Effects of 7 T static magnetic fields on the expression of biological markers and the formation of bone in rats

Static magnetic fields in regenerative medicine

All organisms on Earth live in the weak but ubiquitous geomagnetic field. Human beings are also exposed to magnetic fields generated by multiple sources, ranging from permanent magnets to magnetic resonance imaging (MRI) in hospitals. It has been shown that different magnetic fields can generate various effects on different tissues and cells. Among them, stem cells appear to be one of the most sensitive cell types to magnetic fields, which are the fundamental units of regenerative therapies. In this review, we focus on the bioeffects of static magnetic fields (SMFs), which are related to regenerative medicine. Most reports in the literature focus on the influence of SMF on bone regeneration, wound healing, and stem cell production. Multiple aspects of the cellular events, including gene expression, cell signaling pathways, reactive oxygen species, inflammation, and cytoskeleton, have been shown to be affected by SMFs. Although no consensus yet, current evidence indicates that moderate and high SMFs could serve as a promising physical tool to promote bone regeneration, wound healing, neural differentiation, and dental regeneration. All in vivo studies of SMFs on bone regeneration and wound healing have shown beneficial effects, which unravel the great potential of SMFs in these aspects. More mechanistic studies, magnetic field parameter optimization, and clinical investigations on human bodies will be imperative for the successful clinical applications of SMFs in regenerative medicine.

Effects of different physical factors on osteogenic differentiation

Osteoblasts are essential for bone formation and can perceive external mechanical stimuli, which are translated into biochemical responses that ultimately alter cell phenotypes and respond to environmental stimuli, described as mechanical transduction. These cells actively participate in osteogenesis and the formation and mineralisation of the extracellular bone matrix. This review summarises the basic physiological and biological mechanisms of five different physical stimuli, i.e. light, electricity, magnetism, force and sound, to induce osteogenesis; further, it summarises the effects of changing culture conditions on the morphology, structure and function of osteoblasts. These findings may provide a theoretical basis for further studies on bone physiology and pathology at the cytological level and will be useful in the clinical application of bone formation and bone regeneration technology.

Static magnetic field: A potential tool of controlling stem cells fates for stem cell therapy in osteoporosis

Osteoporosis is a kind of bone diseases characterized by dynamic imbalance of bone formation and bone absorption, which is prone to fracture, and seriously endangers human health. At present, there is a lack of highly effective drugs for it, and the existing measures all have some side effects. In recent years, mesenchymal stem cell therapy has brought a certain hope for osteoporosis, while shortcomings such as homing difficulty and unstable therapeutic effects limit its application widely. Therefore, it is extremely urgent to find effective and reliable means/drugs for adjuvant stem cell therapy or develop new research techniques. It has been reported that static magnetic fields(SMFs) has a certain alleviating and therapeutic effect on varieties of bone diseases, also promotes the proliferation and osteogenic differentiation of mesenchymal stem cells derived from different tissues to a certain extent. Basing on the above background, this article focuses on the key words "static/constant magnetic field, mesenchymal stem cell, osteoporosis", combined literature and relevant contents were studied to look forward that SMFs has unique advantages in the treatment of osteoporosis with mesenchymal stem cells, which can be used as an application tool to promote the progress of stem cell therapy in clinical application.

The use of alkaline phosphatase as a bone turnover marker after spinal cord injury: A scoping review of human and animal studies

BACKGROUND

Serum alkaline phosphatase (ALP) is measured as an indicator of bone or liver disease. Bone-specific alkaline phosphatase (B-ALP) is an isoform of ALP found in the bone tissue which can predict fractures and heterotopic ossification.

OBJECTIVE

The aim of this scoping review was to explore the current use of ALP and B-ALP in studies using humans or animal models of SCI, and to identify ways to advance future research using ALP and B-ALP as a bone marker after SCI.

