Multifunctional polyvinyl alcohol/poly-dopamine hydrogels loaded with bio-nano composites promote wound healing by repairing endogenous electric fields

In this paper, a heart-shaped nanocomposite (MXenen@Cu-MOF, MC) has been prepared by hydrothermal method. This material can effectively prevent the accumulation of MXene, improve the material's electrical conductivity and antibacterial properties. In addition, it is loaded into Polyvinyl alcohol/Poly-dopamine hydrogel wound dressings (PPMC), which can effectively destroy bacterial biofilms and provide a new pathway for internal electrical currents, helping to repair internal electric fields and promote wound healing. Through the concentration gradient experiments of hydrogel such as antibacterial, conductive, hemolysis and cell migration, we believe that the addition of MC can improve the basic properties of hydrogel. Among them, PPMC0.2 is the hydrogel with the best performance under the premise of meeting bio-compatibility. Its resistance, between 500 and 1000 Ω, is lower than the skin resistance at the wound site and provides the basis for the passage of current through the body. In addition, the cell mobility (24h) of PPMC0.2 reached 58%, and the wound healing rate (6day) was 81.84%, which was much higher than that of other experimental groups. The experimental results proved that PPMC hydrogel can promote wound healing, and this study also provided a new therapeutic idea for chronic wound healing.

Cell Migration Assays and Their Application to Wound Healing Assays-A Critical Review

In recent years, cell migration assays (CMAs) have emerged as a tool to study the migration of cells along with their physiological responses under various stimuli, including both mechanical and bio-chemical properties. CMAs are a generic system in that they support various biological applications, such as wound healing assays. In this paper, we review the development of the CMA in the context of its application to wound healing assays. As such, the wound healing assay will be used to derive the requirements on CMAs. This paper will provide a comprehensive and critical review of the development of CMAs along with their application to wound healing assays. One salient feature of our methodology in this paper is the application of the so-called design thinking; namely we define the requirements of CMAs first and then take them as a benchmark for various developments of CMAs in the literature. The state-of-the-art CMAs are compared with this benchmark to derive the knowledge and technological gap with CMAs in the literature. We will also discuss future research directions for the CMA together with its application to wound healing assays.

A high-precision wound healing assay based on photosensitized culture substrates

Quantitative assessment of cell migration in vitro is often required in fundamental and applied research from different biomedical areas including wound repair, tumor metastasis or developmental biology. A collection of assays has been established throughout the years like the most widely used scratch assay or the so-called barrier assay. It is the principle of these assays to introduce a lesion into an otherwise confluent monolayer in order to study the migration of cells from the periphery into this artificial wound and determine the migration rate from the time necessary for wound closure. A novel assay makes use of photosensitizers doped into a polystyrene matrix. A thin layer of this composite material is coated on the bottom of regular cell culture ware showing perfect biocompatibility. When adherent cells are grown on this coating, resonant excitation of the photosensitizer induces a very local generation of 1O2, which kills the cells residing at the site of illumination. Cells outside the site of illumination are not harmed. When excitation of the photosensitizer is conducted by microscopic illumination, high-precision wounding in any size and geometry is available even in microfluidic channels. Besides proof-of-concept experiments, this study gives further insight into the mechanism of photosensitizer-mediated cell wounding.

Enhancing wound healing and adhesion through dopamine-assisted gelatin-silica hybrid dressings

Gelatin, widely employed in hydrogel dressings, faces limitations when used in high fluid environments, hindering effective material adhesion to wound sites and subsequently reducing treatment efficacy. The rapid degradation of conventional hydrogels often results in breakdown before complete wound healing. Thus, there is a pressing need for the development of durable adhesive wound dressings. In this study, 3-glycidoxypropyltrimethoxysilane (GPTMS) was utilized as a coupling agent to create gelatin-silica hybrid (G-H) dressings through the sol-gel method. The coupling reaction established covalent bonds between gelatin and silica networks, enhancing structural stability. Dopamine (DP) was introduced to this hybrid (G-H-D) dressing to further boost adhesiveness. The efficacy of the dressings for wound management was assessed through in-vitro and in-vivo tests, along with ex-vivo bioadhesion testing on pig skin. Tensile bioadhesion tests demonstrated that the G-H-D material exhibited approximately 2.5 times greater adhesion to soft tissue in wet conditions compared to pure gelatin. Moreover, in-vitro and in-vivo wound healing experiments revealed a significant increase in wound healing rates. Consequently, this material shows promise as a viable option for use as a moist wound dressing.

Cytocompatibility and cell migration evaluation of calcium silicate-based root canal sealer compared to epoxide-amine resin sealer in stem cells from human apical papilla: An in-vitro study

The purpose of this study was to assess the effect of a calcium silicate-based sealers (CeraSeal) and an epoxy resin-based sealer (AH Plus) on cytotoxicity and cell migration of stem cell from the human apical papilla (hSCAPs) by using the Alamar Blue, Annexin V-FICT and wound healing assays. In Alamar Blue assay, hSCAPs exposed to undiluted CeraSeal extract had significantly higher cell viability compared with that observed when cells were treated with AH Plus in all experimental period (p < 0.001). The flow cytometry analysis confirmed the comparison on viable cells and indicated that AH Plus increased apoptosis compared to CeraSeal and the control groups (p < 0.001). Additionally, AH Plus exhibited significantly lower level of cell migration than CeraSeal and the control for up to 48 h observation (p < 0.01). In summary, calcium silicate-based sealer (CeraSeal) is less cytotoxic and more biocompatible than epoxy resin-based sealer (AH Plus).

A Novel Role of Hyaluronic Acid and Proteoglycan Link Protein 1 (HAPLN1) in Delaying Vascular Endothelial Cell Senescence

Cardiovascular diseases (CVDs) are the most common cardiovascular system disorders. Cellular senescence is a key mechanism associated with dysfunction of aged vascular endothelium. Hyaluronic acid and proteoglycan link protein 1 (HAPLN1) has been known to non-covalently link hyaluronic acid (HA) and proteoglycans (PGs), and forms and stabilizes HAPLN1-containing aggregates as a major component of extracellular matrix. Our previous study showed that serum levels of HAPLN1 decrease with aging. Here, we found that the HAPLN1 gene expression was reduced in senescent human umbilical vein endothelial cells (HUVECs). Moreover, a recombinant human HAPLN1 (rhHAPLN1) decreased the activity of senescence-associated β-gal and inhibited the production of senescence-associated secretory phenotypes, including IL-1β, CCL2, and IL-6. rhHAPLN1 also down-regulated IL-17A levels, which is known to play a key role in vascular endothelial senescence. In addition, rhHAPLN1 protected senescent HUVECs from oxidative stress by reducing cellular reactive oxygen species levels, thus promoting the function and survival of HUVECs and leading to cellular proliferation, migration, and angiogenesis. We also found that rhHAPLN1 not only increases the sirtuin 1 (SIRT1) levels, but also reduces the cellular senescence markers levels, such as p53, p21, and p16. Taken together, our data indicate that rhHAPLN1 delays or inhibits the endothelial senescence induced by various aging factors, such as replicative, IL-17A, and oxidative stress-induced senescence, thus suggesting that rhHAPLN1 may be a promising therapeutic for CVD and atherosclerosis.

