- Cell migration directionality and speed are independently regulated by RasG and Gβ in Dictyostelium cells in electrotaxis. [Journal Article]
- BOBiol Open 2019 Jul 04; 8(7)
- Motile cells manifest increased migration speed and directionality in gradients of stimuli, including chemoattractants, electrical potential and substratum stiffness. Here, we demonstrate that Dictyo…
Motile cells manifest increased migration speed and directionality in gradients of stimuli, including chemoattractants, electrical potential and substratum stiffness. Here, we demonstrate that Dictyostelium cells move directionally in response to an electric field (EF) with specific acceleration/deceleration kinetics of directionality and migration speed. Detailed analyses of the migration kinetics suggest that migration speed and directionality are separately regulated by Gβ and RasG, respectively, in EF-directed cell migration. Cells lacking Gβ, which is essential for all chemotactic responses in Dictyostelium, showed EF-directed cell migration with the same increase in directionality in an EF as wild-type cells. However, these cells failed to show induction of the migration speed upon EF stimulation as much as wild-type cells. Loss of RasG, a key regulator of chemoattractant-directed cell migration, resulted in almost complete loss of directionality, but similar acceleration/deceleration kinetics of migration speed as wild-type cells. These results indicate that Gβ and RasG are required for the induction of migration speed and directionality, respectively, in response to an EF, suggesting separation of migration speed and directionality even with intact feedback loops between mechanical and signaling networks.
- A novel electro-chemotactic approach to impact the directional migration of transplantable retinal progenitor cells. [Journal Article]
- EEExp Eye Res 2019 Jun 08; 185:107688
- Photoreceptor degeneration is a significant cause of visual impairment in the United States and globally. Cell replacement therapy shows great promise in restoring vision by transplanting stem-like c…
Photoreceptor degeneration is a significant cause of visual impairment in the United States and globally. Cell replacement therapy shows great promise in restoring vision by transplanting stem-like cells into the sub-retinal space as substitutes for damaged photoreceptors. However, vision repair via transplantation has been limited, in large part, by low numbers of replacement cells able to migrate into damaged retinal tissue and integrate with native photoreceptors. Projects have used external chemical fields and applied electric fields to induce the chemotaxis and electrotaxis of replacement cells, respectively, with limited success. However, the application of combined electro-chemotactic fields in directing cells within biomaterials and host tissue has been surprisingly understudied. The current work examined the ability of combined electro-chemotactic fields to direct the migration of transplantable retinal progenitor cells (RPCs) in controlled microenvironments. Experiments used our established galvano-microfluidic system (Gal-MμS) to generate tunable chemotactic concentration fields with and without superimposed electric fields. Result illustrate that combination fields increased the distance migrated by RPCs by over three times that seen in either field, individually, and with greater directionality towards increasing gradients. Interestingly, immunofluorescence assays showed no significant differences in the distribution of the total and/or activated cognate receptor of interest, indicating that changes in ligand binding alone were not responsible for the measured increases in migration. Bioinformatics analysis was then performed to identity potential, synergistic mechanistic pathways involved in the electro-chemotaxis measured. Results indicate that increased RPC migration in electro-chemotactic fields may arise from down-regulation of cell adhesion proteins in tandem with up-regulation of cytoskeletal regulation proteins. These comprehensive results point towards a novel migration-targeted treatment that may dramatically improve transplantation outcomes as well as elucidate unreported synergy across biological mechanisms in response to electro-chemotactic fields.
- Stem cell passage affects directional migration of stem cells in electrotaxis. [Journal Article]
- SCStem Cell Res 2019; 38:101475
- Stem cells can differentiate into various body tissues and organs and thus are considered as promising tools for cell therapy and tissue engineering. Early passage stem cells have high differentiatio…
Stem cells can differentiate into various body tissues and organs and thus are considered as promising tools for cell therapy and tissue engineering. Early passage stem cells have high differentiation ability compared to late passage stem cells. Thus, it is important to use early passage stem cells in cell therapy. Here, we investigated whether cell migration could be used to compare young and senescent cells. We used 'electrotaxis' where cells under electric treatment move towards the anode or cathode. Without an electric stimulus, stem cells moved randomly. However, under a direct electric current, the cells moved with directionality. Under stimulation with a direct electric current, early passage stem cells moved towards the anode; when the cells became senescent with increasing passages, the percentage of cells migrating to the anode decreased. These results suggest that the behavior of stem cells under the influence of a direct electric current is also related to their passage number. Therefore, electrotaxis migration analysis can be used to distinguish between young cell and senescent cells.
