CD9 promotes TßR2-TßR1 association driving the transition of human dermal fibroblasts to myofibroblast under hypoxia.

BACKGROUND: During wound healing, fibroblast to myofibroblast transition is required for wound contraction and remodeling. While hypoxia is an important biophysical factor in wound microenvironment, the exact regulatory mechanism underlying hypoxia and fibroblast-to-myofibroblast transition remains unclear. We previously found that tetraspanin CD9 plays an important role in oxygen sensing and wound healing. Herein, we investigated the effects of physiological hypoxia on fibroblast-to-myofibroblast transition and the biological function and mechanism of CD9 in it. METHODS: Human skin fibroblasts (HSF) and mouse dermis wounds model were established under physiological hypoxia (2% O2). The cell viability and contractility of HSF under hypoxia were evaluated by CCK8 and collagen gel retraction, respectively. The expression and distribution of fibroblast-to-myofibroblast transition markers and CD9 in HSF were detected by Western blotting and immunofluorescence. CD9 slicing and overexpressing HSFs were constructed to determine the role of CD9 by small interfering RNA and recombinant adenovirus vector. The association of TßR2 and TßR1 was measured by immunoprecipitation to explore the regulatory mechanism. Additionally, further validation was conducted on mouse dermis wounds model through histological analysis. RESULTS: Enhanced fibroblast-to-myofibroblast transition and upregulated CD9 expression was observed under hypoxia in vitro and in vivo. Besides, reversal of fibroblast-to-myofibroblast transition under hypoxia was observed when silencing CD9, suggesting that CD9 played a key role in this hypoxia-induced transition. Moreover, hypoxia increased fibroblast-to-myofibroblast transition by activating TGF-ß1/Smad2/3 signaling, especially increased interaction of TßR2 and TßR1. Ultimately, CD9 was determined to directly affect TßR1-TßR2 association in hypoxic fibroblast. CONCLUSION: Collectively, these findings suggest that CD9 promotes TßR2-TßR1 association, thus driving the transition of human dermal fibroblasts to myofibroblast under hypoxia.

A Network Meta-analysis to Explore the Effectiveness of the Different Treatment Modalities in Acne Scars.

BACKGROUND: Multiple treatments are used to treat acne scars, but comparing the effectiveness of these treatments have not been studied yet. This research aimed to conduct a complete analysis of the effectiveness of commonly used therapies in acne scars. METHODS: PubMed, Embase, and Cochrane's Library (Cochrane Center Register of Controlled Trials) databases were searched through May 2023. We used patient satisfaction score as the primary outcome and Goodman Baron qualitative scar grading system as the secondary outcome to evaluate the effectiveness of different commonly used therapies for acne scarring, including laser, microneedling (MN), platelet-rich plasma (PRP), autologous fat grafting and combined therapies. RESULTS: Herein, 495 patients from 13 studies were included. Our results showed that PRP combined with laser was the most effective among therapies in treating acne scars. Ranking of effectiveness by the surface under the cumulative ranking (SUCRA) curve for patient satisfaction score was as following: PRP + laser (96.2%) > laser (71.2%) > MN (45.5%) > MN + PRP (42.0%) > autologous fat grafting (24.5%) > PRP (20.5%). Additionally, ranking of effectiveness by the SUCRA curve for Goodman Baron qualitative scar grading system was as following: PRP + laser (86.3%) > laser (64.2%) > MN + PRP (54.2%) > MN (37.2%) > PRP (8.1%). CONCLUSION: This network meta-analysis indicated that the combined therapy of PRP and laser might be the most effective. Additionally, more high-quality randomized controlled trials are needed to verify our findings. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266 .

Electric field promotes dermal fibroblast transdifferentiation through activation of RhoA/ROCK1 pathway.

