Dextrin–rhEGF conjugates as bioresponsive nanomedicines for wound repair

Growth factors are known to act in concert to promote wound repair, but their topical application rarely leads to a significant clinical improvement of chronic wounds due to premature inactivation in wound environment. The aim of this study was to synthesise a polymer–growth factor conjugate and investigate whether the novel concept called Polymer-masking-UnMasking-Protein Therapy (PUMPT) might be used to generate bioresponsive polymer therapeutics as nanomedicines able to promote tissue repair. Succinoylated dextrin ( 85,000 g/mol;  19 mol% succinoylation), and rhEGF were chosen as a first model combination. The conjugate synthesised contained  16%wt rhEGF and < 1% free protein. It exhibited increased stability towards proteolytic degradation by trypsin and the clinically relevant enzyme neutrophil elastase. The dextrin component was degraded on addition of α-amylase leading to sustained release of free rhEGF over time (52.7% release after 168 h). When biological activity was assessed (± α-amylase) in proliferation assays using epidermoid carcinoma (HEp2) cells and HaCaT keratinocytes, as anticipated, polymer conjugation reduced rhEGF bioactivity (p = 0.0035). However, exposure to physiological concentrations of α-amylase triggered dextrin degradation and this led to protein unmasking with restoration of bioactivity to the level seen for unmodified rhEGF. Indeed, prolongation of HEp2 proliferation was observed over 8 days. The inability of dextrin, succinoylated dextrin or α-amylase alone to induce proliferative effects, and the ability of α-amylase-exposed dextrin–rhEGF to induce phosphorylation of the epidermal growth factor receptor (EGFR) in HEp2 cells confirmed a mechanism of action by stimulation of classical signal transduction pathways. These observations suggest that this dextrin–rhEGF, and other dextrin-growth factor conjugates have potential for further development as bioresponsive nanomedicines for tissue repair.     

Recombinant basic fibroblast growth factor stimulates wound healing in healing-impaired db/db mice

The stimulatory effect of recombinant basic fibroblast growth factor (bFGF) on wound healing was assessed using healing-impaired (db/db) mice. Full-thickness wounds were made in female diabetic C57BL/KsJ db/db mice, and their normal (db/+) littermates with a punch biopsy instrument. Recombinant bFGF was applied locally to the open wound once a day. The mice were later killed and histological sections of the wounds were prepared. The degree of wound healing was evaluated using several histological parameters such as degree of reepithelialization, granulation tissue thickness, matrix density, number of infiltrated cells, and number of capillaries. Wounds from normal mice displayed good reepithelialization rates and granulation tissue formation, while wounds from db/db mice had poor responses, especially in the dermal parameters. Although the application of bFGF to wounds in the normal (db/+) mice had little effect, application of bFGF to wounds in db/db mice induced significant responses in all of the dermal parameters compared with nontreated db/db mice (p less than 0.001). In the presence of bFGF, these parameters approximated those observed in nontreated littermates. A minimum of 0.5 microgram bFGF in either single or multiple applications was required for a significant effect. bFGF that was either boiled or pretreated with neutralizing antibody had little stimulatory effect. Time-course experiments indicated that the granulation response in bFGF-treated mice peaked between 8 and 12 d, and decreased after 12 d, while matrix density continued to increase until the 18th day (p less than 0.05). The breaking strength of healed linear wounds in db/db mice was also decreased when compared with heterozygous littermates. This parameter was also improved by the administration of bFGF to the wounds (p less than 0.05).     

Evaluating the effectiveness of Tegapore wound-contact material

During wound healing, new-forming granulation tissue is often extremely fragile and can be easily disrupted during dressing changes. This can lead to a delay in the completion of wound healing and increased pain and discomfort for the patient (European Wound Management Association, 2002; Fear, 2002).     

