Effects of low frequency electromagnetic fields on the chondrogenic differentiation of human mesenchymal stem cells

Electromagnetic Fields and Stem Cell Fate: When Physics Meets Biology

Controlling stem cell (SC) fate is an extremely important topic in the realm of SC research. A variety of different external cues mainly mechanical, chemical, or electrical stimulations individually or in combination have been incorporated to control SC fate. Here, we will deconstruct the probable relationship between the functioning of electromagnetic (EMF) and SC fate of a variety of different SCs. The electromagnetic (EM) nature of the cells is discussed with the emphasis on the effects of EMF on the determinant factors that directly and/or indirectly influence cell fate. Based on the EM effects on a variety of cellular processes, it is believed that EMFs can be engineered to provide a controlled signal with the highest impact on the SC fate decision. Considering the novelty and broad applications of applying EMFs to change SC fate, it is necessary to shed light on many unclear mechanisms underlying this phenomenon.

Osteogenic differentiation potential of mesenchymal stem cells cultured on nanofibrous scaffold improved in the presence of pulsed electromagnetic field

Nowadays, tissue engineering by using stem cells in combination with scaffolds and bioactive molecules has made significant contributions to the regeneration of damaged bone tissues. Since the usage of bioactive molecules including, growth factors to induce differentiation is safety limited in clinical applications, and it has also been previously observed that extremely low frequency pulsed electromagnetic fields (PEMF) can be effective in the enhancement of proliferation rate and osteogenic differentiation of stem cells, the aim of this study was investigating the osteoinductive potential of PEMF in combination with Poly(caprolactone) (PCL) nanofibrous scaffold. To achieve this aim, Adipose-derived mesenchymal stem cells (ADSCs) isolated and characterized and then osteogenic differentiation of them was investigated after culturing on the surface of PCL scaffold under treatments of PEMF, PEMF plus osteogenic medium (OM) and OM. Analysis of common osteogenic markers such as Alizarin red staining, ALP activity, calcium content and four important bone-related genes in days of 7, 14, and 21 confirmed that the effects of PEMF on the osteogenic differentiation of ADSCs are very similar to the effects of osteogenic medium. Thus, regarding the immunological concerns about the application of bioactive molecules for tissue engineering, PEMF could be a good alternative for osteogenic medium. Although, results were showed a synergetic effect for simultaneous application of PEMF and PCL scaffold in the osteogenesis process of ADSCs. Taking together, ADSCs-seeded PCL nanofibrous scaffold in combination with PEMF could be a great option for use in bone tissue engineering applications.

Combined effect of pulsed electromagnetic field and sound wave on In vitro and In vivo neural differentiation of human mesenchymal stem cells

Biophysical wave stimulus has been used as an effective tool to promote cellular maturation and differentiation in the construction of engineered tissue. Pulsed electromagnetic fields (PEMFs) and sound waves have been selected as effective stimuli that can promote neural differentiation. The aim of this study was to investigate the synergistic effect of PEMFs and sound waves on the neural differentiation potential in vitro and in vivo using human bone marrow mesenchymal stem cells (hBM-MSCs). In vitro, neural-related genes in hBM-MSCs were accelerated by the combined exposure to both waves more than by individual exposure to PEMFs or sound waves. The combined wave also up-regulated the expression of neural and synaptic-related proteins in a three-dimensional (3-D) culture system through the phosphorylation of extracellular signal-related kinase. In a mouse model of photochemically induced ischemia, exposure to the combined wave reduced the infarction volume and improved post-injury behavioral activity. These results indicate that a combined stimulus of biophysical waves, PEMFs and sound can enhance and possibly affect the differentiation of MSCs into neural cells. Our study is meaningful for highlighting the potential of combined wave for neurogenic effects and providing new therapeutic approaches for neural cell therapy. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:201-211, 2017.

The use of electric, magnetic, and electromagnetic field for directed cell migration and adhesion in regenerative medicine

Directed cell migration and adhesion is essential to embryonic development, tissue formation and wound healing. For decades it has been reported that electric field (EF), magnetic field (MF) and electromagnetic field (EMF) can play important roles in determining cell differentiation, migration, adhesion, and evenwound healing. Combinations of these techniques have revealed new and exciting explanations for how cells move and adhere to surfaces; how the migration of multiple cells are coordinated and regulated; how cellsinteract with neighboring cells, and also to changes in their microenvironment. In some cells, speed and direction are voltage dependent. Data suggests that the use of EF, MF and EMF could advance techniques in regenerative medicine, tissue engineering and wound healing. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:5-16, 2017.

