Effects of electrical stimulation on cell activity, cell cycle, cell apoptosis and β‑catenin pathway in the injured dorsal root ganglion cell

Application of Conductive Hydrogels on Spinal Cord Injury Repair: A Review

Spinal cord injury (SCI) causes severe motor or sensory damage that leads to long-term disabilities due to disruption of electrical conduction in neuronal pathways. Despite current clinical therapies being used to limit the propagation of cell or tissue damage, the need for neuroregenerative therapies remains. Conductive hydrogels have been considered a promising neuroregenerative therapy due to their ability to provide a pro-regenerative microenvironment and flexible structure, which conforms to a complex SCI lesion. Furthermore, their conductivity can be utilized for noninvasive electrical signaling in dictating neuronal cell behavior. However, the ability of hydrogels to guide directional axon growth to reach the distal end for complete nerve reconnection remains a critical challenge. In this Review, we highlight recent advances in conductive hydrogels, including the incorporation of conductive materials, fabrication techniques, and cross-linking interactions. We also discuss important characteristics for designing conductive hydrogels for directional growth and regenerative therapy. We propose insights into electrical conductivity properties in a hydrogel that could be implemented as guidance for directional cell growth for SCI applications. Specifically, we highlight the practical implications of recent findings in the field, including the potential for conductive hydrogels to be used in clinical applications. We conclude that conductive hydrogels are a promising neuroregenerative therapy for SCI and that further research is needed to optimize their design and application.

Internal Wireless Electrical Stimulation from Piezoelectric Barium Titanate Nanoparticles as a New Strategy for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive BC subtype with a higher metastatic rate and a worse 5-year survival ratio than the other BC. It is an urgent need to develop a noninvasive treatment with high efficiency to resist TNBC cell proliferation and invasion. Internal wireless electric stimulation (ES) based on piezoelectric materials is an emerging noninvasive strategy, with adjustable ES intensity and excellent biosafety. In this study, three different barium titanate nanoparticles (BTNPs) with different crystal phases and piezoelectric properties were studied. Varying intensities of internal ES were generated from the three BTNPs (i.e., BTO, U-BTO, P-BTO). In vitro tests revealed that the internal ES from BTNPs was efficient at reducing the proliferative potential of cancer cells, particularly BC cells. In vitro experiments on MDA-MB-231, a typical TNBC cell line, further revealed that the internal wireless ES from BTNPs significantly inhibited cell growth and migration up to about 82% and 60%, respectively. In vivo evaluation of MDA-MB-231 tumor-bearing mice indicated that internal ES not only resisted almost 70% tumor growth but also significantly inhibited lung metastasis. More importantly, in vitro and in vivo studies demonstrated a favorable correlation between the anticancer impact and the intensities of ES. The underlying mechanism of MDA-MB-231 cell proliferation and metastasis inhibition caused by internal ES was also investigated. In summary, our results revealed the effect and mechanism of internal ES from piezoelectric nanoparticles on TNBC cell proliferation and migration regulation and proposed a promising noninvasive therapeutic strategy for TNBC with minimal side effects while exhibiting good therapeutic efficiency.

Effect of Electrical Stimulation on Ocular Cells: A Means for Improving Ocular Tissue Engineering and Treatments of Eye Diseases

Tissue engineering is biomedical engineering that uses suitable biochemical and physicochemical factors to assemble functional constructs that restore or improve damaged tissues. Recently, cell therapies as a subset of tissue engineering have been very promising in the treatment of ocular diseases. One of the most important biophysical factors to make this happen is noninvasive electrical stimulation (ES) to target ocular cells that may preserve vision in multiple retinal and optic nerve diseases. The science of cellular and biophysical interactions is very exciting in regenerative medicine now. Although the exact effect of ES on cells is unknown, multiple mechanisms are considered to underlie the effects of ES, including increased production of neurotrophic agents, improved cell migration, and inhibition of proinflammatory cytokines and cellular apoptosis. In this review, we highlighted the effects of ES on ocular cells, especially on the corneal, retinal, and optic nerve cells. Initially, we summarized the current literature on the in vitro and in vivo effects of ES on ocular cells and then we provided the clinical studies describing the effect of ES on ocular complications. For each area, we used some of the most impactful articles to show the important concepts and results that advanced the state of these interactions. We conclude with reflections on emerging new areas and perspectives for future development in this field.