Loss of keratin 6 (K6) proteins reveals a function for intermediate filaments during wound repair

The ability to heal wounds is vital to all organisms. In mammalian tissues, alterations in intermediate filament (IF) gene expression represent an early reaction of cells surviving injury. We investigated the role of keratin IFs during the epithelialization of skin wounds using a keratin 6alpha and 6beta (K6alpha/K6beta)-null mouse model. In skin explant culture, null keratinocytes exhibit an enhanced epithelialization potential due to increased migration. The extent of the phenotype is strain dependent, and is accompanied by alterations in keratin IF and F-actin organization. However, in wounded skin in vivo, null keratinocytes rupture as they attempt to migrate under the blood clot. Fragility of the K6alpha/K6beta-null epidermis is confirmed when applying trauma to chemically treated skin. We propose that the alterations in IF gene expression after tissue injury foster a compromise between the need to display the cellular pliability necessary for timely migration and the requirement for resilience sufficient to withstand the rigors of a wound site.     

Role of prostaglandin E(2) EP receptors and cAMP in the expression of connective tissue growth factor

Wild-type (WT) Rat-1 fibroblasts express undetectable quantities of the prostaglandin E(2) (PGE(2)) EP1, EP2, and EP3 receptor types and detectable amounts of the EP4 receptor. In the WT Rat-1, PGE(2) enhances connective tissue growth factor (CTGF) mRNA. PGE(2) does not stimulate cAMP production in these cells. However, forskolin induces cAMP production and ablates TGF beta-stimulated increases in CTGF mRNA. A similar pattern of CTGF expression in response to PGE(2) and forskolin is observed in neonatal rat primary smooth muscle cell cultures. When WT Rat-1 cells are stably transfected with the EP2 receptor, PGE(2) causes a sizable elevation in intracellular cAMP and ablates the TGF beta-stimulated increase in CTGF mRNA. PGE(2) does not have this effect on cells expressing the EP1, EP3, or EP4 receptor subtypes. These results demonstrate the importance of the EP2 receptor and cAMP in the inhibition of TGF beta-stimulated CTGF production and suggest a role for PGE(2) in increasing CTGF mRNA levels in the absence of the EP2 receptor. Involvement of inositol phosphate in this upregulation of CTGF expression by PGE(2) is doubtful. None of the cell lines containing the four EP transfectants nor the WT Rat-1 cells responded to PGE(2) with inositol phosphate production.     

Purification of flounder (Paralichthys olivaceus) fibronectin and its localization during re-epithelialization at a fin wound

Plasma fibronectin (FN) of flounder Paralichthys olivacem was purified and characterized. Flounder FN was purified by a combination of affinity chromatography using Sepharose coupled with flounder gelatin and gel filtration on Superose 6. Flounder FN was found to be a disulphide-linked heterodimer of 220 and 230 kDa polypeptides. It had cell-spreading activity for baby hamster kidney (BHK) cells, which was inhibited by the synthetic peptide, Gly-Arg-Gly-Asp-Ser-Pro. In flounder explants, anti-flounder FN antiserum distinguished fibroblast-like cells from epithelial cells; indirect immunofluorescence showed that the fibroblast-like cells exhibited a fibrous staining to the antiserum, but that epithelial cells did not. These results suggest that flounder FN is a homologue of mammalian FN.
The localization of FN during re-epithelialization at the site of a severed fin was investigated. When the top of the fin was cut, epidermal cells covered the surface of the wound within 1 h. FN is detected at the wound site during epidermal cell migration, suggesting that it serves as a cell-adhesion factor for prompt re-epithelialization at wound sites.     

Design,Synthesis, Biological Evaluation and Molecular Docking Studies of Quercetin-Linker-H2S Donor Conjugates for the Treatment of Diabetes and Wound Healing**

Based on the use of quercetin for treating diabetes and H₂S for promoting wound healing, a series of three quercetin-linker-H₂S donor conjugates was designed, synthesized and characterized by ¹H-NMR, ¹³C-NMR and MS. Meanwhile, in vitro evaluation of these compounds was also researched by IR-HepG2 treatment experiment, MTT assay, scratch test and tubule formation experiment. The three compounds could be used to treat insulin resistance induced by high glucose and promote the proliferation of human umbilical vein endothelial cells, wound healing, and the formation of tubules in vitro under a high-glucose environment. Our results illustrate that these compounds could be used to treat diabetes and promote wound healing at the same time. Furthermore, molecular docking study results of the compounds were consistent with the evaluated biological activity. In vivo research of compounds is underway.     