With the increased incidence of age-related and lifestyle-related diseases, chronic wounds are sweeping the world, where recent studies reveal that dysfunction of fibroblast plays an indispensable role. Endogenous electric field (EF) generated by skin wound disrupting an epithelial layer has been used as an alternative clinical treatment in chronic wound by modulating cellular behaviours, including fibroblasts transdifferentiation. Although many molecules and signaling pathways have been reported associated with fibroblasts transdifferentiation, studies investigating how the electric field affects the cellular pathways have been limited. For this purpose, a model of electric field treatment in vitro was established, where cells were randomly divided into control and electrified groups. The changes of protein expression and distribution were detected under different conditions, along with Zeiss imaging system observing the response of cells. Results showed that fibroblast transdifferentiation was accompanied by increased expression of a-SMA and extracellular matrix (COL-1 and COL-3) under the EF. Simultaneously, fibroblast transdifferentiation was also consistent with changes of cell arrangement and enhanced motility. Furthermore, we found that electric field activated RhoA signaling pathways activity. Y-27632, a RhoA inhibitor, which was used to treat fibroblasts, resulted in reduced transdifferentiation. The connection between electric field and RhoA signaling pathways is likely to be significant in modulating fibroblast transdifferentiation in acute injury and tissue remodeling, which provides an innovative idea for the molecular mechanism of EF in promoting chronic wound healing.

Autophagy is required for the directed motility of keratinocytes driven by electric fields.

Endogenous wound electric fields (EFs), an important and fundamental occurrence of wound healing, profoundly influence the directed migration of keratinocytes. Although numerous studies have unveiled the signals responsible for EF-biased direction, the mechanisms by which EFs promote keratinocyte motility remains to be elucidated. In our study, EFs enhanced the directed migratory speed of keratinocytes by inducing autophagic activity, thereby facilitating skin barrier restoration. Initially, we found that electrical signals directed keratinocytes to the cathode with enhanced motility parameters [ i.e., trajectory distance, trajectory speed, displacement distance, and displacement speed ( Td/ t)] and more efficient migration (directionality and Td/ t along the x axis, among others). Meanwhile, EFs induced a time-dependent increase in autophagic activity in keratinocytes, with constant autophagic flux, accompanied by increased transcription of numerous autophagy-related genes. Deficiency in Atg5, a key protein necessary for autophagosome formation, led to significant reduction of autophagy, which was accompanied by a substantial reduction in EF-stimulated directed motility. These results demonstrated a causal relationship between autophagy and EF-directed migratory speed. In addition, both cell migration under normal conditions and EF-biased directionality were autophagy independent. Thus, our findings define autophagy as an important functional regulator of electrically enhanced directed motility, adding to a growing understanding of EFs.-Yan, T., Jiang, X., Lin, G., Tang, D., Zhang, J., Guo, X., Zhang, D., Zhang, Q., Jia, J., Huang, Y. Autophagy is required for the directed motility of keratinocytes driven by electric fields.

Electric field down-regulates CD9 to promote keratinocytes migration through AMPK pathway.

Endogenous electric field (EF)-directed keratinocytes migration is known to play a key role in the wound re-epithelialization process. Although many molecules and signaling pathways are reported important for directional keratinocytes migration under EF, the underlying mechanism remains unclear. Our previous research found that CD9, a trans-membrane protein, is involved in wound re-epithelialization and CD9 downregulation contributes to keratinocytes migration. In this study, we observed the effect of EF on CD9 expression and keratinocytes migration. The keratinocytes migrated directionally toward the cathode and CD9 expression was down-regulated under EF (200mV/mm). In addition, CD9 overexpression reversed EF-induced migratory speed and the electrotactic response of keratinocytes. Also, we found that EF reduced AMP-activated protein kinase (AMPK) activity. Furthermore, AICAR, an AMPK activator, increased CD9 expression under EF, while compound C, an AMPK inhibitor, decreased CD9 expression in keratinocytes. Our results demonstrate that EF regulates CD9 expression and keratinocytes directional migration, in which AMPK pathway plays an important role.

