Wound Dressings Based on Chitosans and Hyaluronic Acid for the Release of Chlorhexidine Diacetate in Skin Ulcer Therapy

In the present work wound dressings, based on chitosan hydrochloride (HCS), 5-methyl-pyrrolidinone chitosan (MPC), and their mixtures with an anionic polymer, hyaluronic acid (HA), were prepared by freeze-drying. Chlorhexidine diacetate (CX) was used as an antimicrobic drug. The mechanical properties of the wound dressings were investigated. In particular, the wound dressings were subjected to dynamic hydration measurements to evaluate their capability to absorb wound exudate and to rheological analysis to investigate their resistance to mechanical stresses on hydration. The wound dressings were also characterized for drug release properties. The antioxidant and antimicrobial activities of medicated and non-medicated wound dressings were also investigated. All the wound dressings are characterized by mechanical resistance suitable for skin application. The addition of hyaluronic acid to chitosans leads to a reduction in wound dressing hydration properties and a modulation of drug release. The wound dressing based on MPC is characterized by the highest elastic properties and by the best scavenger activity. Antimicrobial activity against bacteria and C. albicans is shown by the dressing based on chitosan also in absence of chlorhexidine.     

Protease inhibition by oleic acid transfer from chronic wound dressings to albumin

High elastase and cathepsin G activities have been observed in chronic wounds to inhibit healing through degradation of growth factors, cytokines, and extracellular matrix proteins. Oleic acid is a non-toxic elastase inhibitor. Cotton wound dressing material was characterized as a transfer carrier for affinity uptake of oleic acid by albumin under conditions mimicking chronic wounds. The mechanism of oleic acid uptake from cotton and binding by albumin was examined with both intact dressings and cotton fiber-designed chromatography. Raman spectra of the albumin–oleic acid complexes under liquid equilibrium conditions revealed fully saturated albumin–oleic acid complexes with a 1:1 weight ratio of albumin:oleic acid. Liquid–solid equilibrium conditions revealed oleic acid transfer from cotton to albumin at 27 mole equivalents of oleic acid per mole albumin. Comparing oleic acid formulated wound dressings for dose dependent ability to lower elastase activity, we found cotton gauze > hydrogel > hydrocolloid. In contrast, the cationic serine protease cathepsin G was inhibited by oleic acid within a narrow range of oleic acid–cotton formulations. 2% albumin was sufficient to transfer quantities of oleic acid necessary to achieve a significant elastase-lowering effect. Oleic acid bound to cotton wound dressings may have promise in the selective lowering of cationic serine protease activity useful in topical application for chronic inflammatory pathogenesis.     

新型静电纺丝伤口敷料的止血性能及促愈合作用研究

目的 评价新型静电纺丝伤口敷料的止血性能及促创伤愈合作用,为该敷料的进一步开发应用奠定基础。方法 将胶原蛋白和壳聚糖的混合溶液通过静电纺丝技术纺在海藻酸盐无纺布基布上,制备成新型静电纺丝伤口敷料（胶原蛋白-壳聚糖静电纺丝膜复合海藻酸盐敷料,Collagen-Chitosan Electrostatic spinning membrane Alginate Dressing,CCEAD）。通过体外凝血实验、兔耳动脉创伤止血实验和兔背部创伤止血实验评价CCEAD的止血性能。建立大鼠背部全皮层创伤模型,分别在术后3、5、7、12 d拍照计算伤口愈合率,测定CCEAD的促愈合作用;取伤口创面皮肤组织,HE染色观察组织病理学变化;免疫组化染色观察在伤口愈合过程中CD31、FGF-2和TGF-β的表达情况。结果 CCEAD组的体外凝血指数BCI为36.91±6.62,显著小于阳性对照明胶海绵组（69.82±1.83）和阴性对照医用纱布组（79.93±6.30）（P＜0.01）。兔耳动脉创伤止血实验中,CCEAD组的止血时间（107.67±17.62) s短于医用纱布组（163.67±15.50） s（P＜0.05）。兔背部创伤止血实验中,CCEAD组Hb光度吸收值（0.120±0.052）明显低于医用纱布组（0.294±0.021）（P＜0.01）。在促创伤愈合实验中,术后第7天,CCEAD组愈合率为65.70%±4.94%,高于阳性对照壳聚糖敷料组（48.78%±8.33%,P＜0.05）,明显高于医用纱布组（37.76%±6.35%,P＜0.01）。HE染色显示,CCEAD在伤口愈合早期能够促进成纤维细胞生长和新生血管形成,促进肉芽组织的生成。免疫组化结果显示,CCEAD能促进CD31、FGF-2和TGF-β在伤口愈合早期的表达,有利于伤口的愈合。结论 新型静电纺丝伤口敷料（胶原蛋白-壳聚糖静电纺丝膜复合海藻酸盐敷料）止血性能优良,具有明显的促创伤愈合作用,有望开发成新型伤口敷料。     