3D printed inserts for reproducible high throughput screening of cell migration

Cell migration is a fundamental and complex phenomenon that occurs in normal physiology and in diseases like cancer. Hence, understanding cell migration is very important in the fields of developmental biology and biomedical sciences. Cell migration occurs in 3 dimensions (3D) and involves an interplay of migrating cell(s), neighboring cells, extracellular matrix, and signaling molecules. To understand this phenomenon, most of the currently available techniques still rely on 2-dimensional (2D) cell migration assay, also known as the scratch assay or the wound healing assay. These methods suffer from limited reproducibility in creating a cell-free region (a scratch or a wound). Mechanical/heat related stress to cells is another issue which hampers the applicability of these methods. To tackle these problems, we developed an alternative method based on 3D printed biocompatible cell inserts, for quantifying cell migration in 24-well plates. The inserts were successfully validated via a high throughput assay for following migration of lung cancer cell line (A549 cell line) in the presence of standard cell migration promoters and inhibitors. We also developed an accompanying image analysis pipeline which demonstrated that our method outperforms the state-of-the-art methodologies for assessing the cell migration in terms of reproducibility and simplicity.

An effective device to enable consistent scratches for in vitro scratch assays

BACKGROUND

The in-vitro scratch assay is a useful method in wound healing research to assess cell migration. In this assay, a scratch is created in a confluent cell layer by mechanically removing cells through manual scraping with a sharp-edged tool. This step is traditionally done with pipette tips and is unsuitable for high-throughput assays, as the created scratches are highly variable in width and position. Commercially available solutions are often expensive, and require specific cultureware which might not be suitable for all studies.

RESULTS

In this study, we have developed a flexible cell scratch device comprising a single wounding tool, a guide and an imaging template for consistent and reproducible scratch assays in 96-well plates. Our results showed that the device produced a more consistent scratch profile compared to the conventional method of using pipette tips. The imaging template also allowed operators to easily locate and image the same region of interest at different time points, which potentially could be used for other assays.

CONCLUSIONS

Our flexible yet effective scratch device thus enables robust scratch assays that can be applied to different experimental needs, providing researchers with an easy and reliable tool for their studies.

Long noncoding RNA MALAT1 is dynamically regulated in leader cells during collective cancer invasion

Cancer cells collectively invade using a leader-follower organization, but the regulation of leader cells during this dynamic process is poorly understood. Using a dual double-stranded locked nucleic acid (LNA) nanobiosensor that tracks long noncoding RNA (lncRNA) dynamics in live single cells, we monitored the spatiotemporal distribution of lncRNA during collective cancer invasion. We show that the lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) is dynamically regulated in the invading fronts of cancer cells and patient-derived spheroids. MALAT1 transcripts exhibit distinct abundance, diffusivity, and distribution between leader and follower cells. MALAT1 expression increases when a cancer cell becomes a leader and decreases when the collective migration process stops. Transient knockdown of MALAT1 prevents the formation of leader cells and abolishes the invasion of cancer cells. Taken together, our single-cell analysis suggests that MALAT1 is dynamically regulated in leader cells during collective cancer invasion.

Biophysical and Biochemical Regulation of Cell Dynamics in Magnetically Assembled Cellular Structures

Soluble signaling molecules and extracellular matrix (ECM) regulate cell dynamics in various biological processes. Wound healing assays are widely used to study cell dynamics in response to physiological stimuli. However, traditional scratch-based assays can damage the underlying ECM-coated substrates. Here, we use a rapid, non-destructive, label-free magnetic exclusion technique to form annular aggregates of bronchial epithelial cells on tissue-culture treated (TCT) and ECM-coated surfaces within 3 h. The cell-free areas enclosed by the annular aggregates are measured at different times to assess cell dynamics. The effects of various signaling molecules, including epidermal growth factor (EGF), oncostatin M, and interleukin 6, on cell-free area closures are investigated for each surface condition. Surface characterization techniques are used to measure the topography and wettability of the surfaces. Further, we demonstrate the formation of annular aggregates on human lung fibroblast-laden collagen hydrogel surfaces, which mimic the native tissue architecture. The cell-free area closures on hydrogels indicate that the substrate properties modulate EGF-mediated cell dynamics. The magnetic exclusion-based assay is a rapid and versatile alternative to traditional wound healing assays.

LncRNA JHDM1D-AS1 Is a Key Biomarker for Progression and Modulation of Gemcitabine Sensitivity in Bladder Cancer Cells

Long non-coding RNAs are frequently found to be dysregulated and are linked to carcinogenesis, aggressiveness, and chemoresistance in a variety of tumors. As expression levels of the JHDM1D gene and lncRNA JHDM1D-AS1 are altered in bladder tumors, we sought to use their combined expression to distinguish between low-and high-grade bladder tumors by RTq-PCR. In addition, we evaluated the functional role of JHDM1D-AS1 and its association with the modulation of gemcitabine sensitivity in high-grade bladder-tumor cells. J82 and UM-UC-3 cells were treated with siRNA-JHDM1D-AS1 and/or three concentrations of gemcitabine (0.39, 0.78, and 1.56 µM), and then submitted to cytotoxicity testing (XTT), clonogenic survival, cell cycle progression, cell morphology, and cell migration assays. When JHDM1D and JHDM1D-AS1 expression levels were used in combination, our findings indicated favorable prognostic value. Furthermore, the combined treatment resulted in greater cytotoxicity, a decrease in clone formation, G0/G1 cell cycle arrest, morphological alterations, and a reduction in cell migration capacity in both lineages compared to the treatments alone. Thus, silencing of JHDM1D-AS1 reduced the growth and proliferation of high-grade bladder-tumor cells and increased their sensitivity to gemcitabine treatment. In addition, the expression of JHDM1D/JHDM1D-AS1 indicated potential prognostic value in the progression of bladder tumors.

High-throughput screening of toxicants that modulate extravillous trophoblast migration

Migration and subsequent invasion of extravillous trophoblasts into the uterus is essential for proper formation of the placenta. Disruption of these processes may result in poor pregnancy outcomes including preeclampsia, placenta accreta, fetal growth restriction, or fetal death. Currently, there are several methods for quantifying cell migration and invasion in vitro, each with limitations. Therefore, we developed a novel, high-throughput method to screen chemicals for their ability to alter human trophoblast migration. Human HTR8/SVneo trophoblast cells were cultured in Oris™ cell migration plates containing stopper barriers. After EVT cells attached and chemicals were added to media, stoppers were removed thereby creating a cell-free detection zone for migration. Entry of trophoblasts into this zone was monitored through imaging every 6 h and used to calculate a relative cell density. Chemicals known to increase (epidermal growth factor) and decrease (pertussis toxin and cadmium) trophoblast migration were used to validate this in vitro method. Next, a panel of environmental chemicals including bisphenols, mycoestrogens, and flame retardants, were screened for their ability to alter trophoblast invasion. In conclusion, a real-time method to track extravillous trophoblast migration offers potential for screening contaminants as placental toxicants.