Decreased α-tubulin acetylation induced by an acidic environment impairs autophagosome formation and leads to rat cardiomyocyte injury.

Extracellular pH strongly affects cellular metabolism and function. An acidic environment induced under pathological conditions leads to cardiomyocyte injury and dysfunction, but the underlying mechanisms are still poorly understood. Autophagy has been reported as a cytoprotective mechanism that maintains cellular metabolism and viability by removing misfolded proteins and damaged organelles. In our research, we found that acidic environments inhibit autophagosome formation in cardiomyocytes. Up-regulation of autophagic activity, however, ameliorates the cell injury induced by acidic treatments.We also found that acidic treatments reduce the level of α-tubulin acetylation, as detected by Western blot and immunofluorescence staining, and that the number of autophagosomes increase after up-regulating α-tubulin acetylation by Taxol, suggesting that α-tubulin acetylation may play an important role in acidic pH-induced changes in autophagy. Furthermore, an HDAC6 activity assay showed an increase in HDAC6 activity after acidic treatment and that inhibiting HDAC6 activity by tubastatin A or specific siRNA up-regulates α-tubulin acetylation and autophagosome formation. These data confirm that autophagy plays a protective role against acidic pH-induced cell injury and indicate that HDAC6-mediated α-tubulin acetylation is an important mechanism of acidic pH-dependent autophagy in cardiomyocytes.

FG-4592 Accelerates Cutaneous Wound Healing by Epidermal Stem Cell Activation via HIF-1α Stabilization.

BACKGROUND/AIMS: Regional hypoxia promptly develops after trauma because of microvascular injury and increased oxygen consumption. This acute hypoxia plays a positive role in early skin wound healing. One of the mechanisms underlying the beneficial effects of acute hypoxia on wound healing may be increased hypoxia-inducible factor-1 (HIF-1α) expression. HIF-1α may affect the wound-healing process through many aspects, including angiogenesis, metabolism, and extra-cellular matrix synthesis and remodelling. Epidermal stem cells (EpSCs) are important participants in wound repair; however, whether these cells are regulated by hypoxia is unclear. This study aimed to elucidate the regulatory mechanism by which hypoxia acts on EpSCs. METHODS: CCK8 assays, western blots and live cell station observation were employed to compare the viability, proliferation and motility of EpSCs cultured under normoxic conditions (21% O2) with those cultured under hypoxic conditions (2% O2). Moreover, we used FG-4592 (a prolyl hydroxylase inhibitor that stabilizes HIF-1α in normoxia), KC7F2 (a selective inhibitor of HIF-1α transcription) and siRNA against HIF-1α to regulate HIF-1α expression. RESULTS: Acute hypoxia caused EpSCs to switch from a quiescent state to an activated state with higher viability and motility, as well as an earlier proliferation peak. We demonstrated that the HIF-1 signalling pathway mediated hypoxia-induced activation of EpSCs. Finally, the in vivo experiments showed that exogenous FG-4592 effectively accelerates wound healing, shortens healing times and even induces epidermal hyperplasia. CONCLUSION: This study demonstrated that both hypoxia and exogenous FG-4592 improve EpSC proliferation and motility by stabilizing HIF-1α, and its results suggest that HIF-1α is an important target through which wound healing can be accelerated and that FG-4592 is a promising new drug for wound repair.

BNIP3 promotes the motility and migration of keratinocyte under hypoxia.

The migration of keratinocytes from wound margins plays a critical role in the re-epithelialization of skin wounds. Hypoxia occurs immediately after injury and acts as an early stimulus to initiate the healing processes. Although our previous studies have revealed that hypoxia promotes keratinocyte migration, the precise mechanisms involved remain unclear. Here, we found that BNIP3 expression was upregulated in hypoxic keratinocytes, and BNIP3 silencing suppressed hypoxia-induced cell migration. Additionally, hypoxia activated the focal adhesion kinase (FAK) pathway through upregulation of BNIP3, while FAK inhibition attenuated hypoxic keratinocyte migration. Here, we conclusively demonstrate a novel role for BNIP3 in hypoxia-induced keratinocyte migration. Furthermore, we provide a new perspective on the molecular mechanisms of wound healing and identify BNIP3 as a potential new molecular target for clinical treatments to enhance wound healing.

