Fabrication and characterization of phlorotannins/poly (vinyl alcohol) hydrogel for wound healing application

Abstract

Phlorotannins (PH) derived from brown algae have been shown to have biological effects. However, the application of PH in biomedical materials has not been investigated. Here, we investigated the effects of PH on normal human dermal fibroblast (NHDF) proliferation and fabricated a composite hydrogel consisting PH and poly (vinyl alcohol) (PVA) (PVA/PH) by a freezing-thawing method for wound healing applications. Cell proliferation was significantly higher in the PH-treated (0.01 and 0.02%) cells than in non-treated cells. Based on the mechanical properties, the PVA/PH hydrogel had a significantly increased swelling ratio and ultimate strain compared to the PVA hydrogel, but the ultimate tensile strength and tensile modulus were decreased. Additionally, cell attachment and proliferation on the composites were evaluated using NHDFs. The results showed that after 1 and 5 days, cell attachment and proliferation were significantly increased on the PVA/PH hydrogel compared with that on the PVA hydrogel. The findings from this study suggest that the PVA/PH hydrogel may be a candidate biomedical material for wound healing applications.     

Heterogeneity of macrophage populations and expression of galectin-3 in cutaneous wound healing in rats

The aim of this study was to investigate the properties of macrophages that infiltrated the sites of cutaneous wound healing in rats between 1 and 26 days post wounding (dpw). During the inflammation phase (1–3 dpw), ED1⁺ (CD68⁺) macrophages with enhanced lysosomal activity dominated. From 5 to 7 dpw there was formation of granulation tissue as indicated by the presence of myofibroblasts expressing α-smooth muscle actin. At this stage, ED2⁺ (CD163⁺) macrophages, capable of producing inflammatory factors, were dominant. The majority of ED1⁺ macrophages expressed galectin-3, a regulator of fibrosis. Corresponding to the increased numbers of ED1⁺ and ED2⁺ macrophages at 3–9 dpw, there was increased expression of genes encoding transforming growth factor-β1 (a major fibrogenic factor), monocyte chemoattractant protein-1 and colony stimulating factor-1. These macrophage-related factors might contribute to inflammation and formation of granulation tissue. OX6⁺ macrophages expressing class II molecules of the major histocompatibility complex became predominant in the healing stages (15–26 dpw), indicating important roles for antigen-presenting cells in tissue remodelling. The OX6⁺ macrophages were most likely derived from ED1⁺ macrophages. The results of this study show that infiltration of phenotypically- and functionally-distinct macrophage populations characterizes different stages of the wound healing process.     

Wound healing properties of PVA/starch/chitosan hydrogel membranes with nano Zinc oxide as antibacterial wound dressing material

In this work, hydrogel membranes were developed based on poly vinyl alcohol (PVA), starch (St), and chitosan (Cs) hydrogels with nano Zinc oxide (nZnO). PVA/St/Cs/nZnO hydrogel membranes were prepared by freezing-thawing cycles, and the aqueous PVA/St solutions were prepared by dissolving PVA in distilled water. After the dissolution of PVA, starch was mixed, and the mixture was stirred. Then, chitosan powder was added into acetic acid, and the mixture was stirred to form a chitosan solution. Subsequently, Cs, St and PVA solutions were blended together to form a homogeneous PVA/St/Cs ternary blend solution. Measurement of Equilibrium Swelling Ratio (ESR), Water Vapor Transmission Test (WVTR), mechanical properties, scanning electron microscopy (SEM), MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay, antibacterial studies, in vivo wound healing effect and histopathology of the hydrogel membranes were then performed. The examination revealed that the hydrogel membranes were more effective as a wound dressing in the early stages of wound healing and that the gel could be used in topic applications requiring a large spectrum of antibacterial activity; namely, as a bandage for wound dressing.     

Intensity of RNA and protein synthesis in fibroblasts during wound healing in mice

RNA and protein synthesis in fibroblasts was studied by a double-labeling method on the 3rd and 7th days of wound healing in mice by electronmicroscopic autoradiography. The ratio of protein synthesis in the cytoplasm and RNA synthesis in the nucleus was shown to differ significantly in individual cells, with the result that fibroblasts with relative predominance of one of the two types of synthesis were found at both stages of wound healing. On average fibroblasts showed a higher level of protein synthesis on the 3rd day of healing. This high mean level was maintained by an increase in the proportion of fibroblasts in which protein synthesis predominated over RNA synthesis.Department of Pathological Anatomy, A. V. Vishnevskii Institute of Surgery, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR M. I. Kuzin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 11, pp. 617–621, November, 1979.     

