockdown HUVECs was partly rescued by addition of AKT activator SC79 (10 µM). In conclusion, Metrnl deficiency retards skin wound healing in mice, which is related to impaired endothelial Metrnl-mediated angiogenesis. Metrnl deficiency impairs angiogenesis by inhibiting AKT/eNOS signaling pathway.

Pharmacological characterization of MT-1207, a novel multitarget antihypertensive agent.

Hypertension is a serious public health problem worldwide. MT-1207, chemically named 3-(4-(4-(1H-benzotriazole-1-yl)butyl)piperazine-1-yl) benzisothiazole hydrochloride, is a new chemical entity that has entered into clinical trial as antihypertensive agent in China. In this paper we report the pharmacological profile of MT-1207 regarding its acute, subacute, and long-term effects on hypertensive animal models, and its actions on isolated organs in vitro as well as its molecular targets. Blood pressure (BP) was measured in conscious animals; amlodipine was taken as a positive control drug. We showed that both single dose of MT-1207 (1.25-20 mg/kg, ig) in spontaneously hypertensive rats (SHR) and MT-1207 (0.25-6 mg/kg, ig) in two-kidney one-clip (2K1C) dogs dose-dependently decreased BP. MT-1207 quickly decreased BP within 5 min after administration; the hypotensive effect lasted for 8 and 12 h, respectively, in SHR and 2K1C dogs without reflex increase in heart rate. Multiple doses of MT-1207 (5 mg · kg-1 · d-1 in SHR; 2 mg · kg-1 · d-1 in 2K1C dogs, for 7 days) significantly decreased BP, slightly reduced heart rate, and both of them recovered after withdrawal. Long-term administration of MT-1207 (10 mg · kg-1 · d-1 for 4 months or more time) produced a stable BP reduction, improved baroreflex sensitivity, reduced renal and cardiovascular damage in SHR, and delayed stroke occurrence and death in stroke-prone SHR. In isolated rat aortic rings precontracted by adrenaline, KCl, noradrenaline or 5-hydroxytryptamine (5-HT), MT-1207 (10-9-10-4 M) caused concentration-dependent relaxation. In a panel of enzyme activity or radioligand binding assays of 87 molecular targets, MT-1207 potently inhibited adrenergic α1A, α1B, α1D, and 5-HT2A receptors with Ki < 1 nM. The antagonism of MT-1207 against these receptors was confirmed in isolated rabbit arteries. We conclude that MT-1207 is a novel and promising single-molecule multitarget agent for hypertension treatment to reduce hypertensive organ damage and stroke mortality.

Aggravated ulcerative colitis caused by intestinal Metrnl deficiency is associated with reduced autophagy in epithelial cells.

Metrnl is a newly identified secreted protein highly expressed in the intestinal epithelium. This study aimed to explore the role and mechanism of intestinal epithelial Metrnl in ulcerative colitis. Metrnl-/- (intestinal epithelial cell-specific Metrnl knockout) mice did not display any phenotypes of colitis under basal conditions. However, under administration of 3% dextran sodium sulfate (DSS) drinking water, colitis was more severe in Metrnl-/- mice than in WT mice, as indicated by comparisons of body weight loss, the presence of occult or gross blood per rectum, stool consistency, shrinkage in the colon, intestinal damage, and serum levels of inflammatory factors. DSS-induced colitis activated autophagy in the colon. This activation was partially inhibited by intestinal epithelial Metrnl deficiency, as indicated by a decrease in Beclin-1 and LC3-II/I and an increase in p62 in DSS-treated Metrnl-/- mice compared with WT mice. These phenomena were further confirmed by observation of autophagosomes and immunofluorescence staining for LC3 in epithelial cells. The autophagy-related AMPK-mTOR-p70S6K pathway was also activated in DSS-induced colitis, and this pathway was partially blocked by intestinal epithelial Metrnl deficiency, as indicated by a decrease in AMPK phosphorylation and an increase in mTOR and p70S6K phosphorylation in DSS-treated Metrnl-/- mice compared with WT mice. Therefore, Metrnl deficiency deteriorated ulcerative colitis at least partially through inhibition of autophagy via the AMPK-mTOR-p70S6K pathway, suggesting that Metrnl is a therapeutic target for ulcerative colitis.

Nicotinamide phosphoribosyltransferase aggravates inflammation and promotes atherosclerosis in ApoE knockout mice.

Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme of nicotinamide adenine dinucleotide (NAD) salvage biosynthesis in mammals, and is involved in fundamental physiological processes and pathophysiology of many diseases. Thus far, however, the role of Nampt in atherosclerosis development is still in debate. In this study, we crossed global Nampt transgenic mice (Nampt-Tg) with a well-established atherosclerosis animal model (ApoE knockout mice, ApoE-/-) to generate ApoE-/-;Nampt-Tg mice and investigated the effects of Nampt overexpression on atherosclerosis development in ApoE-/- mice. Both ApoE-/- and ApoE-/-;Nampt-Tg mice were fed with a pro-atherosclerotic high-fat diet (HFD) for 16 weeks. Their serum lipid contents and atherosclerotic lesion were assessed. The results showed that there was no significant difference in body weight or serum levels of glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol between the two strains of mice, but ApoE-/-;Nampt-Tg mice had a significantly higher level of serum non-esterified fatty acid. Compared with ApoE-/- mice, ApoE-/-;Nampt-Tg mice displayed significantly increased atherosclerotic lesion area and thickness, lower collagen content, decreased collagen I/III ratio (collagen immaturation), increased number of apoptotic cells, and enhanced activities of caspase-3, caspase-8, and caspase-9. Moreover, macrophage infiltration (F4/80 staining), tumor necrosis factor signaling, and chemokines expression (ICAM-1 and CXCR-4) were all activated in aortic atherosclerotic plaque of ApoE-/-;Nampt-Tg mice compared with ApoE-/- mice. Our results provide in vivo evidence that Nampt transgene aggravates atherosclerotic inflammation and promotes atherosclerosis development in ApoE-/- mice.

Crystal structure-based comparison of two NAMPT inhibitors.

Inhibition of nicotinamide phosphoribosyltransferase (NAMPT) is a novel strategy for cancer therapy, but only two inhibitors of NAMPT (FK866 and CHS828) have progressed into clinical trials. This study seeks to compare a novel potent NAMPT inhibitor, MS0, with a classical inhibitor FK866 in their biological activity and molecular binding mode, thereby contributing to future chemical optimization and a further understanding of the action mode of NAMPT inhibitors. The IC50 values of MS0 and FK866 in inhibition of recombinant human NAMPT activity were 9.08±0.90 and 1.60±0.32 nmol/L, respectively. Consistently, FK866 exerted better antiproliferation in 6 human cancer cell lines (HepG2, A2780, 95-D, A549, U2OS and U266) than MS0 with IC50 values nearly 12-fold to 225-fold lower than those of MS0. Co-crystal structures of wild-type human NAMPT complexed with MS0 or FK866 were elucidated, which revealed that MS0 did not interact with Ser241. The hydrogen bond mediated by crystallographic water between MS0 and His191 or Val350 of NAMPT did not exist in FK866. Instead, FK866 exhibited hydrophobic interactions with Arg349. Based on the activity assays and crystal structure analyses, we elaborate the reason why the antiproliferation activity of MS0 was not as good as that of FK866, which would contributes to the current understanding of the mode of action of NAMPT inhibitors and will also contribute to further development of anticancer drugs in the future.

Chronic nicotine treatment enhances vascular smooth muscle relaxation in rats.

AIM: To investigate the effect of chronic nicotine treatment on vascular function and to identify the underlying mechanisms. METHODS: Adult rats were treated with nicotine (3 mg·kg(-1)·d(-1), sc) for 6 weeks. After the rats were sacrificed, aortic rings were prepared for detecting vascular reactivity, and thoracic aorta and periaortic fat samples were collected for histological and molecular biology studies. RESULTS: Chronic nicotine treatment significantly reduced periaortic fat, and specifically enhanced smooth muscle relaxation without altering the aortic adventitial fat and endothelium function. Pretreatment with the soluble guanylyl cyclase inhibitor ODQ (3 µmol/L) or PKG inhibitor Rp-8-Br-PET-cGMP (30 µmol/L) abolished the nicotine-induced enhancement of smooth muscle relaxation, whereas the cGMP analogue 8-Br-cGMP could mimic the nicotine-induced enhancement of smooth muscle relaxation. However, the chronic nicotine treatment did not alter PKG protein expression and activity in aortic media. CONCLUSION: Chronic nicotine treatment enhances vascular smooth muscle relaxation of rats via activation of PKG pathway.