HSP27 phosphorylation protects against endothelial barrier dysfunction under burn serum challenge.

F-actin rearrangement is an early event in burn-induced endothelial barrier dysfunction. HSP27, a target of p38 MAPK/MK2 pathway, plays an important role in actin dynamics through phosphorylation. The question of whether HSP27 participates in burn-related endothelial barrier dysfunction has not been identified yet. Here, we showed that burn serum induced a temporal appearance of central F-actin stress fibers followed by a formation of irregular dense peripheral F-actin in pulmonary endothelial monolayer, concomitant with a transient increase of HSP27 phosphorylation that conflicted with the persistent activation of p38 MAPK/MK2 unexpectedly. The appearance of F-actin stress fibers and transient increase of HSP27 phosphorylation occurred prior to the burn serum-induced endothelial hyperpermeability. Overexpressing phospho-mimicking HSP27 (HSP27(Asp)) reversed the burn serum-induced peripheral F-actin rearrangement with the augmentation of central F-actin stress fibers, and more importantly, attenuated the burn serum-induced endothelial hyperpermeability; such effects were not observed by HSP27(Ala), a non-phosphorylated mutant of HSP27. HSP27(Asp) overexpression also rendered the monolayer more resistant to barrier disruption caused by Cytochalasin D, a chemical reagent that depolymerizes F-actin specifically. Further study showed that phosphatases and sumoylation-inhibited MK2 activity contributed to the blunting of HSP27 phosphorylation during the burn serum-induced endothelial hyperpermeability. Our study identifies HSP27 phosphorylation as a protective response against burn serum-induced endothelial barrier dysfunction, and suggests that targeting HSP27 wound be a promising therapeutic strategy in ameliorating burn-induced lung edema and shock development.

Ultra-Hydrophobic Gauze Driving Super-Haemostasis.

Controlling bleeding by applying pressing cotton gauze is the most facile treatment in prehospital emergencies. However, the wettable nature of cotton fibers leads to unnecessary blood loss due to excessive blood absorption, inseparable adhesion-induced pain, and pliable to infection. Here, a kind of ultra-hydrophobic haemostatic anti-adhesive gauze whose surface is loaded with polydimethylsiloxane (PDMS) and hydrophobic-modified cellulose nanocrystals (CNCs), achieving a water contact angle of ≈160° is developed. It is demonstrated that the mechanism by which hydrophobic CNCs promote blood clotting is associated with their ability to activate coagulation factors, contributing to fibrin formation, and promoting platelet activation. The blood-restricting effect results from the low surface energy layer formed by PDMS and then the alkyl chains of hydrophobic CNCs are combined. The produced ultra-hydrophobic gauze resists blood flow and diffusion, decreases blood loss, is effortlessly peelable, and minimizes pathogen adhesion. Compared to the commercial cotton gauze, this gauze achieved effective haemostasis and antiadhesion by reducing blood loss by more than 90%, shortening haemostasis time by more than 75%, lowering peeling force by more than 90% and minifying bacterium attachment by more than 95%. This work presents promising applications in terms of prehospital first aid.

Electric fields reverse the differentiation of keratinocyte monolayer by down-regulating E-cadherin through PI3K/AKT/Snail pathway.