Collagen‐based wound dressing for doxycycline delivery: in‐vivo evaluation in an infected excisional wound model in rats

Objectives A novel collagen‐based dressing consisting of 2,3‐dihydroxybenzoic‐acid‐modified gelatin microspheres loaded with doxycycline has previously been reported to address both infection and matrix degradation. In the present study the potential benefits of the dressing were investigated in an excisional wound model in rats challenged with Pseudomonas aeruginosa. Methods A full‐thick excisional wound (1.5 times 1.5 cm) was created on the dorsum of the rats and infection induced by injecting 10⁵ colony‐forming units (CFU) of P. aeruginosa. The healing pattern was assessed from wound reduction, matrix metalloprotease (MMP) levels, CFU reduction and histological and biochemical analysis. Key findings The treated group exhibited complete healing by day 15, compared with day 24 in the control group. Early subsidence of infection (99.9% by day 9) resulted in faster epidermal resurfacing and fibroplasias, whereas the microbial load exceeded 10³ CFU even on day 15 in the control group and caused severe inflammation. Biochemical analysis showed that the expression of both collagen and hexosamine was significantly increased in the treated group. Gelatin zymography revealed prolonged expression of MMPs 2, 8 and 9 in the control group compared with the treated group. Conclusions The study indicates that the developed dressing attenuated both infection and metalloprotease levels, and may therefore have potential application in wound healing.     

Chitosan as a starting material for wound healing applications

Chitosan and its derivatives have attracted great attention due to their properties beneficial for application to wound healing. The main focus of the present review is to summarize studies involving chitosan and its derivatives, especially N,N,N-trimethyl-chitosan (TMC), N,O-carboxymethyl-chitosan (CMC) and O-carboxymethyl-N,N,N-trimethyl-chitosan (CMTMC), used to accelerate wound healing. Moreover, formulation strategies for chitosan and its derivatives, as well as their in vitro, in vivo and clinical applications in wound healing are described.     

Wound healing: a new approach to the topical wound care

Cutaneous wound healing is a complex and well-coordinated interaction between inflammatory cells and mediators, establishing significant overlap between the phases of wound healing. Wound healing is divided into three major phases: inflammatory phase, proliferative phase, and remodeling phase. Unlike the acute wound, the nonhealing wound is arrested in one of the phases of healing, typically the inflammatory phase. A systematic approach to the management of the chronic nonhealing wound emphasizes three important elements of wound bed preparation in chronic wounds: debridement, moisture, and countering bacterial colonization and infection. In this article, wound-healing process and new approaches to the topical wound care have been reviewed.     

Development of polyurethane foam dressing containing silver and asiaticoside for healing of dermal wound

 Polyurethane foam dressings for dermal wounds were formulated with natural polyols in order to improve the foam characteristics and the release of 2 active agents, silver and asiaticoside (AS) as an antimicrobial agent and an herbal wound healing agent, respectively. The foam was instantly formed by interaction of polyols and diisocyanate. Hydroxypropyl methylcellulose, chitosan and sodium alginate were individually mixed with the main polyols, polypropylene glycol, in the formulation while the active components were impregnated into the obtained foam dressing sheets. Although the type and amount of the natural polyols slightly affected the pore size, water sorption-desorption profile and compression strength of the obtained foam sheets, a prominent effect was found in the release of both active components. Among natural polyols formulations, foam sheets with alginate showed the highest silver and AS release. Non-cytotoxicity of these foam sheets to human fibroblast cells was confirmed. Antimicrobial testing on four bacteria strains showed that 1 mg/cm2 silver in formulations with 6% of natural polyols and without natural polyols had sufficient content of the silver release with comparable inhibition zone and significantly larger zone than other formulations. In pig study, the foam dressing with 6% alginate, 1 mg/cm2 silver and 5% AS could improve wound healing in both the percentage of the wound closure and histological parameters of the dermal wound without any dermatologic reactions. In conclusion, this innovative foam dressing had potential to be a good candidate for wound treatment.     