Nicotinamide phosphoribosyltransferase protects against ischemic stroke through SIRT1-dependent adenosine monophosphate-activated kinase pathway.

OBJECTIVE: Stroke is a leading cause of mortality and disability. Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme in mammalian nicotinamide adenine dinucleotide (NAD)(+) biosynthesis and contributes to cell fate decisions. However, the role of Nampt in brain and stroke remains to be investigated. METHODS: We used lentivirus-mediated Nampt overexpression and knockdown to manipulate Nampt expression and explore the effects of Nampt in neuronal survival on ischemic stress both in vivo and in vitro. We also used adenosine monophosphate (AMP)-activated kinase-α2 (AMPKα2) and silent mating type information regulation 2 homolog 1 (SIRT1) knockout mice to investigate the underlying mechanisms of Nampt neuroprotection. RESULTS: Nampt inhibition by a highly-specific Nampt inhibitor, FK866, aggravated brain infarction in experimentally cerebral ischemia rats, whereas Nampt overexpression in local brain and Nampt enzymatic product nicotinamide mononucleotide (NMN) reduced ischemia-induced cerebral injuries. Nampt overexpression and knockdown regulated neuron survival via the AMPK pathway. Neuroprotection of Nampt was abolished in AMPKα2(-/-) neurons. In neurons, Nampt positively modulated NAD(+) levels and thereby controlled SIRT1 activity. SIRT1 coprecipitated with serine/threonine kinase 11 (LKB1), an upstream kinase of AMPK, and promoted LKB1 deacetylation in neurons. Nampt-induced LKB1 deacetylation and AMPK activation disappeared in SIRT1(-/-) neurons. In contrast, Ca(2+) /calmodulin-dependent protein kinase kinase-ß (CaMKK-ß), another upstream kinase of AMPK, was not involved in the neuroprotection of Nampt. More important, Nampt overexpression-induced neuroprotection was abolished in SIRT1(+/-) and AMPKα2(-/-) mice. INTERPRETATION: Our findings reveal that Nampt protects against ischemic stroke through rescuing neurons from death via the SIRT1-dependent AMPK pathway and indicate that Nampt is a new therapeutic target for stroke.

Involvement of leptin receptor long isoform (LepRb)-STAT3 signaling pathway in brain fat mass- and obesity-associated (FTO) downregulation during energy restriction.

Obesity is an important risk factor for cardiovascular disease, diabetes and certain cancers. The fat mass- and obesity-associated (FTO) gene is tightly associated with the pathophysiology of obesity, whereas the exact role of FTO remains poorly understood. Here, we investigated the alternations of FTO mRNA and protein expression in the peripheral metabolic tissues and the brain upon energy restriction (ER) and explored the involvement of the leptin signaling pathway in FTO regulation under ER status. ER decreased the FTO mRNA and protein expression in hypothalamus and brainstem but not in periphery. Using double-immunofluorescence staining, FTO was found to be colocalized with the leptin receptor long isoform (LepRb) in arcuate nucleus of hypothalamus and the nucleus of the solitary tract. In LepRb mutant db/db mice, the FTO downregulation in brain and body weight reduction induced by ER were completely abolished. The enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3) induced by ER was also impaired in db/db mice. Moreover, leptin directly activated the STAT3 signaling pathway and downregulated FTO in in vitro arcuate nucleus of hypothalamus cultures and in vivo wild-type mice but not db/db mice. Thus, our results provide the first evidence that the LepRb-STAT3 signaling pathway is involved in the brain FTO downregulation during ER.

A fluorometric assay for high-throughput screening targeting nicotinamide phosphoribosyltransferase.

Nicotinamide adenine dinucleotide (NAD) plays a crucial role in many cellular processes. As the rate-limiting enzyme of the predominant NAD biosynthesis pathway in mammals, nicotinamide phosphoribosyltransferase (Nampt) regulates the cellular NAD level. Tumor cells are more sensitive to the NAD levels, making them more susceptible to Nampt inhibition than their nontumorigenic counterparts. Experimental evidence has indicated that Nampt might have proangiogenic activity and supports the growth of some tumors, so Nampt inhibitors may be promising as antitumor agents. However, only four Nampt inhibitors have been reported, and no high-throughput screening (HTS) strategy for Nampt has been proposed to date, largely limiting the drug discovery targeting Nampt. Therefore, the development of a robust HTS strategy for Nampt is both imperative and significant. Here we developed a fluorometric method for a Nampt activity assay by measuring the fluorescence of nicotinamide mononucleotide (NMN) derivative resulting from the enzymatic product NMN through simple chemical reactions. Then we set up an HTS system after thorough optimizations of this method and validated that it is feasible and effective through a pilot screening on a small library. This HTS system should expedite the discovery of Nampt inhibitors as antitumor drug candidates.

