Deep Partial-thickness Wounds Research Articles

The efficacy of a nitric oxide-releasing formulation on nares isolated Methicillin-Resistant Staphylococcus aureus in porcine wound infection model

BackgroundThe colonization of Staphylococcus aureus (SA) acquired in nosocomial infections may develop acute and chronic infections such as Methicillin-Resistant Staphylococcus aureus (MRSA) in the nose. As a commensal microorganism with the ability to form a biofilm, SA can dwell on the skin, nostrils, throat, perineum, and axillae of healthy humans. Nitric oxide (NO) is an unstable gas with various molecular functions and has antimicrobial properties which are converted into many potential treatments.MethodsMethicillin-Resistant Staphylococcus aureus MRSA BAA1686 isolated from nasal infection was used in a porcine wound infection model. Deep partial-thickness wounds (10mm x 7mm x 0.5mm) were made on three animals using a specialized electrokeratome. All wounds were inoculated and then covered with polyurethane film dressings for biofilm formation. After 48 hours, three wounds were recovered from each animal for baseline enumeration. The remaining wounds were randomly assigned to six treatment groups and treated once daily. The treatment groups are as follows: NO topical ointments concentrations of 0.3, 0.9 and 1.8%, Vehicle Ointment, Mupirocin 2%, and Untreated Control. Microbiological recoveries were conducted on day 4 and day 7.ResultsThe greatest efficacy observed from the NO formulations against MRSA BAA1686 was the 1.8% concentration. This agent was able to reduce more than 99% of bacterial counts when compared to Baseline, Vehicle Ointment, and Untreated Control wounds on both assessment days. Mupirocin 2% was the overall best treatment against MRSA BAA1686 on both assessment days, with a significant reduction (p ≤ 0.05) of 4.70 ± 0.13 Log CFU/mL from day 4 to day 7.ConclusionsOverall, the positive control Mupirocin 2% was the most effective in eliminating MRSA BAA1686 throughout the study. This experiment demonstrated a downward trend from the highest concentration of NO topical ointment formulations to the lowest concentrations on both assessment days (0.3% - 1.8%). Out of all NO topical ointments, the highest concentration (1.8%) was the most effective with the potential to be an alternative treatment against a MRSA nasal strain biofilm.

49 Bromelain Based Enzymatic Debridement of Pediatric Deep Burns: Top Line Results of a Multicenter RCT

IntroductionBromelain based debridement (BBD) of deep burns with a concentrate of proteolytic enzymes enriched in Bromelain is approved for use in adults in several regions worldwide. Children are a large part of the patient population in many burn centers around the world. Clinical trial experience and off label reports point to BBD safety and efficacy in children as well. The aim of this study was to further assess the safety and efficacy of BBD in children, in efforts to support regulatory approval for the use of BBD in children.MethodsOne hundred and forty five children aged 0-18 years old suffering from deep thermal burns between 1-30% TBSA were enrolled in a multicenter, multinational, open label, randomized, controlled phase III study. Seventy two children were randomized to eschar removal with BBD and 73 children to standard of care (SOC) surgical and/or non-surgical eschar removal methods, at the investigators' discretion. Patients who did not achieve complete eschar removal after BBD application were rescued with SOC eschar removal methods. Wound care after achieving complete eschar removal was according to routine methods, at the investigators' discretion. Patients are currently in stages of long term follow-up, planned for a duration of >2 years. This abstract reports the top line results of the study including the first year of follow-up.ResultsBaseline characteristics were similar between the arms. The median age was 3.4 years in the BBD arm and 3.9 years in the SOC arm. The average burn area was 7.0±4.9 %TBSA in the BBD arm and 6.2±4.8 %TBSA in the SOC arm. The study met all 3 primary endpoints: Median time to complete eschar removal was 1 day for BBD and 6 days for SOC (p< 0.001), the percent wound area excised in order to complete eschar removal was 1.5% for BBD and 48% for SOC (p< 0.0001), and the MVSS scores at 12 months were 3.83 for BBD and 4.86 for SOC (non-inferiority endpoint). Secondary endpoints demonstrated 8.3% incidence of surgical excision to complete eschar removal for BBD and 64.4% for SOC (p< 0.0001), mean eschar removal associated blood loss of 32±284ml for BBD and 202±409 for SOC (NS), a 25.9% incidence of autografting in deep partial thickness wounds for BBD and 37.7% for SOC (p=0.054), and a mean percent area of deep partial thickness wound autografting of 15.9±38.6 for BBD and 22.8±43.7 for SOC (NS). Safety endpoints demonstrated a non-inferior time to complete wound closure (median 32 days for BBD, 34 days for SOC) and no significant safety issues were demonstrated during the study.ConclusionsBBD was shown to be a safe and effective debridement agent in pediatric burns.