Re-epithelialization is an important step in skin wound healing, referring to the migration, proliferation, and differentiation of keratinocytes around the wound. During this process, the edges of the wound begin to form new epithelial cells, which migrate from the periphery of the wound towards the center, gradually covering the entire wound area. These newly formed epithelial cells proliferate and differentiate, ultimately forming a protective layer over the exposed dermal surface. Wound endogenous electric fields (EFs) are known as the dominant factor to facilitate the epidermal migration to wound center. However, the precise mechanisms by which EFs promote epidermal migration remains elusive. Here, we found that in a model of cultured keratinocyte monolayer in vitro, EFs application reversed the differentiation of cells, as indicated by the reduction of the early differentiation markers K1 and K10. Genetic manipulation confirmed that EFs reversed keratinocyte differentiation through down-regulating the E-cadherin-mediated adhesion. By RNA-sequencing analysis, we screened out Snail as the transcription suppressor of E-cadherin. Snail knockdown abolished the down-regulation of E-cadherin and the reversal of differentiation induced by EFs. KEGG analysis identified PI3K/AKT signaling for Snail induction under EFs. Inhibition of PI3K by LY294002 diminished the EFs-induced AKT activation and Snail augmentation, largely restoring the level of E-cadherin reduced by EFs. Finally, in model of full-thickness skin wounds in pigs, we found that weakening of the wound endogenous EFs by the direction-reversed exogenous EFs resulted in an up-regulation of E-cadherin and earlier differentiation in newly formed epidermis in vivo. Our research suggests that electric fields (EFs) decrease E-cadherin expression by suppressing the PI3K/AKT/Snail pathway, thereby reversing the differentiation of keratinocytes. This discovery provides us with new insights into the role of electric fields in wound healing. EFs intervene in intracellular signaling pathways, inhibiting the expression of E-cadherin, which results in a lower differentiation state of keratinocytes. In this state, keratinocytes exhibit increased migratory capacity, facilitating the migration of epidermal cells and wound reepithelialization.

Paxillin/HDAC6 regulates microtubule acetylation to promote directional migration of keratinocytes driven by electric fields.

Endogenous electric fields (EFs) have been demonstrated to facilitate wound healing by directing the migration of epidermal cells. Despite the identification of numerous molecules and signaling pathways that are crucial for the directional migration of keratinocytes under EFs, the underlying molecular mechanisms remain undefined. Previous studies have indicated that microtubule (MT) acetylation is linked to cell migration, while Paxillin exerts a significant influence on cell motility. Therefore, we postulated that Paxillin could enhance EF-induced directional migration of keratinocytes by modulating MT acetylation. In the present study, we observed that EFs (200 mV/mm) induced migration of human immortalized epidermal cells (HaCaT) towards the anode, while upregulating Paxillin, downregulating HDAC6, and increasing the level of microtubule acetylation. Our findings suggested that Paxillin plays a pivotal role in inhibiting HDAC6-mediated microtubule acetylation during directional migration under EF regulation. Conversely, downregulation of Paxillin decreased microtubule acetylation and electrotaxis of epidermal cells by promoting HDAC6 expression, and this effect could be reversed by the addition of tubacin, an HDAC6-specific inhibitor. Furthermore, we observed that EFs also mediated the polarization of Paxillin and acetylated α-tubulin, which is critical for directional migration. In conclusion, our study revealed that MT acetylation in EF-guided keratinocyte migration is regulated by the Paxillin/HDAC6 signaling pathway, providing a novel theoretical foundation for the molecular mechanism of EF-guided directional migration of keratinocytes.

The role of mesenchymal stem cell-derived EVs in diabetic wound healing.

Diabetic foot is one of the most common complications of diabetes, requiring repeated surgical interventions and leading to amputation. In the absence of effective drugs, new treatments need to be explored. Previous studies have found that stem cell transplantation can promote the healing of chronic diabetic wounds. However, safety issues have limited the clinical application of this technique. Recently, the performance of mesenchymal stem cells after transplantation has been increasingly attributed to their production of exocrine functional derivatives such as extracellular vesicles (EVs), cytokines, and cell-conditioned media. EVs contain a variety of cellular molecules, including RNA, DNA and proteins, which facilitate the exchange of information between cells. EVs have several advantages over parental stem cells, including a high safety profile, no immune response, fewer ethical concerns, and a reduced likelihood of embolism formation and carcinogenesis. In this paper, we summarize the current knowledge of mesenchymal stem cell-derived EVs in accelerating diabetic wound healing, as well as their potential clinic applications.