- Doxycycline inhibits electric field-induced migration of non-small cell lung cancer (NSCLC) cells. [Journal Article]
- SRSci Rep 2019 May 30; 9(1):8094
- Adenocarcinoma, large cell carcinoma and squamous cell carcinoma are the most commonly diagnosed subtypes of non-small cell lung cancers (NSCLC). Numerous lung cancer cell types have exhibited electr…
Adenocarcinoma, large cell carcinoma and squamous cell carcinoma are the most commonly diagnosed subtypes of non-small cell lung cancers (NSCLC). Numerous lung cancer cell types have exhibited electrotaxis under direct current electric fields (dcEF). Physiological electric fields (EF) play key roles in cancer cell migration. In this study, we investigated electrotaxis of NSCLC cells, including human large cell lung carcinoma NCI-H460 and human lung squamous cell carcinoma NCI-H520 cells. Non-cancerous MRC-5 lung fibroblasts were included as a control. After dcEF stimulation, NCI-H460 and NCI-H520 cells, which both exhibit epithelial-like morphology, migrated towards the cathode, while MRC-5 cells, which have fibroblast-like morphology, migrated towards the anode. The effect of doxycycline, a common antibiotic, on electrotaxis of MRC-5, NCI-H460 and NCI-H520 cells was examined. Doxycycline enhanced the tested cells' motility but inhibited electrotaxis in the NSCLC cells without inhibiting non-cancerous MRC-5 cells. Based on our finding, further in-vivo studies could be devised to investigate the metastasis inhibition effect of doxycycline in an organism level.
- Electrical Stimulation Activates Fibroblasts through the Elevation of Intracellular Free Ca2+: Potential Mechanism of Pelvic Electrical Stimulation Therapy. [Journal Article]
- BRBiomed Res Int 2019; 2019:7387803
- Ca2+ is an important ion in response to electrical stimulation (ES) and acts as second messenger in the regulation of various physiological processes. Pelvic floor electrical stimulation (PES) is a l…
Ca2+ is an important ion in response to electrical stimulation (ES) and acts as second messenger in the regulation of various physiological processes. Pelvic floor electrical stimulation (PES) is a low-voltage clinical application, available for urinary incontinence (UI) treatment. Fibroblasts, as the main cellular component of vaginal wall and pelvic ligament, play an important role in the maintenance of pelvic health. We studied the effect of ES on fibroblasts in this study. ES was conducted with electrotaxis chambers on L929 fibroblast and the ES parameter was 100 mV/mm×2h. The results showed that ES increased intracellular Ca2+ concentration, promoted the expression of PCNA, CyclinB1, and CyclinD1, and increased the proportion of cells in S and G2 phages. After ES, fibroblasts get activated and proliferated. Besides, BAPTA-AM, a membrane permeated chelator for intracellular free Ca2+, partially inhibited the effect of ES on fibroblasts activation and proliferation promotion. Furthermore, we elucidated that Ca2+, as a second messenger and upstream signal for Smads and Akt signaling, regulated ES-induced nuclear translocation of smad2/3, phosphorylation of smad2/3, Akt, and GSK3β. Finally, we validated the effect of ES on PES mouse model. The results indicated that PES promoted the activation and proliferation of fibroblasts in vivo. In conclusion, we verify that ES can elevate the concentration of intracellular Ca2+ and activate its downstream signaling and then promote the activation of fibroblasts, which may be one of the mechanisms of PES therapy.
- Expression of integrins to control migration direction of electrotaxis. [Journal Article]
- FJFASEB J 2019 May 22; :fj201802657R
- Proper control of cell migration is critically important in many biologic processes, such as wound healing, immune surveillance, and development. Much progress has been made in the initiation of cell…
Proper control of cell migration is critically important in many biologic processes, such as wound healing, immune surveillance, and development. Much progress has been made in the initiation of cell migration; however, little is known about termination and sometimes directional reversal. During active cell migration, as in wound healing, development, and immune surveillance, the integrin expression profile undergoes drastic changes. Here, we uncovered the extensive regulatory and even opposing roles of integrins in directional cell migration in electric fields (EFs), a potentially important endogenous guidance mechanism. We established cell lines that stably express specific integrins and determined their responses to applied EFs with a high throughput screen. Expression of specific integrins drove cells to migrate to the cathode or to the anode or to lose migration direction. Cells expressing αMβ2, β1, α2, αIIbβ3, and α5 migrated to the cathode, whereas cells expressing β3, α6, and α9 migrated to the anode. Cells expressing α4, αV, and α6β4 lost directional electrotaxis. Manipulation of α9 molecules, one of the molecular directional switches, suggested that the intracellular domain is critical for the directional reversal. These data revealed an unreported role for integrins in controlling stop, go, and reversal activity of directional migration of mammalian cells in EFs, which might ensure that cells reach their final destination with well-controlled speed and direction.-Zhu, K., Takada, Y., Nakajima, K., Sun, Y., Jiang, J., Zhang, Y., Zeng, Q., Takada, Y., Zhao, M. Expression of integrins to control migration direction of electrotaxis.