Wound-healing properties of trehalose-stabilized freeze-dried outdated platelets

BACKGROUND: The wound-healing applications of platelet (PLT)-derived cytokines, proteins, and membranes is accepted but continues to be investigated. In this study, it is demonstrated that stabilized freeze-dried PLTs prepared from outdated PLTs (FDPOs) accelerate wound healing and form tube structures as well as stabilized indated freeze-dried PLTs (FDPIs) and room-temperature fresh PLTs (RT-PLTs). STUDY DESIGN AND METHODS: Experiments were designed to compare in vitro and in vivo wound-healing properties of FDPI, FDPO, and RT-PLT preparations. The concentration of PLT-derived growth factor (PDGF)-betabeta and transforming growth factor (TGF)-beta1 was determined, and the abilities of FDPIs, FDPOs and RT-PLTs to induce endothelial cell proliferation and promote endothelial cell tube formation (cells formed solid spouts connecting neighboring cells to form tube structures) were observed. Wound-healing characteristics were measured by surgically inducing 1-cm(2), full-thickness wounds on db/db mice (n = 10 per group). The wounds were treated with single or multiple doses of FDPIs and FDPOs. Wound closure rate was determined, and histology samples were evaluated for cellular makeup. RESULTS: FDPOs retained the same levels of PDGF-betabeta and TGF-beta1 and were able to promote endothelial cell proliferation and tube formation in vitro as well as FDPIs or RT-PLTs. Multiple applications of FDPO accelerated wound closure and enhanced reepithelialization when compared to untreated wounds in db/db mice. CONCLUSION: FDPOs enhanced wound healing in db/db mice as well as FDPIs and RT-PLTs. Wound closure was obtained 6 days earlier than untreated wounds and histologic examination revealed reduced granulation and increased cellular angiogenesis.     

Physiology of wound healing

Despite the emphasis placed on skin care, hospitalized infants often experience injury to their skin. Although skin injuries vary, they have a common innate mechanism for repair and healing. Wound healing is a physiologic process that involves a series of sequential yet overlapping stages. The first stage, hemostasis, occurs immediately at the time of injury. During hemostasis, a provisional matrix seals the injury site and initiates the process of wound healing. The second stage, inflammation, is triggered by a variety of mediators released from injured tissue cells and capillaries, activated platelets and their cytokines, and the by-products of hemostasis. During the third stage, the wound surface is covered with new skin and vascular and structural integrity are restored as granulation tissue fills the defect. The final stage, remodeling, is responsible for maturation of the granulation tissue into mature connective tissue and/or scar. A thorough understanding of wound healing physiology is an important prerequisite to providing care that optimizes wound healing and prevents unnecessary complications. Many of the current wound care practices are based on tradition rather than scientific knowledge. As the interface between the infant and the environment, nurses are in an ideal position to evaluate the soundness of these wound care practices. Physiologic-based care strategies to enhance wound healing are proposed. Copyright © 2001 by W.B. Saunders Company     

Relationship between structure and antibacterial activity of lipophilic N-acyldiamines

We report in this work the preparation and antibacterial evaluation of a series of N-monoacylated diamines against six Gram-positive and 11 Gram-negative bacteria. The results obtained showed the existence of relationship between lipophilicity and antibacterial activity of the tested compounds. The best results were obtained against Gram-positive bacteria for compounds having a 10–12 carbons alkyl chain. Compound 4e was the most active against Microccus lentus (MIC = 2 μg/mL), Staphylococcus aureus ATCC 29213 (MIC = 4 μg/mL) and Enterobacter aerogenes CDC 1680 (MIC = 8 μg/mL).     