4-Phenyl butyric acid does not generally reduce glucose levels in rodent models of diabetes.

1. Endoplasmic reticulum (ER) stress plays a role in the pathogenesis of diabetes. The aim of the present study was to investigate the effect of 4-phenyl butyric acid (PBA), a novel chemical chaperone reducing ER stress, on serum glucose level in different strains of normal and diabetic rodents. 2. 4-Phenyl butyric acid (1 g/kg per day, i.g.) was administered to ob/ob Type 2 diabetic mice, alloxan-induced Type 1 diabetic mice and hydrocortisone (HC)-induced Type 2 diabetic mice as well as normal C57BL/6J mice and Kumming mice for 14 days to evaluate its effect on serum glucose levels. In addition, mice were treated simultaneously with PBA (1 g/kg per day) and HC for 9 days to determine its preventive effect against the development of insulin resistance. PBA (0.7 and 1.4 g/kg per day) was administered to non-obese Type 2 diabetic Goto-Kakizaki (GK) and normal Wistar-Kyoto (WKY) rats for 14 and 7 days, respectively, to determine its effects on serum glucose levels. 3. 4-Phenyl butyric acid significantly reduced serum glucose levels in obese Type 2 diabetic ob/ob mice. Normoglycaemia was obtained in ob/ob mice after 4 days of PBA treatment and was maintained for up to 14 days treatment. 4. 4-Phenyl butyric acid had no glucose-lowering effect in alloxan-induced Type 1 diabetic mice, HC-induced Type 2 diabetic mice and non-obese Type 2 diabetic GK rats. In addition, it had no beneficial effects on insulin resistance in HC-treated mice. 5. 4-Phenyl butyric acid did not affect normal serum glucose levels in C57BL/6 J mice, Kunming mice or WKY rats. 6. In conclusion, PBA does not generally reduce glucose levels in rodent models of diabetes, although it can normalize glucose levels in ob/ob diabetic mice, indicating that restoration of ER function as diabetes therapy is limited to conditions under which ER stress is involved in the high glucose levels.

Visfatin is associated with lipid metabolic abnormalities in Lyon hypertensive rats.

1. Visfatin (also known as nicotinamide phosphoribosyltransferase or Nampt) is a novel adipokine associated with metabolic abnormalities in obesity and diabetes. The aim of the present study was to determine whether visfatin levels in the circulation and visfatin expression in fat tissues are altered in Lyon hypertensive (LH) rats, a hypertensive strain with numerous metabolic abnormalities, and, if so, to explore the possible correlations between blood visfatin levels and the metabolic abnormalities in LH rats. 2. Male 18-20-week-old LH rats and their control, Lyon normotensive (LN) rats, were used. Blood pressure was recorded in conscious, unrestrained rats. Fat tissue weight was determined. Serum visfatin concentrations were determined by enzyme immunoassay, whereas visfatin expression in fat tissues was determined by western blotting. Relationships between two parameters were evaluated by linear regression analysis. 3. The LH rats had significantly higher bodyweight and fat tissue weight compared with LN rats. Serum lipid levels of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and triglyceride (TG) were all significantly higher in LH rats than in LN rats. Moreover, serum visfatin levels were higher in LH rats than in LN rats and were positively correlated with bodyweight, fat tissue weight and serum lipid levels (i.e. TC, HDL-C, LDL-C, TG and the TG:HDL-C ratio). There were no significant differences in serum glucose and insulin concentrations, or in the whole-body insulin resistance index, between LN and LH rats, and serum visfatin levels were not correlated with any of these parameters. Visfatin expression in visceral fat tissue, but not in subcutaneous fat tissue, was markedly upregulated in LH compared with LN rats. 4. In conclusion, the results of the present study demonstrate that serum visfatin levels in LH rats are elevated and are associated with lipid metabolic abnormalities.

