Cytotoxicity of silver dressings on diabetic fibroblasts

Activated carbon cloth versus silver-based dressings in a population with diabetic foot ulcer: a randomised controlled trial

OBJECTIVE

Activated carbon cloth (ACC), known as Zorflex dressing, has emerged as an innovative approach in managing bacterial infection in diabetic foot ulcer (DFU) treatment. This pilot study was undertaken to determine the efficacy of Zorflex ACC dressing (Chemviron Carbon Cloth Division, UK) compared to standard silver-based dressing on DFUs.

METHOD

An open label, comparative, randomised controlled trial enrolling patients who attended the diabetic foot clinic was conducted between August 2022 and August 2023. The primary endpoint was a difference of 20% in wound area reduction with the ACC dressing compared to silver-based dressing within eight weeks. The secondary endpoints were proportion of complete healing, time to healing and adverse events.

RESULTS

The cohort comprised 40 patients. The mean wound reduction percentage at 8 weeks for patients in the ACC arm was 85.40±16.00% compared with 65.08±16.36% in the silver-based dressing arm. Complete healing was observed in six of 20 patients in the ACC arm compared to two of 20 in the silver-based dressing arm.

CONCLUSION

These data suggest that the ACC dressing promotes better ulcer healing in DFU patients than the silver-based dressing.

Natural and biocompatible dressing unit based on tea carbon dots modified core-shell electrospun fiber for diabetic wound disinfection and healing

Wound infection and healing in patients with diabetes is one of the complex problems in trauma treatment. Therefore, designing and preparing an advanced dressing membrane for treating the wounds of such patients is essential. In this study, a zein film with biological tea carbon dots (TCDs) and calcium peroxide (CaO₂) as the main components for promoting diabetic wound healing was prepared by an electrospinning technique, which combines the advantages of natural degradability and biosafety. CaO₂ is a biocompatible material with a microsphere structure that reacts with water to release hydrogen peroxide and calcium ions. TCDs with a small diameter were doped in the membrane to mitigate its properties while improving the antibacterial and healing effects of the membrane. TCDs/CaO₂ was mixed with ethyl cellulose-modified zein (ZE) to prepare the dressing membrane. The antibacterial properties, biocompatibility and wound-healing properties of the composite membrane were investigated by antibacterial experiment, cell experiment and a full-thickness skin defect. TCDs/CaO₂ @ZE exhibited significant anti-inflammatory and wound healing-promoting properties in diabetic rats, without any cytotoxicity. This study is meaningful in developing a natural and biocompatible dressing membrane for diabetic wound healing, which shows a promising application in wound disinfection and recovery in patients with chronic diseases.

Efficacy of Silver Nanoparticles-Loaded Bone Cement against an MRSA Induced-Osteomyelitis in a Rat Model

Background and Objectives: The purpose of this study was to assess the cytotoxicity and antibacterial effects of AgNP-impregnated Tetracalcium phosphate-dicalcium phosphate dihydrate (TTCP-DCPD). Materials and Methods: Using in vitro experiments, the cytotoxicity of AgNP-impregnated TTCP-DCPD against fibroblasts and osteocytes was assessed in terms of cell viability by water-soluble tetrazolium salt assay. To assess antibacterial effects, a disc diffusion test was used; osteomyelitis was induced first in vivo, by injection of methicillin-resistant Staphylococcus aureus into the tibia of rats. AgNP-impregnated TTCP-DCPD bone cement was then applied at various silver concentrations for 3 or 12 weeks. Antibacterial effects were assessed by culturing and reverse transcription-polymerase chain reaction (RT-PCR). For histological observation, the bone tissues were stained using hematoxylin and eosin. Results: Cell viability was decreased by the impregnated bone cement but did not differ according to AgNP concentration. The diameter of the growth-inhibited zone of MRSA was between 4.1 and 13.3 mm on the disks treated with AgNP, indicating antimicrobial effects. In vivo, the numbers of bacterial colonies were reduced in the 12-week treatment groups compared to the 3-week treatment groups. The groups treated with a higher (10×) dose of AgNP (G2-G5) showed a tendency of lower bacterial colony counts compared to the group without AgNP (G1). The PCR analysis results showed a tendency of decreased bacterial gene expression in the AgNP-impregnated TTCP-DCPD groups (G2-G5) compared to the group without AgNP (G1) at 3 and 12 weeks. In the H&E staining, the degree of inflammation and necrosis of the AgNP-impregnated TTCP-DCPD groups (G2-G5) showed a tendency to be lower at 3 and 12 weeks compared to the control group. Our results suggest that AgNP-impregnated TTCP-DCPD cement has antimicrobial effects. Conclusions: This study indicates that AgNP-impregnated TTCP-DCPD bone cement could be considered to treat osteomyelitis.