Effect of Extremely Low Frequency Electromagnetic Field on MAP2 and Nestin Gene Expression of Hair Follicle Dermal Papilla Cells

Introduction

In recent years, the extremely low frequency electromagnetic field (ELF-EMF) has attracted a great deal of scientific interest. The ELF-EMF signal is able to control ion transport across ion channels and therefore induce cell differentiation.

Aim

The purpose of this study was to investigate the effect of ELF-EMF (50 Hz, 1 mT) on MAP2 and Nestin gene expression of dermal papilla mesenchymal cells (DPCs).

Methods

In order to examine the effect of chemical and electromagnetic factors on gene expression, 4 experimental groups, namely chemical (cell exposure to chemical signals), EMF (exposing cells to ELF-EMF), chemical-EMF (subjecting cells to chemical signals and ELF-EMF) and control (with no treatment) groups, were prepared, treated for 5 days, and studied. To assess the effect of extended test time on the expression of neural differentiation markers (Nestin and MAP2), an EMF group was prepared and treated for a period of 14 consecutive days. The beneficial role of EMF in inducing neural differentiation was shown by real-time PCR analysis.

Results

The higher expression of MAP2 after 14 days compared to that after 5 days and decrease of cell proliferation on days 5 to 20 were indicative of the positive effect of extending treatment time on neural differentiation by evaluation of gene expression in EMF group.

Induction of chondrogenic differentiation of human adipose-derived stem cells by low frequency electric field

BACKGROUND

Since when the cartilage damage (e.g., with the osteoarthritis) it could not be repaired in the body, hence for its reconstruction needs cell therapy. For this purpose, adipose-derived stem cells (ADSCs) is one of the best cell sources because by the tissue engineering techniques it can be differentiated into chondrocytes. Chemical and physical inducers is required order to stem cells to chondrocytes differentiating. We have decided to define the role of electric field (EF) in inducing chondrogenesis process.

MATERIALS AND METHODS

A low frequency EF applied the ADSCs as a physical inducer for chondrogenesis in a 3D micromass culture system which ADSCs were extracted from subcutaneous abdominal adipose tissue. Also enzyme-linked immunosorbent assay, methyl thiazolyl tetrazolium, real time polymerase chain reaction and flowcytometry techniques were used for this study.

RESULTS

We found that the 20 minutes application of 1 kHz, 20 mv/cm EF leads to chondrogenesis in ADSCs. Although our results suggest that application of physical (EF) and chemical (transforming growth factor-β3) inducers at the same time, have best results in expression of collagen type II and SOX9 genes. It is also seen EF makes significant decreased expression of collagens type I and X genes.

CONCLUSION

The low frequency EF can be a good motivator to promote chondrogenic differentiation of human ADSCs.

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.

Extremely Low Frequency Electromagnetic Field in Mesenchymal Stem Cells Gene Regulation: Chondrogenic Markers Evaluation

There is little evidence demonstrating the effects of electromagnetic fields (EMFs) generated within the biological entity and the effect of extrinsic fields on cellular programing. Taking the path of the more studied stimuli into attention, mechanical forces, it could be understood that nonchemical factors play a consequential role in transcriptional regulatory networks. Cartilaginous tissue consists of collagen protein that is considered as a piezoelectric substrate and is influenced by electric fields making chondrogenic specific genes an exciting candidate for bioelectromagnetic studies. As electromagnetic properties highly depend on the frequencies applied, this study delves into the ability of two EMFs with the frequency of 25 Hz and 50 Hz in inducing SOX9 and COL2 gene expressions in a three-dimensional (3D) mesenchymal stem cell (MSC)-alginate construct. Cell-alginate beads were divided into six groups and treated for a time period of 21 days. To determine the results, qualitative and quantitative data were both reviewed. On observation of real-time polymerase chain reaction (PCR) data, it was apparent that TGF-β1 treatment had a greater COL2 and SOX9 gene expression impact on MSCs compared to pulsed electromagnetic field (PEMF) treatments alone. COL2 was shown to have a greater transcriptional tendency to PEMF, whereas under defined electromagnetic parameters applied in this study, no significant difference was detected in SOX9 gene expressions compared to the control group. PEMF co-treatments enhanced the deposition of extracellular matrix molecules, as the matrix-rich beads were positively stained by Alcian blue. This genre of study is the venue for the control and healing of connective tissue defects.

