Electric fields regulate cellular elasticity through intracellular Ca2+ concentrations.

Cellular elasticity is a key factor related to a broad range of physiological and pathological processes. The elasticity of a single cell has thus emerged as a potential biomarker to characterize the cellular state. Both internal and external stimuli affect cellular elasticity, and changes in elasticity can cause alterations in cellular characteristics or function. The application of electric fields (EFs) is a promising method that can be used to change cellular elasticity; however, the mechanisms underlying its effect remain unknown. Here, we demonstrate EFs-induced elasticity changes in human dermal fibroblasts and discuss the underlying mechanism related to actin polymerization. Cellular elasticity increases after EF (50 mV/mm) stimulation, reaching a maximum at 30 min before decreasing between 30 and 120 min. The cellular elasticity under EF stimulation, regardless of stimulation time, is higher than that of the control. F-actin regulates the elasticity of cells through gelsolin activation. We show changes in intracellular Ca2+ caused by EFs, which induced gelsolin activation and F-actin content changes. This result demonstrates a series of processes in which external electrical stimulation conditions regulate cellular elasticity.

Challenges of applying multicellular tumor spheroids in preclinical phase.

The three-dimensional (3D) multicellular tumor spheroids (MCTs) model is becoming an essential tool in cancer research as it expresses an intermediate complexity between 2D monolayer models and in vivo solid tumors. MCTs closely resemble in vivo solid tumors in many aspects, such as the heterogeneous architecture, internal gradients of signaling factors, nutrients, and oxygenation. MCTs have growth kinetics similar to those of in vivo tumors, and the cells in spheroid mimic the physical interaction of the tumors, such as cell-to-cell and cell-to-extracellular matrix interactions. These similarities provide great potential for studying the biological properties of tumors and a promising platform for drug screening and therapeutic efficacy evaluation. However, MCTs are not well adopted as preclinical tools for studying tumor behavior and therapeutic efficacy up to now. In this review, we addressed the challenges with MCTs application and discussed various efforts to overcome the challenges.

Electric field-induced changes in biomechanical properties in human dermal fibroblasts and a human skin equivalent.

PURPOSE: An electric field (EF) can be used to change the mechanical properties of cells and skin tissues. We demonstrate EF-induced elasticity changes in human dermal fibroblasts (HDFs) and a human skin equivalent and identify the underlying principles related to the changes. METHODS: HDFs and human skin equivalent were stimulated with electric fields of 1.0 V/cm. Change in cellular elasticity was determined by using atomic force microscopy. Effects of EF on the biomechanical and chemical properties of a human skin equivalent were analyzed. In cells and tissues, the effects of EF on biomarkers of cellular elasticity were investigated at the gene and protein levels. RESULTS: In HDFs, the cellular elasticity was increased and the expression of biomarkers of cellular elasticity was regulated by the EF. Expression of the collagen protein in the human skin equivalent was changed by EF stimulation; however, changes in density and microstructure of the collagen fibrils were not significant. The viscoelasticity of the human skin equivalent increased in response to EF stimulation, but molecular changes were not observed in collagen. CONCLUSIONS: Elasticity of cells and human skin equivalent can be regulated by electrical stimulation. Especially, the change in cellular elasticity was dependent on cell age.

Surface Roughness on the Slots and Wings of Various Ceramic Self-Ligating Brackets and their Potential Concern on Biofilm Formation.

OBJECTIVE: The surface roughness of various orthodontic materials could affect biofilm formation and friction. The purpose of this study was to examine the surface roughness and chemical composition of the slots and wings of several ceramic self-ligating brackets. STUDY DESIGN: Four types of ceramic self-ligating brackets were separated into experimental groups (DC, EC, IC, and QK) while a metal self-ligating bracket (EM) was used as the control group. Atomic force microscopy and energy-dispersive x-ray spectroscope were used to examine the surface roughness and chemical composition of each bracket slot and wing. RESULTS: The control group was made of ferrum and chrome while all the experimental groups were comprised of aluminum and oxide. There was a statistically significant difference in the roughness average (Sa) among the various self-ligating brackets (p< 0.001 in slots and p<0.01 in the wing). The slots in the EC group had the lowest Sa, followed by the DC, IC, control, and QK groups. The wings in the IC group had the lowest Sa, followed by the EC, DC, control, and QK groups. CONCLUSIONS: There is a significant difference in the surface roughness of the slots and wings among several types of ceramic self-ligating brackets.

Biomechanical properties of red blood cells infected by Plasmodium berghei ANKA.

