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.     

Pulsed Electromagnetic Fields in Bone Healing: Molecular Pathways and Clinical Applications

In this article, we provide an extensive review of the recent literature of the signaling pathways modulated by Pulsed Electromagnetic Fields (PEMFs) and PEMFs clinical application. A review of the literature was performed on two medical electronic databases (PubMed and Embase) from 3 to 5 March 2021. Three authors performed the evaluation of the studies and the data extraction. All studies for this review were selected following these inclusion criteria: studies written in English, studies available in full text and studies published in peer-reviewed journal. Molecular biology, identifying cell membrane receptors and pathways involved in bone healing, and studying PEMFs target of action are giving a solid basis for clinical applications of PEMFs. However, further biology studies and clinical trials with clear and standardized parameters (intensity, frequency, dose, duration, type of coil) are required to clarify the precise dose-response relationship and to understand the real applications in clinical practice of PEMFs.     

Piezoelectric Electrospun Fibrous Scaffolds for Bone,Articular Cartilage and Osteochondral Tissue Engineering

Osteochondral tissue (OCT) related diseases, particularly osteoarthritis, number among the most prevalent in the adult population worldwide. However, no satisfactory clinical treatments have been developed to date to resolve this unmet medical issue. Osteochondral tissue engineering (OCTE) strategies involving the fabrication of OCT-mimicking scaffold structures capable of replacing damaged tissue and promoting its regeneration are currently under development. While the piezoelectric properties of the OCT have been extensively reported in different studies, they keep being neglected in the design of novel OCT scaffolds, which focus primarily on the tissue’s structural and mechanical properties. Given the promising potential of piezoelectric electrospun scaffolds capable of both recapitulating the piezoelectric nature of the tissue’s fibrous ECM and of providing a platform for electrical and mechanical stimulation to promote the regeneration of damaged OCT, the present review aims to examine the current state of the art of these electroactive smart scaffolds in OCTE strategies. A summary of the piezoelectric properties of the different regions of the OCT and an overview of the main piezoelectric biomaterials applied in OCTE applications are presented. Some recent examples of piezoelectric electrospun scaffolds developed for potentially replacing damaged OCT as well as for the bone or articular cartilage segments of this interfacial tissue are summarized. Finally, the current challenges and future perspectives concerning the use of piezoelectric electrospun scaffolds in OCT regeneration are discussed.     

脉冲电场对Fe-C-P系合金熔体凝固过程的影响研究

在Fe-C-P系合金熔体的凝固过程中加入脉冲电场能有效减轻晶界偏聚,改善凝固组织,同时也引起了元素的迁移和重新分布,C元素与P元素呈现出相似的迁移规律,随着电压的增加,P元素偏析标准偏差从1.67降到1.26,C元素也由1.03降到0.65. 处理后的熔体凝固组织中夹杂物主要分布在中心区域,凝固组织中未观察到含磷夹杂物,存在少量MnS和Al2O3夹杂物.     

Constant Rate Expressing of Juice from Biological Tissue Enhanced by Pulsed Electric Field

Abstract

Pulsed electric field (PEF) is an innovative technology, which can be successfully combined with solid/liquid expressing of juice from biological materials. The fresh juicy plants contain the juice in closed cells. The application of PEF ensures the electropermeabilization of cellular membranes, which facilitates the expulsion of liquid from the interior of cells. This article describes the influence of PEF on the kinetics of juice extraction from the layer of sugar beet particles expressed at a constant rate. Experimental study was carried out using a laboratory filter-press cell connected to a PEF treatment system. The PEF was applied by two different modes: as a pretreatment operation before pressing and as a treatment during pressing. The application of PEF to nonpressurized cake leads to increase of energy consumption and higher applied voltage. The PEF treatment of excessively pressurized cakes enhances the juice yield; however, the expressing of juice is significantly delayed. The best result is obtained when the sugar beet tissue is treated with PEF at 1.5–5 bars. The influence of PEF parameters on the juice yield was also studied. The intensity of PEF was varied from 0 to 1000 V/cm and the number of pulses was varied between 0 and 1000. It was established that the optimal parameters of PEF after the cake pressurization at 5 bar were in the next range: intensity of PEF E = 500 V/cm and duration of PEF application 0.03–0.05 s.     

交变电磁场对PFS溶解液电导率的影响研究

电磁场变化具有改变PFS(聚合硫酸铁)溶解液电导率的特性.通过交变电磁实验证明:常温条件下,聚合硫酸铁溶解液的电导率在电压为0～220 V、电流为0～1.2A、频率为0～400 Hz、磁化时间为0～180 s范围内均呈现“V”字形变化,其最佳参数为电压100 V、电流0.7A、频率150 Hz、磁化时间60s;由正交试验分析可得,4个因素影响PFS溶解液电导率的主次顺序为:磁化时间＞频率＞电压＞电流.经交变电磁场磁化处理的PFS溶解液的电导率值比常规电导率值提高了14％,稳定性提高了1倍.     