Effects of electromagnetic field frequencies on chondrocytes in 3D cell-printed composite constructs

In cartilage tissue engineering, electromagnetic field (EMF) therapy has been reported to have a modest effect on promoting cartilage regeneration. However, these studies were conducted using different frequencies of EMF to stimulate chondrocytes. Thus, it is necessary to investigate the effect of EMF frequency on cartilage formation. In addition to the stimulation, a scaffold is required to satisfy the characteristics of cartilage such as its hydrated and dense extracellular matrix, and a mechanical resilience to applied loads. Therefore, we 3D-printed a composite construct composed of a polymeric framework and a chondrocyte-laden hydrogel. Here, we observed frequency-dependent positive and negative effects on chondrogenesis using a 3D cell-printed cartilage tissue. We found that a frequency of 45 Hz promoted gene expression and secretion of extracellular matrix molecules of chondrocytes. In contrast, a frequency of 7.5 Hz suppressed chondrogenic differentiation in vitro. Additionally, the EMF-treated composite constructs prior to implantation showed consistent results with those of in vitro, suggesting that in vitro pre-treatment with different EMF frequencies provides different capabilities for the enhancement of cartilage formation in vivo. This correlation between EMF frequency and 3D-printed chondrocytes suggests the necessity for optimization of EMF parameters when this physical stimulus is applied to engineered cartilage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1797-1804, 2016.

Nanotechnology for mesenchymal stem cell therapies

Mesenchymal stem cells (MSC) display great proliferative, differentiative, chemotactic, and immune-modulatory properties required to promote tissue repair. Several clinical trials based on the use of MSC are currently underway for therapeutic purposes. The aim of this article is to examine the current trends and potential impact of nanotechnology in MSC-driven regenerative medicine. Nanoparticle-based approaches are used as powerful carrier systems for the targeted delivery of bioactive molecules to ensure MSC long-term maintenance in vitro and to enhance their regenerative potential. Nanostructured materials have been developed to recapitulate the stem cell niche within a tissue and to instruct MSC toward the creation of regeneration-permissive environment. Finally, the capability of MSC to migrate toward the site of injury/inflammation has allowed for the development of diagnostic imaging systems able to monitor transplanted stem cell bio-distribution, toxicity, and therapeutic effectiveness.

Magnetic Nanocomposite Hydrogel for Potential Cartilage Tissue Engineering: Synthesis, Characterization, and Cytocompatibility with Bone Marrow Derived Mesenchymal Stem Cells

Hydrogels possess high water content and closely mimic the microenvironment of extracellular matrix. In this study, we created a hybrid hydrogel containing type II collagen, hyaluronic acid (HA), and polyethylene glycol (PEG) and incorporated magnetic nanoparticles into the hybrid hydrogels of type II collagen-HA-PEG to produce a magnetic nanocomposite hydrogel (MagGel) for cartilage tissue engineering. The results showed that both the MagGel and hybrid gel (Gel) were successfully cross-linked and the MagGel responded to an external magnet while maintaining structural integrity. That is, the MagGel could travel to the tissue defect sites in physiological fluids under remote magnetic guidance. The adhesion density of bone marrow derived mesenchymal stem cells (BMSCs) on the MagGel group in vitro was similar to the control group and greater than the Gel group. The morphology of BMSCs was normal and consistent in all groups. We also found that BMSCs engulfed magnetic nanoparticles in culture and the presence of magnetic nanoparticles did not affect BMSC adhesion and morphology. We hypothesized that the ingested nanoparticles may be eventually broken down by lysosome and excreted through exocytosis; further studies are necessary to confirm this. This study reports a promising magnetic responsive nanocomposite hydrogel for potential cartilage tissue engineering applications, which should be further studied for its effects on cell functions when combined with electromagnetic stimulation.