放射延迟伤口愈合机制的初步研究

目的：初步探索放射延迟伤口愈合的机制。方法：用光镜、电镜及原位末端标记法并结合图象分析技术，观察大鼠创伤组和放射复合创伤组伤口病理形态学、伤口面积和伤口区细胞数量、细胞凋亡等方面的变化。结果：（1）照射后伤口愈合：早期炎症反应明显受抑，创面渗出物减少，出血、坏死明显；中期肉芽组织生长成熟减慢，伤口收缩受到抑制；后期上皮覆盖滞后，与单伤且相比愈合时间明显延长。伤口面积测定显示：在伤口愈合过程中伤照组面积始终大于单伤组。（2）肉芽组织中细胞数量测定：照射后伤口区细胞数量的增多明显滞后于单伤组，部分成纤维细胞出现变性、坏死。（3）细胞凋亡在伤口愈合中的发生规律分析：与单伤组相比，伤照组细胞凋亡出现较早、频率较高、消失推迟。结论：大剂量辐射确实可延迟伤口愈合；辐射后细胞数量、形态及功能异常，尤其是细胞凋亡发生过度，可能是导致辐射延迟伤口愈合的延迟伤口愈合的重要机制。     

Antibiotic-releasing porous polymethylmethacrylate/gelatin/antibiotic constructs for craniofacial tissue engineering

An antibiotic-releasing porous polymethylmethacrylate (PMMA) construct was developed to maintain the bony space and prime the wound site in the initial step of a two-stage regenerative medicine approach toward reconstructing significant bony or composite craniofacial tissue defects. Porous PMMA constructs incorporating gelatin microparticles (GMPs) were fabricated by the sequential assembly of GMPs, the antibiotic colistin, and a clinically used bone cement formulation of PMMA powder and methylmethacrylate liquid. PMMA/gelatin/antibiotic constructs with varying gelatin incorporation and drug content were investigated to elucidate the relationship between material composition and construct properties (porosity and drug release kinetics). The porosity of PMMA/gelatin/antibiotic constructs ranged between 7.6 ± 1.8% and 38.4 ± 1.4% depending on the amount of gelatin incorporated and the drug solution added for gelatin swelling. The constructs released colistin over 10 or 14 days with an average release rate per day above 10 μg/ml. The porosity and in vitro colistin release kinetics of PMMA/gelatin/antibiotic constructs were tuned by varying the material composition and fabrication parameters. This study demonstrates the potential of gelatin-incorporating PMMA constructs as a functional space maintainer for both promoting tissue healing/coverage and addressing local infections, enabling better long-term success of the definitive regenerated tissue construct.     

藻酸盐银联合水凝胶敷料对慢性创面愈合的作用

背景:研究发现藻酸盐及水凝胶敷料等均可促进创面愈合,而新型敷料藻酸盐银联合水凝胶敷料,对于难治慢性创面的愈合作用尚不清楚。目的:观察藻酸盐银联合水凝胶敷料对慢性创面治疗的作用。方法:选择江苏省人民医院烧伤整形科住院慢性创面患者34例,随机分为2组:治疗组应用藻酸盐银联合水凝胶敷料序贯换药;对照组采用1%磺胺嘧啶银冷霜抹在凡士林纱布上外敷,于治疗后7,10,14,17,21d进行创面分泌物细菌培养、观察创面愈合情况及速度、药物不良反应、换药时创面痛感、肉芽破坏等情况。结果与结论:治疗组创面细菌检出率明显低于对照组(P<0.05)。治疗组创面愈合时间比对照组平均缩短约6d,创面愈合速度较对照组明显加快(P<0.05)。两组均无药物不良反应,治疗组创面换药时无明显疼痛感,肉芽组织无明显破坏。提示藻酸盐银联合水凝胶敷料序贯治疗慢性创面具有显著抗菌及促进创面肉芽组织和上皮再生、促进创面愈合的作用,且无不良反应。     

Lactobacillus rhamnosus GG improves glucose tolerance through alleviating ER stress and suppressing macrophage activation in db/db mice