Hyaluronic acid modified chitosan nanoparticles for effective management of glaucoma: development,characterization, and evaluation

In clinical practices, solution of dorzolamide hydrochloride (DH) and timolol maléate (TM) is recommended for the treatment of glaucoma. However, low drug-contact time and poor ocular bioavailability of drugs due to drainage of solution, tear turnover and its dilution or lacrimation limits its uses. In addition, systemic absorption of TM may induce undesirable cardiovascular side effects. Chitosan (CS) is a polycationic biodegradable polymer which provides sustained and local delivery of drugs to the ocular sites. Hyaluronic acid (HA) also provides synergistic effect for mucoadhesion in association with chitosan. In the present study, hyaluronic acid modified chitosan nanoparticles (CS-HA-NPs) loaded with TM and DH were developed and characterized. The CS-HA-NPs were evaluated for size, shape, zeta potential, entrapment efficiency, and mucoadhesive strength. The in vitro release study was also performed in PBS pH 7.4. The ocular irritation potential of CS-HA-NPs was estimated using draize test on albino rabbits. A significant reduction in IOP level was obtained using CS-HA-NPs as compared to plain solution of drug and a comparable higher reduction in IOP level was observed as to CS-NPs. These results suggest that HA potentialy enhance the mucoadhesiveness and efficiency of CS-NPs and may be promising carrier for ocular drug delivery.     

Hyaluronic acid/Chitosan nanoparticles as delivery vehicles for VEGF and PDGF-BB

The development of a vascular network in tissue-engineered constructs is a fundamental bottleneck of bioregenerative medicine, particularly when the size of the implant exceeds a certain limit given by diffusion lengths and/or if the host tissue shows a very active metabolism. One of the approaches to achieve the vascularization of tissue constructs is generating a sustained release of proangiogenic factors from the ischemic site. This work describes the formation and characterization of hyaluronic acid-chitosan (HA/CS) nanoparticles for the delivery of two pro-angiogenic growth factors: vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF-BB). These nanoparticles were prepared by an ionic gelification technique, and different formulations were developed by encapsulating the growth factors in association with two stabilizing agents: bovine serum albumin or heparin sodium salt. These carriers were characterized with regard to their physicochemical properties, their stability in biological media, and their cytotoxicity in the C3a hepatoma cell line. The results show that nanoparticles around 200?nm can be prepared by this method. HA/CS nanoparticles were stable when incubated in EMEM cell culture medium or in water at 37°C for 24?h. Cell culture tests confirmed that HA/CS nanoparticles are not cytotoxic within the concentration range used for growth factor delivery. Moreover, HA/CS nanoparticles were able to entrap efficiently both growth factors, reaching association values of 94% and 54% for VEGF and PDGF, respectively. In vitro release studies confirm that PDGF-BB is released from HA/CS nanoparticles in a sustained manner over ～ 1 week. On the other hand, VEGF is completely released within the first 24?h.     

Novel chitosan and bacterial cellulose biocomposites tailored with polymeric nanoparticles for modern wound dressing development

Dressing biomaterials play a key role in wound management keeping a moisture medium and protecting against external factors. Natural and synthetic materials could be used as dressings where chitosan and bacterial cellulose is one of the most important solutions. These biopolymers have been used for wound dressing based on their non-toxic, biodegradable, and biocompatible features. In this study, biocomposites based on bacterial cellulose and chitosan membranes tailored with antimicrobial loaded poly(N-isopropylacrylamide)/polyvinyl alcohol nanoparticles were prepared. Core-shell polymeric nanoparticles, bacterial cellulose/chitosan membranes, and biocomposites were independently loaded with silver sulfadiazine, a well-known sulfonamide antibacterial agent used in the therapy of mild-to-moderate infections for sensitive organisms. The chemistry, structure, morphology, and size distribution were investigated by Fourier transformed infrared spectroscopy (FTIR-ATR), RAMAN spectroscopy, Scanning electron (SEM) and Transmission electron microscopy (TEM), and Dynamic light scattering (DLS). In vitro release behaviors of silver sulfadiazine from polymeric nanoparticles and biocomposites were investigated. The biological investigations revealed good biocompatibility of both the nanoparticles and the biocomposites in terms of human dermal fibroblasts viability and proliferation potential. Finally, the drug-loaded polymeric biomaterials showed promising characteristics, proving their high potential as an alternative support to develop a biocompatible and antibacterial wound dressing.     