- DC Electric Fields Induce Perpendicular Alignment and Enhanced Migration in Schwann Cell Cultures. [Journal Article]
- ABAnn Biomed Eng 2019; 47(7):1584-1595
- Schwann cells (SCs) are PNS glia that play numerous support functions including myelination of axons. After PNS injury, SCs facilitate regeneration by phagocytosing cellular debris and providing phys…
Schwann cells (SCs) are PNS glia that play numerous support functions including myelination of axons. After PNS injury, SCs facilitate regeneration by phagocytosing cellular debris and providing physical and biochemical cues to guide axon growth. This reparative phenotype suggests SCs could be critical cellular targets for enhancing nerve regeneration. One method for altering cell morphology and motility is the application of direct current (DC) electric fields (EFs). Endogenous EFs have physiologic relevance during embryogenesis and serve as guidance and polarization cues. While much literature exists on EFs and CNS and PNS neurons, the effects of EFs on SCs have not been extensively studied. In this work, cell alignment, migration, and morphology of rat SCs were measured in response to several EF stimulation regimes including constant DC, 50% duty cycle DC and oscillating DC. SCs were found to re-orient perpendicular to field lines and respond to DC EFs as low as 75 mV/mm. EF exposure promoted directed migration, with travel towards the cathode at a mean rate of 7.5 µm/h. The data highlight the utility of EFs in modulating SC morphology, alignment and migration. Results may have implications for using EFs to attract and realign SCs at the site of PNS trauma.
- Electrotaxis of Glioblastoma and Medulloblastoma Spheroidal Aggregates. [Journal Article]
- SRSci Rep 2019 Mar 29; 9(1):5309
- Treatment of neuroepithelial cancers remains a daunting clinical challenge, particularly due to an inability to address rampant invasion deep into eloquent regions of the brain. Given the lack of acc…
Treatment of neuroepithelial cancers remains a daunting clinical challenge, particularly due to an inability to address rampant invasion deep into eloquent regions of the brain. Given the lack of access, and the dispersed nature of brain tumor cells, we explore the possibility of electric fields inducing directed tumor cell migration. In this study we investigate the properties of populations of brain cancer undergoing electrotaxis, a phenomenon whereby cells are directed to migrate under control of an electrical field. We investigate two cell lines for glioblastoma and medulloblastoma (U87mg & DAOY, respectively), plated as spheroidal aggregates in Matrigel-filled electrotaxis channels, and report opposing electrotactic responses. To further understand electrotactic migration of tumor cells, we performed RNA-sequencing for pathway discovery to identify signaling that is differentially affected by the exposure of direct-current electrical fields. Further, using selective pharmacological inhibition assays, focused on the PI3K/mTOR/AKT signaling axis, we validate whether there is a causal relationship to electrotaxis and these mechanisms of action. We find that U87 mg electrotaxis is abolished under pharmacological inhibition of PI3Kγ, mTOR, AKT and ErbB2 signaling, whereas DAOY cell electrotaxis was not attenuated by these or other pathways evaluated.
- Keratinocyte electrotaxis induced by physiological pulsed direct current electric fields. [Journal Article]
- BBioelectrochemistry 2019; 127:113-124
- Endogenous electric fields (EFs) direct the migration (electrotaxis) of keratinocytes in skin wounds, and the exogenous application of EFs may therefore improve wound healing, but the potential benef…
Endogenous electric fields (EFs) direct the migration (electrotaxis) of keratinocytes in skin wounds, and the exogenous application of EFs may therefore improve wound healing, but the potential benefits are limited by the side effects of constant direct current (DC) passing through tissues. In contrast, with pulsed DC (characterized by intermittent output), parameters can be adjusted to minimize the adverse effects of electric currents. However, it remains unknown whether pulsed DC can reliably induce keratinocyte electrotaxis. In this study, using primary keratinocytes in an electrotaxis chamber, we found that a pulsed DCEF at physiological strength (EF = 150 mV/mm, duty cycle = 60%, frequency = 0.1 Hz) could induce robust electrotaxis. This effect was dependent on both voltage and duty cycle, but not on frequency. As predicted, fewer electrochemical reactions and cytotoxic reactions were detected with pulsed DCEF than with constant DCEF. In summary, we here demonstrate for the first time, that pulsed DCEF can trigger keratinocyte electrotaxis comparable to that induced by constant DCEF, while minimizing the electrochemical side effects. These findings support the future development of a pulsed DCEF device to improve wound healing in human patients.
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- An Essential and Synergistic Role of Purinergic Signaling in Guided Migration of Corneal Epithelial Cells in Physiological Electric Fields. [Journal Article]
- CPCell Physiol Biochem 2019; 52(2):198-211
- CONCLUSIONS: Extracellular ATP and physiological electric fields synergistically enhanced the galvanotaxis response of hTCEpi cells. hTCEpi cells are likely to secrete ATP actively, and purinergic signaling is down-regulated by ecto-ATPases. Both P2X and P2Y receptors coordinately play a role for galvanotaxis of hTCEpi cells.