Effects of electromagnetic fields on osteogenesis of human alveolar bone-derived mesenchymal stem cells

Mesenchymal stem cell therapy for neurological disorders: The light or the dark side of the force?

Neurological disorders are recognized as major causes of death and disability worldwide. Because of this, they represent one of the largest public health challenges. With awareness of the massive burden associated with these disorders, came the recognition that treatment options were disproportionately scarce and, oftentimes, ineffective. To address these problems, modern research is increasingly looking into novel, more effective methods to treat neurological patients; one of which is cell-based therapies. In this review, we present a critical analysis of the features, challenges, and prospects of one of the stem cell types that can be employed to treat numerous neurological disorders-mesenchymal stem cells (MSCs). Despite the fact that several studies have already established the safety of MSC-based treatment approaches, there are still some reservations within the field regarding their immunocompatibility, heterogeneity, stemness stability, and a range of adverse effects-one of which is their tumor-promoting ability. We additionally examine MSCs' mechanisms of action with respect to in vitro and in vivo research as well as detail the findings of past and ongoing clinical trials for Parkinson's and Alzheimer's disease, ischemic stroke, glioblastoma multiforme, and multiple sclerosis. Finally, this review discusses prospects for MSC-based therapeutics in the form of biomaterials, as well as the use of electromagnetic fields to enhance MSCs' proliferation and differentiation into neuronal cells.

The Role of Low-Frequency Electromagnetic Fields on Mesenchymal Stem Cells Differentiation: A Systematic Review

BACKGROUND

Low-frequency electromagnetic fields (EMFs) influence biological processes. This present study was aimed at the scientific literature on the use of EMFs in the mesenchymal stem cell differentiation process.

MATERIALS AND METHODS

The electronic search was carried out in PubMed and Web of Science, a database with a combination of the sinusoidal and pulsed low- and extremely low-frequency electromagnetic fields stimulation and mesenchymal stem cells differentiation, considering the period of publication until December 2021. The literature search identified 118 references in PubMed and Web of Science of which 46 articles were selected, respectively, according to the eligibility requirements.

CONCLUSION

The analysis of research indicated that EMFs are an easy-to-apply and practical way in cell therapy and tissue engineering when regulation of stem cells is required. Studies have shown that EMFs have positive effects on stem cell differentiation, accelerating its process regardless of the parameters and type of stem cells. However, the exact amplitude, frequency, duration of the electrical field, and application method remain elusive and need more study in future work.

Osteogenic effect of electromagnetic fields on stem cells derived from rat bone marrow cultured in osteogenic medium versus conditioned medium in vitro

OBJECTIVES

This study assessed possible osteogenic differentiation caused by electromagnetic fields (EMF) on rat bone-marrow-derived stem cells (rBMSCs) cultured in osteogenic medium (OM) or in human adipose-stem cell-conditioned medium (hADSC-CM).

MATERIALS AND METHODS

The rBMSCs were divided into negative and positive control groups, cultured in α-MEM plus 10% FBS or OM respectively. CM and CM + EMF  groups, cultured cells in hADSCs-CM or exposed to EMF (50 Hz, 1 mT) for 30 min/day plus hADSCs-CM, respectively. Cells from the OM + EMF were simultaneously cultured in OM and exposed to EMF. Osteogenesis was investigated through alkaline phosphatase activity, alizarin red staining and real-time PCR.

RESULTS

A meaningfully higher level of ALP activity was observed in the OM + EMF group compared to the other groups. There was a considerable increase in Runx2 expression in the CM + EMF group compared to the positive control and CM groups and a significant increase in Runx2 expression in the OM + EMF in comparison with all other groups after 21 days. Runx2 expression increased significantly in the CM, CM + EMF and positive control groups on day 21 compared to the same groups on day 14. From days 14-21, Ocn expression increased in the CM and CM + EMF groups, but both groups showed a significant decrease compared to the positive controls. CM and EMF had no effect on Ocn expression. On day 21, Ocn expression was significantly higher in the OM + EMF group than in the positive control group.

CONCLUSION

The synergistic effect of EMF and OM increased the expression of Runx2 and Ocn in rBMSCs.