纳米银抗菌水凝胶敷料联合重组人碱性成纤维细胞生长因子在踝部开放骨折创面的应用

背景:纳米银抗菌敷料和水凝胶是新型敷料,用于感染伤口的治疗.重组人碱性成纤维细胞生长因子是临床常应用于开放性伤口的活性多肽类药物.目的:探究外用重组人碱性成纤维细胞生长因子、纳米银抗菌水凝胶敷料在踝部开放骨折清创术后创面愈合中的应用.方法:收集踝部开放骨折清创术后患者99例,根据随机对照表分为对照组、试验A组和试验B组...     

Fibronectin and tenascin in rat tracheal wound healing and their relation to cell proliferation

To investigate the relationship between cell proliferation and distribution of fibronectin and tenascin during wound healing, light and electron microscopy and immunohistochemistry for fibronectin, tenascin, and 5-bromodeoxyuridine (BrdU) were performed following mechanical injury of rat trachea. Tenascin staining appeared 18h after curettage, when the percentage of BrdU-positive nuclei was maximal in the epithelium. Once tenascin appeared, the labeling index of BrdU-positive epithelial nuclei decreased rapidly. Distribution of tenascin was restricted to granulation tissue In curetted areas which were covered with regenerating epithelium, while fibronectin stained diffusely in both curetted and non-curetted areas. Analysis of the relative intensity of fibronectin and tenascin staining showed that decreases of fibronectin staining were followed by increasing tenascin staining. It is proposed that fibronectin and tenascin may contribute differently to tissue repair in the trachea by interfering with cell proliferation of epithelial cells and fibroblasts.     

Wound healing: the role of gap junctional communication in rat granulation tissue maturation.

Granulation tissue maturation is dependent upon the orientation of collagen fibers and cell differentiation. Gap junctions are intercellular membrane gated channels that facilitate direct communication between cells known as gap junctional intercellular communication (GJIC). The hypothesis is that GJIC modulates the maturation of granulation tissue during wound repair. In vitro, GJIC optimizes fibroblast-populated collagen lattice contraction and influences cell morphology. It is reported that LiCl increases GJIC in cultured cardiac myocytes. Polyvinyl alcohol (PVA) sponge implants with central reservoirs were placed within separate subcutaneous pockets on the backs of adult male Sprague-Dawley rats. Each PVA implant received either 20 mM LiCl or saline injections on days 5, 7, and 10 after implantation. On day 11 implants were harvested and processed for light microscopy. By H&E staining LiCl-treated implants showed increased vascularization and decreased cell density compared to saline controls. Polarized light microscopy of Sirius red-stained specimens revealed more intense collagen fiber birefringence secondary to dense, parallel-organized collagen fiber bundles after LiCl treatment. This suggests that LiCl enhancement of GJIC between fibroblasts advances the maturation of granulation tissue. It is proposed that the degree of GJIC between granulation tissue fibroblasts influences both the quantity and the quality of granulation tissue deposited during the wound healing process.     

In vitro and in vivo evaluation of the chitosan/Tur composite film for wound healing applications

We have developed tourmaline/chitosan (Tur/CS) composite films for wound healing applications. The characteristics of composite films were studied by optical microscope, infrared spectra and X-ray diffraction. Tur particles were uniformly distributed in the CS film and the crystal structure of CS was not remarkably changed except the decrease of crystallinity. The influence of Tur on wound healing applications was characterized by modulating Tur concentrations in the Tur/CS composite film prepared by loading Tur powder into CS matrix with different proportion (0, 1/40 and 1/10). Then L929 cells were co-cultured on the composite films to access the cytotoxicity in vitro. Tur concentrations strongly influenced cell process extension. Tur/CS composite film with 1/40 mass ratio could promote the cell adhesion and proliferation. Fewer and shorter processes were observed at high Tur density. When the composite films were transplanted on porcine full-thickness burn wounds, histological results demonstrated that the Tur/CS group with 1/40 mass ratio had a significantly higher number of newly-formed and mature blood vessels, and fastest regeneration of dermis. Based on the observed facts these films can be tailored for their potential utilization in wound healing and skin tissue engineering applications.     

Ski, a modulator of wound healing and scar formation in the rat skin and rabbit ear

We recently demonstrated that Ski is a novel wound healing-related factor that promotes fibroblast proliferation and inhibits collagen secretion. Here, we show that increasing local Ski expression by gene transfer not only significantly accelerated wound healing by relieving inflammation, accelerating re-epithelialization and increasing formation of granulation tissue, but also reduced scar formation by decreasing collagen production in rat dermal wounds. Similarly, ski gene transfer accelerated wound healing, reduced the protuberant height and volume of scars and increased collagen maturity in a hypertrophic scar model in the rabbit ear. Conversely, reducing Ski expression in the wound by RNA interference resulted in significantly slower wound healing and increased scar area in rat dermal wounds. We demonstrated that these effects of Ski are associated with transforming growth factor-β-mediated signalling pathways through both Smad2/3-dependent and Smad-independent pathways. Together, our results define a dual role for Ski in promoting wound healing and alleviating scar formation, identifying a new target for therapeutic approaches to preventing scar hyperplasia and accelerating wound healing.     