Prospective randomised placebo-controlled trial assessing the efficacy of silver dressings to enhance healing of acute diabetes-related foot ulcers

AIMS/HYPOTHESIS

Silver dressings are used for their antimicrobial properties but there is limited evidence of clinical benefit when managing diabetes-related foot ulcers (DFUs). We aimed to assess whether silver dressings in acute DFUs increased the proportion of ulcers healed compared with non-silver dressings.

METHODS

In this open-labelled, randomised controlled trial, consecutive individuals who presented to a tertiary multidisciplinary diabetic foot service with a DFU without osteomyelitis or tendon on view of <6 weeks' duration were randomised 1:1 via a computer-generated randomisation process to receive Acticoat (Smith & Nephew, England) dressing (silver group) or dressing without silver (control group) in addition to standard care. Stratified randomisation was performed to ensure that the presence of peripheral arterial disease and infection were equally managed within the two groups. The primary outcome was the proportion of ulcers healed at 12 weeks. Secondary outcomes included time to heal and to 50% ulcer reduction, rates of osteomyelitis and amputation, and need for and duration of antibiotics.

RESULTS

Seventy-six ulcers (55 participants) in the control group and 91 ulcers (63 participants) in the silver group were included. There was no difference in the proportion of ulcers healed by 12 weeks in the control vs silver group (75% vs 69%, p=0.49). After adjustment for presence of peripheral arterial disease, infection and initial ulcer size, silver dressing was not associated with odds of healing (OR 0.92; CI 0.26, 3.22; p=0.53). There was no difference in time to healing, progression to osteomyelitis, need for amputation, or duration of or need for antibiotic treatment.

CONCLUSIONS/INTERPRETATION

In individuals with acute DFUs without osteomyelitis or tendon on view, Acticoat silver dressings did not improve wound healing or reduce need for antibiotics compared with non-silver dressings.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12614001234606 FUNDING: Australian Diabetes Society-unrestricted research award.

Update on the role of antiseptics in the management of chronic wounds with critical colonisation and/or biofilm

Biofilms play a major role in delaying chronic wounds from healing. A wound infiltrated with biofilm, or "critically colonised" wound, may become clinically infected if the number of microbes exceeds a critical level. Chronic wound biofilms represent a significant treatment challenge by demonstrating recalcitrance towards antimicrobial agents. However, a "window of opportunity" may exist after wound debridement when biofilms are more susceptible to topical antiseptics. Here, we discuss the role of antiseptics in the management of chronic wounds and biofilm, focusing on povidone-iodine (PVP-I) in comparison with two commonly used antiseptics: polyhexanide (PHMB) and silver. This article is based on the literature reviewed during a focus group meeting on antiseptics in wound care and biofilm management, and on a PubMed search conducted in March 2020. Compared with PHMB and silver, PVP-I has a broader spectrum of antimicrobial activity, potent antibiofilm efficacy, no acquired bacterial resistance or cross-resistance, low cytotoxicity, good tolerability, and an ability to promote wound healing. PVP-I represents a viable therapeutic option in wound care and biofilm management, with the potential to treat biofilm-infiltrated, critically colonised wounds. We propose a practical algorithm to guide the management of chronic, non-healing wounds due to critical colonisation or biofilm, using PVP-I.