Biophysical Stimuli as the Fourth Pillar of Bone Tissue Engineering

The repair of critical bone defects remains challenging worldwide. Three canonical pillars (biomaterial scaffolds, bioactive molecules, and stem cells) of bone tissue engineering have been widely used for bone regeneration in separate or combined strategies, but the delivery of bioactive molecules has several obvious drawbacks. Biophysical stimuli have great potential to become the fourth pillar of bone tissue engineering, which can be categorized into three groups depending on their physical properties: internal structural stimuli, external mechanical stimuli, and electromagnetic stimuli. In this review, distinctive biophysical stimuli coupled with their osteoinductive windows or parameters are initially presented to induce the osteogenesis of mesenchymal stem cells (MSCs). Then, osteoinductive mechanisms of biophysical transduction (a combination of mechanotransduction and electrocoupling) are reviewed to direct the osteogenic differentiation of MSCs. These mechanisms include biophysical sensing, transmission, and regulation. Furthermore, distinctive application strategies of biophysical stimuli are presented for bone tissue engineering, including predesigned biomaterials, tissue-engineered bone grafts, and postoperative biophysical stimuli loading strategies. Finally, ongoing challenges and future perspectives are discussed.

Evaluation of the Sensing Potential of Stem Cell-Secreted Proteins via a Microchip Device under Electromagnetic Field Stimulation

Most bone tissue engineering models fail to demonstrate the complex cellular functions of living bone; therefore, most translational studies on bone tissue are performed in live models. To reduce the need for live models, we developed a stimulated microchip model for monitoring protein secretion during osteogenesis using human mesenchymal stem cells (hMSCs). We established a bone microchip system for monitoring the in vitro differentiation and sensing the secreted proteins of hMSCs under a sinusoidal electromagnetic field (SEMF), which ameliorates bone healing in a biomimetic natural bone matrix. A 3 V-1 Hz SEMF biophysically stimulated osteogenesis by activating ERK-1/2 and promoting phosphorylation of p38 MAPK kinases. Exposure to a 3 V-1 Hz SEMF upregulated the expression of osteogenesis-related genes and enhanced the expression of key osteoregulatory proteins. We identified 23 proteins that were differentially expressed in stimulated human bone marrow mesenchymal stem cell secretomes or were absent in the control groups. Our on-chip stimulation technology is easy to use, versatile, and nondisruptive and should have diverse applications in regenerative medicine and cell-based therapies.

Increasing Odontoblast-like Differentiation from Dental Pulp Stem Cells through Increase of β-Catenin/p-GSK-3β Expression by Low-Frequency Electromagnetic Field

Odontoblasts produce proteins that form the dentinal extracellular matrix, which can protect the dental pulp from external stimuli and is required for tooth regeneration. This study showed that a pulsed electromagnetic field (PEMF) can regulate cell metabolism and induce cell differentiation. This study determined the frequency of PEMF that is effective for odontoblast differentiation. Human dental pulp stem cells (hDPSCs) were cultured in odontoblast differentiation medium containing dexamethasone, BMP2, TGF-β1, and FGF-2, and then exposed to 10 mT intensity of PEMF at 40, 60, 70, and 150 Hz for 15 min/day. The MTT assay, LDH assay, flow cytometry, protein and gene expression, and immunofluorescence were performed to check if hDPSCs differentiated into odontoblast-like cells. The hDPSCs showed frequency-dependent differences in protein and gene expression. The mesenchymal stem cell markers were reduced to a greater extent at 60 and 70 Hz than at other frequencies, and odontoblast-related markers, particularly β-catenin, p-GSK-3β, and p-p38, were increased at 60 and 70 Hz. Exposure to 10 mT intensity of PEMF at 70 Hz influenced the differentiation of hDPSCs considerably. Taken together, PEMF treatment can promote differentiation of hDPSCs into odontoblast-like cells by increasing p-GSK-3β and β-catenin expression.

Design and experimental validation of a magnetic device for stem cell culture

Cell culture of bone and tendon tissues requires mechanical stimulation of the cells in order to mimic their physiological state. In the present work, a device has been conceived and developed to generate a controlled magnetic field with a homogeneous gradient in the working space. The design requirement was to maximize the magnetic flux gradient, assuring a minimum magnetizing value in a 15 mm × 15 mm working area, which highly increases the normal operating range of this sort of devices. The objective is to use the machine for two types of biological tests: magnetic irradiation of biological samples and force generation on paramagnetic particles embedded in scaffolds for cell culture. The device has been manufactured and experimentally validated by evaluating the force exerted on magnetic particles in a viscous fluid. Apart from the magnetic validation, the device has been tested for irradiating biological samples. In this case, viability of human dental pulp stem cells has been studied in vitro after electromagnetic field exposition using the designed device. After three days of irradiation treatment, cellular microtissues showed a 59% increase in the viable cell number. Irradiated cells did not show morphological differences when compared with control cells.