电磁场对形成MgO-C质耐火材料MgO致密层的影响

采用碳含量为6%（质量分数）的MgO–C质耐火材料和CaO与SiO2质量比为0.87的钢渣,分别在中频感应炉和电阻炉中氩气气氛下进行抗渣侵蚀实验,利用X射线衍射仪、扫描电子显微镜和能谱仪对抗渣样品渣线界面层进行分析。结果表明：在电磁场环境中,MgO–C质耐火材料界面层没有发生Mg（g）氧化反应,因此未形成MgO致密层;...     

Incorporation of graphene oxide and calcium phosphate in the PCL/PHBV core-shell nanofibers as bone tissue scaffold

Bone tissue scaffolds should have both desired mechanical stability and cell activities including biocompatibility, cell differentiation, and maturation. Also, suitable mineralization is another key factor for these materials. Hence, in current work, in order to achieve a scaffold with desired mechanical and bioactivity properties, core-shell nanofibers based on the polycaprolactone and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with different concentration of graphene oxide (GO) (0.5, 1, and 1.5 wt%) and calcium phosphate (CP) (1 and 3 wt%) were prepared to utilize as bone scaffold. Microstructure of nanofibers observed by field emission scanning electron microscope (FE-SEM) and results exhibited that the most of nanofibers had 270–500 nm diameter. Attenuated total reflectance Fourier transform infrared spectroscopy and energy dispersive X-ray evaluations verified appearance of GO and CP into the electrospun scaffolds (ES). Transmission electron microscopy analysis endorsed core-shell structure of nanofibers. X-ray diffraction study moreover determination of semicrystalline structure, verified presence of GO and CaPO₄ into the nanofibers. Water contact angle demonstrates that, ES2 and ES3 situated in suitable domain of hydrophilicity. Tensile analysis determined that, ES2, ES3, and ES4 had the highest mechanical properties for use as bone scaffold. Cell viability assessment confirmed biocompatibility of scaffold during 7 days. Alkaline phosphatase and alizarin red staining exhibited maturating and differentiating of osteocytes after 21 days seeding on the scaffolds.     

Constant Rate Expressing of Juice from Biological Tissue Enhanced by Pulsed Electric Field

Pulsed electric field (PEF) is an innovative technology, which can be successfully combined with solid/liquid expressing of juice from biological materials. The fresh juicy plants contain the juice in closed cells. The application of PEF ensures the electropermeabilization of cellular membranes, which facilitates the expulsion of liquid from the interior of cells. This article describes the influence of PEF on the kinetics of juice extraction from the layer of sugar beet particles expressed at a constant rate. Experimental study was carried out using a laboratory filter-press cell connected to a PEF treatment system. The PEF was applied by two different modes: as a pretreatment operation before pressing and as a treatment during pressing. The application of PEF to nonpressurized cake leads to increase of energy consumption and higher applied voltage. The PEF treatment of excessively pressurized cakes enhances the juice yield; however, the expressing of juice is significantly delayed. The best result is obtained when the sugar beet tissue is treated with PEF at 1.5-5 bars. The influence of PEF parameters on the juice yield was also studied. The intensity of PEF was varied from 0 to 1000 V/cm and the number of pulses was varied between 0 and 1000. It was established that the optimal parameters of PEF after the cake pressurization at 5 bar were in the next range: intensity of PEF E = 500 V/cm and duration of PEF application 0.03-0.05 s.     

Development and Characterization of Novel Biomimetic Composite Scaffolds Based on Bioglass‐Collagen‐Hyaluronic Acid‐Phosphatidylserine for Tissue Engineering Applications

Summary: Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies. The present study prepared novel biomimetic composite scaffolds with similar composite to natural bone using bioactive glass, collagen, hyaluronic acid, and phosphatidylserine. The microstructure, swelling ratio, biodegradability, and biomineralization characteristic of the composite scaffolds with and without hyaluronic acid and phosphatidylserine were compared and analyzed by SEM/EDAX, XRD, and FTIR techniques and in vitro test, and the properties can be influenced by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC)/N‐hydroxysuccinimide (NHS) crosslinking. The optimized properties of the crosslinked composite scaffolds observed in this study show the possibility of their use of bioactive and bioresorbable scaffolds in bone tissue engineering.