Toxicity of silver nanoparticles on wound healing: A case study of zebrafish fin regeneration model

Dressings coated with silver nanoparticle (AgNP) are widely used in the management of acute and chronic wounds. However, whether AgNP exerts toxicity on wound healing remains ambiguous. To demonstrate the effects of AgNP on wound healing, we precisely quantified the recovery speed of wound by taking advantage of the fin regeneration of zebrafish. This method also enabled assessment of the adverse effect of AgNP on various steps of wound healing in vivo. We revealed that AgNP treatment at the concentration of 2 μg/ml impaired fin regeneration when exposure was performed at the phases of epithelialization and the beginning of blastema formation. Cell proliferation of regenerative blastema was significantly decreased after AgNP exposure. But the canonical signals including Wingless/Integrated (Wnt), Notch and Fibroblast growth factor (Fgf) which play important roles in cell proliferation during fin regeneration were not modulated at 36 hours post amputation (hpa). Further study showed that AgNP impaired fin regeneration through declining amputation-induced ROS as early as epithelialized phase at 18 hpa, rather than inducing ROS generation. AgNP exposure also promoted recruitment of neutrophils in the early phase of wound healing, which suggests that this event dampened amputation-induced ROS. Overall, this study suggested that application of AgNP-coated dressings should be carefully considered at the beginning stage of wound healing.

Response of Human Macrophages to Clinically Applied Wound Dressings Loaded With Silver

Wound infections constitute an increasing clinical problem worldwide. To reverse this trend, several wound dressings with antimicrobial properties have been developed. Considering the increasing presence of antibiotic-resistant microorganisms, product developers have been focusing their efforts in introducing antibiotic-free antibacterial wound dressings to the market, with silver being the most commonly incorporated antimicrobial agent. In this scenario, gaining information about the microbial and eukaryotic cells' response to these dressings is needed for a proper selection of antimicrobial dressings for the different cases of infected wounds. In particular, one insufficiently explored parameter is the effect of the dressings on the immunomodulation of macrophages, the main immune cell population participating in the repair process, because of their pivotal role in the transition of the inflammation to the proliferation phase of wound healing. In this work, three different clinically applied antimicrobial, silver impregnated wound dressings were selected: Atrauman® Ag, Biatain® Alginate Ag and PolyMem WIC Silver® Non-adhesive. Antimicrobial susceptibility tests (disk diffusion and broth dilution), cell viability evaluation (CellTiter-Blue®) and experiments to determine macrophage polarization (e.g., flow cytometry, ELISA and glucose uptake) were performed after 24 h of incubation. Among all products tested, Biatain® Alginate Ag induced the most evident bactericidal effect on Gram-positive and Gram-negative bacteria, followed by PolyMem WIC Silver® Non-adhesive, but did not show good cytocompatibility in vitro. On the other hand, Atrauman® Ag showed excellent cytocompatibility on L929 fibroblasts, HaCaT keratinocytes and THP-1 derived macrophages, but no significant antimicrobial activity was observed. Overall, it was confirmed that macrophages initiate, in fact, an alteration of their metabolism and phenotype in response to wound dressings of different composition in a short period of contact (24 h). M0 resting state macrophages common response to all silver-containing dressings used in this study was to increase the production of the anti-inflammatory cytokine TGF-β, which indicates an acquisition of M2-like macrophages characteristics.

Dressings, Topical Therapy, and Negative Pressure Wound Therapy

The current epidemic of diabetes has created a high demand for skilled wound-care professionals. Wound-care treatment begins with an appreciation of the cause of the ulceration and an adherence to the fundamental pillars of wound care. Also critical in the wound management paradigm is the optimization of the wound environment to facilitate the progression through the stages of healing. This can be accomplished through the use of different topical therapies and wound dressings to generate a favorable condition conducive to healing. This article summarizes the updated literature and best practices related to this topic.