Isolation and characterization of mesenchymal stem cells in orthopaedics and the emergence of compact bone mesenchymal stem cells as a promising surgical adjunct

The potential clinical and economic impact of mesenchymal stem cell (MSC) therapy is immense. MSCs act through multiple pathways: (1) as “trophic” cells, secreting various factors that are immunomodulatory, anti-inflammatory, anti-apoptotic, proangiogenic, proliferative, and chemoattractive; (2) in conjunction with cells native to the tissue they reside in to enhance differentiation of surrounding cells to facilitate tissue regrowth. Researchers have developed methods for the extraction and expansion of MSCs from animal and human tissues. While many sources of MSCs exist, including adipose tissue and iliac crest bone graft, compact bone (CB) MSCs have shown great potential for use in orthopaedic surgery. CB MSCs exert powerful immunomodulatory effects in addition to demonstrating excellent regenerative capacity for use in filling boney defects. CB MSCs have been shown to have enhanced response to hypoxic conditions when compared with other forms of MSCs. More work is needed to continue to characterize the potential applications for CB MSCs in orthopaedic trauma.

Effects of Low-Frequency Pulsed Electromagnetic Fields on High-Altitude Stress Ulcer Healing in Rats

High-altitude stress ulcer (HSU) has constantly been a formidable clinical challenge for high-altitude and severe hypoxia. Pulsed electromagnetic fields (PEMFs) have been verified to have the ability to penetrate tissues, and the biological effects have been confirmed effective on various tissue restorations. However, the therapeutic effect of PEMFs on HSU has been rarely reported. This study aimed to evaluate the effects of PEMFs on HSU healing systematically. Sprague–Dawley rats were assigned to control, HSU, and HSU+PEMF groups. The HSU models were induced by restraint stress under low-pressure hypoxia. The HSU+PEMF group was subjected to PEMF exposure. During the HSU healing, gastric juice pH values, ulcer index (UI), and histopathologic changes were investigated. Furthermore, tumor necrosis factor-α (TNF-α) was determined to analyze the severity of gastric membrane inflammations. Norepinephrine (NE), which influences gastric acid secretion, was measured. Results indicated the UI of the HSU+PEMF decreased faster than that of the HSU group. Histopathologic observation suggested that the ulcer tissue healing is faster in the HSU+PEMF group than in the HSU group. The TNF-α/total protein results revealed that the inflammation of the HSU+PEMF group is suppressed effectively. The pH values are higher in the HSU+PEMF group than in the HSU, as confirmed by NE examination. The results indicated that low-frequency PEMFs can penetrate stomach tissues to relieve the symptoms of HSU and promote the regeneration of disturbed tissues, thus implying the clinical potential of PEMF therapy for HSU treatment.

On the electrical conductivity of alginate hydrogels

Hydrogels have been extensively used in the field of biomedical applications, offering customizable natural, synthetic or hybrid materials, particularly relevant in the field of tissue engineering. In the bioelectronics discipline, hydrogels are promising mainly as sensing platforms with or without encapsulated cells, showing great potential in healthcare and medicine. However, to date there is little data in the literature which characterizes the electrical properties of tissue engineering materials which are relevant to bioelectronics. In this work, we present electrical characterization of alginate hydrogels, a natural polysaccharide, using a four-probe method similar to electrical impedance spectroscopy. The acquired conductance data show distinct frequency-dependent features that change as a function of alginate and crosslinker concentration reflecting ion kinetics inside the measured sample. Furthermore, the presence of NIH 3T3 fibroblasts encapsulated in the hydrogels matrix was found to alter the artificial tissue's electrical properties. The method used provides valuable insight to the frequency-dependent electrical response of the resulting systems. It is hoped that the outcome of this research will be of use in the development of cell/electronic interfaces, possibly toward diagnostic biosensors and therapeutic bioelectronics.

