Pulsed Electromagnetic Field Stimulation in Osteogenesis and Chondrogenesis: Signaling Pathways and Therapeutic Implications

Mesenchymal stem cells (MSCs) are the main cell players in tissue repair and thanks to their self-renewal and multi-lineage differentiation capabilities, they gained significant attention as cell source for tissue engineering (TE) approaches aimed at restoring bone and cartilage defects. Despite significant progress, their therapeutic application remains debated: the TE construct often fails to completely restore the biomechanical properties of the native tissue, leading to poor clinical outcomes in the long term. Pulsed electromagnetic fields (PEMFs) are currently used as a safe and non-invasive treatment to enhance bone healing and to provide joint protection. PEMFs enhance both osteogenic and chondrogenic differentiation of MSCs. Here, we provide extensive review of the signaling pathways modulated by PEMFs during MSCs osteogenic and chondrogenic differentiation. Particular attention has been given to the PEMF-mediated activation of the adenosine signaling and their regulation of the inflammatory response as key player in TE approaches. Overall, the application of PEMFs in tissue repair is foreseen: (1) in vitro: to improve the functional and mechanical properties of the engineered construct; (2) in vivo: (i) to favor graft integration, (ii) to control the local inflammatory response, and (iii) to foster tissue repair from both implanted and resident MSCs cells.     

D-limonene Inhibits Pentylenetetrazole-Induced Seizure via Adenosine A2A Receptor Modulation on GABAergic Neuronal Activity

Background: Epilepsy is a chronic neurological disorder characterized by the recurrence of seizures. One-third of patients with epilepsy may not respond to antiseizure drugs. Purpose: We aimed to examine whether D-limonene, a cyclic monoterpene, exhibited any antiseizure activity in the pentylenetetrazole (PTZ)-induced kindling mouse model and in vitro. Methods: PTZ kindling mouse model was established by administering PTZ (30 mg/kg) intraperitoneally to mice once every 48 h. We performed immunoblot blots, immunohistochemistry (IHC), and high-performance liquid chromatography (HPLC) analysis after the behavioral study. Results: An acute injection of PTZ (60 mg/kg) induced seizure in mice, while pretreatment with D-limonene inhibited PTZ-induced seizure. Repeated administration of PTZ (30 mg/kg) increased the seizure score gradually in mice, which was reduced in D-limonene (10 mg/kg)-pretreated group. In addition, D-limonene treatment increased glutamate decarboxylase-67 (GAD-67) expression in the hippocampus. Axonal sprouting of hippocampal neurons after kindling was inhibited by D-limonene pretreatment. Moreover, D-limonene reduced the expression levels of Neuronal PAS Domain Protein 4 (Npas4)-induced by PTZ. Furthermore, the adenosine A2A antagonist {"type":"entrez-protein","attrs":{"text":"SCH58261","term_id":"1052882304","term_text":"SCH58261"}}SCH58261 and ZM241385 inhibited anticonvulsant activity and gamma-aminobutyric acid (GABA)ergic neurotransmission-induced by D-limonene. Conclusion: These results suggest that D-limonene exhibits anticonvulsant activity through modulation of adenosine A2A receptors on GABAergic neuronal function.     

偏振CARS研究核苷分子振动结构

用偏振灵敏ＣＡＮＳ光谱研究尿嘧啶、胸腺嘧啶、胞嘧啶和腺嘌呤四种核苷分子的振动结构。谱的非共振背景被有效地消除，核苷的双键振动模清晰可辨，对每种核苷分子的特征谱线进行了标识，作为在生物分子中识别它们的标志。     

Hyperhomocysteinemia and Cardiovascular Disease: Is the Adenosinergic System the Missing Link?

The influence of hyperhomocysteinemia (HHCy) on cardiovascular disease (CVD) remains unclear. HHCy is associated with inflammation and atherosclerosis, and it is an independent risk factor for CVD, stroke and myocardial infarction. However, homocysteine (HCy)-lowering therapy does not affect the inflammatory state of CVD patients, and it has little influence on cardiovascular risk. The HCy degradation product hydrogen sulfide (H₂S) is a cardioprotector. Previous research proposed a positive role of H₂S in the cardiovascular system, and we discuss some recent data suggesting that HHCy worsens CVD by increasing the production of H₂S, which decreases the expression of adenosine A_2A receptors on the surface of immune and cardiovascular cells to cause inflammation and ischemia, respectively.     