A Novel In Vitro Wound Healing Assay Using Free-Standing, Ultra-Thin PDMS Membranes

Advances in polymer science have significantly increased polymer applications in life sciences. We report the use of free-standing, ultra-thin polydimethylsiloxane (PDMS) membranes, called CellDrum, as cell culture substrates for an in vitro wound model. Dermal fibroblast monolayers from 28- and 88-year-old donors were cultured on CellDrums. By using stainless steel balls, circular cell-free areas were created in the cell layer (wounding). Sinusoidal strain of 1 Hz, 5% strain, was applied to membranes for 30 min in 4 sessions. The gap circumference and closure rate of un-stretched samples (controls) and stretched samples were monitored over 4 days to investigate the effects of donor age and mechanical strain on wound closure. A significant decrease in gap circumference and an increase in gap closure rate were observed in trained samples from younger donors and control samples from older donors. In contrast, a significant decrease in gap closure rate and an increase in wound circumference were observed in the trained samples from older donors. Through these results, we propose the model of a cell monolayer on stretchable CellDrums as a practical tool for wound healing research. The combination of biomechanical cell loading in conjunction with analyses such as gene/protein expression seems promising beyond the scope published here.

Accelerating the excisional wound closure by using the patterned microstructural nanofibrous mats/gentamicin-loaded hydrogel composite scaffold

Ideal artificial tissue scaffolds should provide an in vitro microenvironment comparable to native human skin tissue to direct cell functions, regulate tissue homeostasis, and promote tissue regeneration. A sandwich-like composite scaffold consisting of a hydrogel layer and two aligned nanofibre layers was fabricated and applied as a wound-healing dressing. Gentamicin was preloaded into the hydrogel middle layer and naturally released for antibacterial activity during the healing period. Nanofibrous layers embedded on the top and bottom surfaces of the hydrogel improved the tensile strength fivefold (1560 ​kPa and 465% strain) while serving as a diffusion barrier to reduce the gentamicin initial burst release (30%–15%). Inspired by the extracellular matrix (ECM), the surface of nanofibre top layer was patterned with triangular microarrays using micro-moulding approach to reflect the multidimensional structure of ECM. Biocompatibility of the scaffold is proven from cytotoxicity and haemolysis studies. Fibroblast cells revealed a highly elongated and consistent alignment modulated by the micropatterned fibrous layer and directed their migration towards the wound area. Excisional wounds treated with the scaffold promoted 97.49% wound closure with low inflammation and rapid re-epithelialization and angiogenesis. This scaffold, with its tailored functionality capable of accelerating wound healing, has high potential in tissue engineering applications.

Combinational Growth Factor and Gas Delivery for Thrombosis Prevention

Cardiovascular stents enable the rapid re-endothelialization of endothelial cells (ECs), and the constant suppression of smooth muscle cell (SMC) proliferation has been proved to effectively prevent thrombosis. However, the development and application of such stents are still insufficient due the delayed re-endothelialization progress, as well as the poor durability of the SMC inhibition. In this paper, we developed a mussel-inspired coating with the ability for the dual delivery of both growth factor (e.g., platelet-derived growth factor, PDGF) and therapeutic gas (e.g., nitric oxide, NO) for thrombosis prevention. We firstly synthesized the mussel-inspired co-polymer (DMHM) of dopamine methacrylamide (DMA) and hydroxyethyl methacrylate (HEMA) and then coated the DMHM on 316L SS stents combined with CuII. Afterwards, we immobilized the PDGF on the DMHM-coated stent and found that the PDGF could be released in the first 3 days to enhance the recruitment, proliferation, and migration of human umbilical vein endothelial cells (HUVECs) to promote re-endothelialization. The CuII could be “sealed” in the DMHM coating, with extended durability (2 months), with the capacity for catalyzed NO generation for up to 2 months to suppress the proliferation of SMCs. Such a stent surface modification strategy could enhance the development of the cardiovascular stents for thrombosis prevention.

In Vitro and In Vivo Biological Activity of Ruthenium 1,10-Phenanthroline-5,6-dione Arene Complexes

Ruthenium(II) arene complexes exhibit promising chemotherapeutic properties. In this study, the effect of the counter anion in Ru(II) complexes was evaluated by analyzing the biological effect of two Ru(II) p-cymene derivatives with the 1,10-phenanthroline-5,6-dione ligand of general-formula [(η6-arene)Ru(L)Cl][X] X = CF3SO3 (JHOR10) and PF6 (JHOR11). The biological activity of JHOR10 and JHOR11 was examined in the ovarian carcinoma cell line A2780, colorectal carcinoma cell line HCT116, doxorubicin-resistant HCT116 (HCT116-Dox) and in normal human dermal fibroblasts. Both complexes JHOR10 and JHOR11 displayed an antiproliferative effect on A2780 and HCT116 cell lines, and low cytotoxicity in fibroblasts. Interestingly, JHOR11 also showed antiproliferative activity in the HCT116-Dox cancer cell line, while JHOR10 was inactive. Studies in A2780 cells showed that JHOR11 induced the production of reactive oxygen species (ROS) that trigger autophagy and cellular senescence, but no apoptosis induction. Further analysis showed that JHOR11 presented no tumorigenicity, with no effect in the cellular mobility, as evaluated by thye wound scratch assay, and no anti- or pro-angiogenic effect, as evaluated by the ex-ovo chorioallantoic membrane (CAM) assay. Importantly, JHOR11 presented no toxicity in chicken and zebrafish embryos and reduced in vivo the proliferation of HCT116 injected into zebrafish embryos. These results show that these are suitable complexes for clinical applications with improved tumor cell cytotoxicity and low toxicity, and that counter-anion alteration might be a viable clinical strategy for improving chemotherapy outcomes in multidrug-resistant (MDR) tumors.

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.

Modelling human placental villous development: designing cultures that reflect anatomy

The use of in vitro tools to study trophoblast differentiation and function is essential to improve understanding of normal and abnormal placental development. The relative accessibility of human placentae enables the use of primary trophoblasts and placental explants in a range of in vitro systems. Recent advances in stem cell models, three-dimensional organoid cultures, and organ-on-a-chip systems have further shed light on the complex microenvironment and cell-cell crosstalk involved in placental development. However, understanding each model's strengths and limitations, and which in vivo aspects of human placentation in vitro data acquired does, or does not, accurately reflect, is key to interpret findings appropriately. To help researchers use and design anatomically accurate culture models, this review both outlines our current understanding of placental development, and critically considers the range of established and emerging culture models used to study this, with a focus on those derived from primary tissue.