The effect of low-frequency electromagnetic field on human bone marrow stem/progenitor cell differentiation

Human bone marrow stromal cells (hBMSCs, also known as bone marrow-derived mesenchymal stem cells) are a population of progenitor cells that contain a subset of skeletal stem cells (hSSCs), able to recreate cartilage, bone, stroma that supports hematopoiesis and marrow adipocytes. As such, they have become an important resource in developing strategies for regenerative medicine and tissue engineering due to their self-renewal and differentiation capabilities. The differentiation of SSCs/BMSCs is dependent on exposure to biophysical and biochemical stimuli that favor early and rapid activation of the in vivo tissue repair process. Exposure to exogenous stimuli such as an electromagnetic field (EMF) can promote differentiation of SSCs/BMSCs via ion dynamics and small signaling molecules. The plasma membrane is often considered to be the main target for EMF signals and most results point to an effect on the rate of ion or ligand binding due to a receptor site acting as a modulator of signaling cascades. Ion fluxes are closely involved in differentiation control as stem cells move and grow in specific directions to form tissues and organs. EMF affects numerous biological functions such as gene expression, cell fate, and cell differentiation, but will only induce these effects within a certain range of low frequencies as well as low amplitudes. EMF has been reported to be effective in the enhancement of osteogenesis and chondrogenesis of hSSCs/BMSCs with no documented negative effects. Studies show specific EMF frequencies enhance hSSC/BMSC adherence, proliferation, differentiation, and viability, all of which play a key role in the use of hSSCs/BMSCs for tissue engineering. While many EMF studies report significant enhancement of the differentiation process, results differ depending on the experimental and environmental conditions. Here we review how specific EMF parameters (frequency, intensity, and time of exposure) significantly regulate hSSC/BMSC differentiation in vitro. We discuss optimal conditions and parameters for effective hSSC/BMSC differentiation using EMF treatment in an in vivo setting, and how these can be translated to clinical trials.

Human chondrocyte migration behaviour to guide the development of engineered cartilage

Tissue-engineering techniques have been successful in developing cartilage-like tissues in vitro using cells from animal sources. The successful translation of these strategies to the clinic will likely require cell expansion to achieve sufficient cell numbers. Using a two-dimensional (2D) cell migration assay to first identify the passage at which chondrocytes exhibited their greatest chondrogenic potential, the objective of this study was to determine a more optimal culture medium for developing three-dimensional (3D) cartilage-like tissues using human cells. We evaluated combinations of commonly used growth factors that have been shown to promote chondrogenic growth and development. Human articular chondrocytes (AC) from osteoarthritic (OA) joints were cultured in 3D environments, either in pellets or encapsulated in agarose. The effect of growth factor supplementation was dependent on the environment, such that matrix deposition differed between the two culture systems. ACs in pellet culture were more responsive to bone morphogenetic protein (BMP2) alone or combinations containing BMP2 (i.e. BMP2 with PDGF or FGF). However, engineered cartilage development within agarose was better for constructs cultured with TGFβ3. These results with agarose and pellet culture studies set the stage for the development of conditions appropriate for culturing 3D functional engineered cartilage for eventual use in human therapies. Copyright © 2015 John Wiley & Sons, Ltd.

Experimental model for ELF-EMF exposure: Concern for human health

Low frequency (LF) electromagnetic fields (EMFs) are abundantly present in modern society and in the last 20 years the interest about the possible effect of extremely low frequency (ELF) EMFs on human health has increased progressively. Epidemiological studies, designed to verify whether EMF exposure may be a potential risk factor for health, have led to controversial results. The possible association between EMFs and an increased incidence of childhood leukemia, brain tumors or neurodegenerative diseases was not fully elucidated. On the other hand, EMFs are widely used, in neurology, psychiatry, rheumatology, orthopedics and dermatology, both in diagnosis and in therapy. In vitro studies may help to evaluate the mechanism by which LF-EMFs affect biological systems. In vitro model of wound healing used keratinocytes (HaCaT), neuroblastoma cell line (SH-SY5Y) as a model for analysis of differentiation, metabolism and functions related to neurodegenerative processes, and monocytic cell line (THP-1) was used as a model for inflammation and cytokines production, while leukemic cell line (K562) was used as a model for hematopoietic differentiation. MCP-1, a chemokine that regulates the migration and infiltration of memory T cells, natural killer (NK), monocytes and epithelial cells, has been demonstrated to be induced and involved in various diseases. Since, varying the parameters of EMFs different effects may be observed, we have studied MCP-1 expression in HaCaT, SH-SY5Y, THP-1 and K562 exposed to a sinusoidal EMF at 50 Hz frequency with a flux density of 1 mT (rms). Our preliminary results showed that EMF-exposure differently modifies the expression of MCP-1 in different cell types. Thus, the MCP-1 expression needs to be better determined, with additional studies, with different parameters and times of exposure to ELF-EMF.