Manipulation of cellular interactions with biomaterials toward a therapeutic outcome: A perspective

Manipulation of the Wound healing process and the manner in which tissues interact with inertbiomaterials were both made possible with the discovery of arginine-glucine (RGD) acid as a major cell recognition signal in the extracellular matrix. Whether promoting cell adhesion can be rationally designed to incorporate both stability and integrin specificity. Synthetic peptides containing this sequence have been linked to biodegradable biopolumers and introduced for the enhancement of dermal and corneal wound healing. By accelerating the healing reaction using RGD-containing peptides, the quality of regenerted tissue seems to be improved, the extent of fibrosis retricted, and the risk of microbial infection may be reduced. Controlling the degree of fibrosis that often accmmpanies the healing of wounds and the reaction of tissue to foreign materials can also be achieved by natural antagonists of fibrogenic activity of TGF-beta animal models of kidney fobrosis. There advances in the biotechnology of wound healing and tissue regeneration eventually will have an overal impact on the quality of health care.     

Wound dressing based on PVA nanofiber containing silk fibroin modified with GO/ZnO nanoparticles for superficial wound healing: In vitro and in vivo evaluations

Silk fibroin (SF), extracted from Bombyx mori, has unique physicochemical properties to achieve an efficient wound dressing. In this study, reduced graphene oxide (RGO)/ZnO NPs/silk fibroin nanocomposite was made, and an innovative nanofiber of SF/polyvinyl alcohol (PVA)/RGO/ZnO NPs was ready with the electrospinning technique and successfully characterized. The results of MIC and OD analyses were used to investigate the synthesized materials' antibacterial effects and displayed that the synthesized materials could inhibit growth against Staphylococcus aureus and Escherichia coli bacteria. However, both in vitro cytotoxicity (MTT) and scratch wound studies have shown that RGO/ZnO NPs and SF/PVA/RGO/ZnO NPs are not only non-toxic to NIH 3T3 fibroblasts, but also can cause cell viability, cell proliferation, and cell migration. Furthermore, improving the synthesized nanofiber's structural properties in the presence of RGO and ZnO NPs has been confirmed by performing tensile strength, contact angle, and biodegradation analyses. Also, in a cell attachment analysis, fibroblast cells had migrated and expanded well in the nanofibrous structures. Moreover, in vivo assay, SF/PVA/RGO/ZnO NPs nanofiber treated rats and has been shown significant healing activity and tissue regeneration compared with other treated groups. Therefore, this study suggests that SF/PVA/RGO/ZnO NPs nanofiber is a hopeful wound dressing for preventing bacteria growth and improving superficial wound repair.     

Wound healing and regeneration in the imaginal wing disc ofDrosophila

Summary When complementary fragments of an imaginal disc ofDrosophila are cultured for several days prior to metamorphosis, usually one fragment will regenerate while the other will duplicate. It has been proposed that wound healing plays an important part in disc regulation (French et al. 1976; Reinhardt et al. 1977) by initiating cell proliferation and determining the mode of regulation. We tried to delay the wound healing process by leaving a region of dead cells between the wound edges. In 06 fragments (Bryant 1975a) wound healing has occurred after 1–2 days of culture and the regeneration of missing structures after 2–4 days of culture. We observed that leaving a region of dead cells between the wound edges delays both wound healing and the regeneration of missing structures by 2 days.When disc fragments are cultured in female abdomens and then exposed to³H-thymidine to label replicating cells, then the label is found to be localised around the wound. We observed that delaying wound healing does not delay this localisation of labelled nuclei indicating that wound healing may not be required to initiate DNA replication.     

In vivo 3-D distributions of electric fields in pig skin with rectangular pulse electrical current stimulation (RPECS)

We developed stimulating and detecting electrodes. We experimentally examined three dimensional (3-D) distributions of electric fields in living pig skin under and around the stimulating electrodes with the detecting electrodes and rectangular pulsed electrical current stimulation (RPECS). We verified our previous physical assumption, E ≈ I / (A σ_dz), in the skin under the electrode, where E, I, A and σ_dz respectively represent the electric field, the externally imposed peak current, the cross sectional area of the stimulating electrode and the perpendicular conductivity of the skin. Pulses were 30 mA, 140 μs and 128 pulses per second (pps). These parameters were previously used in our laboratory to enhance cutaneous regeneration, in vivo, with RPECS. © 1996 Wiley-Liss, Inc.