新型敷料配合湿润烧伤膏在慢性伤口护理中的应用研究

目的探讨湿润烧伤膏与新型敷料联合应用促进慢性伤口康复的方法及效果。方法按随机分组抽签法将60例慢性伤口患者随机分对照组和实验组各30例,对照组换药用生理盐水清洗,让伤口自然愈合、变干,每天换药1次等常规治疗及护理,实验组在常规治疗护理的基础上采用湿润烧伤膏与新型敷料联合应用,措施包括：正确评估伤口,根据伤口愈合不同阶段选择新型敷料及应用湿润烧伤膏,加强基础护理,增加营养,提高免疫力,落实严密的慢性伤口护理监控措施。结果实验组有效率为93.3％,对照组为70％,实验组明显高于对照组,两组比较差异统计学意义（P〈0．05）;经治疗2、3、5W后伤口愈合例数实验组明显多于对照组,两组比较差异统计学意义（P〈0．05）。结论湿润烧伤膏与新型敷料联合应用于慢性伤口的治疗及护理,可有效地缩短伤口的愈合时间,提高治疗效果。     

新型抗溃疡及促进伤口愈合药--重组人角质细胞生长因子-2

重组人角质细胞生长因子-2(rhKGF-2)能与人体上皮细胞内的成纤维细胞生长因子受体(FGFR)结合而发挥生理作用。研究显示，rhKGF-2可特异性地刺激上皮细胞增殖，促进表皮细胞生长和肉芽组织形成，可用于治疗因上皮细胞损伤引起的溃疡，加速伤口的愈合，耐受性好，值得临床推广。     

Bilayer hydrogel dressing with lysozyme-enhanced photothermal therapy for biofilm eradication and accelerated chronic wound repair

Biofilms are closely associated with the tough healing and dysfunctional inflammation of chronic wounds. Photothermal therapy (PTT) emerged as a suitable alternative which could destroy the structure of biofilms with local physical heat. However, the efficacy of PTT is limited because the excessive hyperthermia could damage surrounding tissues. Besides, the difficult reserve and delivery of photothermal agents makes PTT hard to eradicate biofilms as expectation. Herein, we present a GelMA-EGF/Gelatin-MPDA-LZM bilayer hydrogel dressing to perform lysozyme-enhanced PTT for biofilms eradication and a further acceleration to the repair of chronic wounds. Gelatin was used as inner layer hydrogel to reserve lysozyme (LZM) loaded mesoporous polydopamine (MPDA) (MPDA-LZM) nanoparticles, which could rapidly liquefy while temperature rising so as to achieve a bulk release of nanoparticles. MPDA-LZM nanoparticles serve as photothermal agents with antibacterial capability, could deeply penetrate and destroy biofilms. In addition, the outer layer hydrogel consisted of gelatin methacryloyl (GelMA) and epidermal growth factor (EGF) promoted wound healing and tissue regeneration. It displayed remarkable efficacy on alleviating infection and accelerating wound healing in vivo. Overall, the innovative therapeutic strategy we came up with has significant effect on biofilms eradication and shows promising application in promoting the repair of clinical chronic wounds.     