无定形水凝胶敷料对大鼠皮肤烫伤及创伤模型的疗效分析

目的:探讨无定形水凝胶敷料对大鼠深Ⅱ度烫伤及创伤模型的治疗应用效果。方法:分别制备大鼠深Ⅱ度烫伤及创伤模型,给予无定形水凝胶创面涂抹治疗,观察2类创面的完全脱痂时间、完全愈合时间及组织病理学特征;同时采用康惠尔水凝胶敷料(简称清创胶)作为平行对照。结果:对于深Ⅱ度烫伤和创伤创面,无定形水凝胶组和清创胶组的上皮化时间均短于相应的模型组,同一类型创面2种敷料治疗的愈合时间无明显差异,但无定形水凝胶组的完全脱痂时间短于清创胶组。病理结果显示,2种敷料使用后的皮肤烫伤创面上皮细胞、新生毛细血管及成纤维细胞数多于烫伤模型组,而炎症细胞数少于烫伤模型组;2种创面完全愈合后无定形水凝胶组的毛囊、汗腺均明显多于清创胶组。结论:无定形水凝胶主要通过促进创面上皮化缩短创面修复时间,在促进毛囊、汗腺形成上更胜一筹。     

Prognostic factors in the prediction of chronic wound healing by electrical stimulation

The aim of the study is to determine the effects of wound, patient and treatment attributes on the wound healing rate and to propose a system for wound healing rate prediction. Predicting the wound healing rate from the initial wound, patient and treatment data collected in a database of 300 chronic wounds is not possible. After considering weekly follow-ups, it was determined that the best prognostic factors are weekly follow-ups of the wound healing process, which alone were found to predict accurately the wound healing rate after a minimum follow-up period of four weeks (at least five measurements of wound area). After combining the follow-ups with wound, patient and treatment attributes, the minimum follow-up period was reduced to two weeks (at least three measurements of wound area). After a follow-up period of two weeks, it was possible to predict the wound healing rate of an independent test set of chronic wounds with a relative squared error of 0.347, and after three weeks, with a relative squared error of 0.181 (using regression trees with linear equations in its leaves). Regression trees with a relative squared error close to 0 produce better prediction than with an error closer to 1. Results show that the type of treatment is just one of many prognostic factors. Arranged in order of decreasing prediction capability, prognostic factors are: wound size, patient's age, elapsed time from wound appearance to the beginning of the treatment, width-to-length ratio, location and type of treatment. The data collected support former findings that the biphasic- and direct-current stimulation contributes to faster healing of chronic wounds. The model of wound healing dynamics aids the prediction of chronic wound healing rate, and hence helps with the formulation of appropriate treatment decisions.     

Mathematical models of wound healing in embryonic and adult epidermis

Epidermal wound healing occurs by quite different mechanismsin embryos and adults. In the latter case, it has long beenknown that cells crawl inwards via lamellipodia to close thedefect. In the embryonic system, recent evidence suggests thathealing may be caused by a quite different mechanism, namelythe contraction of a cable of filamentous actin at the woundedge. The authors use mathematical modelling to investigateboth systems. A mechanical model for the initial formation ofthe actin cable in embryonic epidermal wounds is presented,which incorporates the important phenomenon of stress-inducedmicrofilament alignment Also discussed is a reaction-diffusionmodel for the healing of adult wounds subject to auto-regulationof cell division. In both cases, the results suggest possiblebiological mechanisms for key aspects of the healing process.     

Macrophage-fibroblast interaction and its possible role in the regulation of collagen metabolism during wound healing

The role of macrophages in the resorption of the denatured collagen of wound detritus was established by transmission and scanning electron microscopy of healing skin wounds. In the period preceding active collagen synthesis and fibrillogenesis a phenomenon of close cellular contact between macrophages and fibroblasts of the granulation tissue was found. It is postulated that the role of macrophage-fibroblast interaction consists of the transmission of specific information with the aid of processed collagen breakdown products on the basis of feedback between collagen catabolism and biosynthesis. This feedback may be part of the homeostatic mechanism regulating the development of connective tissue.Central Scientific-Research Laboratory, I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. I. Strukov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 627–630, May, 1977.     