Cerebral Organoids Repair Ischemic Stroke Brain Injury.

Stroke is the second leading cause of death and main cause of disability worldwide, but with few effective therapies. Although stem cell-based therapy has been proposed as an exciting regenerative medicine strategy for brain injury, there are limitations. The developed cerebral organoids (COs) represent a promising transplantation source for stroke that remains to be answered. Here, we transplanted COs at 55 days and explored the feasibility in the rat middle cerebral artery occlusion (MCAO) model of stroke. COs transplantation at 6 h or even 24 h after MCAO significantly reduces brain infarct volume and improves neurological motor function. Transplanted COs show the potential of multilineage differentiation to mimic in vivo cortical development, support motor cortex region-specific reconstruction, form neurotransmitter-related neurons, and achieve synaptic connection with host brain via in situ differentiation and cell replacement in stroke. Cells from transplanted COs show extensive migration into different brain regions along corpus callosum. The mechanisms underlying COs transplantation therapy are also associated with enhanced neurogenesis, synaptic reconstruction, axonal regeneration and angiogenesis, and decreased neural apoptosis with more survival neurons after stroke. Moreover, COs transplantation promotes predominantly exogenous neurogenesis in the transplantation periphery of ipsilateral cortex and predominantly endogenous neurogenesis in the hippocampus and subventricular zone. Together, we demonstrate the efficacy and underlying mechanisms of COs transplantation in stroke. This preliminary but promising study provides first-hand preclinical evidence for COs transplantation as a potential and effective intervention for stroke treatment.

Clinical characteristics associated with long-term viral shedding in patients with coronavirus disease 2019.

BACKGROUND: To delineate the clinical characteristics associated with long-term viral shedding (>21 days) in patients with coronavirus disease 2019 (COVID-19). METHODS: In this retrospective study, factors associated with long-term (>21 days) severe acute respiratory coronavirus 2 (SARS-CoV-2) RNA shedding were evaluated in a conhort of 609 patients from two hospitals in Wuhan. RESULTS: The median duration of SARS-CoV-2 viral shedding was 19 days (interquartile range, 10-28 days) among all patients. There were 42% of patients having prolonged viral shedding time (>21 days), in which the longest viral shedding time was 58 days. When comparing patients with early (≤21 days) and late viral RNA clearance (>21 days), prolonged viral shedding was associated with age <65 (P=0.015), female sex (P=0.028), cough (P=0.025), fatigue (P=0.035), sore throat (P=0.013), aspartate aminotransferase (P=0.038), procalcitonin (P=0.010), albumin (P=0.003), D-dimer (P=0.011), lung involvement (P=0.014), reticular shadow (P<0.001) and lung consolidation (P=0.004). Age range (<65 years) (odds ratio [OR], 1.46 [95% CI, 1.05-2.03]) and female sex (odds ratio [OR], 1.40 [95% CI, 1.00-1.94]) were independent risk factors. CONCLUSIONS: Long-term viral shedding (>21 days) is not a rare phenomenon among COVID-19 infectious patients. Age range (<65) and female sex are independent risk factors for long-term viral shedding. Early antiviral treatment should be considered for COVID-19 patients with such risk factors. Further study should be conducted to know the infectivity of patients with long-term viral shedding in order to develop reasonable control measures.

Cerebral organoids transplantation improves neurological motor function in rat brain injury.

BACKGROUND AND PURPOSE: Cerebral organoids (COs) have been used for studying brain development, neural disorders, and species-specific drug pharmacology and toxicology, but the potential of COs transplantation therapy for brain injury remains to be answered. METHODS: With preparation of traumatic brain injury (TBI) model of motor dysfunction, COs at 55 and 85 days (55 and 85 d-CO) were transplanted into damaged motor cortex separately to identify better transplantation donor for brain injury. Further, the feasibility, effectiveness, and underlying mechanism of COs transplantation therapy for brain injury were explored. RESULTS: 55 d-CO was demonstrated as better transplantation donor than 85 d-CO, evidenced by more neurogenesis and higher cell survival rate without aggravating apoptosis and inflammation after transplantation into damaged motor cortex. Cells from transplanted COs had the potential of multilinage differentiation to mimic in-vivo brain cortical development, support region-specific reconstruction of damaged motor cortex, form neurotransmitter-related neurons, and migrate into different brain regions along corpus callosum. Moreover, COs transplantation upregulated hippocampal neural connection proteins and neurotrophic factors. Notably, COs transplantation improved neurological motor function and reduced brain damage. CONCLUSIONS: This study revealed 55 d-CO as better transplantation donor and demonstrated the feasibility and efficacy of COs transplantation in TBI, hoping to provide first-hand preclinical evidence of COs transplantation for brain injury.