RESULTS

HUMAN STUDIES: 42 studies were included. The evidence regarding changes or differences in ALP levels in individuals with SCI compared to controls is conflicting. For example, a negative correlation between B-ALP and total femur BMD was observed in only one of three studies examining the association. B-ALP seemed to increase after administration of teriparatide, and to decrease after treatment with denosumab. The effects of exercise on ALP and B-ALP levels are heterogeneous and depend on the type of exercise performed. ANIMAL STUDIES: 11 studies were included. There is uncertainty regarding the response of ALP or B-ALP levels after SCI; levels increased after some interventions, including vibration protocols, curcumin supplementation, cycles in electromagnetic field or hyperbaric chamber. Calcitonin or bisphosphonate administration did not affect ALP levels.

CONCLUSION

Researchers are encouraged to measure the bone-specific isoform of ALP rather than total ALP in future studies in humans of animal models of SCI.

Magnetic Susceptibility Difference-Induced Nucleus Positioning in Gradient Ultrahigh Magnetic Field

Despite the importance of magnetic properties of biological samples for biomagnetism and related fields, the exact magnetic susceptibilities of most biological samples in their physiological conditions are still unknown. Here we used superconducting quantum interferometer device to detect the magnetic properties of nonfixed, nondehydrated live cell and cellular fractions at a physiological temperature of 37°C (310 K). It is obvious that there are paramagnetic components within human nasopharyngeal carcinoma CNE-2Z cells. More importantly, the magnetic properties of the cytoplasm and nucleus are different. Although within a single cell, the magnetic susceptibility difference between cellular fractions (nucleus and cytoplasm) could only cause ∼41-130 pN forces to the nucleus by gradient ultrahigh magnetic fields of 13.1-23.5 T (92-160 T/m), these forces are enough to cause a relative position shift of the nucleus within the cell. This not only demonstrates the importance of magnetic susceptibility in the biological effects of magnetic field but also illustrates the potential application of high magnetic fields in biomedicine.

Safety of exposure to high static magnetic fields (2 T-12 T): a study on mice

OBJECTIVES

We aimed to evaluate the biological effects of high static magnetic field (HiSMF, 2-12 Tesla [T]) exposure on mice in a stable and effective breeding environment in the chamber of a superconducting magnet.

METHODS

C57BL/6 mice were bred in the geomagnetic field and HiSMF with different magnetic field strengths (2-4 T, 6-8 T, and 10-12 T) for 28 days. The body weight, blood indices, organ coefficients, and histomorphology of major organs were analyzed.

RESULTS

The results showed that the HiSMF had no significant effect on the body weight, organ coefficients, or histomorphology of major organs in mice. The HiSMF had no effect on most routine blood and biochemical indices, but the value of the mean corpuscular hemoglobin (MCH) was increased in the 2-4 T group compared with that of the other groups, and the uric acid level (UA) was decreased in the three HiSMF groups compared with that of the control group.

CONCLUSION

The C57BL/6 mice were not affected when they were exposed to different HiSMF environments for 28 days.

KEY POINTS

• No physiological problems were observed in mice with long-term whole-body exposure to HiSMF.

Preparation and biocompatibility of Fe50Ni50p/HAP/PEEK biocomposites with weak magnetic properties

Hydroxyapatite (HAP)/polyetheretherketone (PEEK) composites are widely used in the new generation of bone implant materials. The use of weak magnetic fields can promote the biocompatibility of PEEK materials. In this paper, Fe50Ni50 alloy nanopowders and Fe50Ni50/HAP/PEEK composites were prepared by liquid phase chemical reduction and liquid phase mixing. The prepared Fe50Ni50 alloy nanopowders have a particle size of about 100 nm and good chemical activity and magnetic properties. The saturation magnetization (M s) of the Fe50Ni50 alloy powders is 70 emu g-1. Fe50Ni50 nano-powders in Fe50Ni50/HAP/PEEK composites are uniformly distributed in the matrix in the form of individual particles, achieving nano-level dispersion. With the increase of Fe50Ni50 alloy powders content, the magnetic properties of the composites are significantly enhanced. The biocompatibility of Fe50Ni50/HAP/PEEK composites is significantly better than that of PEEK and HAP/PEEK materials. The 2% Fe50Ni50/HAP/PEEK composite has the best comprehensive performance, and its biocompatibility is good. The contact angle is only 55.85°. The M s reaches 1.5 emu g-1 and the hardness reaches 42 HBa.