Although recent studies have reported that Lactobacillus rhamnosus GG (LGG), the most extensively studied probiotic strain, exerts an anti-hyperglycemic effect on several rodent models, the underlying mechanism remains unclear. In this study, twenty male C57BL/KsJ-db/db (db/db) mice were divided into 2 groups, LGG-treated and control group, which received a daily dose of LGG (1 × 10⁸ CFU per mouse) and PBS orally for 4 weeks, respectively. We observed that glucose tolerance was significantly improved in LGG-treated db/db mice. Insulin-stimulated Akt phosphorylation and GLUT4 translocation were higher in skeletal muscle of LGG-treated mice relative to their controls. It was also observed that LGG treatment caused significant reductions in endoplasmic reticulum (ER) stress in skeletal muscle and M1-like macrophage activation in white adipose tissues. Our results indicate that the anti-diabetic effect of LGG in db/db mice is associated with alleviated ER stress and suppressed macrophage activation, resulting in enhanced insulin sensitivity. These findings suggest a therapeutic potential of probiotics for prevention and treatment of type 2 diabetes.     

银离子敷料联合水凝胶对Ⅱ度烧伤创面愈合的作用

目的:了解银离子敷料联合水凝胶促进Ⅱ度烧伤创面愈合的作用.方法:选择2007-05/2009-05南通市第一人民医院烧伤整形科住院烧伤患者104例作为观察对象.随机分为2组:治疗组应用银离子敷料联合水凝胶序贯换药;对照组采用1%磺胺嘧啶银冷霜抹在凡士林纱布上外敷,于伤后7,10,15,17,21 d进行创面分泌物细菌培养、观察记录创面愈合情况及速度、观察药物不良反应、换药时创面痛感、肉芽破坏情况.结果:治疗组创面细菌检出率明显低于对照组(P<0.05).治疗组浅Ⅱ度创面愈合时间比对照组平均缩短三四天,治疗组深Ⅱ度创面愈合时间比对照组平均缩短五六天.治疗组创面愈合速度较对照组明显加快(P<0.05).两组均无药物不良反应,治疗组创面换药时无明显疼痛感,肉芽组织无明显破坏.结论:银离子敷料联合水凝胶序贯治疗Ⅱ度烧伤创面具有显著抗菌及促进创面肉芽组织和上皮再生、促进创面愈合的作用,且无不良反应.     

重组人表皮生长因子用于大鼠Ⅲ期压疮模型的实验研究

[目的]观察重组人表皮生长因子(rhEGF)用于治疗大鼠Ⅲ期压疮溃疡创面的疗效.[方法]采用SD大鼠制备Ⅲ期压疮动物模型,实验组16只用rhEGF喷洒创面,对照组16只用生理盐水溶液湿敷创面,治疗后的第3天、第7天、第10天、第14天取创伤组织制成组织切片,观察其病理学变化;动态观察rhEGF和生理盐水对溃疡愈合时间及愈合率的影响.[结果]两组溃疡创面愈合时间及动态愈合率比较差异有统计学意义(P< 0.05).[结论]重组人表皮生长因子可以促进大鼠Ⅲ期压疮溃疡创面的愈合.     

重组人表皮生长因子和碱性成纤维生长因子促进人角膜上皮细胞的增殖

背景：重组人表皮生长因子和碱性成纤维生长因子的制剂临床上已经用于眼表创伤的修复,但是对于使用何种浓度的生长因子就能够最大程度的促进愈合以及两种生长因子促进创面愈合的效果比较一直存在争议。 目的：初步观察重组人表皮生长因子、碱性成纤维生长因子对培养的人角膜上皮细胞克隆的影响。 方法：用不同浓度的重组人表皮生长因子和碱性成纤维生长因子作用于体外培养的人角膜上皮细胞,应用四甲基偶氮唑盐比色法分别在不同浓度的生长因子作用人角膜上皮细胞3,5,7 d后检测人角膜上皮细胞的增殖能力;平板克隆形成实验法观察细胞克隆形态及计算细胞克隆形成率。 结果与结论：不同质量浓度的重组人表皮生长因子和碱性成纤维生长因子分别对人角膜上皮细胞干预5d后,重组人表皮生长因子和碱性成纤维生长因子在10μg/L质量浓度时MTT值最大;质量浓度10μg/L重组人表皮生长因子促进人角膜上皮细胞克隆形成率高于质量浓度10μg/L碱性成纤维生长因子（P=0.02）。结果证实,重组人表皮生长因子和碱性成纤维生长因子均能促进人角膜上皮细胞增殖并增加其克隆形成能力。质量浓度10μg/L 重组人表皮生长因子干预5 d促进人角膜上皮细胞克隆形成效果最好。     