Stimulation of chondrogenic differentiation of adult human bone marrow-derived stromal cells by a moderate-strength static magnetic field

Tissue-engineering strategies for the treatment of osteoarthritis would benefit from the ability to induce chondrogenesis in precursor cells. One such cell source is bone marrow-derived stromal cells (BMSCs). Here, we examined the effects of moderate-strength static magnetic fields (SMFs) on chondrogenic differentiation in human BMSCs in vitro. Cells were cultured in pellet form and exposed to several strengths of SMFs for various durations. mRNA transcript levels of the early chondrogenic transcription factor SOX9 and the late marker genes ACAN and COL2A1 were determined by reverse transcription-polymerase chain reaction, and production of the cartilage-specific macromolecules sGAG, collage type 2 (Col2), and proteoglycans was determined both biochemically and histologically. The role of the transforming growth factor (TGF)-β signaling pathway was also examined. Results showed that a 0.4 T magnetic field applied for 14 days elicited a strong chondrogenic differentiation response in cultured BMSCs, so long as TGF-β3 was also present, that is, a synergistic response of a SMF and TGF-β3 on BMSC chondrogenic differentiation was observed. Further, SMF alone caused TGF-β secretion in culture, and the effects of SMF could be abrogated by the TGF-β receptor blocker SB-431542. These data show that moderate-strength magnetic fields can induce chondrogenesis in BMSCs through a TGF-β-dependent pathway. This finding has potentially important applications in cartilage tissue-engineering strategies.

Extremely low-frequency electromagnetic field influences the survival and proliferation effect of human adipose derived stem cells

BACKGROUND

Extremely low-frequency electromagnetic fields (ELF-EMF) can effect on biological systems and alters some cell functions like proliferation rate. Therefore, we aimed to attempt the evaluation effect of ELF-EMF on the growth of human adipose derived stem cells (hADSCs).

MATERIALS AND METHODS

ELF-EMF was generated by a system including autotransformer, multi-meter, solenoid coils, teslameter and its probe. We assessed the effect of ELF-EMF with intensity of 0.5 and 1 mT and power line frequency 50 Hz on the survival of hADSCs for 20 and 40 min/day for 7 days by MTT assay. One-way analysis of variance was used to assessment the significant differences in groups.

RESULTS

ELF-EMF has maximum effect with intensity of 1 mT for 20 min/day on proliferation of hADSCs. The survival and proliferation effect (PE) in all exposure groups were significantly higher than that in sham groups (P < 0.05) except in group of 1 mT and 40 min/day.

CONCLUSION

Our results show that between 0.5 m and 1 mT ELF-EMF could be enhances survival and PE of hADSCs conserving the duration of exposure.

Pressureless mechanical induction of stem cell differentiation is dose and frequency dependent

Movement is a key characteristic of higher organisms. During mammalian embryogenesis fetal movements have been found critical to normal tissue development. On the single cell level, however, our current understanding of stem cell differentiation concentrates on inducing factors through cytokine mediated biochemical signaling. In this study, human mesenchymal stem cells and chondrogenesis were investigated as representative examples. We show that pressureless, soft mechanical stimulation precipitated by the cyclic deformation of soft, magnetic hydrogel scaffolds with an external magnetic field, can induce chondrogenesis in mesenchymal stem cells without any additional chondrogenesis transcription factors (TGF-β1 and dexamethasone). A systematic study on the role of movement frequency revealed a classical dose-response relationship for human mesenchymal stem cells differentiation towards cartilage using mere mechanical stimulation. This effect could even be synergistically amplified when exogenous chondrogenic factors and movement were combined.