Carbohydrate‐derived Fulvic acid (CHD‐FA) inhibits Carrageenan‐induced inflammation and enhances wound healing: efficacy and Toxicity study in rats

The objectives of this study were to evaluate the safety and anti‐inflammatory and wound‐healing characteristics of carbohydrate‐derived fulvic acid (CHD‐FA) in rats. CHD‐FA (≥100 mg/kg p.o.) effectively reduced carrageenan‐induced paw edema in rats, which was comparable to 10 mg/kg p.o. indomethacin. Topical application of CHD‐FA, formulated to contain 1.75% active product in a cetomicrogol cream at pH 1.98, compared favorably with fusidic acid cream (10 mg/g) in accelerating the healing of excised wounds infected with Staphylococcus aureus. No signs of toxicity were observed in rats during the 6‐day acute and 6‐month chronic treatment with CHD‐FA (100 mg/kg p.o.). Topical application of CHD‐FA, formulated in UEA cream and applied to the right ears of mice at 400 mg/g body weight on days 1 and 7–38, produced no adverse events. No signs of toxicity were observed in the teratogenicity study, in which CHD‐FA was administered at 100 mg/kg p.o. to pregnant female mice 3 days before fertilization to 14 days of pregnancy. In conclusion, CHD‐FA is a safe compound with anti‐inflammatory and wound‐healing properties and merits further evaluation in the treatment of patients suffering from similar conditions. Drug Dev Res 73: 18–23, 2012. © 2011 Wiley Periodicals, Inc.     

Efficacy and tolerance of a hydrocolloid dressing containing hyaluronic acid for the treatment of leg ulcers of venous or mixed origin

ABSTRACT

Objective: This study was aimed at comparing efficacy and tolerance of a new hydrocolloid dressing containing hyaluronic acid (HC?+?HA) to a reference hydrocolloid not containing hyaluronic acid (HC) in the treatment of leg ulcers of venous or mixed origin.

Research design and methods: This was an open, prospective study, randomized in parallel groups, in which 125 patients were enrolled and treated for up to 42 days. The primary efficacy criterion was the reduction of the wound area; other efficacy criteria were the condition of the wound bed, and of the surrounding skin, and presence and severity of symptoms such as pain and itching.

Results: After 42 days of treatment the median reduction of ulcer area was ?42.6% (95% confidence interval [CI]: ?66.6; ?5.7) and ?31.0% (95% CI: ?51.6; ?8.8) in the HC?+?HA group and in the reference HC group, respectively. The difference between treatments was not statistically significant. A reduction ≥?90% of the initial ulcer area was seen in 15 patients in the HC?+?HA dressing group and in only seven patients in the HC dressing group. Changes in wound bed condition in the two groups were not significantly different, except for a more marked reduction of fibrinous tissue in the HC?+?HA dressing group (?p?=?0.04), at Day 28. Both treatments were well tolerated.

Conclusions: The HC?+?HA dressing was equally well tolerated and with a trend to be more effective than the reference HC dressing in the treatment of leg ulcers of venous or mixed origin. Further research is needed to confirm these findings.     

PVA-PEG physically cross-linked hydrogel film as a wound dressing: experimental design and optimization

The development of hydrogel films as wound healing dressings is of a great interest owing to their biological tissue-like nature. Polyvinyl alcohol/polyethylene glycol (PVA/PEG) hydrogels loaded with asiaticoside, a standardized rich fraction of Centella asiatica, were successfully developed using the freeze–thaw method. Response surface methodology with Box–Behnken experimental design was employed to optimize the hydrogels. The hydrogels were characterized and optimized by gel fraction, swelling behavior, water vapor transmission rate and mechanical strength. The formulation with 8% PVA, 5% PEG 400 and five consecutive freeze–thaw cycles was selected as the optimized formulation and was further characterized by its drug release, rheological study, morphology, cytotoxicity and microbial studies. The optimized formulation showed more than 90% drug release at 12?hours. The rheological properties exhibited that the formulation has viscoelastic behavior and remains stable upon storage. Cell culture studies confirmed the biocompatible nature of the optimized hydrogel formulation. In the microbial limit tests, the optimized hydrogel showed no microbial growth. The developed optimized PVA/PEG hydrogel using freeze–thaw method was swellable, elastic, safe, and it can be considered as a promising new wound dressing formulation.     