534 Allogeneic Cellularized Living Tissue in Pediatric Deep Partial Thickness Burns Reduces Need for Donor Sites

IntroductionHealing potential of deep partial thickness burns is not easily determined early after injury. Prolonged and continued inflammation can contribute to burn wound conversion. Early excision compared to a wait and see approach to wound healing decreases inflammation, shortens length of stay, and decreases painful wound procedures. However, early excision is at the expense of removing tissue that may otherwise heal without autografting. Use of a cryopreserved, allogeneic cellularized scaffold living tissue product (CTP) in pediatric deep partial thickness wounds with dermal elements remaining after excision is an alternative approach to wound closure. CTP may allow early excision without compromising healing potential, thereby minimize donor site morbidity, infectious complications and decrease length of stay. This case series describes the expanded access experience of a CTP on pediatric patients with thermal injury.MethodsExpanded use approval of a CTP was obtained through the FDA for pediatric patients with burns at three burn centers. Patients were taken to the operating room for excision and grafting of burns at the discretion of the attending surgeon. In wounds with dermal elements present after excision, CTP was grafted to the wound bed (Table 1). Postoperative wound care and follow up was per institutional standards of care.ResultsSix pediatric patients (9 weeks – 13 years old) with mixed depth burns having dermal elements remaining after excision were treated successfully with a CTP. Donor site surface area was reduced in all patients. No serious adverse events related to the CTP were noted in any of the cases. Average time to heal wounds treated with the CTP was approximately 2-3 weeks. In wounds ultimately deemed to be full thickness, CTP was not detrimental to subsequent autograft take. See Table 1.ConclusionsThis case series demonstrates that use of a CTP in pediatric patients is donor site sparing without any serious adverse events. Furthermore, use in full thickness burns is not detrimental to subsequent autograft take. The degree of dermal elements necessary to support wound healing is unknown and requires further study. This case series supports the application for a clinical trial investigating the safety and efficacy of CTP as an adjunct to wound healing in pediatric deep partial thickness burns.