A More Biomimetic Cell Migration Assay with High Reliability and Its Applications

Cell migration refers to the directional movement of cells to the surrounding cell-free zone in response to chemical and mechanical stimuli. A cell migration assay is an essential device for studying pharmaceutical and medical problems. In this paper, we present a novel approach to a cell migration assay on a chip with two merits, namely (i) simultaneous creation of many cell samples on the same condition and (ii) cells migrating while being stressed in a fluidic environment. The first merit has addressed the problem of poor reproducibility in experimental studies for medical problems such as wound healing, and the second merit has made the cell migration device, which is an in vitro environment, more biomimetic. The two merits are attributed to a novel mechanical method to simultaneously create many cell-free zones and to the design of a microfluidic process to create shear stress in cells uniformly. Two applications were studied on our device to explore its effectiveness. The first application is regarding the combination chemotherapy of cisplatin and doxorubicin (Adriamycin) on cervical cancer cells (HeLa). The second application is regarding inhibiting the migration of endothelial cells (HUVEC) in the process of anti-angiogenesis.

Oral antimicrobial peptide-EGCG nanomedicines for synergistic treatment of ulcerative colitis

The pathogenesis of ulcerative colitis (UC) is associated with severe inflammation, damaged colonic barriers, increased oxidative stress, and intestinal dysbiosis. The majority of current medications strive to alleviate inflammation but fail to target additional disease pathologies. Addressing multiple symptoms using a single 'magic bullet' remains a challenge. To overcome this, a smart epigallocatechin-3-gallate (EGCG)-loaded silk fibroin-based nanoparticle (NP) with the surface functionalization of antimicrobial peptides (Cathelicidin-BF, CBF) was constructed, which were internalized by Colon-26 cells and RAW 264.7 macrophages with high efficiencies. These CBF-EGCG-NPs efficiently restored colonic epithelial barriers by relieving oxidative stress and promoting epithelium migration. They also alleviated immune responses through the downregulation of pro-inflammatory factors, upregulation of anti-inflammatory factors, M2 macrophage polarization, and lipopolysaccharide (LPS) elimination. Interestingly, oral administration of hydrogel (chitosan/alginate)-embedding CBF-EGCG-NPs could not only retard progression and treat UC, but also modulate intestinal microbiota by increasing their overall diversity and richness and augmenting the abundance of beneficial bacteria (e.g., Firmicutes and Lactobacillaceae). Our work provides a "many birds with one stone" strategy for addressing UC symptoms using a single NP-based oral platform that targets immune microenvironment modulation, LPS clearance, and microbial remodeling.

Circular gap forming device and two-dimensional area calculation for in vitro cell migration study

Cell wound healing assay is an important experimental technique for the detection of cell migration in vitro. At present, scratch on monolayer cells using a pipette tip is commonly used. However, it is difficult to guarantee the scratch with same width, and only the migration distance of a certain part is calculated. Therefore, the experimental method needs to be optimized. ATRA was used to treat hepa1-6 mouse hepatoma cells. Circular wound with diameter of 0.2 cm were formed by a circular gap forming device. The whole cell wound region could be captured under the microscope to observe cell migration. There are almost no crawling cells in the wound region. The migration capacity of hepa1-6 cells was evaluated by calculating the healing area. ATRA could significantly inhibit the migration of hepa1-6 cells. Compared with linear wound, the standard deviation of wound healing rate in the circular cell wound method is smaller. The circular cell wound method can ensure the dynamic observation of the same wound region, and calculate the healing area at the two-dimensional level with small error and high repetition rate. It is reliable and easy to operate, can be widely used in laboratory.

Fibroblast Derived Skin Wound Healing Modeling on Chip under the Influence of Micro-Capillary Shear Stress

Fibroblast cell migration plays a crucial role in the wound-healing process. Hence, its quantitative investigation is important to understand the mechanism of the wound-healing process. The dynamic nature of the wound-healing process can be easily implemented using a microfluidic-based wound-healing assay. This work presented the use of a microfluidics device to simulate traumatic wounds on fibroblast cell monolayers by utilizing trypsin flow and PDMS barrier. In this study, a microfluidic chip with a transparent silk film is reported. The placement of film provides 3D cell culture conditions that mimic a 3D extracellular matrix (ECM) like environment and allows real-time monitoring of cells. A numerical study was conducted to evaluate the influence of dynamic medium-induced shear stress on the base and wall of the microchannel. This could facilitate the optimization of the inlet flow conditions of the media in the channel. At the same time, it could help in identifying stress spots in the channel. The scaffolds were placed in those spots for evaluating the influence of shear forces on the migratory behavior of fibroblast cells. The in vitro microfluidic assembly was then evaluated for cell migration under the influence of external shear forces during the wound-healing phenomena. A faster wound healing was obtained at the end of 24 h of the creation of the wound in the presence of optimal shear stress. On increasing the shear stress beyond a threshold limit, it dissociates fibroblast cells from the surface of the substrate, thereby decelerating the wound-healing process. The above phenomena were transformed in both coplanar microfluidics surfaces (by realizing in the multichannel interlinked model) and transitional microfluidics channels (by realizing in the sandwich model).

Modeling the Role of Cancer-Associated Fibroblasts in Tumor Cell Invasion

Simple Summary

Accurate in vitro modeling of diseases is essential to making breakthrough and clinically relevant discoveries. Assays to examine the process of invasion—a classical hallmark of cancer—have evolved over the years to overcome shortfalls in their design and accommodate new knowledge in the field, such as the role of the tumor microenvironment (TME) in propagating this process. The goals of this review are two-fold: To walk through the tried-and-true plus novel and new invasion assays currently used in cancer research with a focus on those incorporating cancer-associated fibroblasts (CAFs), and to be a resource for researchers to find the correct invasion assays that suit their own unique needs and biological questions.

Abstract

The major cause of cancer-related deaths can be attributed to the metastatic spread of tumor cells—a dynamic and complex multi-step process beginning with tumor cells acquiring an invasive phenotype to allow them to travel through the blood and lymphatic vessels to ultimately seed at a secondary site. Over the years, various in vitro models have been used to characterize specific steps in the cascade to collectively begin providing a clearer picture of the puzzle of metastasis. With the discovery of the TME’s supporting role in activating tumor cell invasion and metastasis, these models have evolved in parallel to accommodate features of the TME and to observe its interactions with tumor cells. In particular, CAFs that reside in reactive tumor stroma have been shown to play a substantial pro-invasive role through their matrix-modifying functions; accordingly, this warranted further investigation with the development and use of invasion assays that could include these stromal cells. This review explores the growing toolbox of assays used to study tumor cell invasion, from the simple beginnings of a tumor cell and extracellular matrix set-up to the advent of models that aim to more closely recapitulate the interplay between tumor cells, CAFs and the extracellular matrix. These models will prove to be invaluable tools to help tease out the intricacies of tumor cell invasion.

Robust Quantification of Regional Patterns of Migration in Three-Dimensional Cell Culture Models

Purpose

Wound healing assays is a common two-dimensional migration model, with the spheroid assay three-dimensional migration model recently emerging as being more representative of in vivo migration behaviours. These models provide insight into the overall migration of cells in response to various factors such as biological, chemotactic and molecular agents. However, currently available analysis techniques for these assays fall short on providing quantifiable means to measure regional migration patterns, which is essential to allow a more robust assessment of drug treatments on cell migration in a chemotactic fashion. Therefore, this study aims to develop a finite element (FE) based pipeline that can objectively quantify regional migration patterns of cells.

