A pulsed current electric field alters protein expression creating a wound healing phenotype in human skin cells.

Pulsed current (PC) electric field (EF) devices promote healing in chronic wounds but the underpinning mechanisms are largely unknown. The gap between clinical evidence and mechanistic understanding limits device uptake in clinics. Migration, proliferation and gene/protein expression profiles were investigated in the presence/absence of PCEF, in skin: keratinocytes (NHK); dermal fibroblasts (HDF); dermal microvascular endothelial cells (HDMEC) and macrophages (THP-1).

ATP Release and P2 Y Receptor Signaling are Essential for Keratinocyte Galvanotaxis.

Repair to damaged tissue requires directional cell migration to heal the wound. Immediately upon wounding an electrical guidance cue is created with the cathode of the electric field (EF) located at the center of the wound. Previous research has demonstrated directional migration of keratinocytes toward the cathode when an EF of physiological strength (100-150 mV/mm) is applied in vitro, but the "sensor" by which keratinocytes sense the EF remains elusive.

The role of phosphoinositide 3-kinases in neutrophil migration in 3D collagen gels.

The entry of neutrophils into tissue has been well characterised; however the fate of these cells once inside the tissue microenvironment is not fully understood. A variety of signal transduction pathways including those involving class I PI3 Kinases have been suggested to be involved in neutrophil migration. This study aims to determine the involvement of PI3 Kinases in chemokinetic and chemotactic neutrophil migration in response to CXCL8 and GM-CSF in a three-dimensional collagen gel, as a model of tissue.

β2-adrenoceptor activation modulates skin wound healing processes to reduce scarring.

During wound healing, excessive inflammation, angiogenesis, and differentiated human dermal fibroblast (HDF ) function contribute to scarring, whereas hyperpigmentation negatively affects scar quality. Over 100 million patients heal with a scar every year. To investigate the role of the beta 2 adrenergic receptor (β2AR) in wound scarring, the ability of beta 2 adrenergic receptor agonist (β2ARag) to alter HDF differentiation and function, wound inflammation, angiogenesis, and wound scarring was explored in HDFs, zebrafish, chick chorioallantoic membrane assay (CAM), and a porcine skin wound model, respectively.

Beta-Adrenoceptor Activation Reduces Both Dermal Microvascular Endothelial Cell Migration via a cAMP-Dependent Mechanism and Wound Angiogenesis.

Angiogenesis is an essential process during tissue regeneration; however, the amount of angiogenesis directly correlates with the level of wound scarring. Angiogenesis is lower in scar-free foetal wounds while angiogenesis is raised and abnormal in pathophysiological scarring such as hypertrophic scars and keloids. Delineating the mechanisms that modulate angiogenesis and could reduce scarring would be clinically useful.

Long-term channel block is required to inhibit cellular transformation by human ether-à-go-go-related gene (hERG1) potassium channels.

Both human ether-à-go-go-related gene (hERG1) and the closely related human ether-à-go-go (hEAG1) channel are aberrantly expressed in a large proportion of human cancers. In the present study, we demonstrate that transfection of hERG1 into mouse fibroblasts is sufficient to induce many features characteristic of malignant transformation. An important finding of this work is that this transformation could be reversed by chronic incubation (for 2-3 weeks) with the hERG channel blocker dofetilide (100 nM), whereas more acute applications (for 1-2 days) were ineffective.

Keratinocyte galvanotaxis in combined DC and AC electric fields supports an electromechanical transduction sensing mechanism.

Sedentary keratinocytes at the edge of a skin wound migrate into the wound, guided by the generation of an endogenous electric field (EF) generated by the collapse of the transepithelial potential. The center of the wound quickly becomes more negative than the surrounding tissue and remains the cathode of the endogenous EF until the wound is completely re-epithelialized. This endogenous guidance cue can be studied in vitro.

β2AR antagonists and β2AR gene deletion both promote skin wound repair processes.

Skin wound healing is a complex process requiring the coordinated, temporal orchestration of numerous cell types and biological processes to regenerate damaged tissue. Previous work has demonstrated that a functional β-adrenergic receptor autocrine/paracrine network exists in skin, but the role of β2-adrenergic receptor (β2AR) in wound healing is unknown. A range of in vitro (single-cell migration, immunoblotting, ELISA, enzyme immunoassay), ex vivo (rat aortic ring assay), and in vivo (chick chorioallantoic membrane assay, zebrafish, murine wild-type, and β2AR knockout excisional skin wound models) models were used to demonstrate that blockade or loss of β2AR gene deletion promoted wound repair, a finding that is, to our knowledge, previously unreported.

Tensin 2 modulates cell contractility in 3D collagen gels through the RhoGAP DLC1.

Cytoskeletal proteins of the tensin family couple integrins to the actin cytoskeleton. They are found in both focal adhesions and the fibrillar adhesions formed between cells and the fibronectin matrix. There are four tensin genes which encode three large (approximately 200 kDa) tensin isoforms (tensin 1, 2, 3) and one short isoform (cten).

Conformationally constrained mimetics of laminin peptide YIGSR as precursors for antimetastatic disintegrins.

Conformationally constrained mimetics of the laminin cell-adhesion site, YIGSR, are described. The site is the natural antagonist of the integrin-associated laminin receptor 1 (LAMR1) known to mediate metastatic tumor adhesion. The attachment of selected metastatic cell lines toward the constrained antagonists has been assessed.

Stress-mediated increases in systemic and local epinephrine impair skin wound healing: potential new indication for beta blockers.