壳寡糖在糖尿病皮肤伤口愈合中的应用及研究进展

糖尿病慢性皮肤伤口的愈合,是临床治疗中的难点和基础研究中的热点。传统治疗方法效果并不理想,而组织工程技术的发展,为其治疗提供了新途径。现今已有将壳寡糖作为伤口敷料的研究,并引起越来越多的关注,但关于壳寡糖用于糖尿病难愈性创面的研究并不多。本篇综述将概述壳寡糖促进伤口愈合的生物学机制及特点,以及糖尿病皮肤创面的病理学改变,总结壳寡糖在糖尿病皮肤伤口愈合中的研究进展。     

Development of a functional wound dressing composed of hyaluronic acid spongy sheet containing bioactive components: evaluation of wound healing potential in animal tests

This study aimed to develop a novel wound dressing composed of hyaluronic acid (HA) spongy sheet containing bioactive components. The wound dressing prepared by the freeze-drying method has a two-layered structure: an upper layer composed of cross-linked high-molecular-weight HA (HMW-HA) and a lower layer composed of low-molecular-weight HA (LMW-HA) containing arginine (Arg), magnesium ascorbyl phosphate (vitamin C derivative: VC), and epidermal growth factor (EGF) (referred to as EGF-dressing). A wound dressing containing only Arg and VC was prepared in a similar manner (referred to as EGF-free-dressing). The potential of each wound dressing was evaluated in animal tests using Sprague Dawley (SD) rats and diabetic mice. In the first experiment, each wound dressing was applied to a full-thickness skin defect in the abdominal region of SD rats. Wound conditions after 1?week and 2?weeks of treatment were evaluated based on macroscopic and histological appearance. A commercially available non-woven alginate wound dressing (Alg-dressing) was used in a control group. Both EGF-free-dressing and EGF-dressing decreased wound size and promoted granulation tissue formation associated with angiogenesis more effectively when compared with Alg-dressing. In particular, EGF-dressing promoted re-epithelialization. In the second experiment, each wound dressing was applied to a full-thickness skin defect in the dorsal region of diabetic mice. Wound conditions after 1?week and 2?weeks of treatment were evaluated based on macroscopic and histological appearance. A commercially available Alg-dressing was used in a control group. Both EGF-free-dressing and EGF-dressing decreased wound size and promoted granulation tissue formation associated with angiogenesis more effectively when compared with Alg-dressing. These findings indicate that EGF-free-dressing and EGF-dressing have the potential for more effective wound healing when compared with Alg-dressing. In particular, EGF-dressing has a higher potential for wound healing when compared with EGF-free-dressing.     

环状RNA在皮肤相关疾病及创面愈合中的研究进展

环状RNA(circRNA)为一类具有连续共价闭环结构的新型非编码RNA(ncRNA),无3′及5′游离末端。其可作为微小RNA(miRNA)"分子海绵"调节转录或剪接,也可与RNA结合蛋白相互作用,在机体生理和病理过程中都起着关键作用。近来有研究表明,在与创面愈合相关的细胞(血管内皮细胞、角质细胞)增殖、迁移等活动中,有circRNA参与其中。本文回顾了circRNA在不同类型皮肤细胞中发挥的调节作用及其与皮肤相关疾病如皮肤鳞状细胞癌、基底细胞癌、重度痤疮的联系,旨在为阐释创面愈合的细胞分子机制提供新思路,以期为解决临床上创面治疗难题开拓新方向。     

Relationship between the distribution of myofibroblasts,and stellar and circular scar formation due to the contraction of square and circular wound healing

Square skin wounds can heal to form a stellar scar with four protrusions at the four angles, whereas circular wounds can heal to form an ellipsoid scar. It is not clear why these differences occur and the aim of the present study was to clarify this phenomenon. Two square or circular full-thickness skin wounds were made on the dorsum of mice, and covered with hydrocolloid dressing. They were observed from day 0 to 15 after wounding, and used to prepare paraffin sections stained with anti-alpha-smooth muscle actin antibody to detect myofibroblasts. The square wound was transiently enlarged by edema and skin tension on day 3, at which time the angles became round, and thus the square form became more circular. Thereafter, the wound contracted rapidly and the circular form was maintained until day 11. On day 11 distinct angles appeared where the scar formation had progressed further, and there were fewer myofibroblasts than in any other section. A stellar scar with protrusions from the four angles was formed on day 15, when myofibroblasts almost disappeared in the protrusions. This indicates that due to the earlier disappearance of myofibroblasts and earlier scarring in the angles of the square wound, the scar angle cannot be pulled into the center of the wound but residual myofibroblasts on the side can pull the side into the center due to myofibroblastic contraction and consequently a stellar scar is formed. Thus, the earlier disappearance of myofibroblasts in the angles is very important for the formation of stellar scars.