Adenosine Receptor Agonist HE-NECA Enhances Antithrombotic Activities of Cangrelor and Prasugrel in vivo by Decreasing of Fibrinogen Density in Thrombus

Blood platelets’ adenosine receptors (AR) are considered to be a new target for the anti-platelet therapy. This idea is based on in vitro studies which show that signaling mediated by these receptors leads to a decreased platelet response to activating stimuli. In vivo evidence for the antithrombotic activity of AR agonists published to date were limited, however, to the usage of relatively high doses given in bolus. The present study was aimed at verifying if these substances used in lower doses in combination with inhibitors of P2Y₁₂ could serve as components of dual anti-platelet therapy. We have found that a selective A_2A agonist 2-hexynyl-5’-N-ethylcarboxamidoadenosine (HE-NECA) improved the anti-thrombotic properties of either cangrelor or prasugrel in the model of ferric chloride-induced experimental thrombosis in mice. Importantly, HE-NECA was effective not only when applied in bolus as other AR agonists in the up-to-date published studies, but also when given chronically. In vitro thrombus formation under flow conditions revealed that HE-NECA enhanced the ability of P2Y₁₂ inhibitors to decrease fibrinogen content in thrombi, possibly resulting in their lower stability. Adenosine receptor agonists possess a certain hypotensive effect and an ability to increase the blood–brain barrier permeability. Therefore, the effects of anti-thrombotic doses of HE-NECA on blood pressure and the blood–brain barrier permeability in mice were tested. HE-NECA applied in bolus caused a significant hypotension in mice, but the effect was much lower when the substance was given in doses corresponding to that obtained by chronic administration. At the same time, no significant effect of HE-NECA was observed on the blood–brain barrier. We conclude that chronic administration of the A_2A agonist can be considered a potential component of a dual antithrombotic therapy. However, due to the hypotensive effect of the substances, dosage and administration must be elaborated to minimize the side-effects. The total number of animals used in the experiments was 146.     

Adenosine Signaling in Mast Cells and Allergic Diseases

Adenosine is a nucleoside involved in the pathogenesis of allergic diseases. Its effects are mediated through its binding to G protein-coupled receptors: A1, A2a, A2b and A3. The receptors differ in the type of G protein they recruit, in the effect on adenylyl cyclase (AC) activity and the downstream signaling pathway triggered. Adenosine can produce both an enhancement and an inhibition of mast cell degranulation, indicating that adenosine effects on these receptors is controversial and remains to be clarified. Depending on the study model, A1, A2b, and A3 receptors have shown anti- or pro-inflammatory activity. However, most studies reported an anti-inflammatory activity of A2a receptor. The precise knowledge of the adenosine mechanism of action may allow to develop more efficient therapies for allergic diseases by using selective agonist and antagonist against specific receptor subtypes.     

负压吸引技术应用于大面积烧伤患者围术期的效果探究

目的:探究环磷酸腺苷联合负压吸引技术应用于大面积烧伤患者围术期的效果及肾保护作用探究。方法:选择2018年12月到2020年12月于医院治疗的120例大面积烧伤患者为研究对象,以随机数字表法对患者分组,60例患者为研究组,60例患者为对照组,对照组给予负压吸引技术治疗,研究组在此基础上给予环磷酸腺苷治疗,治疗前、后测定两组患者干扰素-γ(IFN-γ)、白细胞介素-2(IL-2)、白细胞介素-10(IL-0)、白细胞介素-6(IL-6)、可溶性血管细胞粘附分子-1(sVCAM-1)、一氧化氮(NO)、内皮素(ET-1)、血管内皮生长因子(VEGF)、胱抑素C(Cys-C)、肌酐(Scr)、血尿素氮(BUN)、肾损伤分子-1(KIM-1)水平,记录两组患者手术时间、麻醉苏醒时间、住院时间。结果:研究组IFN-γ、IL-6水平低于对照组(P<0.05),研究组患者IL-2、IL-10水平高于对照组(P<0.05),研究组NO、VEGF水平高于对照组(P<0.05),研究组患者sVCAM-1、ET-1水平低于对照组(P<0.05),研究组患者Cys-C、Scr、BUN、KIM-1水平低于对照组(P<0.05),研究组手术时间低于对照组(P>0.05),研究组麻醉苏醒时间、住院时间低于对照组(P<0.05)。结论:环磷酸腺苷联合负压吸引技术应用于大面积烧伤围术期患者,可降低患者IFN-γ、IL-6水平,提升患者IL-2、IL-10水平,抑制患者炎症,改善患者血管内皮功能,降低患者Cys-C、Scr、BUN、KIM-1水平,减少患者肾功能损伤,减少患者麻醉苏醒时间及住院时间。     

