Optimal currents for electrical stimulation of bone fracture repair: A computational analysis including variations in frequency, tissue properties, and fracture morphology

A Biomimetic Nanogenerator to Enhance Bone Regeneration by Restoring Electric Microenvironments

Piezoelectric materials have received increasing attention in bone regeneration due to their prominent role in bioelectricity in bone homeostasis. This study aimed to develop bioactive barium titanate-chitosan-graphene oxide piezoelectric nanoparticles (BCG-NPs) to improve biocompatibility and stimulate bone repair. Butterfly loops, hysteresis loops, and in vitro microcurrent studies on BCG-NPs confirmed their good piezoelectric properties. BCG-NPs exhibited enhanced alkaline phosphatase activity, mineralized nodule formation, and expression of osteogenic-associated proteins and genes in human umbilical cord Wharton's jelly-derived mesenchymal stem cells by creating microelectric environments in response to noninvasive ultrasound stimulation. Further, BCG-NPs upregulated intracellular calcium ions via electrical stimulation. They acted synergistically with piezo-type mechanosensitive ion channel component 1 and calcium-permeable cation channel transient receptor potential vanilloid 4 to activate osteogenic differentiation. In conclusion, ultrasound-assisted BCG-NPs created a microelectric environment that putatively promoted bone repair in a noninvasive manner.

Electromagnetic Fields Generated by the IteraCoil Device Differentiate Mesenchymal Stem Progenitor Cells Into the Osteogenic Lineage

Rapid advances in mesenchymal stem progenitor cells (MSPCs) have rendered impetus into the area of cell therapy and regenerative medicine. The main promise of future stem cell therapies is their reliance on autologous stem cells derived from adipose tissue, which also includes treatments of bone fractures and degeneration. The effectiveness of different electric devices utilized to reprogram MSPCs toward osteogenic differentiation has provided varying degrees of effectiveness for clinical use. Adipose tissue-derived MSPCs were flow-cytometrically characterized and further differentiated into osteoblasts by culturing either in growth medium with pro-osteogenic supplements or without supplements with alternating electromagnetic field (EMF) generated by IteraCoil. IteraCoil is a multi-solenoid coil with a specific complex geometry that creates a 3D-EMF with desired parameters without directly applying electrodes to the cells and tissues. The flow-cytometric analysis of highly enriched (≥95%) adipose-derived MSPCs (CD34^- , CD73⁺ , CD90⁺ , and CD105⁺ ) was utilized for the study. Osteoblasts and chondrocyte differentiations were then assessed by specific staining and quantified using ImageJ (National Institutes of Health). The osteoblastic differentiation of MSPCs cultured in regular medium and exposed to EMF at 0.05 and 1 kHz frequencies was compared with MSPCs cultured in a pro-osteogenic supplemented medium. In this study, we demonstrated that EMF from IteraCoil might have affected the signaling pathways that induce the osteogenic differentiation of human adipose-derived MSPCs in the absence of exogenous osteogenic factors. Therefore, EMF-generated osteogenic differentiation of reprogrammed adipose-derived autologous MSPCs may treat the loss of osteoblasts and osteoporosis and open new avenues for the development of regenerative cellular therapy. © 2022 Bioelectromagnetics Society.

On the Effect of Electroacupuncture in Promoting Healing after High Tibial Osteotomy

Purpose

To explore the clinical effect of electroacupuncture in promoting the healing of the osteotomy area after high tibial osteotomy.

Methods

50 patients with knee osteoarthritis who underwent open wedge high tibial osteotomy (OWHTO) were selected and randomly divided into the observation group and control group. The control group got the common postoperative treatment, and the observation group was added electroacupuncture from the 3rd day after the operation on the basis of the control group. The electroacupuncture acupoints were selected SP10, ST34, ST32, EX-LE2, ST40,KI6, KI3, SP6, and ST41, once a day, and 14 days were a course of treatment. And then we contrasted the index of the Lane-Sandhu X-ray score, the skin incision healing time, the swelling subsided time, Visual Analogue Scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index Score (WOMAC), and Lysholm in different time.

Results

The Lane-Sandhu X-ray score of the observation group was better than that of the control group at all time points (P < 0.05), and the time to achieve bone healing was about 2 weeks earlier than that of the control group. The skin healing and swelling were the subsided time in the osteotomy area. Both were better than the control group, and the difference was statistically significant (P < 0.05). The VAS score, WOMAC score, and Lysholm score of the two groups were significantly improved compared with preoperatively, and the difference was statistically significant (P < 0.05). The improvement of the observation group's VAS score, WOMAC score, and Lysholm score at 1 week, 4 weeks, and 8 weeks after the end of the treatment course was better than that of the control group, and the difference was statistically significant (P < 0.05).

Conclusion

Electroacupuncture can quicken the healing of bone tissue and surrounding soft tissues in the osteotomy area after high tibial osteotomy, and at the same time, it can help the relief of knee joint pain and improve knee joint function.

Theoretical analysis of the electrochemical systems used for the application of direct current/voltage stimuli on cell cultures

Endogenous electric fields drive many essential functions relating to cell proliferation, motion, differentiation and tissue development. They are usually mimicked in vitro by using electrochemical systems to apply direct current or voltage stimuli to cell cultures. The many studies devoted to this topic have given rise to a wide variety of experimental systems, whose results are often difficult to compare. Here, these systems are analysed from an electrochemical standpoint to help harmonize protocols and facilitate optimal understanding of the data produced. The theoretical analysis of single-electrode systems shows the necessity of measuring the Nernst potential of the electrode and of discussing the results on this basis rather than using the value of the potential gradient. The paper then emphasizes the great complexity that can arise when high cell voltage is applied to a single electrode, because of the possible occurrence of anode and cathode sites. An analysis of two-electrode systems leads to the advice to change experimental practices by applying current instead of voltage. It also suggests that the values of electric fields reported so far may have been considerably overestimated in macro-sized devices. It would consequently be wise to revisit this area by testing considerably lower electric field values.

Biomedical applications of electrical stimulation

This review provides a comprehensive overview on the biomedical applications of electrical stimulation (EStim). EStim has a wide range of direct effects on both biomolecules and cells. These effects have been exploited to facilitate proliferation and functional development of engineered tissue constructs for regenerative medicine applications. They have also been tested or used in clinics for pain mitigation, muscle rehabilitation, the treatment of motor/consciousness disorders, wound healing, and drug delivery. However, the research on fundamental mechanism of cellular response to EStim has fell behind its applications, which has hindered the full exploitation of the clinical potential of EStim. Moreover, despite the positive outcome from the in vitro and animal studies testing the efficacy of EStim, existing clinical trials failed to establish strong, conclusive supports for the therapeutic efficacy of EStim for most of the clinical applications mentioned above. Two potential directions of future research to improve the clinical utility of EStim are presented, including the optimization and standardization of the stimulation protocol and the development of more tissue-matching devices.