Green microparticles based on a chitosan/lactobionic acid/linoleic acid association. Characterisation and evaluation as a new carrier system for cosmetics

The association chitosan/linoleic acid/lactobionic acid in aqueous solution spontaneously led to the formation of stable microparticles with a liquid hydrophobic core consisting of linoleic acid surrounded by a shell of chitosan/lactobionic acid. The originality of the microparticles arises from the fact that they are formed by the association of three ingredients of cosmetic interest, including a skin penetration enhancer (linoleic acid). Dynamic light scattering (DLS) measurements showed microparticles with a mean diameter of 1–2?μm. The presence of a hydrophobic liquid core was observed by transmission electron microscopy (TEM). The ability of these microparticles to encapsulate phenylethyl resorcinol, a hydrophobic skin lightener, was evaluated and its encapsulation was confirmed thanks to T₂ measurements and nuclear Overhauser effects (nOe) signs.     

Thioctamer: a novel thioctic acid–glatiramer acetate nanoconjugate expedites wound healing in diabetic rats

The current work aims to design thioctic acid (TA) and glatiramer acetate (GA) nanoconjugate (thioctamer) loaded hydrogel formula as well as evaluation of thioctamer preclinical efficacy in expediting wound healing in a rat model of the diabetic wound. Thioctamer was prepared by conjugation of GA and TA in a 1:1 molar ratio. Particle size, zeta potential, and thermodynamic stability of the prepared thioctamer were assessed. Thioctamer was loaded in hydroxypropyl methylcellulose-based hydrogel and in vitro release study was investigated. The ability of thioctamer to enhance the process of wound healing in diabetic rats was investigated by assessing wound contraction and immunohistochemical assessment of the inflammation markers IL-6 and TNF-α. The results demonstrated that thioctamer showed particle size of 137 ± 21.4 nm, polydispersity index (PDI) of 0.235, and positive zeta potential value of 7.43 ± 4.95 mV. On day 10 of making a skin excision, diabetic rat wounds administered thioctamer preparation showed almost complete healing (95.6 ± 8.6%). Meanwhile, % of wound contraction in animals treated with TA or GA groups exhibited values amounting to 56.5 ± 5.8% and 62.6 ± 7.1%, respectively. Histological investigation showed that the highest healing rate was noted in the thioctamer group animals, as the surface of the wound was nearly fully protected by regenerated epithelium with keratinization, with few inflammatory cells noticed. Thioctamer significantly (p<.05) inhibited IL-6 and TNF-α expression as compared with sections obtained from the negative control, TA, GA, or positive control group animals on day 14. The evidence of the ability of thioctamer to significantly expedite wound healing in the diabetic rats is presented.     

Curcumin‐loaded poly(ε‐caprolactone) nanofibres: Diabetic wound dressing with anti‐oxidant and anti‐inflammatory properties

• 1 Curcumin is a naturally occurring poly‐phenolic compound with a broad range of favourable biological functions, including anti‐cancer, anti‐oxidant and anti‐inflammatory activities. The low bioavailability and in vivo stability of curcumin require the development of suitable carrier vehicles to deliver the molecule in a sustained manner at therapeutic levels.
• 2 In the present study, we investigated the feasibility and potential of poly(caprolactone) (PCL) nanofibres as a delivery vehicle for curcumin for wound healing applications. By optimizing the electrospinning parameters, bead‐free curcumin‐loaded PCL nanofibres were developed.
• 3 The fibres showed sustained release of curcumin for 72 h and could be made to deliver a dose much lower than the reported cytotoxic concentration while remaining bioactive. Human foreskin fibroblast cells (HFF‐1) showed more than 70% viability on curcumin‐loaded nanofibres.
• 4 The anti‐oxidant activity of curcumin‐loaded nanofibres was demonstrated using an oxygen radical absorbance capacity (ORAC) assay and by the ability of the fibres to maintain the viability of HFF‐1 cells under conditions of oxidative stress.
• 5 The curcumin‐loaded nanofibres also reduced inflammatory induction, as evidenced by low levels of interleukin‐6 release from mouse monocyte–macrophages seeded onto the fibres following stimulation by Escherichia coli‐derived lipopolysaccharide.
• 6 The in vivo wound healing capability of the curcumin loaded PCL nanofibres was demonstrated by an increased rate of wound closure in a streptozotocin‐induced diabetic mice model.
• 7 These results demonstrate that the curcumin‐loaded PCL nanofibre matrix is bioactive and has potential as a wound dressing with anti‐oxidant and anti‐inflammatory properties.