Application of micellar electrokinetic chromatography for detection of silver nanoparticles released from wound dressing

The recent emergence of nanotechnology has provided a new therapeutic modality in case of silver nanoparticles. Dressings containing silver form the basis for the treatment of burns and wounds, either acute or chronic ones. The aim of the study was to examine silver release from the different wound dressings: commercially available (Atrauman Ag, Aquacel Ag) and experimental (FKDP-AgNPs) using MEKC. In order to characterize prepared keratin based wound dressing before and after its modification with AgNPs, a compositional analysis was conducted using energy dispersive X-ray spectroscopy. Nanosilver toxicity was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4 sulfophenyl)-2H-tetrazolium test. Silver release from wound dressings was assessed using MEKC. The best separation was observed for MEKC in 20 mM borate buffer at pH 9 with 20 mM SDS addition. In vitro studies showed silver at higher concentration than 10 ppm exerted a toxic effect on fibroblasts isolated from diabetic mice versus. NIH/3T3 and BJ cell lines (p < 0.05). We observed silver was released more gradually from experimental FKDP-AgNPs wound dressing, in compare to commercially available wound dressings. The fast and low-cost method utilizing MEKC can be used in clinical practice to detect silver release from the wound dressings.

ZIF nano-dagger coated gauze for antibiotic-free wound dressing

ZIF nano-dagger coated gauze was used for antibiotic-free and biocompatible wound dressing with a lower haemolytic activity, less cytotoxicity and improved wound healing performance.

Visfatin Promotes Wound Healing through the Activation of ERK1/2 and JNK1/2 Pathway

Visfatin, a member of the adipokine family, plays an important role in many metabolic and stress responses. The mechanisms underlying the direct therapeutic effects of visfatin on wound healing have not been reported yet. In this study, we examined the effects of visfatin on wound healing in vitro and in vivo. Visfatin enhanced the proliferation and migration of human dermal fibroblasts (HDFs) and keratinocytes the expression of wound healing-related vascular endothelial growth factor (VEGF) in vitro and in vivo. Treatment of HDFs with visfatin induced activation of both extracellular signal-regulated kinases 1 and 2 (ERK1/2) and c-Jun N-terminal kinases 1 and 2 (JNK1/2) in a time-dependent manner. Inhibition of ERK1/2 and JNK1/2 led to a significant decrease in visfatin-induced proliferation and migration of HDFs. Importantly, blocking VEGF with its neutralizing antibodies suppressed the visfatin-induced proliferation and migration of HDFs and human keratinocytes, indicating that visfatin induces the proliferation and migration of HDFs and human keratinocytes via increased VEGF expression. Moreover, visfatin effectively improved wound repair in vivo, which was comparable to the wound healing activity of epidermal growth factor (EGF). Taken together, we demonstrate that visfatin promotes the proliferation and migration of HDFs and human keratinocytes by inducing VEGF expression and can be used as a potential novel therapeutic agent for wound healing.

The Management of Critically Colonized and Locally Infected Leg Ulcers with an Acid-Oxidizing Solution: A Pilot Study

OBJECTIVE:

Critical colonization or local infection is very common in chronic wounds, but clinically problematic. Because therapeutic options for these conditions are limited in number and efficacy, the study authors tested a new acid-oxidizing solution (AOS [Nexodyn]; APR Applied Pharma Research S.A., Balerna, Switzerland) to determine its ancillary antimicrobial properties and potential support for wound healing.

DESIGN AND SETTING:

This open-label clinical case series was conducted with a prospective, single-arm design at the Federal County Hospital in Bregenz, Austria.

PATIENTS:

In the study, 30 patients with critically colonized or locally infected chronic leg ulcers of any origin were included.

INTERVENTIONS:

The AOS was applied on each leg ulcer at every dressing change for 35 days.

