富血小板血浆注射治疗在膝骨关节炎中的应用进展

富血小板血浆(platelet-rich plasma，PRP)由于富含多种活性生长因子，能够刺激软骨细胞增殖，促进软骨前体细胞增殖、迁移、向软骨细胞分化，促进胶原蛋白合成以及抑制软骨的炎性反应和退变，提供有利于组织修复的内环境，延缓病情进展。近年来PRP注射治疗已成为治疗与骨关节炎(osteoarthritis，OA)相关疾病的新型选择，并且疗效显著。为了进一步提高其效用，PRP注射治疗不仅在关节腔内进行，还可在软骨下骨内进行注射。软骨下骨的病变会加速软骨损耗，故有必要将软骨下骨也当作OA众多发病机制和病理过程的关键因素之一。根据PRP的生物特效以及PRP注射治疗在膝骨关节炎(knee osteoarthritis，KOA)中应用的研究进展进行了综述，同时对软骨下骨内PRP注射治疗KOA的研究进行了展望，以期为KOA的治疗提供更加有效的方法。     

Effects and Mechanisms of Exogenous Electromagnetic Field on Bone Cells: A Review

Osteoporosis, fractures, and other bone diseases or injuries represent serious health problems in modern society. A variety of treatments including drugs, surgeries, physical therapies, etc. have been used to prevent or delay the progression of these diseases/injuries with limited effects. Electromagnetic field (EMF) has been used to non-invasively treat bone diseases, such as fracture and osteoporosis, for many years. However, because a variety of cellular and molecular events can be affected by EMF with various parameters, the precise bioeffects and underlying mechanisms of specific EMF on bone cells are still obscure. Here, we summarize the common therapeutic parameters (frequency and intensity) of major types of EMF used to treat bone cells taken from 32 papers we selected from the PubMed database published in English from 1991 to 2018. Briefly, pulse EMF promotes the proliferation of osteoblasts when its frequency is 7.5–15 Hz or 50–75 Hz and the intensity is 0.40–1.55 mT or 3.8–4 mT. Sinusoidal EMF, with 0.9–4.8 mT and 45–60 Hz, and static magnetic field with 0.1–0.4 mT or 400 mT, can promote osteoblast differentiation and maturation. Finally, we summarize the latest advances on the molecular signaling pathways influenced by EMF in osteoblasts and osteoclasts. A variety of molecules such as adenosine receptors, calcium channels, BMP2, Notch, Wnt1, etc., can be influenced by EMF in osteoblasts. For osteoclasts, EMF affects RANK, NF-κB, MAPK, etc. We speculate that EMF with different frequencies and intensities exert distinct bioeffects on specific bone cells. More high-quality work is required to explore the detailed effects and underlying mechanisms of EMF on bone cells/skeleton to optimize the application of EMF on bone diseases/injuries. Bioelectromagnetics. 2020;41:263–278 © 2020 Bioelectromagnetics Society.     

A Study of the Effects of Flux Density and Frequency of Pulsed Electromagnetic Field on Neurite Outgrowth in PC12 Cells

The aim of this study was to investigate the influence of pulsed electromagnetic fields with various flux densities and frequencies on neurite outgrowth in PC12 rat pheochromocytoma cells. We have studied the percentage of neurite-bearing cells, average length of neurites and directivity of neurite outgrowth in PC12 cells cultured for 96 hours in the presence of nerve growth factor (NGF). PC12 cells were exposed to 50 Hz pulsed electromagnetic fields with a flux density of 1.37 mT, 0.19 mT and 0.016 mT respectively. The field was generated through a Helmholtz coil pair housed in one incubator and the control samples were placed in another identical incubator. It was found that exposure to both a relatively high flux density (1.37 mT) and a medium flux density (0.19 mT) inhibited the percentage of neurite-bearing cells and promoted neurite length significantly. Exposure to high flux density (1.37 mT) also resulted in nearly 20% enhancement of neurite directivity along the field direction. However, exposure to low flux density field (0.016 mT) had no detectable effect on neurite outgrowth. We also studied the effect of frequency at the constant flux density of 1.37 mT. In the range from 1 ∼ 100 Hz, only 50 and 70 Hz pulse frequencies had significant effects on neurite outgrowth. Our study has shown that neurite outgrowth in PC12 cells is sensitive to flux density and frequency of pulsed electromagnetic field.