SEM micrographs of BG‐COL‐HYA‐PS composite scaffolds after immersion in SBF for 1 d.     

电磁场强度对层流火焰和NO生成特性的影响

在液化气与空气燃烧的层流火焰两侧施加放电磁场,测定磁场强度,采用双铂铑热电偶和综合烟气分析仪检测层流自由射流火焰温度和NO浓度,分析了不同磁场强度下层流自由射流火焰特性和NO生成特性. 结果表明,在电磁场作用下火焰长度变短,火焰下部直径增大;随磁场强度增大,火焰面下部温度提高. 电磁场可减少火焰中N, HCN, CN等离子和离子团与氧的碰撞几率,导致NO浓度降低,最大下降值为4.26 mg/m3,最大降幅为78.60%.     

高压脉冲电场对餐厨垃圾发酵产气特性的影响

为了实现餐厨垃圾的减量化,采用高压脉冲电场(pulsed electric field,PEF)对餐厨垃圾预处理后接种厌氧污泥进行厌氧发酵,考察pH、挥发性有机酸(VFA)与日产气量的关系,分析PEF对餐厨垃圾厌氧发酵的影响.结果表明:在温度50℃条件下,日产气量与pH成正比例变化趋势,与VFA呈反比例关系.经PEF(电场强度为9.0 kV·cm-1)预处理后,接种20％厌氧污泥,餐厨垃圾干物质产气量(285.1 mL·(g·TS)-1)与TS去除率(28.5％)均达到最高,高于无PEF预处理餐厨垃圾的干物质产气量(267.3 mL·(g· TS)-1)和TS去除率(26.8％).PEF能够杀死餐厨垃圾样品中的微生物,改善接种后微生物的生存环境,减少微生物发生种间竞争的概率,利于提高产气量.     

Influence of Human Jaw Periosteal Cells Seeded β-Tricalcium Phosphate Scaffolds on Blood Coagulation

Tissue engineering offers auspicious opportunities in oral and maxillofacial surgery to heal bone defects. For this purpose, the combination of cells with stability-providing scaffolds is required. Jaw periosteal cells (JPCs) are well suited for regenerative therapies, as they are easily accessible and show strong osteogenic potential. In this study, we analyzed the influence of uncoated and polylactic-co-glycolic acid (PLGA)-coated β-tricalcium phosphate (β-TCP) scaffolds on JPC colonization and subsequent osteogenic differentiation. Furthermore, interaction with the human blood was investigated. This study demonstrated that PLGA-coated and uncoated β-TCP scaffolds can be colonized with JPCs and further differentiated into osteogenic cells. On day 15, after cell seeding, JPCs with and without osteogenic differentiation were incubated with fresh human whole blood under dynamic conditions. The activation of coagulation, complement system, inflammation, and blood cells were analyzed using ELISA and scanning electron microscopy (SEM). JPC-seeded scaffolds showed a dense cell layer and osteogenic differentiation capacity on both PLGA-coated and uncoated β-TCP scaffolds. SEM analyses showed no relevant blood cell attachment and ELISA results revealed no significant increase in most of the analyzed cell activation markers (β-thromboglobulin, Sc5B-9, polymorphonuclear (PMN)-elastase). However, a notable increase in thrombin-antithrombin III (TAT) complex levels, as well as fibrin fiber accumulation on JPC-seeded β-TCP scaffolds, was detected compared to the scaffolds without JPCs. Thus, this study demonstrated that besides the scaffold material the cells colonizing the scaffolds can also influence hemostasis, which can influence the regeneration of bone tissue.     

电磁场对聚合硫酸铁水解聚合物形态分布及其混凝性能的影响

为了提高聚合硫酸铁的混凝性能,增强对污水的去除能力.利用自制交流变频磁化装置,对聚合硫酸铁溶液进行磁化处理,以铁盐水解形态Feb为指标,交流变频电磁场的频率、电压、电流及磁化时间为实验因素,对电磁场作用下的聚合硫酸铁溶液进行形态分析,并与非磁化的PFS溶液进行对比;以高炉煤气洗涤水为实验水样,通过混凝试验对比聚合硫酸铁溶液磁化前后的出水浊度及COD值.研究结果表明:电磁场作用下的聚合硫酸铁溶液的形态分布发生了变化,与非磁化相比,Feb百分比含量增加了1倍,Fec百分比含量减少了1/3,且当频率为300 Hz、电压为100 V、电流为0.8A、磁化时间为2 min时Feb的百分比含量达到最大;电磁场能明显提高聚合硫酸铁的混凝性能,与非磁化的聚合硫酸铁溶液相比出水浊度与COD值降为原来的一半,投药量节省了1倍.     