Reshaping the Endogenous Electric Field to Boost Wound Repair via Electrogenerative Dressing.

The endogenous electric field (EF) generated by transepithelial potential difference plays a decisive role in wound reepithelialization. For patients with large or chronic wounds, negative-pressure wound therapy (NPWT) is the most effective clinical method in inflammation control by continuously removing the necrotic tissues or infected substances, thus creating a proproliferative microenvironment beneficial for wound reepithelialization. However, continuous negative-pressure drainage causes electrolyte loss and weakens the endogenous EF, which in turn hinders wound reepithelialization. Here, an electrogenerative dressing (EGD) is developed by integrating triboelectric nanogenerators with NPWT. By converting the negative-pressure-induced mechanical deformation into electricity, EGD produces a stable and high-safety EF that can trigger a robust epithelial electrotactic response and drive the macrophages toward a reparative M2 phenotype in vitro. Translational medicine studies confirm that EGD completely reshapes the wound EF weakened by NPWT, and promotes wound closure by facilitating an earlier transition of inflammation/proliferation and guiding epithelial migration and proliferation to accelerate reepithelialization. Long-term EGD therapy remarkably advances tissue remodeling with mature epithelium, orderly extracellular matrix, and less scar formation. Compared with the golden standard of NPWT, EGD orchestrates all the essential wound stages in a noninvasive manner, presenting an excellent prospect in clinical wound therapy.

CD9 negatively regulates collective electrotaxis of the epidermal monolayer by controlling and coordinating the polarization of leader cells.

Background: Endogenous electric fields (EFs) play an essential role in guiding the coordinated collective migration of epidermal cells to the wound centre during wound healing. Although polarization of leadercells is essential for collective migration, the signal mechanisms responsible for the EF-induced polarization of leader cells under electrotactic collective migration remain unclear. This study aims to determine how the leader cells are polarized and coordinated during EF-guided collective migration of epidermal cell sheets. Methods: Collective migration of the human epidermal monolayer (human immortalized keratinocytes HaCaT) under EFs was observed via time-lapse microscopy. The involvement of tetraspanin-29 (CD9) in EF-induced fibrous actin (F-actin) polarization of leader cells as well as electrotactic migration of the epidermal monolayer was evaluated by genetic manipulation. Blocking, rescue and co-culture experiments were conducted to explore the downstream signalling of CD9. Results: EFs guided the coordinated collective migration of the epithelial monolayer to the anode, with dynamic formation of pseudopodia in leader cells at the front edge of the monolayer along the direction of migration. F-actin polarization, as expected, played an essential role in pseudopod formation in leader cells under EFs. By confocal microscopy, we found that CD9 was colocalized with F-actin on the cell surface and was particularly downregulated in leader cells by EFs. Interestingly, genetic overexpression of CD9 abolished EF-induced F-actin polarization in leader cells as well as collective migration in the epidermal monolayer. Mechanistically, CD9 determined the polarization of F-actin in leader cells by downregulating a disintegrin and metalloprotease 17/heparin-binding epidermal growth factor-like growth factor/epidermal growth factor receptor (ADAM17/HB-EGF/EGFR) signalling. The abolished polarization of leader cells due to CD9 overexpression could be restored in a co-culture monolayer where normal cells and CD9-overexpressing cells were mixed; however, this restoration was eliminated again by the addition of the HB-EGF-neutralizing antibody. Conclusion: CD9 functions as a key regulator in the EF-guided collective migration of the epidermal monolayer by controlling and coordinating the polarization of leader cells through ADAM17/HB-EGF/EGFR signalling.