Evaluation of the Wound-healing Activity of Ethanolic Extract of Morinda citrifolia L. Leaf

Morinda citrifolia L. (noni) is one of the most important traditional Polynesian medicinal plants. The primary indigenous use of this plant appears to be of the leaves, as a topical treatment for wound healing. The ethanol extract of noni leaves (150 mg kg⁻¹ day⁻¹) was used to evaluate the wound-healing activity on rats, using excision and dead space wound models. Animals were randomly divided into two groups of six for each model. Test group animals in each model were treated with the ethanol extract of noni orally by mixing in drinking water and the control group animals were maintained with plain drinking water. Healing was assessed by the rate of wound contraction, time until complete epithelialization, granulation tissue weight and hydoxyproline content. On day 11, the extract-treated animals exhibited 71% reduction in the wound area when compared with controls which exhibited 57%. The granulation tissue weight and hydroxyproline content in the dead space wounds were also increased significantly in noni-treated animals compared with controls (P < 0.002). Enhanced wound contraction, decreased epithelialization time, increased hydroxyproline content and histological characteristics suggest that noni leaf extract may have therapeutic benefits in wound healing.     

负压封闭引流技术联合湿性疗法治疗肿瘤病人难愈性伤口的效果观察

[目的]探讨负压封闭引流技术(VSD)联合湿性疗法治疗肿瘤病人难愈性伤口的效果,以期为寻找治疗肿瘤难愈性伤口的最佳方法提供依据。[方法]入选的32例具有难愈性伤口的肿瘤病人随机分为对照组A(湿性疗法),对照组B(负压引流技术)和干预组(联合治疗组)。在基础处理阶段后,A组病人给予系统的湿性疗法,采用的湿性敷料为藻酸盐和水胶体敷料;B组采用负压封闭引流疗法;干预组采用负压联合湿性序贯疗法,根据伤口创面分期动态选择适当的疗法。干预结束后,观察伤口面积缩小率及肉芽组织覆盖伤口床≥75%的时间,随访2个月,观察比较对照组与干预组的伤口愈合率。[结果]联合治疗组在伤口面积缩小率及肉芽组织覆盖伤口床≥75%的时间均优于单一治疗组(P0.05)。A组伤口愈合率为60%,B组愈合率81.8%,干预组愈合率90.9%,干预组在愈合率上优于湿性疗法组,与负压引流组相比无明显差异。[结论]负压引流联合湿性疗法进行交替序贯治疗,可显著改善肿瘤病人难愈性伤口治疗效果,加速创面愈合。     