Methods

We have developed a novel FE based approach that is able to accurately measure changes in overall migration areas of 3D Glioblastoma Multiforme (GBM) spheroids that we generated using the primary cell lines from patients undergoing tumour resection surgery. We live-imaged the migration patterns of GBM spheroids and analysed them, first with the standard ImageJ method. We then performed the same analysis with the proposed FE method.

Results

When compared to the standard ImageJ method, our proposed method was able to measure the changes in a more quantitative and accurate manner. Furthermore, our regional migration analysis provided means to analyse the migration pattern seen in the phantom data and our experimental results.

Conclusion

Our FE based method will be a a robust tool for analysing cell migration patterns of GBM and other migrating cells in various diseases and degenerations.

Platinum(II) and Copper(II) complexes of asymmetric halogen-substituted [NN'O] ligands: Synthesis, characterization, structural investigations and antiproliferative activity

In order to better understand the effect of structure, halogen substitution, metal ions and ligand flexibility on antiproliferative activity, eight Cu(II) complexes and eight Pt(II) complexes were obtained of 2,4-X₁,X₂-6-((pyridine-2-ylmethylamino)methyl)phenol and 2,4-X₁,X₂-6-((pyridine-2-ylmethylamino)ethyl)phenol (where X is Cl, Br, or I) ligands. The compounds were characterized with various techniques, such as FT-IR, NMR, elemental analysis and single-crystal X-ray diffraction (SCXRD). The X-ray structures showed that ligand acts as a bidentate and tridentate donor in Cu(II) and Pt(II) complexes, respectively. This difference in structures is due to the use or non-use of base in the preparation of complexes. Also, complexation of Cl₂-H₂L₁ with CuCl₂·2H₂O gives two different types of structures: polymer (Cl₂-H₂L₁-Cu^polymer) and dimer (Cl₂-H₂L₁-Cu^dimer), according to the crystal color. In addition, ¹H NMR spectrum for platinum complexes display two set of signals that can be attributed to the presence of two isomers in solution. All complexes induced moderate to high reduction in A2780 and HCT116 cancer cell viability. However, only complexes bearing iodo- substituted in ligands exhibited significantly low cytotoxicity in normal fibroblasts when compared with cancer cell lines. The antiproliferative effect exhibited by I₂-H₂L₂-Cu complex in A2780 cell line was due to induction of cell death mechanisms, namely by apoptosis and autophagy. I₂-H₂L₂-Cu complex does not cause DNA cleavage but a slight delay in cell cycle was observed for the first 24 h of exposition. High cytotoxicity was related with the induction of intracellular ROS. This increase in intracellular ROS was not accompanied by destabilization of the mitochondrial membrane which is an indication that ROS are being triggered externally by I₂-H₂L₂-Cu complex and in agreement with an extrinsic apoptosis activation. I₂-H₂L₂-Cu complex has a pro-angiogenic effect, increasing the vascularization of the CAM in chicken embryos. This is also a very important characteristic in cancer treatment since the increased vascularization in tumors might facilitate the delivery of therapeutic drugs. Taken together, these results support the potential therapeutic of the I₂-H₂L₂-Cu complex.

Interfacing Live Cells with Surfaces: A Concurrent Control Technique for Quantifying Surface Ligand Activity

Surface ligand activity is a key design parameter for successfully interfacing surfaces with cells─whether in the context of in vitro investigations for understanding cellular signaling pathways or more applied applications in drug delivery and medical implants. Unlike other crucial surface parameters, such as stiffness and roughness, surface ligand activity is typically based on a set of assumptions rather than directly measured, giving rise to interpretations of cell adhesion that can vary with the assumptions made. To fill this void, we have developed a concurrent control technique for directly characterizing in vitro ligand surface activity. Pairs of gold-coated glass chips were biofunctionalized with RGD ligand in a parallel workflow: one chip for in vitro applications and the other for surface plasmon resonance (SPR)-based RGD activity characterization. Recombinant α_Vβ₃ integrins were injected over the SPR chip surface as mimics of the cellular-membrane-bound receptors and the resulting binding kinetics parameterized to quantify surface ligand activity. These activity measurements were correlated with cell morphological features, measured by interfacing MDA-MB-231 cells with the in vitro chip surfaces on the live cell microscope. We demonstrate how the interpretation of a cell phenotype based on direct activity measurements can vary markedly from interpretations based on assumed activity. The SPR concurrent control approach has multiple advantages due to the fact that SPR is a standardized technique and has the sensitivity to measure ligand activity across the most relevant range of extracellular surface densities, while the in vitro chip design can be used with all commonly used light microscopy modalities (e.g., phase contrast, DIC, and fluorescence) so that a wide range of phenotypic and molecular markers can be correlated to the ligand surface activity.

Adhesive-Based Fabrication Technique for Culture of Lung Airway Epithelial Cells with Applications in Cell Patterning and Microfluidics

This work describes a versatile and cost-effective cell culture method for micropatterning and growing adherent cells on porous membranes using pressure-sensitive double-sided adhesives. This technique also allows cell culture using conventional methods and their easy integration into microfluidic chip devices. Adhesives can be used to form different patterns of cultured cells, which can be used for cell proliferation and wound-healing models. To demonstrate the viability of our system, we evaluate the toxicity effect of five different adhesives on two distinct airway epithelial cell lines and show functional applications for cell patterning and microfluidic cell culture chip fabrication. We developed a sandwiched microfluidic device that enabled us to culture cells in a submerged condition and transformed it into a dynamic platform when required. The viability of cells and their inflammatory responses to IL-1β stimulation were investigated. Our technique is applicable for conventional culturing of cells, widely available in biomedical research labs, while enabling the introduction of perfusion for an advanced dynamic cell culture model when needed.

Manganese(I) tricarbonyl complexes as potential anticancer agents

The antiproliferative activity of [Mn(CO)₃(N^N)Br] (N^N = phendione 1, bipy 3) and of the two newly synthesized Mn complexes [Mn(CO)₃(acridine)(phendione)]OTf (2) and [Mn(CO)₃(di-triazole)Br] (4) has been evaluated by MTS against three tumor cell lines A2780 (ovarian carcinoma), HCT116 (colorectal carcinoma), HCT116doxR (colorectal carcinoma resistant to doxorubicin), and in human dermal fibroblasts. The antiproliferative assay showed a dose-dependent effect higher in complex 1 and 2 with a selectivity toward ovarian carcinoma cell line 21 times higher than in human fibroblasts. Exposure of A2780 cells to IC₅₀ concentrations of complex 1 and 2 led to an increase of reactive oxygen species that led to the activation of cell death mechanisms, namely via intrinsic apoptosis for 2 and autophagy and extrinsic apoptosis for 1. Both complexes do not target DNA or interfere with cell cycle progression but are able to potentiate cell migration and neovascularization (for 2) an indicative that their application might be directed for initial tumor stages to avoid tumor invasion and metastization and opening a new avenue for complex 2 application in regenerative medicine. Interestingly, both complexes do not show toxicity in both in vivo models (CAM and zebrafish).