MAIN OUTCOME MEASURES:

The tolerability and performance of the AOS were assessed by evaluating the ulcer characteristics and comparing them with those at baseline. The clinical course of wounds was analyzed using standard measures for bioburden, local infection, pain, pH, and wound healing.

MAIN RESULTS:

Application of the solution was well tolerated, and no adverse events were recorded. In all patients, local infection was overcome, and wound bed pH and wound area decreased significantly. In addition, patient pain levels decreased to a level where interventions were not required after study day 7. In 37% of all patients, a complete resolution of chronic ulcers was achieved by the end of the study period.

CONCLUSION:

According to these results, the AOS seems to be a valid and highly tolerable treatment to support wound healing in locally infected ulcers. Nevertheless, larger controlled cohort studies are needed to substantiate these findings.

The wound-healing effects of a next-generation anti-biofilm silver Hydrofiber wound dressing on deep partial-thickness wounds using a porcine model

Topical antimicrobials are widely used to control wound bioburden and facilitate wound healing; however, the fine balance between antimicrobial efficacy and non-toxicity must be achieved. This study evaluated whether an anti-biofilm silver-containing wound dressing interfered with the normal healing process in non-contaminated deep partial thickness wounds. In an in-vivo porcine wound model using 2 pigs, 96 wounds were randomly assigned to 1 of 3 dressing groups: anti-biofilm silver Hydrofiber dressing (test), silver Hydrofiber dressing (control), or polyurethane film dressing (control). Wounds were investigated for 8 days, and wound biopsies (n = 4) were taken from each dressing group, per animal, on days 2, 4, 6, and 8 after wounding and evaluated using light microscopy. No statistically significant differences were observed in the rate of reepithelialisation, white blood cell infiltration, angiogenesis, or granulation tissue formation following application of the anti-biofilm silver Hydrofiber dressing versus the 2 control dressings. Overall, epithelial thickness was similar between groups. Some differences in infiltration of specific cell types were observed between groups. There were no signs of tissue necrosis, fibrosis, or fatty infiltration in any group. An anti-biofilm silver Hydrofiber wound dressing did not cause any notable interference with normal healing processes.

Evaluation of a polyurethane foam dressing impregnated with 3% povidone-iodine (Betafoam) in a rat wound model

Purpose

The purpose of this study was to evaluate the efficacy of Betafoam in terms of wound healing and safety.

Methods

Fifty-four male adult Sprague-Dawley rats (weight, 200–250 g) were used in the study. Full-thickness skin defects were created on the back of each rats. The rats were assigned to 6 groups according to the type of wound dressing used (n = 9 for each group): Betafoam, Allevyn-Ag, Mepilex-Ag, Medifoam silver, Polymem-Ag, and gauze. The wound size, histological findings, and amount of DNA on the changed dressings for each group were analyzed and compared.

Results

All groups showed an effective decrease in wound size. However, the differences between Betafoam and the other dressings were statistically significant on day 14 (P < 0.05). The number of newly generated blood vessels in the Betafoam group was significantly higher than in the gauze, Allevyn-Ag, and Medifoam silver groups (P < 0.001). In the Betafoam group, the proportion of collagen deposition was highest and showed a significantly superior arrangement of collagen fibers compared with the gauze, Allevyn-Ag, Mepilex-Ag, and Medifoam silver groups. The total content of the remaining DNA counts of the exchanged dressings were significantly lower in the Betafoam group than the others.

Conclusion

Betafoam is effective in wound healing and provides the best performance amongst the various types of dressing materials in terms of re-epithelialization, angiogenesis, collagen deposition, and tissue invasion.

In Vitro Parallel Evaluation of Antibacterial Activity and Cytotoxicity of Commercially Available Silver-Containing Wound Dressings

PURPOSE

This study evaluated the in vitro antibacterial activity and cytotoxicity of various commercially available silver-containing dressings (Ag dressing).