[The effects of climate change on isoprene emission rate from leaves of Pleioblastus amarus in different regions.] / 气候变化影响下不同地区苦竹异戊二烯排放速率对比.

Based on the RCP2.6, RCP4.5, RCP6.0 and RCP8.5 climate change scenarios produced by the global climate model NorESM1-M and plant isoprene emissions model, the effects of climate change on the isoprene emission rate from leaves of Pleioblastus amarus in Yixing City of Jiangsu Province, Longmen County of Guangdong Province, Yulong Naxi Autonomous County of Yunnan Province and Wanyuan City of Sichuan Province were simulated. The differences of isoprene emission rate from leaves of P. amarus distributed in four regions were compared under future climate change scenarios. The results showed that mean annual air temperature would increase, annual precipitation and radiation intensity would greatly fluctuate, with the coexistence of increasing and decreasing trends in the four regions. In the baseline scenario, daily mean emission rate of isoprene from leaves of P. amarus was 71-470 µg·g-1·d-1, and annual mean value was 25954-171231 µg·g-1·a-1. The daily and annual emission rates in the four regions decreased with the order of Longmen, Yixing, Wanyuan and Yulong. Compared with the baseline scenario, daily mean emission rate of isoprene from leaves of P. amarus was about 4-45 µg·g-1·d-1 higher in future climate change scenario, and which was about 23, 29, 4, and 14 µg·g-1·d-1 higher than that in baseline in Yixing, Longmen, Yulong and Wanyuan, respectively. In addition, the emission rate of isoprene from leaves of P. amarus was more than 5% higher in the future climate change scenario than that in the baseline scenario, which was higher in Wanyuan and Yixing (>13%) than and lower in Longmen and Yulong (>5%). All the four regions reached the highest rate under RCP8.5 scenario (increased by about 11%-18%). Compared with the baseline scenario, annual emission rate of isoprene in the future climate change scenario was about 1500-17000 µg·g-1·a-1, and which was about 8560-13208 µg·g-1·a-1 higher in Yixing, 10862-16131 µg·g-1·a-1 higher in Longmen, 1574-3028 µg·g-1·a-1 higher in Yulong, 5288-8532 µg·g-1·a-1 higher in Wanyuan. In addition, the increasing rate of annual isoprene emission rates was 6%-14%. The rates in Yixing (8%-12%) and Wanyuan (8%-14%) were higher than that in the other two regions, the rate in Yulong (6%-12% increase) was the lowest, with all four regions increasing substantially (9%-14%) under RCP8.5 scenario. The results suggested that climate change would have different effects on the rate of isoprene emissions from leaves of P. amarus distributed in diffe-rent regions.

Organoid technology for brain and therapeutics research.

Brain is one of the most complex organs in human. The current brain research is mainly based on the animal models and traditional cell culture. However, the inherent species differences between humans and animals as well as the gap between organ level and cell level make it difficult to study human brain development and associated disorders through traditional technologies. Recently, the brain organoids derived from pluripotent stem cells have been reported to recapitulate many key features of human brain in vivo, for example recapitulating the zone of putative outer radial glia cells. Brain organoids offer a new platform for scientists to study brain development, neurological diseases, drug discovery and personalized medicine, regenerative medicine, and so on. Here, we discuss the progress, applications, advantages, limitations, and prospects of brain organoid technology in neurosciences and related therapeutics.

Targeting Nicotinamide Phosphoribosyltransferase as a Potential Therapeutic Strategy to Restore Adult Neurogenesis.