Malaria is a pathogenic disease in mammal species and typically causes destruction of red blood cells (RBCs). The malaria-infected RBCs undergoes alterations in morphology and its rheological properties, and the altered rheological properties of RBCs have a significant impact on disease pathophysiology. In this study, we investigated detailed topological and biomechanical properties of RBCs infected with malaria Plasmodium berghei ANKA using atomic force microscopy. Mouse (BALB/c) RBCs were obtained on Days 4, 10, and 14 after infection. We found that malaria-infected RBCs changed significantly in shape. The RBCs maintained a biconcave disk shape until Day 4 after infection and then became lopsided on Day 7 after infection. The central region of RBCs began to swell beginning on Day 10 after infection. More schizont stages were present on Days 10 and 14 compared with on Day 4. The malaria-infected RBCs also showed changes in mechanical properties and the cytoskeleton. The stiffness of infected RBCs increased 4.4-4.6-fold and their cytoskeletal F-actin level increased 18.99-67.85% compared with the control cells. The increase in F-actin depending on infection time was in good agreement with the increased stiffness of infected RBCs. Because more schizont stages were found at a late period of infection at Days 10 and 14, the significant changes in biomechanical properties might contribute to the destruction of RBCs, possibly resulting in the release of merozoites into the blood circulation.

Differential response of MDA­MB­231 breast cancer and MCF10A normal breast cells to cytoskeletal disruption.

Metastasis remains a major clinical problem in cancer diagnosis and treatment. Metastasis is the leading cause of cancer­related mortality but is still poorly understood. Cytoskeletal proteins are considered potential therapeutic targets for metastatic cancer cells because the cytoskeleton serves a key role in the migration and invasion of these cells. Vimentin and F­actin exhibit several functional similarities and undergo quantitative and structural changes during carcinogenesis. The present study investigated the effects of vimentin and F­actin deficiency on the survival and motility of breast cancer cells. In metastatic breast cancer cells (MDA­MB­231) and breast epithelial cells (MCF10A), vimentin was knocked down by small interfering RNA and F­actin was depolymerized by latrunculin A, respectively. The effect of reduced vimentin and F­actin content on cell viability was analyzed using the MTT assay and the proliferative capacity was compared by analyzing the recovery rate. The effect on motility was analyzed based on two processes: The distance traveled by tracking the cell nucleus and the movement of the protrusions. The effects on cell elasticity were measured using atomic force microscopy. Separately reducing vimentin or F­actin did not effectively inhibit the growth and motility of MDA­MB­231 cells; however, when both vimentin and F­actin were simultaneously deficient, MDA­MB­231 cells growth and migration were severely impaired. Vimentin deficiency in MDA­MB­231 cells was compensated by an increase in F­actin polymerization, but no complementary action of vimentin on the decrease in F­actin was observed. In MCF10A cells, no complementary interaction was observed for both vimentin and F­actin.

Contribution of mechanical homeostasis to epithelial-mesenchymal transition.

BACKGROUND: Metastasis refers to the spread of cancer cells from a primary tumor to other parts of the body via the lymphatic system and bloodstream. With tremendous effort over the past decades, remarkable progress has been made in understanding the molecular and cellular basis of metastatic processes. Metastasis occurs through five steps, including infiltration and migration, intravasation, survival, extravasation, and colonization. Various molecular and cellular factors involved in the metastatic process have been identified, such as epigenetic factors of the extracellular matrix (ECM), cell-cell interactions, soluble signaling, adhesion molecules, and mechanical stimuli. However, the underlying cause of cancer metastasis has not been elucidated. CONCLUSION: In this review, we have focused on changes in the mechanical properties of cancer cells and their surrounding environment to understand the causes of cancer metastasis. Cancer cells have unique mechanical properties that distinguish them from healthy cells. ECM stiffness is involved in cancer cell growth, particularly in promoting the epithelial-mesenchymal transition (EMT). During tumorigenesis, the mechanical properties of cancer cells change in the direction opposite to their environment, resulting in a mechanical stress imbalance between the intracellular and extracellular domains. Disruption of mechanical homeostasis may be one of the causes of EMT that triggers the metastasis of cancer cells.

Effects of red ginseng on the elastic properties of human skin.

BACKGROUND: Red ginseng contains components, including microelements, vitamins, essential oils, and fatty acids, that can be used in skincare to delay the aging process. We investigated the effects of red ginseng treatment on skin elasticity by assessing cellular stiffness and measuring collagen protein synthesis. METHODS: Human dermal fibroblasts were treated with red ginseng, and the resulting changes in stiffness were investigated using atomic force microscopy. Cytoskeletal changes and mRNA expression of biomarkers of aging, including that of procollagens I and VII, elastin, and fibrillin-1, were investigated. Collagen in a human skin equivalent treated with red ginseng was visualized via hematoxylin and eosin staining, scanning electron microscopy, and atomic force microscopy. RESULTS AND CONCLUSION: The stiffness of fibroblasts was significantly reduced by treatment with red ginseng concentrations of ≥ 0.8 mg/mL. The ratio of F-actin to G-actin decreased after treatment, which corresponded to a change in fibroblast stiffness. The storage modulus (G') and loss modulus (G″) of the skin equivalent were both lowered by red ginseng treatment. This result indicates that the viscoelasticity of the skin equivalent can be restored by red ginseng treatment.