Photothermal Agarose Microfabrication Technology for Collective Cell Migration Analysis

Agarose photothermal microfabrication technology is one of the micropatterning techniques that has the advantage of simple and flexible real-time fabrication even during the cultivation of cells. To examine the ability and limitation of the agarose microstructures, we investigated the collective epithelial cell migration behavior in two-dimensional agarose confined structures. Agarose microchannels from 10 to 211 micrometer width were fabricated with a spot heating of a focused 1480 nm wavelength infrared laser to the thin agarose layer coated on the cultivation dish after the cells occupied the reservoir. The collective cell migration velocity maintained constant regardless of their extension distance, whereas the width dependency of those velocities was maximized around 30 micrometer width and decreased both in the narrower and wider microchannels. The single-cell tracking revealed that the decrease of velocity in the narrower width was caused by the apparent increase of aspect ratio of cell shape (up to 8.9). In contrast, the decrease in the wider channels was mainly caused by the increase of the random walk-like behavior of component cells. The results confirmed the advantages of this method: (1) flexible fabrication without any pre-designing, (2) modification even during cultivation, and (3) the cells were confined in the agarose geometry.

Oncogenic and Circadian Effects of Small Molecules Directly and Indirectly Targeting the Core Circadian Clock

Circadian rhythms are essential for controlling the cell cycle, cellular proliferation, and apoptosis, and hence are tightly linked to cell fate. Several recent studies have used small molecules to affect circadian oscillations; however, their concomitant cellular effects were not assessed, and they have not been compared under similar experimental conditions. In this work, we use five molecules, grouped into direct versus indirect effectors of the circadian clock, to modulate periods in a human osteosarcoma cell line (U2OS) and determine their influences on cellular behaviors, including motility and colony formation. Luciferase reporters, whose expression was driven via Bmal1- or Per2-promoters, were used to facilitate the visualization and quantitative analysis of circadian oscillations. We show that all molecules increase or decrease the circadian periods of Bmal1 and Per2 in a dose-dependent manner, but period length does not correlate with the extent of cell migration or proliferation. Nonetheless, molecules that affected circadian oscillations to a greater degree resulted in substantial influence on cellular behaviors (ie, motility and colony formation), which may also be attributable to noncircadian targets. Furthermore, we find that the ability and extent to which the molecules are able to affect oscillations is independent of whether they are direct or indirect modulators. Because of the numerous connections and feedback between the circadian clock and other pathways, it is important to consider the effects of both in assessing these and other compounds.

Isolation and Time-Lapse Imaging of Primary Mouse Embryonic Palatal Mesenchyme Cells to Analyze Collective Movement Attributes

Development of the palate is a dynamic process, which involves vertical growth of bilateral palatal shelves next to the tongue followed by elevation and fusion above the tongue. Defects in this process lead to cleft palate, a common birth defect. Recent studies have shown that palatal shelf elevation involves a remodeling process that transforms the orientation of the shelf from a vertical to a horizontal one. The role of the palatal shelf mesenchymal cells in this dynamic remodeling has been difficult to study. Time-lapse-imaging-based quantitative analysis has been recently used to show that primary mouse embryonic palatal mesenchymal (MEPM) cells can self-organize into a collective movement. Quantitative analyses could identify differences in mutant MEPM cells from a mouse model with palate elevation defects. This paper describes methods to isolate and culture MEPM cells from E13.5 embryos-specifically for time-lapse imaging-and to determine various cellular attributes of collective movement, including measures for stream formation, shape alignment, and persistence of direction. It posits that MEPM cells can serve as a proxy model for studying the role of palatal shelf mesenchyme during the dynamic process of elevation. These quantitative methods will allow investigators in the craniofacial field to assess and compare collective movement attributes in control and mutant cells, which will augment the understanding of mesenchymal remodeling during palatal shelf elevation. Furthermore, MEPM cells provide a rare mesenchymal cell model for investigation of collective cell movement in general.

Accessible dynamic micropatterns in monolayer cultures via modified desktop xurography

Micropatterned cell cultures provide an important tool to understand dynamic biological processes, but often require specialized equipment and expertise. Here we present subtractive bioscribing (SuBscribe), a readily accessible and inexpensive technique to generate dynamic micropatterns in biomaterial monolayers on-the-fly. We first describe our modifications to a commercially available desktop xurographer and demonstrate the utility and limits of this system in creating micropatterned cultures by mechanically scribing patterns into a brittle, non-adhesive biomaterial layer. Patterns are sufficiently small to influence cell morphology and orientation and can be extended to pattern large areas with complex reproducible shapes. We also demonstrate the use of this system as a dynamic patterning tool for cocultures. Finally, we use this technique to explore and improve upon the well-established epithelial scratch assay, and demonstrate that robotic control of the scratching tool can be used to create custom-shaped wounds in epithelial monolayers, and that the scribing direction leaves trace remnants of matrix molecules that may significantly affect conventional implementations of this common assay.

Polarization of ADAM17-driven EGFR signalling in electric field-guided collective migration of epidermal sheets

Endogenous electric field is considered to play an important role in promoting collective migration of epidermis to the wound centre. However, most studies are focused on the effect of bioelectric field on the movement and migration of single epithelial cell; the molecular mechanisms about collective migration of epidermal monolayers remain unclear. Here, we found that EFs dramatically promoted the collective migration of HaCaT cells towards the anode, activated the sheddase activity of ADAM17 and increased the phosphorylation level of EGFR. Moreover, EGFR phosphorylation and HB‐EGF shedding level were significantly decreased by the ADAM17 inhibitor TAPI‐2 or siADAM17 under EFs, which subsequently attenuated the directed migration of HaCaT sheets. Notably, the inhibition of EF‐regulated collective migration by siADAM17 was rescued by addition of recombinant HB‐EGF. Furthermore, we observed that F‐actin was dynamically polarized along the leading edge of the migrated sheets under EFs and that this polarization was regulated by ADAM17/HB‐EGF/EGFR signalling. In conclusion, our study indicated that ADAM17 contributed to the collective directional movement of the epidermal monolayer by driving HB‐EGF release and activating EGFR under EFs, and this pathway also mediated the polarization of F‐actin in migrating sheets, which is essential in directional migration.