Adult neurogenesis is the process of generating new neurons throughout life in the olfactory bulb and hippocampus of most mammalian species, which is closely related to aging and disease. Nicotinamide phosphoribosyltransferase (NAMPT), also an adipokine known as visfatin, is the rate-limiting enzyme for mammalian nicotinamide adenine dinucleotide (NAD) salvage synthesis by generating nicotinamide mononucleotide (NMN) from nicotinamide. Recent findings from our laboratory and other laboratories have provided much evidence that NAMPT might serve as a therapeutic target to restore adult neurogenesis. NAMPT-mediated NAD biosynthesis in neural stem/progenitor cells is important for their proliferation, self-renewal, and formation of oligodendrocytes in vivo and in vitro. Therapeutic interventions by the administration of NMN, NAD, or recombinant NAMPT are effective for restoring adult neurogenesis in several neurological diseases. We summarize adult neurogenesis in aging, ischemic stroke, traumatic brain injury, and neurodegenerative disease and review the advances of targeting NAMPT in restoring neurogenesis. Specifically, we provide emphasis on the P7C3 family, a class of proneurogenic compounds that are potential NAMPT activators, which might shed light on future drug development in neurogenesis restoration.

Neuroprotective Efficacy of an Aminopropyl Carbazole Derivative P7C3-A20 in Ischemic Stroke.

AIM: NAMPT is a novel therapeutic target of ischemic stroke. The aim of this study was to investigate the effect of a potential NAMPT activator, P7C3-A20, an aminopropyl carbazole derivative, on ischemic stroke. METHODS: In vitro study, neuron protection effect of P7C3-A20 was investigated by co-incubation with primary neurons subjected to oxygen-glucose deprivation (OGD) or oxygen-glucose deprivation/reperfusion (OGD/R) injury. In vivo experiment, P7C3-A20 was administrated in middle cerebral artery occlusion (MCAO) rats and infarct volume was examined. Lastly, the brain tissue nicotinamide adenine dinucleotide (NAD) levels were detected in P7C3-A20 treated normal or MCAO mice. RESULTS: Cell viability, morphology, and Tuj-1 staining confirmed the neuroprotective effect of P7C3-A20 in OGD or OGD/R model. P7C3-A20 administration significantly reduced cerebral infarction in MCAO rats. Moreover, brain NAD levels were elevated both in normal and MCAO mice after P7C3-A20 treatment. CONCLUSIONS: P7C3-A20 has neuroprotective effect in cerebral ischemia. The study contributes to the development of NAMPT activators against ischemic stroke and expands the horizon of the neuroprotective effect of aminopropyl carbazole chemicals.

Hepatic NAD(+) deficiency as a therapeutic target for non-alcoholic fatty liver disease in ageing.

BACKGROUND AND PURPOSE: Ageing is an important risk factor of non-alcoholic fatty liver disease (NAFLD). Here, we investigated whether the deficiency of nicotinamide adenine dinucleotide (NAD(+) ), a ubiquitous coenzyme, links ageing with NAFLD. EXPERIMENTAL APPROACH: Hepatic concentrations of NAD(+) , protein levels of nicotinamide phosphoribosyltransferase (NAMPT) and several other critical enzymes regulating NAD(+) biosynthesis, were compared in middle-aged and aged mice or patients. The influences of NAD(+) decline on the steatosis and steatohepatitis were evaluated in wild-type and H247A dominant-negative, enzymically-inactive NAMPT transgenic mice (DN-NAMPT) given normal or high-fat diet (HFD). KEY RESULTS: Hepatic NAD(+) level decreased in aged mice and humans. NAMPT-controlled NAD(+) salvage, but not de novo biosynthesis pathway, was compromised in liver of elderly mice and humans. Given normal chow, middle-age DN-NAMPT mice displayed systemic NAD(+) reduction and had moderate NAFLD phenotypes, including lipid accumulation, enhanced oxidative stress, triggered inflammation and impaired insulin sensitivity in liver. All these NAFLD phenotypes, especially release of pro-inflammatory factors, Kupffer cell accumulation, monocytes infiltration, NLRP3 inflammasome pathway and hepatic fibrosis (Masson's staining and α-SMA staining), deteriorated further under HFD challenge. Oral administration of nicotinamide riboside, a natural NAD(+) precursor, completely corrected these NAFLD phenotypes induced by NAD(+) deficiency alone or HFD, whereas adenovirus-mediated SIRT1 overexpression only partially rescued these phenotypes. CONCLUSIONS AND IMPLICATIONS: These results provide the first evidence that ageing-associated NAD(+) deficiency is a critical risk factor for NAFLD, and suggest that supplementation with NAD(+) substrates may be a promising therapeutic strategy to prevent and treat NAFLD.