Osteogenic Effect and Cell Signaling Activation of Extremely Low-Frequency Pulsed Electromagnetic Fields in Adipose-Derived Mesenchymal Stromal Cells

Extremely low-frequency pulsed electromagnetic field (ELF-PEMF) devices have been used in the clinic for the treatment of bone disorders over the past 30 years. However, the underlying mechanism of which ELF-PEMFs exert an effect on tissues at a cellular level is not well understood. Hence, in this study, we explored the potential of different ELF-PEMF signals in modulating human adipose-derived mesenchymal stromal cells' (hAMSC) osteogenic capability. The cell proliferation rate was assessed using carboxyfluorescein succinimidyl ester (CFSE) method. The osteogenesis potential of cells was determined by alkaline phosphatase (ALP) activity, Alizarin-Red S staining, and RT-qPCR. Finally, the intracellular signaling pathway of a selected ELF-PEMF signal was examined using the PathScan Intracellular Signaling Array. Among the tested ELF-PEMF signals, program 20 (26 Hz) showed activation of the Akt and MAPK/ERK signaling cascade and significant upregulations of collagen I, alkaline phosphatase, and osteocalcin when compared to nonstimulated cells. This study demonstrates the potential of certain ELF-PEMF signal parameters to induce osteogenic differentiation of hAMSC and provides important clues in terms of the molecular mechanisms for the stimulation of osteogenic effects by ELF-PEMF on hAMSC.

The Effects of a Pulsed Electromagnetic Field on the Proliferation and Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Background

A low frequency pulsed electromagnetic field (PEMF) has been confirmed to play an important role in promoting the osteogenic differentiation of human bone marrow stem cells (BMSCs). Adipose-derived stem cells (ASCs) possess some attractive characteristics for clinical application compared to BMSCs, such as abundant stem cells from lipoaspirates, faster growth, less discomfort and morbidity during surgery. ASCs can become adipocytes, osteoblasts, chondrocytes, myocytes, neurocytes, and other cell types. Thus, ASCs might be a good alternative in clinical work involving treatment with PEMF.

Material/Methods

Human ASCs (hASCs)were divided into a control group (without PEMF exposure) and an experimental group (PEMF for two hours per day). We examined the effect of PEMF on promoting cell proliferation and osteogenic differentiation from several aspects: CCK-8 proliferation assay, RNA extraction, qRT-PCR detection, western blotting, and immunofluorescence staining experiments.

Results

PEMF could promote cell proliferation of human ASCs (hASCs) at an early stage as determined by CCK-8 assay. A specific intensity (1 mT) and frequency (50 Hz) of PEMF promoted osteogenic differentiation in hASCs in alkaline phosphatase (ALP) staining experiments. In addition, bone-related gene expression increased after two weeks of PEMF exposure, the protein expression of OPN, OCN, and RUNX-2 also increased after a longer period (three weeks) of PEMF treatment as determined by western blotting and immunofluorescence staining.

Conclusions

We found for the first time that PMEF has a role in stimulating cell proliferation of hASCs at an early period, subsequently promoting bone-related gene expression and inducing the expression of related proteins to stimulate osteogenic differentiation.

Enhancement of osteogenic differentiation of rat adipose tissue-derived mesenchymal stem cells by zinc sulphate under electromagnetic field via the PKA, ERK1/2 and Wnt/β-catenin signaling pathways

Zinc ion as an essential trace element and electromagnetic fields (EMFs) has been reported to be involved in the regulation of bone metabolism. The aim of this study was to elucidate the effects of zinc sulphate (ZnSO₄) on the osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) in the presence of EMF as a strategy in osteoporosis therapy. Alkaline phophatase (ALP) activity measurement, calcium assay and expression of several osteoblastic marker genes were examined to assess the effect of ZnSO₄ on the osteogenic differentiation of ADSCs under EMF. The expression of cAMP and PKA was evaluated by ELISA. The expression of β-catenin, Wnt1, Wnt3a, low-density lipoprotein receptor-related protein 5 (LRP5) and reduced dickkopf1 (DKK1) genes were used to detect the Wnt/β-catenin pathway. It was found that ZnSO₄, in the presence of EMF, resulted in an increase in the expression of osteogenic genes, ALP activity and calcium levels. EMF, in the presence of ZnSO₄, increased the cAMP level and protein kinase A (PKA) activity. Treatment of ADSCs with (MAPK)/ERK kinase 1/2 inhibitor, or PKA inhibitor, significantly inhibited the promotion of osteogenic markers, indicating that the induction of osteogenesis was dependent on the ERK and PKA signaling pathways. Real-time PCR analysis showed that ZnSO₄, in the presence of EMF, increased the mRNA expressions of β-catenin, Wnt1, Wnt3a, LRP5 and DKK1. In this study, it was shown that 0.432 μg/ml ZnSO₄, in the presence of 50 Hz, 20 mT EMF, induced the osteogenic differentiation of ADSCs via PKA, ERK1/2 and Wnt/β-catenin signaling pathways.