A novel image analysis algorithm reveals that media conditioned with chitosan and platelet-rich plasma biomaterial dose dependently increases fibroblast migration in a scratch assay

Chitosan (CS) and Platelet-Rich Plasma (PRP) both display interesting properties for wound healing applications. A hybrid CS-PRP biomaterial was previously developped, consisting of a freeze dried CS formulation solubilized in PRP that promotes tissue repair and regeneration. The purpose of the current study was to investigate the ability of the CS-PRP biomaterial to stimulate cell migrationin vitro. Scratch assays revealed that CS-PRP significantly stimulates the migration rate of cells compared to cells in culture medium but not differently than PRP alone. The increase in the migration rate is dose-dependent at low dose and reaches a plateau corresponding with maximum cell motility. Cell migration rate as a function of the number of platelets that have degranulated in culture medium (to which total concentration of growth factors contributing to cell response is proportionnal), follows a modified Hill model. To analyze photographs taken during the assay and follow cell migration, an open source image analysis algorithm was developed: SAMScratch (Systematic Area Measurement of Scratch - available here:https://github.com/Biomaterials-and-Cartilage-Laboratory/SAM-Scratch). Compared with other existing analysis tools, the algorithm is precise in the determination of the scratch area and performs equally well with usual and challenging images. This study resulted in the creation of a freely available application for scratch assay analysis and provided evidence that CS-PRP implants hold promise for treatment of wounds.

Real-Time Impedance Monitoring of Epithelial Cultures with Inkjet-Printed Interdigitated-Electrode Sensors

From electronic devices to large-area electronics, from individual cells to skin substitutes, printing techniques are providing compelling applications in wide-ranging fields. Research has thus fueled the vision of a hybrid, printing platform to fabricate sensors/electronics and living engineered tissues simultaneously. Following this interest, we have fabricated interdigitated-electrode sensors (IDEs) by inkjet printing to monitor epithelial cell cultures. We have fabricated IDEs using flexible substrates with silver nanoparticles as a conductive element and SU-8 as the passivation layer. Our sensors are cytocompatible, have a topography that simulates microgrooves of 300 µm width and ~4 µm depth, and can be reused for cellular studies without detrimental in the electrical performance. To test the inkjet-printed sensors and demonstrate their potential use for monitoring laboratory-growth skin tissues, we have developed a real-time system and monitored label-free proliferation, migration, and detachment of keratinocytes by impedance spectroscopy. We have found that variations in the impedance correlate linearly to cell densities initially seeded and that the main component influencing the total impedance is the isolated effect of the cell membranes. Results obtained show that impedance can track cellular migration over the surface of the sensors, exhibiting a linear relationship with the standard method of image processing. Our results provide a useful approach for non-destructive in-situ monitoring of processes related to both in vitro epidermal models and wound healing with low-cost ink-jetted sensors. This type of flexible sensor as well as the impedance method are promising for the envisioned hybrid technology of 3D-bioprinted smart skin substitutes with built-in electronics.

Collective cell migration of fibroblasts is affected by horizontal vibration of the cell culture dish

Regulating the collective migration of cells is an important issue in bioengineering. Enhancing or suppressing cell migration and controlling the migration direction is useful for various physiological phenomena such as wound healing. Several methods of migration regulation based on different mechanical stimuli have been reported. While vibrational stimuli, such as sound waves, show promise for regulating migration, the effect of the vibration direction on collective cell migration has not been studied in depth. Therefore, we fabricated a vibrating system that can apply horizontal vibration to a cell culture dish. Here, we evaluated the effect of the vibration direction on the collective migration of fibroblasts in a wound model comprising two culture areas separated by a gap. Results showed that the vibration direction affects the cell migration distance: vibration orthogonal to the gap enhances the collective cell migration distance while vibration parallel to the gap suppresses it. Results also showed that conditions leading to enhanced migration distance were also associated with elevated glucose consumption. Furthermore, under conditions promoting cell migration, the cell nuclei become elongated and oriented orthogonal to the gap. In contrast, under conditions that reduce the migration distance, cell nuclei were oriented to the direction parallel to the gap.

A microfluidics-based wound-healing assay for studying the effects of shear stresses, wound widths, and chemicals on the wound-healing process

Collective cell migration plays important roles in various physiological processes. To investigate this collective cellular movement, various wound-healing assays have been developed. In these assays, a “wound” is created mechanically, chemically, optically, or electrically out of a cellular monolayer. Most of these assays are subject to drawbacks of run-to-run variations in wound size/shape and damages to cells/substrate. Moreover, in all these assays, cells are cultured in open, static (non-circulating) environments. In this study, we reported a microfluidics-based wound-healing assay by using the trypsin flow-focusing technique. Fibroblasts were first cultured inside this chip to a cellular monolayer. Then three parallel fluidic flows (containing normal medium and trypsin solution) were introduced into the channels, and cells exposed to protease trypsin were enzymatically detached from the surface. Wounds of three different widths were generated, and subsequent wound-healing processes were observed. This assay is capable of creating three or more wounds of different widths for investigating the effects of various physical and chemical stimuli on wound-healing speeds. The effects of shear stresses, wound widths, and β-lapachone (a wound healing-promoting chemical) on wound-healing speeds were studied. It was found that the wound-healing speed (total area healed per unit time) increased with increasing shear stress and wound width, but under a shear stress of 0.174 mPa the linear healing speed (percent area healed per unit time) was independent of the wound width. Also, the addition of β-lapachone up to 0.5 μM did not accelerate wound healing. This microfluidics-based assay can definitely help in understanding the mechanisms of the wound-healing process and developing new wound-healing therapies.

Design, Synthesis and Preliminary Biological Evaluation of Benzylsulfone Coumarin Derivatives as Anti-Cancer Agents

In this work, a series of benzylsulfone coumarin derivatives 5a–5o were synthesized and characterized. Kinase inhibitory activity assay indicated that most of the compounds showed considerable activity against PI3K. Anti-tumor activity studies of the active compounds were also carried out in vitro on the Hela, HepG2, H1299, HCT-116, and MCF-7 tumor cell lines by MTS assay. The structure–activity relationships (SARs) of these compounds were analyzed in detail. Compound 5h exhibited the most potent activities against the mentioned cell lines with IC₅₀ values ranging from 18.12 to 32.60 μM, followed by 5m with IC₅₀ values of 29.30–42.14 μM. Furthermore, 5h and 5m clearly retarded the migration of Hela cells in vitro. Next, an in silico molecular docking study was conducted to evaluate the binding models of 5h and 5m towards PI3Kα and PI3Kβ. Collectively, the above findings suggested that compounds 5h and 5m might be promising PI3K inhibitors deserving further investigation for cancer treatment.

A novel magnet-based scratch method for standardisation of wound-healing assays

A novel magnetic scratch method achieves repeatability, reproducibility and geometric control greater than pipette scratch assays and closely approximating the precision of cell exclusion assays while inducing the cell injury inherently necessary for wound healing assays. The magnetic scratch is affordable, easily implemented and standardisable and thus may contribute toward better comparability of data generated in different studies and laboratories.