On-off switching of cell cycle and melanogenesis regulation of melanocytes by non-thermal atmospheric pressure plasma-activated medium.

Non-thermal atmospheric pressure (NAP) plasma has demonstrated potential in biomedical applications, such as cancer treatment, bactericidal sterilization, and cell growth promotion or inhibition. In this study, for the first time, we demonstrated on-off switching of cell cycle progression and regulated melanogenesis in normal human skin melanocytes by NAP plasma-activated medium (PAM). The melanocytes were exposed to NAP plasma at durations varying from 0 to 20 min, and the effects of PAM on cell proliferation, cell cycle progression, and melanogenesis were investigated. Although PAM showed no cytotoxicity, the proliferation of melanocytes was inhibited. The melanocyte cell cycle was arrested by PAM for a relatively short period (48 h), after which it recovered slowly. PAM promoted melanogenesis through the activation of the enzymes tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2. These effects seem to be related to reactive oxygen species induced by PAM. Our finding that PAM modulates the cell cycle may provide insight into the recurrence of cancer. The regulation of the melanogenesis of melanocytes may facilitate the control of skin tone without incurring negative side effects.

Surface analysis of metal clips of ceramic self-ligating brackets.

OBJECTIVE: The aim of this study was to analyze the surface composition, roughness, and relative friction of metal clips from various ceramic self-ligating brackets. METHODS: Six kinds of brackets were examined. The control group (mC) consisted of interactive metal self-ligating brackets while the experimental group (CC, EC, MA, QK, and WA) consisted of interactive ceramic self-ligating brackets. Atomic force microscopy-lateral force microscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy were used to analyze the surface of each bracket clip. RESULTS: All the clips in the experimental groups were coated with rhodium except for the QK clip. The results showed that the QK clip had the lowest average roughness on the outer surface, followed by the MA, EC, WA, and CC clips. However, the CC clip had the lowest average roughness on the inner surface, followed by the QK, WA, MA, and EC clips. The QK clip also had the lowest relative friction on the outer surface, followed by the MA, EC, CC, and WA clips. Likewise, the CC clip had the lowest relative friction on the inner surface, followed by the QK, WA, MA, and EC clips. CONCLUSIONS: The surface roughness and relative friction of the rhodium-coated clips were generally higher than those of the uncoated clips.

Apoptotic effect of Gyejibokryunghwan on uterine sarcoma cells (SK-UT-1B).

BACKGROUND: Diagnosis of uterine sarcomais is a challenging task for clinicians because its position is not easily accessible by current conventional techniques. In addition, standardized treatment for uterine sarcoma has not yet been established due to its rarity and heterogeneity. HYPOTHESIS/PURPOSE: We investigated the apoptotic cell death of uterine sarcoma cells (SK-UT-1B) induced by Gyejibokryunghwan (GBH). GBH, an herbal medicine, has been widely used for gynecological diseases in Koean medicine. METHODS: SK-UT-1B cells were treated with GBH of varying concentrations from 0 to 500 µg/ml. The mechanism of cell death was investigated through multiple analysis methods, including flow cytometry, cell cycle, and western blotting. RESULTS: Flow cytometric analysis revealed that the number of apoptotic cells increased in a GBH dose-dependent manner. The cell populations of sub-G1 and G0/G1 phases were increased by GBH treatment, indicating apoptosisand cell arrest, while the population of S and G2/M phases decreased. With GBH, the expression levels of cleaved caspase-3, -6, and -9 were upregulated, while the expression levels of pro-caspase-3, -6, and -9 were down-regulated in SK-UT-1B cells. CONCLUSION: These results are the first observation of uterine sarcoma cell death induced by GBH and confirmation of the mechanism of cell death, which occurred through the intrinsic apoptotic pathway. Clinically, uterine sarcoma has a poor prognosis with no appropriate treatment. GBH may become a new treatment modality for uterine sarcoma.

Applications of Microfluidic Devices for Urology.

Microfluidics is considered an important technology that is suitable for numerous biomedical applications, including cancer diagnosis, metastasis, drug delivery, and tissue engineering. Although microfluidics is still considered to be a new approach in urological research, several pioneering studies have been reported in recent years. In this paper, we reviewed urological research works using microfluidic devices. Microfluidic devices were used for the detection of prostate and bladder cancer and the characterization of cancer microenvironments. The potential applications of microfluidics in urinary analysis and sperm sorting were demonstrated. The use of microfluidic devices in urology research can provide high-throughput, high-precision, and low-cost analyzing platforms.