Lidocaine via lontophoresis in laceration repair: A preliminary safety study

Iontophoresis is a painless technique for topical anesthesia that uses an electric field to drive charged ions across an epithelial surface. The safety of this technique for laceration repair has never been demonstrated. The purpose of this study was to investigate the effect of iontophoretic fields on rapidly proliferating cells involved in laceration wound healing. The study was a prospective single-blinded animal study using a guinea pig model. Twelve guinea pigs each received four induced, uncontaminated lacerations. Each guinea pig was randomly assigned to 1 of 3 groups (4 guinea pigs in each group). One group received lidocaine via iontophoresis, one group received injected lidocaine, and one group received half iontophoresis and half injected lidocaine. After anesthetic treatment, wounds were then repaired in a standard fashion. The wounds were examined grossly on a daily basis and on day 10 the incised skin containing the laceration was examined by a pathologist blinded to the treatment group. A total of 48 wounds were assessed for wound healing, 24 of which received lidocaine via iontophoresis and 24 lidocaine via injection. The power of the study to determine a 40% difference between the two groups was 0.8. There was significantly more granuloma and granulation tissue formation in the iontophoresis group than in the injected lidocaine control group (P = .0004, Fisher's exact test). There were no statistically significant differences in degree of inflammation between the two groups (lidocaine via injection v lidocaine via iontophoresis) measured by amount of dermal fibrosis (P = .14, Fisher's exact test), giant cell formation (P = .21, Fisher's exact test), and presence of acute and/or chronic inflammation (P = .17, Wilcoxon's rank sum test). Wound healing proceeded normally with 100% in both groups having normal scar formation and healing at day 10. In conclusion, iontophoresis appears to be a safe method of anesthesia delivery in this guinea pig model with lacerations. Increased granuloma and granulation tissue formation may indicate an enhancement of wound healing via iontophoresis.     

藻酸盐银联合水凝胶敷料对慢性创面愈合的作用

背景：研究发现藻酸盐及水凝胶敷料等均可促进创面愈合,而新型敷料藻酸盐银联合水凝胶敷料,对于难治慢性创面的愈合作用尚不清楚。目的：观察藻酸盐银联合水凝胶敷料对慢性创面治疗的作用。方法：选择江苏省人民医院烧伤整形科住院慢性创面患者34例,随机分为2组：治疗组应用藻酸盐银联合水凝胶敷料序贯换药;对照组采用1%磺胺嘧啶银冷霜抹在凡士林纱布上外敷,于治疗后7,10,14,17,21d进行创面分泌物细菌培养、观察创面愈合情况及速度、药物不良反应、换药时创面痛感、肉芽破坏等情况。结果与结论：治疗组创面细菌检出率明显低于对照组（P〈0.05）。治疗组创面愈合时间比对照组平均缩短约6d,创面愈合速度较对照组明显加快（P〈0.05）。两组均无药物不良反应,治疗组创面换药时无明显疼痛感,肉芽组织无明显破坏。提示藻酸盐银联合水凝胶敷料序贯治疗慢性创面具有显著抗菌及促进创面肉芽组织和上皮再生、促进创面愈合的作用,且无不良反应。     

A graphene hybrid supramolecular hydrogel with high stretchability,self-healable and photothermally responsive properties for wound healing

Wound healing is a ubiquitous healthcare problem in clinical wound management. In this paper, the fabrication of a graphene hybrid supramolecular hydrogel (GS hydrogel) for wound dressing applications is demonstrated. The hydrogel is composed of two components, including N-acryloyl glycinamide (NAGA) as the scaffold and graphene as the photothermally responsive active site for photothermal therapy. Based on the multiple hydrogen bonds between the dual amide motifs in the side chain of N-acryloyl glycinamide, the hydrogel exhibits high tensile strength (≈1.7 MPa), good stretchability (≈400%) and self-recoverability. In addition, the GS hydrogel shows excellent antibacterial activity towards methicillin-resistant Staphylococcus aureus (MRSA), benefiting from the addition of graphene that possesses great photothermal transition activity (≈85%). Significantly, in vivo animal experiments also demonstrated that the GS hydrogel effectively accelerates the wound healing processes by eradicating microbes, promoting collagen deposition and angiogenesis. In summary, this GS hydrogel demonstrates excellent mechanical performance, photothermal antimicrobial activity, and promotes skin tissue regeneration, and so has great application potential as a promising wound dressing material in clinical use.

The hydrogel demonstrated properties with high stretchability, self-healable and photothermal properties. Notably, photothermal therapy could be established due to its photothermal responsiveness, benefiting infected wound healing.