811 Statistical Analyses of Multiple Burn Wounds within an Animal

IntroductionPorcine animal models are frequently used to study the effects of various burn wound treatments and conditions. In these studies, multiple wounds are created on the dorsum of an anesthetized pig. Wounds within an animal are correlated, and the analysis of such a design should account for this dependence. Two recent studies are used as examples to illustrate the use of random effects for animal to account for the dependence of wound measurements within each pig.MethodsIn both studies, treatments were randomized to wound location, and neither contained repeated measurements within a wound.Study #1 investigated the effectiveness of enzymatic debridement. Forty 3-cm diameter partial-thickness burn wounds were created on the dorsum of 5 anesthetized pigs, arranged in 4 rows and 10 columns. Dorsal quadrants with 10 wounds each were created by combinations of two conditions: wounds that were wet or dry and wounds that were treated for either 72 or 96 hours. Debridement Efficiency Scores were calculated for each wound and evaluated for differences by inferential statistical comparisons between experimental treatments and conditions. The multilevel statistical model contained Treatment Group (5 levels), Treatment Time (2 levels: 72 hour and 96 hour), and Wet/Dry Condition (2 levels) as fixed effects, which were crossed to create a 3-way block, resulting in 2 wounds per animal for each Treatment, Wet/Dry, and Time combination. Random effects of animal and treatment block within animal were included in the model.Study #2 investigated the effectiveness of an experimental treatment applied at 3 different post-burn injury time points versus a standard of care (SOC). Up to 12 5-cm2 deep partial thickness wounds were created in 2 rows and 6 columns on each dorsum of 6 anesthetized pigs. Each treated wound was compared with a SOC wound located along the same cranio-caudal axis. Paired differences for wound closure % were calculated and analyzed with time as a fixed effect with a random effect for animal.ResultsFor Study #1, there were 200 total wounds, and for Study #2 there were 72 total wounds. These experimental units are not independent, as required by statistical testing. For both studies, there was graphical evidence that the burn wound measurements differed both within and between pigs. The statistical tests accounted for this variability by incorporating the effects due to pigs.ConclusionsMatching the statistical model to the experimental design is critical for correct interpretation of the results. Failure to use the correct model by assuming wounds within a pig are independent (and thereby ignoring any effect due to the pig) will result in erroneous statistical test results and less powerful tests of treatment differences.

A novel dressing with silver to treat meticillin-resistant Staphylococcus aureus biofilm infection in a pig model.

The purpose of this study was to use an in vivo biofilm porcine model to examine a new polyvinyl alcohol-based gelling fibre dressing with silver and compare it to other commercial dressings containing: polyvinyl alcohol-based gelling fibre without silver; carboxymethyl cellulose-based fibre with silver, benzethonium chloride and ethylenediaminetetraacetic acid; and untreated control. A total of 52 deep partial-thickness wounds (10x7x0.5mm) were created on each of three animals and inoculated with 25µl of meticillin-resistant Staphylococcus aureus (MRSA) (106 colony forming units (CFU)/ml). Wounds were covered for 24 hours to allow biofilm formation and were randomly designated to one of the four treatments. Samples were recovered for microbiological and histological analysis on days 3, 5 and 7 post-treatment. Polyvinyl alcohol-based gelling fibre dressing with silver was able to significantly reduce biofilm more effectively than the other treatment groups. By day 7, wounds treated with the dressing had a 2.72±0.01 log CFU/g reduction in MRSA count versus untreated control wounds and a 2.59±0.01 log CFU/g reduction versus baseline counts. For histology analysis, all wounds reached 100% re-epithelialisation by day 5. The results of this study indicated that polyvinyl alcohol-based gelling fibre dressing with silver was effective against biofilm of antibiotic-resistant staphylococcal strains without inhibiting the wound healing process, and may have important clinical implications when treating acute and/or hard-to-heal wounds.

Evaluation of healing outcomes combining a novel polymer formulation with autologous skin cell suspension to treat deep partial and full thickness wounds in a porcine model: a pilot study

Autologous skin cell suspensions (ASCS) can treat burns of varying depths with the advantage of reduced donor site wound burden. The current standard primary dressing for ASCS is a nonabsorbant, non-adherent, perforated film (control) which has limited conformability over heterogeneous wound beds and allows for run-off of the ASCS. To address these concerns, a novel spray-on polymer formulation was tested as a potential primary dressing in porcine deep partial thickness (DPT) and full thickness (FT) wounds. It was hypothesized that the polymer would perform as well as control dressing when evaluating wound healing and scarring.DPT or FT wounds were treated with either a spray-on poly(lactic-co-glycolic acid) (PLGA) and poly(lactide-co-caprolactone) (PLCL) formulation or control ASCS dressings. Throughout the experimental time course (to day 50), we found no significant differences between polymer and control wounds in % re-epithelialization, graft-loss, epidermal or dermal thickness, or % dermal cellularity in either model. Pigmentation, erythema, elasticity, and trans-epidermal water loss (TEWL), were not significantly altered between the treatment groups, but differences between healing wounds/scars and un-injured skin were observed. No cytotoxic effect was observed in ASCS incubated with the PLGA and PLCL polymers.These data suggest that the novel spray-on polymer is a viable option as a primary dressing, with improved ease of application and conformation to irregular wounds. Polymer formulation and application technique should be a subject of future research.