Adjustable viscoelasticity allows for efficient collective cell migration

Cell migration is essential for a wide range of biological processes such as embryo morphogenesis, wound healing, regeneration, and also in pathological conditions, such as cancer. In such contexts, cells are required to migrate as individual entities or as highly coordinated collectives, both of which requiring cells to respond to molecular and mechanical cues from their environment. However, whilst the function of chemical cues in cell migration is comparatively well understood, the role of tissue mechanics on cell migration is just starting to be studied. Recent studies suggest that the dynamic tuning of the viscoelasticity within a migratory cluster of cells, and the adequate elastic properties of its surrounding tissues, are essential to allow efficient collective cell migration in vivo. In this review we focus on the role of viscoelasticity in the control of collective cell migration in various cellular systems, mentioning briefly some aspects of single cell migration. We aim to provide details on how viscoelasticity of collectively migrating groups of cells and their surroundings is adjusted to ensure correct morphogenesis, wound healing, and metastasis. Finally, we attempt to show that environmental viscoelasticity triggers molecular changes within migrating clusters and that these new molecular setups modify clusters' viscoelasticity, ultimately allowing them to migrate across the challenging geometries of their microenvironment.

Effects of Substrate-Coating Materials on the Wound-Healing Process

The wound-healing assay is commonly and widely used for investigating collective cell migration under various physical and chemical stimuli. Substrate-coating materials are shown to affect the wound-healing process in a cell-type dependent manner. However, experiment-to-experiment variations make it difficult to compare results from different assays. In this paper, a modified barrier wound-healing assay was reported for studying the wound-healing process on different substrates in one single petri dish. In short, half of a dish was covered with the tape, and coating materials, poly-l-lysine and gelatin, were applied to the surface. After peeling off the tape, half of the surface was coated with the desired material. Then a customized barrier was placed inside the dish to create the wound. The results indicated that surface coating did not affect cell proliferation/viability, and the wound-healing rate increased in coated surfaces compared to uncoated ones. The present study provides a platform for further understanding the mechanisms of substrate coating-dependent wound-healing processes.

Development of Bioinspired Gelatin and Gelatin/Chitosan Bilayer Hydrofilms for Wound Healing

In the current study, we developed a novel gelatin-based bilayer wound dressing. We used different crosslinking agents to confer unique properties to each layer, obtaining a bioinspired multifunctional hydrofilm suitable for wound healing. First, we produced a resistant and non-degradable upper layer by lactose-mediated crosslinking of gelatin, which provided mechanical support and protection to overall design. For the lower layer, we crosslinked gelatin with citric acid, resulting in a porous matrix with a great swelling ability. In addition, we incorporated chitosan into the lower layer to harness its wound healing ability. FTIR and SEM analyses showed that lactose addition changed the secondary structure of gelatin, leading to a more compact and smoother structure than that obtained with citric acid. The hydrofilm was able to swell 384.2 ± 57.2% of its dry weight while maintaining mechanical integrity. Besides, its water vapour transmission rate was in the range of commercial dressings (1381.5 ± 108.6 g/m2·day). In vitro, cytotoxicity assays revealed excellent biocompatibility. Finally, the hydrofilm was analysed through an ex vivo wound healing assay in human skin. It achieved similar results to the control in terms of biocompatibility and wound healing, showing suitable characteristics to be used as a wound dressing.

Raising fluid walls around living cells

An effective transformation of the cell culture dishes that biologists use every day into microfluidic devices would open many avenues for miniaturizing cell-based workflows. In this article, we report a simple method for creating microfluidic arrangements around cells already growing on the surface of standard petri dishes, using the interface between immiscible fluids as a "building material." Conventional dishes are repurposed into sophisticated microfluidic devices by reshaping, on demand, the fluid structures around living cells. Moreover, these microfluidic arrangements can be further reconfigured during experiments, which is impossible with most existing microfluidic platforms. The method is demonstrated using workflows involving cell cloning, the selection of a particular clone from among others in a dish, drug treatments, and wound healing. The versatility of the approach and its biologically friendly aspects may hasten uptake by biologists of microfluidics, so the technology finally fulfills its potential.

Listeria innocua Dps as a nanoplatform for bioluminescence based photodynamic therapy utilizing Gaussia princeps luciferase and zinc protoporphyrin IX

Listeria innocua DNA binding protein from starved cells (LiDps) belongs to the ferritin family and provides a promising self-assembling spherical 12-mer protein scaffold for the generation of functional nanomaterials. We report the creation of a Gaussia princeps luciferase (Gluc)-LiDps fusion protein, with chemical conjugation of Zinc (II)-protoporphyrin IX (ZnPP) to lysine residues on the fusion protein (giving Gluc-LiDps-ZnPP). The Gluc-LiDps-ZnPP conjugate is shown to generate reactive oxygen species (ROS) via Bioluminescence Resonance Energy Transfer (BRET) between the Gluc (470-490 nm) and ZnPP. In vitro, Gluc-LiDps-ZnPP is efficiently taken up by tumorigenic cells (SKBR3 and MDA-MB-231 breast cancer cells). In the presence of coelenterazine, this construct inhibits the proliferation of SKBR3 due to elevated ROS levels. Following exposure to Gluc-LiDps-ZnPP, migration of surviving SKBR3 cells is significantly suppressed. These results demonstrate the potential of the Gluc-LiDps-ZnPP conjugate as a platform for future development of an anticancer photodynamic therapy agent.

Collective Cell Migration in 3D Epithelial Wound Healing

Collective cell migration plays a pivotal role in development, wound healing, and metastasis, but little is known about the mechanisms and coordination of cell migration in 3D microenvironments. Here, we demonstrate a 3D wound healing assay by photothermal ablation for investigating collective cell migration in epithelial tissue structures. The nanoparticle-mediated photothermal technique creates local hyperthermia for selective cell ablation and induces collective cell migration of 3D tissue structures. By incorporating dynamic single cell gene expression analysis, live cell actin staining, and particle image velocimetry, we show that the wound healing response consists of 3D vortex motion moving toward the wound followed by the formation of multicellular actin bundles and leader cells with active actin-based protrusions. Inhibition of ROCK signaling disrupts the multicellular actin bundle and enhances the formation of leader cells at the leading edge. Furthermore, single cell gene expression analysis, pharmacological perturbation, and RNA interference reveal that Notch1-Dll4 signaling negatively regulates the formation of multicellular actin bundles and leader cells. Taken together, our study demonstrates a platform for investigating 3D collective cell migration and underscores the essential roles of ROCK and Notch1-Dll4 signaling in regulating 3D epithelial wound healing.

Assembly of Fully Substituted 2H-Indazoles Catalyzed by Cu2 O Rhombic Dodecahedra and Evaluation of Anticancer Activity

Simultaneous C-N, and N-N bond-forming methods for one-pot transformations are highly challenging in synthetic organic chemistry. In this study, the Cu₂ O rhombic dodecahedra-catalyzed synthesis of 2H-indazoles is demonstrated with good to excellent yields from readily available chemicals. This one-pot procedure involves Cu₂ O nanoparticle-catalyzed consecutive C-N, and N-N bond formation followed by cyclization to yield 2H-indazoles with broad substrate scope and high functional group tolerance. Various cell-based bioassay studies demonstrated that 2H-indazoles inhibit the growth of cancer cells, typically through induction of apoptosis in a dose-dependent manner. Moreover, 2H-indazoles tested in the MDA-MB-468 cell line were capable of inhibiting cancer cell migration and invasion. Thus, it is shown that 2H-indazoles have potent in vitro anticancer activity that warrant further investigation of this compound class.