Treatment of Critical Size Femoral Bone Defects with Biomimetic Hybrid Scaffolds of 3D Plotted Calcium Phosphate Cement and Mineralized Collagen Matrix

To treat critical-size bone defects, composite materials and tissue-engineered bone grafts play important roles in bone repair materials. The purpose of this study was to investigate the bone regenerative potential of hybrid scaffolds consisting of macroporous calcium phosphate cement (CPC) and microporous mineralized collagen matrix (MCM). Hybrid scaffolds were synthetized by 3D plotting CPC and then filling with MCM (MCM-CPC group) and implanted into a 5 mm critical size femoral defect in rats. Defects left empty (control group) as well as defects treated with scaffolds made of CPC only (CPC group) and MCM only (MCM group) served as controls. Eight weeks after surgery, micro-computed tomography scans and histological analysis were performed to analyze the newly formed bone, the degree of defect healing and the activity of osteoclasts. Mechanical stability was tested by 3-point-bending of the explanted femora. Compared with the other groups, more newly formed bone was found within MCM-CPC scaffolds. The new bone tissue had a clamp-like structure which was fully connected to the hybrid scaffolds and thereby enhanced the biomechanical strength. Together, the biomimetic hybrid MCM-CPC scaffolds enhanced bone defect healing by improved osseointegration and their differentiated degradation provides spatial effects in the process of critical-bone defect healing.     

Chemotactic and Angiogenic Potential of Mineralized Collagen Scaffolds Functionalized with Naturally Occurring Bioactive Factor Mixtures to Stimulate Bone Regeneration

To develop cost-effective and efficient bone substitutes for improved regeneration of bone defects, heparin-modified mineralized collagen scaffolds were functionalized with concentrated, naturally occurring bioactive factor mixtures derived from adipose tissue, platelet-rich plasma and conditioned medium from a hypoxia-treated human bone marrow-derived mesenchymal stem cell line. Besides the analysis of the release kinetics of functionalized scaffolds, the bioactivity of the released bioactive factors was tested with regard to chemotaxis and angiogenic tube formation. Additionally, functionalized scaffolds were seeded with human bone marrow-derived mesenchymal stromal cells (hBM-MSC) and their osteogenic and angiogenic potential was investigated. The release of bioactive factors from the scaffolds was highest within the first 3 days. Bioactivity of the released factors could be confirmed for all bioactive factor mixtures by successful chemoattraction of hBM-MSC in a transwell assay as well as by the formation of prevascular structures in a 2D co-culture system of hBM-MSC and human umbilical vein endothelial cells. The cells seeded directly onto the functionalized scaffolds were able to express osteogenic markers and form tubular networks. In conclusion, heparin-modified mineralized collagen scaffolds could be successfully functionalized with naturally occurring bioactive factor mixtures promoting cell migration and vascularization.     

Bioengineered Living Bone Grafts—A Concise Review on Bioreactors and Production Techniques In Vitro

It has been observed that bone fractures carry a risk of high mortality and morbidity. The deployment of a proper bone healing method is essential to achieve the desired success. Over the years, bone tissue engineering (BTE) has appeared to be a very promising approach aimed at restoring bone defects. The main role of the BTE is to apply new, efficient, and functional bone regeneration therapy via a combination of bone scaffolds with cells and/or healing promotive factors (e.g., growth factors and bioactive agents). The modern approach involves also the production of living bone grafts in vitro by long-term culture of cell-seeded biomaterials, often with the use of bioreactors. This review presents the most recent findings concerning biomaterials, cells, and techniques used for the production of living bone grafts under in vitro conditions. Particular attention has been given to features of known bioreactor systems currently used in BTE: perfusion bioreactors, rotating bioreactors, and spinner flask bioreactors. Although bioreactor systems are still characterized by some limitations, they are excellent platforms to form bioengineered living bone grafts in vitro for bone fracture regeneration. Moreover, the review article also describes the types of biomaterials and sources of cells that can be used in BTE as well as the role of three-dimensional bioprinting and pulsed electromagnetic fields in both bone healing and BTE.     

纳秒脉冲电场灭菌对舒心糖浆质量影响的初步研究

探讨纳秒脉冲电场灭菌对舒心糖浆质量变化的影响作用。以性状、密度、p H值、有效成分黄芪甲苷含量为质量评价指标,考察纳秒脉冲电场灭菌对舒心糖浆的影响作用。舒心糖浆在经纳秒脉冲电场灭菌前后在外观、密度、p H值、黄芪甲苷含量均无明显变化。纳秒脉冲电场灭菌对舒心糖浆质量无影响,可作为一种新型灭菌方式来继续深入研究。