Influence of extremely low frequency, low energy electromagnetic fields and combined mechanical stimulation on chondrocytes in 3-D constructs for cartilage tissue engineering

Articular cartilage, once damaged, has very low regenerative potential. Various experimental approaches have been conducted to enhance chondrogenesis and cartilage maturation. Among those, non-invasive electromagnetic fields have shown their beneficial influence for cartilage regeneration and are widely used for the treatment of non-unions, fractures, avascular necrosis and osteoarthritis. One very well accepted way to promote cartilage maturation is physical stimulation through bioreactors. The aim of this study was the investigation of combined mechanical and electromagnetic stress affecting cartilage cells in vitro. Primary articular chondrocytes from bovine fetlock joints were seeded into three-dimensional (3-D) polyurethane scaffolds and distributed into seven stimulated experimental groups. They either underwent mechanical or electromagnetic stimulation (sinusoidal electromagnetic field of 1 mT, 2 mT, or 3 mT; 60 Hz) or both within a joint-specific bioreactor and a coil system. The scaffold-cell constructs were analyzed for glycosaminoglycan (GAG) and DNA content, histology, and gene expression of collagen-1, collagen-2, aggrecan, cartilage oligomeric matrix protein (COMP), Sox9, proteoglycan-4 (PRG-4), and matrix metalloproteinases (MMP-3 and -13). There were statistically significant differences in GAG/DNA content between the stimulated versus the control group with highest levels in the combined stimulation group. Gene expression was significantly higher for combined stimulation groups versus static control for collagen 2/collagen 1 ratio and lower for MMP-13. Amongst other genes, a more chondrogenic phenotype was noticed in expression patterns for the stimulated groups. To conclude, there is an effect of electromagnetic and mechanical stimulation on chondrocytes seeded in a 3-D scaffold, resulting in improved extracellular matrix production.

Fentanyl is less toxic on adult human mesenchymal stem cells compared to ropivacaine when used intraarticularly. A controlled in vitro study

The purpose of this study was to evaluate the toxicity of ropivacaine and fentanyl on adult human mesenchymal stem cells (hMSC). hMSC's were seeded in monolayer triple-flasks and then plated into 96-well plates at a density of 5000 cells per well. After fully aspirating the culture medium, ropivacaine or fentanyl in its corresponding concentration (0.5%, 0.25%, 0.125% for ropivacaine and 0.05%, 0.025%, 0.0125% for fentanyl) or culture medium only was added to each well. After 30 min, the anaesthetic was removed and fresh culture medium was added. hMSCs mitochondrial activity as a marker of cell proliferation and apoptosis marker was evaluated after 1, 24 h and 7 days. Proliferation was significantly decreased after a 30 min exposure to 0.5% and 0.125% ropivacaine, respectively compared to the control group after 24 h (p < 0.001). Simultaneously, apoptosis was significantly induced. Proliferation of hMSC's was decreased after 24 h when exposed to 0.05%, 0.025% and 0.0125% fentanyl (p < 0.001). Apoptosis was only induced 24 h after an exposure to 0.05% fentanyl. Our data suggest that both drugs have a concentration-dependent effect on proliferation in adult hMSC's in vitro. This effect was more distinct with ropivacaine compared to fentanyl. Translating these results into clinical practice, this in vitro study suggests fentanyl as a potentially less toxic analgetic drug for intraarticular application after arthroscopic bone marrow stimulation or rotator cuff repair with comparable to prolonged pain reduction.

Electromagnetic fields counteract IL-1β activity during chondrogenesis of bovine mesenchymal stem cells

Osteoarthritis (OA) is a common joint disease associated with articular cartilage degeneration. To improve the therapeutic options of OA, tissue engineering based on the use of mesenchymal stem cells (MSCs) has emerged. However, the presence of inflammatory cytokines, such as interleukin-1β (IL-1β), during chondrogenesis reduces the efficacy of cartilage engineering repair procedures by preventing chondrogenic differentiation. Previous studies have shown that electromagnetic fields (EMFs) stimulate anabolic processes in OA cartilage and limit IL-1β catabolic effects. We investigated the role of EMFs during chondrogenic differentiation of MSCs, isolated from bovine synovial fluid, in the absence and presence of IL-1β. Pellets of MSCs were differentiated for 3 and 5 weeks with transforming growth factor-β3 (TGFβ3), in the absence and presence of IL-1β and exposed or unexposed to EMFs. Biochemical, quantitative real-time RT-PCR and histological results showed that EMFs alone or in the presence of TGFβ3 play a limited role in promoting chondrogenic differentiation. Notably, in the presence of IL-1β and TGFβ3 a recovery of proteoglycan (PG) synthesis, PG content and aggrecan and type II collagen mRNA expression in the EMF-exposed compared to unexposed pellets was observed. Also, histological and immunohistochemical results showed an increase in staining for alcian blue, type II collagen and aggrecan in EMF-exposed pellets. In conclusion, this study shows a significant role of EMFs in counteracting the IL-1β-induced inhibition of chondrogenesis, suggesting EMFs as a therapeutic strategy for improving the clinical outcome of cartilage engineering repair procedures, based on the use of MSCs.