An Electrospun Poly-Ethylene Oxide/Cerium (III) Nitrate Dressing for Delayed Debridement and Improved Wound Healing of Warfighter Contact Burns

Introduction: Thermal burns account for 5-10% of casualties sustained in present-day conflicts and are expected to be one of the most common wounds to occur in future conflicts. Timely debridement of necrotic burn tissue can greatly reduce the chances of mortality and late-stage complications. However, future conflicts are anticipated to occur in austere environments where surgical debridement may not be plausible and casualty evacuations significantly delayed. Without access to prompt surgical interventions and standard treatment, burn wounds can progress (become deeper and more extensive) and become highly susceptible to infection. Several studies have demonstrated that topical applications of Cerium (III) Nitrate (Cen) can be used to delay the need for surgical eschar removal, a delay which may be forced upon injured warfighters in austere environments. The proof-of-concept studies described herein suggest that an electrospun dressing with a Polyethylene Oxide (PEO) shell and CeN core could prolong the time before surgical intervention is required and/or mitigate late-stage burn pathophysiologies in Prolonged Field Care (PFC) scenarios. Materials and Methods: Coaxially electrospun PEO dressings with a CeN payload were synthesized for application in a swine burn model. Dressings were first evaluated ex vivo using a Lactate Dehydrogenase (LDH) assay to confirm that no cytotoxic effects were present. Then, one female Yorkshire pig was anesthetized and received ten 5 cm x 5 cm contact burns with a brass burn device that was heated to 100°C. The deep-partial thickness wounds were randomly assigned to one of five treatment groups: 1) 1-Layer of the PEO/CeN dressing, 2) 4-Layers of the PEO/CeN dressing, 3) 4-layers of a control electrospun PEO dressing, 4) Flammacerium® cream (silver sulfadiazine 1%, cerium nitrate 2.2%), or 5) the PFC standard of care (SOC; gauze). Wounds were observed over an 18-day period, with surgical debridement occurring on Day 4 for all wounds. Transepidermal water loss, depth to debridement, and histologic measurements of necrosis were utilized to assess the burns. Research was conducted in compliance with the Animal Welfare Act, the implementing Animal Welfare regulations, and the principles of the Guide for the Care and Use of Laboratory Animals, National Research Council. The facility’s Institutional Animal Care and Use Committee approved all research conducted in this study. The facility where this research was conducted is fully accredited by AAALAC International. Experimental design and statistical comparisons were approved by an accredited epidemiologist and biostatistician. Results: The PEO/CeN dressings did not elicit a cytotoxic response ex vivo. Compared to the PFC SOC, treatments containing CeN reduced the amount of necrotic tissue produced by second-degree thermal injuries, as evidenced both histologically and in the depth required to reach viable tissue during surgical debridement. Importantly, the dressing did not adversely impact the live tissue surrounding the burn site. Conclusions: There are currently no field dressings that can delay the need for immediate debridement and thereby promote burn wound healing. This proof-of-concept study strongly suggests that the electrospun PEO/CeN dressing could fulfill this unmet medical need and advocates for further evaluation for use in imminent PFC scenarios.