Effect of a low-frequency pulsed electromagnetic field on expression and secretion of IL-1β and TNF-α in nucleus pulposus cells

Objective

To investigate changes in nucleus pulposus cell expression and secretion of interleukin (IL)-1β and tumour necrosis factor (TNF)-α following stimulation with a low-frequency (LF) pulsed electromagnetic field (PEMF).

Methods

Primary rat nucleus pulposus cells were isolated and cultured in vitro, followed by stimulation with LF-PEMFs at a frequency of 2 Hz and different intensities, ranging from 0.5–3.0 A/m. Cells were observed for morphological changes, and proliferation rates were measured by cell viability counts. Expression of IL-1β and TNF-α within the nucleus pulposus cells was measured using western blotting, and levels of IL-1β and TNF-α secreted in the culture media were measured using enzyme-linked immunosorbent assay.

Results

Stimulation of nucleus pulposus cells with LF-PEMFs did not appear to affect cell morphology or nucleus pulposus cell IL-1β and TNF-α expression levels. LF-PEMFs did not significantly affect cell proliferation, however, levels of IL-1β and TNF-α secreted into the culture media were found to be significantly reduced in an intensity-dependent manner.

Conclusion

Low-frequency PEMF stimulation may inhibit secretion of IL-1β and TNF-α in cultured nucleus pulposus cells.

Therapeutic potential of dental stem cells

Stem cell biology has become an important field in regenerative medicine and tissue engineering therapy since the discovery and characterization of mesenchymal stem cells. Stem cell populations have also been isolated from human dental tissues, including dental pulp stem cells, stem cells from human exfoliated deciduous teeth, stem cells from apical papilla, dental follicle progenitor cells, and periodontal ligament stem cells. Dental stem cells are relatively easily obtainable and exhibit high plasticity and multipotential capabilities. The dental stem cells represent a gold standard for neural-crest-derived bone reconstruction in humans and can be used for the repair of body defects in low-risk autologous therapeutic strategies. The bioengineering technologies developed for tooth regeneration will make substantial contributions to understand the developmental process and will encourage future organ replacement by regenerative therapies in a wide variety of organs such as the liver, kidney, and heart. The concept of developing tooth banking and preservation of dental stem cells is promising. Further research in the area has the potential to herald a new dawn in effective treatment of notoriously difficult diseases which could prove highly beneficial to mankind in the long run.

Interplay of Substrate Conductivity, Cellular Microenvironment, and Pulsatile Electrical Stimulation toward Osteogenesis of Human Mesenchymal Stem Cells in Vitro

The influences of physical stimuli such as surface elasticity, topography, and chemistry over mesenchymal stem cell proliferation and differentiation are well investigated. In this context, a fundamentally different approach was adopted, and we have demonstrated the interplay of inherent substrate conductivity, defined chemical composition of cellular microenvironment, and intermittent delivery of electric pulses to drive mesenchymal stem cell differentiation toward osteogenesis. For this, conducting polyaniline (PANI) substrates were coated with collagen type 1 (Coll) alone or in association with sulfated hyaluronan (sHya) to form artificial extracellular matrix (aECM), which mimics the native microenvironment of bone tissue. Further, bone marrow derived human mesenchymal stem cells (hMSCs) were cultured on these moderately conductive (10(-4)-10(-3) S/cm) aECM coated PANI substrates and exposed intermittently to pulsed electric field (PEF) generated through transformer-like coupling (TLC) approach over 28 days. On the basis of critical analysis over an array of end points, it was inferred that Coll/sHya coated PANI (PANI/Coll/sHya) substrates had enhanced proliferative capacity of hMSCs up to 28 days in culture, even in the absence of PEF stimulation. On the contrary, the adopted PEF stimulation protocol (7 ms rectangular pulses, 3.6 mV/cm, 10 Hz) is shown to enhance osteogenic differentiation potential of hMSCs. Additionally, PEF stimulated hMSCs had also displayed different morphological characteristics as their nonstimulated counterparts. Concomitantly, earlier onset of ALP activity was also observed on PANI/Coll/sHya substrates and resulted in more calcium deposition. Moreover, real-time polymerase chain reaction results indicated higher mRNA levels of alkaline phosphatase and osteocalcin, whereas the expression of other osteogenic markers such as Runt-related transcription factor 2, Col1A, and osteopontin exhibited a dynamic pattern similar to control cells that are cultured in osteogenic medium. Taken together, our experimental results illustrate the interplay of multiple parameters such as substrate conductivity, electric field stimulation, and aECM coating on the modulation of hMSC proliferation and differentiation in vitro.

