How electromagnetic fields can influence adult stem cells: positive and negative impacts

The electromagnetic field (EMF) has a great impact on our body. It has been successfully used in physiotherapy for the treatment of bone disorders and osteoarthritis, as well as for cartilage regeneration or pain reduction. Recently, EMFs have also been applied in in vitro experiments on cell/stem cell cultures. Stem cells reside in almost all tissues within the human body, where they exhibit various potential. These cells are of great importance because they control homeostasis, regeneration, and healing. Nevertheless, stem cells when become cancer stem cells, may influence the pathological condition. In this article we review the current knowledge on the effects of EMFs on human adult stem cell biology, such as proliferation, the cell cycle, or differentiation. We present the characteristics of the EMFs used in miscellaneous assays. Most research has so far been performed during osteogenic and chondrogenic differentiation of mesenchymal stem cells. It has been demonstrated that the effects of EMF stimulation depend on the intensity and frequency of the EMF and the time of exposure to it. However, other factors may affect these processes, such as growth factors, reactive oxygen species, and so forth. Exploration of this research area may enhance the development of EMF-based technologies used in medical applications and thereby improve stem cell-based therapy and tissue engineering.

Many, if not all, tissues of the human body are thought to contain stem cells (called adult stem cells/adult tissue stem cells/progenitor cells) that are responsible for tissue regeneration and repair after injury. Adult stem cells are influenced by many biochemical and biophysical stimuli in their in vivo microenvironment, including fluid shear stress, hydrostatic pressure, substrate strains, trophic factors, the electromagnetic field (EMF), and so forth. Depending on the niche in which they reside, as well as the biochemical and biophysical stimuli, stem cells may differentiate or not into desired tissues [1–3]. These factors are of great importance because dysregulation of tissue regeneration and homeostasis may result in various pathological conditions, cancer being the most extensively described. Several studies have focused on the circumstances that result in adult stem cells becoming cancer stem cells (tumor-initiating cells) that participate in carcinogenesis and metastasis. However, the nature of the interaction between adult and cancer stem cells and the mechanisms underlying the putative transition remain elusive. It is believed that during the initial stage of the pathological process, adult stem cells may be both “heroes” and “villains”.

External environmental factors are commonly known to be simultaneously involved in pathological processes, making the maintenance of homeostasis a difficult challenge. Biophysical stimuli may cause downstream signaling towards pleiotropic processes in adult stem cells.

The EMF is pervasive throughout the environment and, owing to technological developments, seems to have great potential as a therapeutic tool. It has significant effects on cells, tissues, and many processes within organisms and plays an important role in biological processes involving adult stem cells, such as embryogenesis, regeneration, and wound healing [4], as well as in cell migration, DNA synthesis, and gene expression [5–7]. However, the data regarding the influence of the EMF on adult stem cell biology are inconsistent.

Here, we review the current knowledge on the effects of EMFs on adult stem cells. Our goal is to present all available evidence for both the positive (stimulative and prodifferentiative) and negative (carcinogenic) impact of EMFs on stem cell biology.