Background: Stress, both acute and chronic, can impair cutaneous wound repair, which has previously been mechanistically ascribed to stress-induced elevations of cortisol. Here we aimed to examine an alternate explanation that the stress-induced hormone epinephrine directly impairs keratinocyte motility and wound re-epithelialization. Burn wounds are examined as a prototype of a high-stress, high-epinephrine, wound environment.

beta-Adrenergic receptor modulation of wound repair.

Adrenergic receptors and their downstream effector molecules are expressed in all cell types in the skin, and it is only recently that functionality of the catecholamine agonist activated signaling in the cutaneous repair process has been revealed. In addition to responding to systemic elevations in catecholamines (as in stress situations) or to pharmacologically administered adrenergic agonists, epidermal keratinocytes themselves can synthesize catecholamine ligands. They also respond to these systemic or self-generated agonists via receptor mediated signaling, resulting in altered migration, and changes in wound re-epithelialization.

Beta2-adrenergic receptor signaling mediates corneal epithelial wound repair.

Purpose: Beta-adrenergic receptor (AR) antagonists are frequently prescribed ophthalmic drugs, yet previous investigations into how catecholamines affect corneal wound healing have yielded conflicting

Results: With the use of an integrated pharmacologic and genetic approach, the authors investigated how the beta-AR impacts corneal epithelial healing.

Methods: Migratory rates of cultured adult murine corneal epithelial (AMCE) cells and in vivo corneal wound healing were examined in beta2-AR(+/+) and beta2-AR(-/-) mice. Signaling pathways were evaluated by immunoblotting.

Beta-adrenergic receptor agonists delay while antagonists accelerate epithelial wound healing: evidence of an endogenous adrenergic network within the corneal epithelium.

Wound healing is a complex and well-orchestrated biological process. Corneal epithelial cells (CECs) must respond quickly to trauma to rapidly restore barrier function and protect the eye from noxious agents. They express a high level of beta2-adrenergic receptors but their function is unknown.

beta4 integrin and epidermal growth factor coordinately regulate electric field-mediated directional migration via Rac1.

Endogenous DC electric fields (EF) are present during embryogenesis and are generated in vivo upon wounding, providing guidance cues for directional cell migration (galvanotaxis) required in these processes. To understand the role of beta (beta)4 integrin in directional migration, the migratory paths of either primary human keratinocytes (NHK), beta4 integrin-null human keratinocytes (beta4-), or those in which beta4 integrin was reexpressed (beta4+), were tracked during exposure to EFs of physiological magnitude (100 mV/mm). Although the expression of beta4 integrin had no effect on the rate of cell movement, it was essential for directional (cathodal) migration in the absence of epidermal growth factor (EGF).

beta-Adrenergic receptor antagonists accelerate skin wound healing: evidence for a catecholamine synthesis network in the epidermis.

The skin is our primary defense against noxious environmental agents. Upon injury, keratinocytes migrate directionally into the wound bed to initiate re-epithelialization, essential for wound repair and restoration of barrier integrity. Keratinocytes express a high level of beta2-adrenergic receptors (beta2-ARs) that appear to play a role in cutaneous homeostasis as aberrations in either keratinocyte beta2-AR function or density are associated with various skin diseases.

The beta 2-adrenergic receptor activates pro-migratory and pro-proliferative pathways in dermal fibroblasts via divergent mechanisms.

Dermal fibroblasts are required for skin wound repair; they migrate into the wound bed, proliferate, synthesize extracellular matrix components and contract the wound. Although fibroblasts express beta2-adrenergic receptors (beta2-AR) and cutaneous keratinocytes can synthesize beta-AR agonists (catecholamines), the functional significance of this hormonal mediator network in the skin has not been addressed. Emerging studies from our laboratory demonstrate that beta2-AR activation modulates keratinocyte migration, essential for wound re-epithelialization.

Beta2-adrenergic receptor activation delays wound healing.

Keratinocytes migrate directionally into the wound bed to initiate re-epithelialization, necessary for wound closure and restoration of barrier function. They solely express the beta2-adrenergic receptor (beta2-AR) subtype of beta-ARs and can also synthesize beta-AR agonists generating a hormonal mediator network in the skin. Emerging studies from our laboratory demonstrate that beta-AR agonists decrease keratinocyte migration via a protein phosphatase (PP) 2A-dependent mechanism.

Beta 2-adrenergic receptor activation delays dermal fibroblast-mediated contraction of collagen gels via a cAMP-dependent mechanism.

Dermal fibroblasts actively contribute to wound healing by migrating to the wound, synthesizing extracellular matrices, and generating mechanical forces within the wound to initiate wound contraction. Fibroblast-seeded collagen gels provide an in vitro model to study wound contraction. The authors are evaluating the role of the adrenergic signaling system in cutaneous wound repair and recently found that beta2-adrenergic receptor (beta2-AR) activation markedly decreases keratinocyte migration, an essential step in wound reepithelialization.

Cyclic AMP mediates keratinocyte directional migration in an electric field.

Re-epithelialization of wounded skin is necessary for wound closure and restoration of barrier function and requires directional keratinocyte migration towards the center of the wound. The electric field (EF) generated immediately upon wounding could be the earliest signal keratinocytes receive to initiate directional migration and healing. Keratinocytes express many beta2-adrenergic receptors (beta2-ARs), but their role in the epidermis is unknown.

PP2A activation by beta2-adrenergic receptor agonists: novel regulatory mechanism of keratinocyte migration.

Understanding the mechanisms that regulate cell migration is important for devising novel therapies to control metastasis or enhance wound healing. Previously, we demonstrated that beta2-adrenergic receptor (beta2-AR) activation in keratinocytes inhibited their migration by decreasing the phosphorylation of a critical promigratory signaling component, the extracellular signal-related kinase (ERK). Here we demonstrate that beta2-AR-induced inhibition of migration is mediated by the activation of the serine/threonine phosphatase PP2A.