Nicotinamide pretreatment protects cardiomyocytes against hypoxia-induced cell death by improving mitochondrial stress.

BACKGROUND/AIMS: Nicotinamide plays a protective role in hypoxia-induced cardiomyocyte dysfunction. However, the underlying molecular mechanisms remain poorly understood. The purpose of this study was to investigate these and the effect of nicotinamide pretreatment on hypoxic cardiomyocytes. METHODS: Cultured rat cardiomyocytes were pretreated with nicotinamide, subjected to hypoxia for 6 h, and then cell necrosis and apoptosis were examined. The effects of nicotinamide pretreatment on hypoxia-induced reactive oxygen species (ROS) formation, antioxidant enzyme expression, nicotinamide adenine dinucleotide (NAD(+)) and nicotinamide adenine dinucleotide phosphate (NADP(+)) levels, adenosine triphosphate (ATP) production and mitochondrial membrane potential were tested to elucidate the underlying mechanisms. RESULTS: Based on the findings that nicotinamide treatment decreased protein expression of receptor-interacting protein (RIP; a marker for cell necrosis) and cleaved caspase-3 (CC3; a marker for cell apoptosis) in normoxic cardiomyocytes, we found that it dramatically reduced hypoxia-induced necrosis and apoptosis in cardiomyocytes. The underlying mechanisms of these effects are associated with the fact that it increased protein expression of superoxide dismutase and catalase, increased intracellular levels of NAD(+) and ATP concentration, decreased mitochondrial ROS generation and prevented the loss of mitochondrial membrane potential. CONCLUSION: All of these results indicate that nicotinamide pretreatment protects cardiomyocytes by improving mitochondrial stress. Our study provides a new clue for the utilization of nicotinamide in therapies for ischemic heart disease.

Hypoxic preconditioning promotes galvanotaxis of human dermal microvascular endothelial cells through NF-κB pathway.

Angiogenesis plays an important role in wound healing, especially in chronic wound. The directional migration of the human dermal microvascular endothelial cells (HDMECs) is the key regulation of angiogenesis. The wound healing can be regulated by numerous microenvironment factors including the electric fields, hypoxia and chemotaxis. During wound repair, the electric fields mediates the directional migration of cells and the hypoxia, which occurs immediately after injury, acts as an early stimulus to initiate the healing process. However, the mechanism of hypoxia and the endogenous electric fields coordinating to promote angiogenesis remain elusive. In this study, we observed the effect of hypoxia on the directional migration of HDMECs under electric fields. The galvanotaxis of HDMECs under the electric fields (200 mV/mm) was significantly improved, and the expression of VEGF/VEGFR2 was up-regulated after 4h of hypoxic preconditioning. In addition, the knockdown of VEGFR2 reversed the directivity of HDMECs promoted by hypoxia in the electric fields. Moreover, knockdown of VEGFR2 inhibited the migration directionality of HDMECs in the electric field after hypoxic preconditioning. Hypoxia decreased the activation of NF-κB in HDMECs. Activated NF-κB by fusicoccin decreased the expression of VEGFR2/VEGF and negatively regulated the migration direction of HDMECs in the electric fields. Enhancing the galvanotaxis response of cells might therefore be a clinically attractive approach to induce improved angiogenesis.

Bioelectric fields coordinate wound contraction and re-epithelialization process to accelerate wound healing via promoting myofibroblast transformation.