腺苷A2AR拮抗剂对中枢炎症性小胶质细胞形态和功能的影响

目的:探讨腺苷A2A受体拮抗剂对实验性自身免疫性脑脊髓炎（EAE）的治疗作用及其对中枢炎症性小胶质细胞形态和功能的影响。方法:MOG35-55免疫诱导建立EAE模型,EAE小鼠出现神经功能缺损症状后开始腹腔注射腺苷A2AR拮抗剂至发病后第10天。ELISA法检测中枢神经系统内IFN-γ、IL-17、TGF-β、IL-10的表达情况,免疫荧光双重染色法检测小胶质细胞内M1型细胞标志物诱导型一氧化氮合酶（iNOS）和M2型细胞标志物精氨酸酶I（ArgI）的合成情况。离体培养BV-2小胶质细胞,LPS诱导的小胶质细胞炎症反应,并予A2AR拮抗剂干预,Real-time PCR和ELISA法检测M1型和M2型细胞相关的细胞因子RNA表达水平和分泌水平。Western Blot法检测各组小胶质细胞内M1型和M2型细胞标志物的表达量。结果:腺苷A2AR拮抗剂能有效缓解发病后EAE小鼠的神经功能缺损症状,降低IFN-γ的分泌水平,使M1型细胞相关的iNOS合成减少,M2型细胞相关的ArgI合成增多。腺苷A2AR拮抗剂能减少LPS刺激后BV-2小胶质细胞M1型细胞相关的细胞因子IL-1β的mRNA表达量和分泌量,对M2型细胞相关的细胞因子及蛋白无显著影响。结论:腺苷A2AR拮抗剂对发病后的EAE小鼠有肯定的治疗作用,其机制可能与改变中枢炎症过程中小胶质细胞的表型（M1/M2转换）改变（形态和功能）有关。     

In对S-TiO_2纳米材料的吸附与缓释特性的调控

以固相反应法所合成的铟、硫掺杂二氧化钛纳米粉体为载体,研究了三磷酸腺苷(ATP)的吸附与缓释行为。结果表明,以TiO2为基体的纳米材料对ATP都有良好的吸附作用。40 min内,Inx-S-TiO2(x=0.01,0.02,0.03,0.04,0.05)、STiO2和TiO2纳米粉体对ATP的吸附率(%)依次为82.3、91.5、98.6、93.7、89.2、75.7和66.0。其中In0.03-S-TiO2纳米粉体的载药量比纯TiO2提高了32.6%。In的含量与其吸附ATP的量呈抛物线型。纯TiO2及In、S改性纳米材料对ATP的释放均有一定的调控作用。5.5 h内,其释药百分比分别为In0.01-S-TiO2(61.4%)In0.05-S-TiO2(59.23%)In0.02-S-TiO2(57.9%)In0.04-S-TiO2(55.30%)In0.03-S-TiO2(51.45%)TiO2(37.5%)S-TiO2(25.8%)。In的掺杂,对S-TiO2纳米材料缓释ATP的速率起到明显缓释控制作用。ATP的缓释过程符合骨架溶蚀扩散机理。In在ATP释放过程中的流失量很少,均不足2%。In含量的变化对微球的突释效应有一定的调控作用。     

Potent,Metabolically Stable 2‐Alkyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐adenines as Adenosine A2A Receptor Ligands

Inhibition of adenosine A_2A receptors has been shown to elicit a therapeutic response in preclinical animal models of Parkinson’s disease (PD). We previously identified the triazolo‐9H‐purine, ST1535, as a potent A_2AR antagonist. Studies revealed that ST1535 is extensively hydroxylated at the ω‐1 position of the butyl side chain. Here, we describe the synthesis and evaluation of derivatives in which the ω‐1 position has been substituted (F, Me, OH) in order to block metabolism. The stability of the compounds was evaluated in human liver microsomes (HLM), and the affinity for A_2AR was determined. Two compounds, (2‐(3,3‐dimethylbutyl)‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐6‐amine ( 3 b ) and 4‐(6‐amino‐9‐methyl‐8‐(2H‐1,2,3‐triazol‐2‐yl)‐9H‐purin‐2‐yl)‐2‐methylbutan‐2‐ol ( 3 c ), exhibited good affinity against A_2AR (K_i=0.4 nM and 2 nM , respectively) and high in vitro metabolic stability (89.5 % and 95.3 % recovery, respectively, after incubation with HLM for two hours).