METHODS

Biohesive Ag (hydrocolloid, silver sulfadiazine), Aquacel® Ag (nonwoven fabric, ionic silver [Ag]), Algisite™ Ag (nonwoven fabric, Ag), Mepilex® Ag (foam, silver sulfate), and PolyMem® Ag (foam, nanocrystalline silver) were tested for characteristics of Ag release, antibacterial activity, and cytotoxicity. The release of Ag was investigated in cell culture medium at immersion periods of 6, 24, and 48 hours. The antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa were accessed by a disc diffusion test. The cytotoxicity was evaluated using V79 cells, by an extraction method.

RESULTS

The cytotoxicity was not a monotonic function of the antibacterial activity among the Ag dressings and could not be simply explained by Ag-release properties. Biohesive Ag was regarded as a slow-release Ag dressing, showing the lowest cytotoxicity, while the antibacterial activity was classified as "strong" or "significant" against the two species of bacteria. Aquacel Ag and Algisite Ag showed higher antibacterial activity and cytotoxic effects, which were supported by the higher Ag release. Mepilex Ag showed the highest release of Ag, and the cytotoxicity was the highest among the Ag dressings. However, the antibacterial activity was classified as "significant" or "no activity" for P. aeruginosa and S. aureus, respectively. PolyMem Ag showed the lowest Ag release, and the antibacterial activity classified as "significant" or "no activity" for S. aureus and P. aeruginosa, respectively, whereas the cytotoxicity was similar to those of Aquacel Ag and Algisite Ag.

CONCLUSION

The efficacy and adverse effects of the Ag dressings revealed differences that should be considered by clinicians during wound management.

Imparting commercial antimicrobial dressings with low-adherence to burn wounds

The objective of our study was to decrease the wound adherence of commercial silver based wound dressings by depositing a non-adherent layer. Our hypothesis was that this non-adherent layer will lower the dressing's adherence to burn wounds without compromising the antimicrobial activity or increasing the cytotoxicity. A polyacrylamide (PAM) hydrogel layer was grafted on two commercial silver antimicrobial dressings (silver nanocrystal dressing (NC) and silver plated dressing (SP)) using a proprietary technique. The grafted PAM served as the non-adherent layer. Dressing adherence was measured with a previously published in vitro gelatin model using an Instron mechanical force testing instrument. The dressings were challenged with two clinically retrieved bacterial strains (Methicillin-resistant Staphylococcus aureus (MRSA) and multidrug resistant (MDR) Pseudomonas aeruginosa) with both a disk diffusion test, and a suspension antibacterial test. The cytotoxicity of samples to human neonatal fibroblast cells was evaluated with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. Both untreated dressings showed high peeling energy: 2070±453J/m(2) (NC) and 669±68J/m(2) (SP), that decreased to 158±119J/m(2) (NC) and 155±138J/m(2) (SP) with the PAM deposition. Addition of the PAM caused no significant difference in zone of inhibition (ZOI) (disk diffusion test) or antibacterial kinetics (suspension test) against both bacteria (p>0.05, n=6) in either dressing. Survival of fibroblasts was improved by the PAM grafting from 48±5% to 60±3% viable cells in the case of NC and from 55±8% to 61±4% viable cells in SP (p<0.05, n=12). It was concluded that PAM as a non-adherent layer significantly decreases the adherence of these two commercial antimicrobial dressings in an in vitro gelatin model while preserving their antimicrobial efficacy, and reducing their cytotoxicity.

Electron transfer driven highly valent silver for chronic wound treatment

This paper shows that reducing the dose of silver, additionally conferring electron transfer potential, could simultaneously achieve good biocompatibility and strong bactericidal ability without introducing extra chemical residuals for chronic wound treatment.