Electric fields (EFs) are thought to play a decisive role in wound healing. However, most studies focused on the effects of EF on single species of cells in vitro. Here, we aimed to investigate the coordination function of EFs on wound healing. Using a bamamini pig whole-layer wound model, we further evaluated the potential of EFs as a treatment modality by applying continuous and stable EF to the wound, and we found that EF promoted wound contraction and re-epithelialization in vivo, which accelerated wound healing. In vitro, we found that EFs significantly promoted the collective migration of HaCaT cells, guided HSF cells rearrangement, and promoted collagen secretion and myofibroblast transformation, and the electrotaxis of HaCaT cells was significantly enhanced on the collagen substrate and F-actin polarization at the leading edge of the cells was more pronounced. Overall, we determined that EF promotes wound contraction by promoting myofibrillar transformation, while accelerating the formation of collagen substrates, and the substrates could provide a good basis for electric field-guided re-epithelialization. EF may promote wound healing in multiple dimensions interaction and coordinate the whole process of wound healing. These findings provide support for the continued development of EF for wound treatment applications.

Autophagy promotes directed migration of HUVEC in response to electric fields through the ROS/SIRT1/FOXO1 pathway.

Endogenous electric fields (EFs) have been confirmed to facilitate angiogenesis through guiding directional migration of endothelial cells (ECs), but the underlying mechanisms remain obscure. Recent studies suggest that the directed migration of ECs in angiogenesis is correlated with autophagy, and the latter of which could be augmented by EFs. We hypothesize that autophagy may participate in the EFs-guided migration of ECs during angiogenesis. Herein, we showed that EFs induced human umbilical vein endothelial cells (HUVEC) migration toward the cathode with enhanced autophagy. Genetic ablation of autophagy by silencing the autophagy-related gene (Atg) 5 abolished the EFs-directed migration of HUVEC, indicating that autophagy is definitely required for EFs-guided migration of cells. Mechanistically, we identified the intracellular reactive oxygen species (ROS) as a crucial mediator in EFs-triggered autophagy through augmenting the silencing information regulator 2 related enzyme1 (SIRT1)/forkhead box protein O1 (FOXO1) signaling. Either ROS scavenging or SIRT1 knockdown eliminated the EFs-triggered autophagy in HUVEC. Further study showed that SIRT1 promoted FOXO1 deacetylation, facilitating its nuclear accumulation and transcriptional activity, and thereby activating autophagy in EFs-treated HUVECs. In conclusion, our study demonstrated a pivotal role for autophagy in EFs-induced directed migration of HUVECs through the ROS/SIRT1/FOXO1 pathway, and provided a novel theoretical foundation for angiogenesis.

Elastic Silicone Occlusive Sheeting Versus Silicone Occlusive Sheeting in the Treatment of Scars: A Randomized Controlled Trial.

INTRODUCTION: Hypertrophic scarring caused by conventional open thyroidectomy is prevalent among Asians and published trials have proved that silicone occlusive sheeting is a useful treatment for hypertrophic scarring. However, silicone occlusive sheeting does not effectively prevent scar widening. Here, we report elastic silicone occlusive sheeting as a new type of silicone application. In this study, we compared the effects of elastic silicone occlusive sheeting on scar width and appearance after conventional open thyroidectomy with those of silicone occlusive sheeting. METHODS: In this prospective, randomized, assessor-blinded study, a total of 74 patients who underwent conventional open thyroidectomy were recruited to undergo elastic silicone occlusive sheeting and silicone occlusive sheeting on the healed wound. Split scar study and scar quality were assessed on the basis of scar width, Vancouver scar scale, pain/itching visual analogue scale, and patients' subjective degree of satisfaction with the scar, during the patients' 6-month review. RESULTS: A total of 61 patients completed the study. Scar width, Vancouver scar scale score, and patients' subjective degree of satisfaction indicated that elastic silicone occlusive sheeting was associated with narrower scars and significant improvement in scar appearance. The two methods did not differ significantly with regard to pain/itching visual analogue scale. CONCLUSIONS: Our findings highlight elastic silicone occlusive sheeting as an effective treatment for scarring, resulting in narrower and better scars after conventional open thyroidectomy. The use of elastic silicone occlusive sheeting after conventional open thyroidectomy may minimize the formation of hypertrophic scars in the early postoperative period. TRIAL REGISTRATION: ChiCTR2100049740.