Impact of electromagnetic fields on stem cells: common mechanisms at the crossroad between adult neurogenesis and osteogenesis

In the recent years adult neural and mesenchymal stem cells have been intensively investigated as effective resources for repair therapies. In vivo and in vitro studies have provided insights on the molecular mechanisms underlying the neurogenic and osteogenic processes in adulthood. This knowledge appears fundamental for the development of targeted strategies to manipulate stem cells. Here we review recent literature dealing with the effects of electromagnetic fields on stem cell biology that lends support to their use as a promising tool to positively influence the different steps of neurogenic and osteogenic processes. We will focus on recent studies revealing that extremely-low frequency electromagnetic fields enhance adult hippocampal neurogenesis by inducing epigenetic modifications on the regulatory sequences of genes responsible for neural stem cell proliferation and neuronal differentiation. In light of the emerging critical role played by chromatin modifications in maintaining the stemness as well as in regulating stem cell differentiation, we will also attempt to exploit epigenetic changes that can represent common targets for electromagnetic field effects on neurogenic and osteogenic processes.

Effects of long-term 50Hz power-line frequency electromagnetic field on cell behavior in Balb/c 3T3 cells

Power-line frequency electromagnetic field (PF-EMF) was reported as a human carcinogen by some epidemiological research, but the conclusion is lack of robust experiment evidence. To identify the effects of long-term PF-EMF exposure on cell behavior, Balb/c 3T3 cells in exponential growth phase were exposed or sham-exposed to 50 Hertz (Hz) PF-EMF at 2.3 mT for 2 hours (h) one day, 5 days every week. After 11 weeks exposure, cells were collected instantly. Cell morphology was observed under invert microscope and Giemsa staining, cell viability was detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and apoptosis was examined by flow cytometry, the protein level of Proliferating Cell Nuclear Antigen (PCNA) and CyclinD1 was detected by western blot, cell transformation was examined by soft agar clone assay and plate clone forming test, and cell migration ability was observed by scratch adhesion test. It was found that after PF-EMF exposure, cell morphology, apoptosis, cell migration ability and cell transformation didn't change. However, compared with sham group, cell viability obviously decreased and cell cycle distribution also changed after 11 weeks PF-EMF exposure. Meanwhile, the protein level of PCNA and CyclinD1 significantly decreased after PF-EMF exposure. These data suggested that although long-term 50Hz PF-EMF exposure under this experimental condition had no effects on apoptosis, cell migration ability and cell transformation, it could affect cell proliferation and cell cycle by down-regulation the expression of PCNA and CyclinD1 protein.

In vitro effects of low-intensity pulsed ultrasound stimulation on the osteogenic differentiation of human alveolar bone-derived mesenchymal stem cells for tooth tissue engineering

Ultrasound stimulation produces significant multifunctional effects that are directly relevant to alveolar bone formation, which is necessary for periodontal healing and regeneration. We focused to find out effects of specific duty cycles and the percentage of time that ultrasound is being generated over one on/off pulse period, under ultrasound stimulation. Low-intensity pulsed ultrasound ((LIPUS) 1 MHz) with duty cycles of 20% and 50% was used in this study, and human alveolar bone-derived mesenchymal stem cells (hABMSCs) were treated with an intensity of 50 mW/cm(2) and exposure time of 10 min/day. hABMSCs exposed at duty cycles of 20% and 50% had similar cell viability (O.D.), which was higher (*P < 0.05) than that of control cells. The alkaline phosphatase (ALP) was significantly enhanced at 1 week with LIPUS treatment in osteogenic cultures as compared to control. Gene expressions showed significantly higher expression levels of CD29, CD44, COL1, and OCN in the hABMSCs under LIPUS treatment when compared to control after two weeks of treatment. The effects were partially controlled by LIPUS treatment, indicating that modulation of osteogenesis in hABMSCs was related to the specific stimulation. Furthermore, mineralized nodule formation was markedly increased after LIPUS treatment than that seen in untreated cells. Through simple staining methods such as Alizarin red and von Kossa staining, calcium deposits generated their highest levels at about 3 weeks. These results suggest that LIPUS could enhance the cell viability and osteogenic differentiation of hABMSCs, and could be part of effective treatment methods for clinical applications.