The Anti-Inflammatory and Antibacterial Action of Nanocrystalline Silver and Manuka Honey on the Molecular Alternation of Diabetic Foot Ulcer: A Comprehensive Literature Review

Honey and silver have been used since ancient times for treating wounds. Their widespread clinical application has attracted attention in light of the increasing prevalence of antibiotic-resistant bacteria. While there have been a number of studies exploring the anti-inflammatory and antibacterial effects of manuka honey and nanocrystalline silver, their advantages and limitations with regard to the treatment of chronic wounds remain a subject of debate. The aim of this paper is to examine the evidence on the use of nanocrystalline silver and manuka honey for treating diabetic foot ulcers through a critical and comprehensive review of in vitro studies, animal studies, and in vivo studies. The findings from the in vitro and animal studies suggest that both agents have effective antibacterial actions. Their anti-inflammatory action and related impact on wound healing are unclear. Besides, there is no evidence to suggest that any topical agent is more effective for use in treating diabetic foot ulcer. Overall, high-quality, clinical human studies supported by findings from the molecular science on the use of manuka honey or nanocrystalline silver are lacking. There is a need for rigorously designed human clinical studies on the subject to fill this knowledge gap and guide clinical practice.

Recent accomplishments in wound healing

The challenge to balance limited resources with infinite demand has encouraged an evolution in the way health care services are managed and operated. Chronic wound management is complex and prolonged, and places a considerable financial burden on health services. A typical driver of cost includes the necessity to change dressings on a regular basis. Over the last few decades, several scientific and biological advances have furthered the development of wound care products and facilitated wound management. This article investigates some of the major advancements that have occurred within the wound-care arena during the last 5 years and how these advancements are being translated to provide better delivery of clinical care to patients.

Cell therapy for wound healing

In covering wounds, efforts should include utilization of the safest and least invasive methods with goals of achieving optimal functional and cosmetic outcome. The recent development of advanced wound healing technology has triggered the use of cells to improve wound healing conditions. The purpose of this review is to provide information on clinically available cell-based treatment options for healing of acute and chronic wounds. Compared with a variety of conventional methods, such as skin grafts and local flaps, the cell therapy technique is simple, less time-consuming, and reduces the surgical burden for patients in the repair of acute wounds. Cell therapy has also been developed for chronic wound healing. By transplanting cells with an excellent wound healing capacity profile to chronic wounds, in which wound healing cannot be achieved successfully, attempts are made to convert the wound bed into the environment where maximum wound healing can be achieved. Fibroblasts, keratinocytes, adipose-derived stromal vascular fraction cells, bone marrow stem cells, and platelets have been used for wound healing in clinical practice. Some formulations are commercially available. To establish the cell therapy as a standard treatment, however, further research is needed.

Comparative evaluation of silver-containing antimicrobial dressings on in vitro and in vivo processes of wound healing

OBJECTIVES

To compare the in vitro and in vivo effects of silver products on wound healing.

METHODS

Eight silver products were compared to determine: fibroblast function using fibroblast-populated collagen lattices (FPCLs), fibroblast viability using the Trypan Blue exclusion test, and fibroblast mitochondrial activity using the MTT [yellow tetrazolium salt; 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In vivo effects of 9 silver products were evaluated utilizing a rat model of contaminated wounds. Serial quantitative bacteriology was performed on tissue biopsies over a 10-day period and serial wound areas were obtained over 12 days.

RESULTS

Fibroblast cytotoxicity occurred for all of the silver products evaluated. Remaining viable fibroblasts were insufficient to allow FPCL contraction. Mitochondrial activity of the fibroblasts allowed a separation of the various silver compounds. Actisorb Silver and Silvercel had the greatest viable fibroblast activity, but less than the control. Despite in vitro cytotoxicity, all of the silver products except Contreet Foam and Acticoat Moisture Control accelerated wound healing.

CONCLUSIONS

Silver-containing dressings appeared to benefit healing of the wounds. Just as in vitro bacterial analyses do not fully predict the effect of an antimicrobial in the in vivo setting, in vitro cytotoxicity tests do not fully predict the effect of an agent on wound healing trajectories. Because of the varied antimicrobial and wound healing responses among products, a careful consideration of the particular effects of individual silver-containing dressings or drugs is warranted.