Intrinsically superparamagnetic Fe-hydroxyapatite nanoparticles positively influence osteoblast-like cell behaviour

BACKGROUND

Superparamagnetic nanoparticles (MNPs) have been progressively explored for their potential in biomedical applications and in particular as a contrast agent for diagnostic imaging, for magnetic drug delivery and more recently for tissue engineering applications. Considering the importance of having safe MNPs for such applications, and the essential role of iron in bone remodelling, this study developed and analysed novel biocompatible and bioreabsorbable superparamagnetic nanoparticles, that avoid the use of poorly tolerated magnetite based nanoparticles, for bone tissue engineering applications.

RESULTS

MNPs were obtained by doping hydroxyapatite (HA) with Fe ions, by directly substituting Fe2+ and Fe3+ into the HA structure yielding superparamagnetic bioactive phase. In the current study, we have investigated the effects of increasing concentrations (2000 μg/ml; 1000 μg/ml; 500 μg/ml; 200 μg/ml) of FeHA MNPs in vitro using Saos-2 human osteoblast-like cells cultured for 1, 3 and 7 days with and without the exposure to a static magnetic field of 320 mT. Results demonstrated not only a comparable osteoblast viability and morphology, but increased in cell proliferation, when compared to a commercially available Ha nanoparticles, even with the highest dose used. Furthermore, FeHA MNPs exposure to the static magnetic field resulted in a significant increase in cell proliferation throughout the experimental period, and higher osteoblast activity.In vivo preliminary results demonstrated good biocompatibility of FeHA superparamagnetic material four weeks after implantation into a critical size lesion of the rabbit condyle.

CONCLUSIONS

The results of the current study suggest that these novel FeHA MNPs may be particularly relevant for strategies of bone tissue regeneration and open new perspectives for the application of a static magnetic field in a clinical setting of bone replacement, either for diagnostic imaging or magnetic drug delivery.

Engineered microenvironments for self-renewal and musculoskeletal differentiation of stem cells

Stem cells hold great promise for therapies aimed at regenerating damaged tissue, drug screening and studying in vitro models of human disease. However, many challenges remain before these applications can become a reality. One such challenge is developing chemically defined and scalable culture conditions for derivation and expansion of clinically viable human pluripotent stem cells, as well as controlling their differentiation with high specificity. Interaction of stem cells with their extracellular microenvironment plays an important role in determining their differentiation commitment and functions. Regenerative medicine approaches integrating cell-matrix and cell-cell interactions, and soluble factors could lead to development of robust microenvironments to control various cellular responses. Indeed, several of these recent developments have provided significant insight into the design of microenvironments that can elicit the targeted cellular response. In this article, we will focus on some of these developments with an emphasis on matrix-mediated expansion of human pluripotent stem cells while maintaining their pluripotency. We will also discuss the role of matrix-based cues and cell-cell interactions in the form of soluble signals in directing stem cell differentiation into musculoskeletal lineages.

Engineered approaches to the stem cell microenvironment for cardiac tissue regeneration

Micro- and nanoscale engineering approaches in medicine have the potential to recreate physiologically relevant stem cell microenvironments to enhance our understanding of stem cell behaviour and bring stem cell therapy closer to fruition. The realization of such advancements will impact a number of therapeutic applications, the most immediate of which may be the repair of heart tissue. Despite profound advances in creating physiologically relevant in vivo stem cell niches through the control of biochemical regulatory factors, further synergism of innovative techniques promise to elucidate the impact of a number of physical cues such as stem cell differentiation into cardiac cells, the electromechanical coupling among these cells, and the formation of bioengineered cardiac tissue grafts. This review examines the recent physiologically relevant micro- and nanoengineering efforts that have been made to address these factors. In Sections II and III, we introduce the traditional focuses of stem cell derived cardiac tissue: differentiation directed by transcription factors and structural cues within the stem cell niche. However, the majority of this review, Sections IV-VII, endeavours to highlight innovative and unconventional microscale engineering techniques that have employed topographic, biomaterial, microfluidic, mechanical, electrical, and optical stimulation for stem cell based cardiac tissue engineering.