31 A phase 3 open-label, controlled, randomized trial evaluating the efficacy and safety of a bioengineered allogeneic cellularized construct in patients with deep partial-thickness thermal burns

Abstract Introduction Autograft (AG) is the standard of care for treatment of severe burns. While AG provides effective wound closure (WC), the procedure creates a donor site wound prone to pain and scarring. In a phase 1b trial, no deep partial-thickness (DPT) wound treated with a bioengineered allogeneic cellularized construct (BACC) required AG by Day 28 and WC at the BACC site was achieved in 93% of patients by Month (M) 3. This phase 3 study (NCT03005106) evaluated the efficacy and safety of this BACC in patients with DPT burns. Methods Enrolled patients were aged ≥18 years with 3–49% TBSA thermal burns on the torso or extremities. In each patient, two DPT areas (≤2,000 cm2 total) deemed comparable following excision were randomized to treatment with either cryopreserved BACC or AG. Coprimary endpoints were 1) the difference in percent area of BACC treatment site and AG treatment site autografted at M3 and 2) the proportion of patients achieving durable WC of the BACC treatment site without AG at M3. Ranked secondary endpoints were: 1) the difference between BACC and AG donor sites in average donor site pain intensity through Day 14; 2) the difference between BACC and AG donor site cosmesis at M3; and 3) the difference between BACC and AG treatment site cosmesis at M12. Safety assessments were performed in all patients through M12. Results Seventy-one patients were enrolled. By M3, there was a 96% reduction in mean percent area of BACC treatment sites that required AG, compared with AG treatment sites (4.3% vs 102.1%, respectively; P&amp;lt;.0001). BACC treatment resulted in durable WC at M3 without AG in 92% (95% CI: 85.6, 98.8; 59/64) of patients for whom data was available. By M3, mean donor site Patient and Observer Scar Assessment Scale (POSAS) observer total score (±SD) was significantly lower (more like normal skin) for BACC donor sites compared with AG donor sites (6.3 ± 1.71 vs 16.3 ± 7.71; P&amp;lt;.0001). At M12, mean POSAS observer total score (±SD) was 15.6 (± 8.34) for BACC treatment sites compared with 16.3 (± 9.41) for AG treatment sites (P=.4268). The most common BACC-related adverse event (AE) was pruritus, which occurred in 11 (15%) patients. All BACC-related AEs were mild or moderate in severity. Conclusions This phase 3 study achieved both coprimary endpoints, including significant autograft sparing and durable WC in DPT burns. Both donor site pain and donor site cosmesis were favorable outcomes of significantly reduced use of AG in BACC-treated patients. M12 POSAS for BACC did not differ significantly from AG. This BACC may offer a new treatment for severe burns to reduce or eliminate the need for AG. Applicability of Research to Practice This BACC has shown clinical benefit in patients with DPT thermal burns, potentially mitigating donor site morbidity. External Funding Stratatech, a Mallinckrodt Company; Funding and technical support for the Phase 3 clinical study were provided by the Biomedical Advanced Research and Development Authority (BARDA), under the Assistant Secretary for Preparedness and Response, within the U.S. Department of Health and Human Services, under Project BioShield Contract No. HHSO100201500027C.

Treatment of partial thickness burns of the face with Acticoat7™ : Aretrospective single center study.

SummaryBackgroundThe face is affected in more than 50% of patients with extensive burn trauma. Effective treatment is of importance to avoid hypertrophic scarring, functional impairment and social stigmatization.Material and methodsAll patients treated with Acticoat7™ due to superficial and deep partial thickness burns of the face between 2008 and 2017 at the intensive care unit (ICU) for burn trauma at the Department for Plastic and Reconstructive Surgery of the Medical University of Vienna were retrospectively analyzed. Patients were evaluated for the number of required dressing changes until complete re-epithelialization, bacterial colonization, potential complications and the need for primary and secondary surgery.ResultsA total of 100 patients were analyzed. It took a median dressing change rate of 1 (range 0–5) in the superficial partial thickness and 3 (range 1–11) in the deep partial thickness group. Conservative treatment of deep partial thickness wounds was possible in 79% and 17% of these patients required secondary scar revision. Although bacterial colonization of the wounds frequently occurred, wound infections were rarely observed.ConclusionActicoat7™ is a valuable dressing for treating superficial and deep partial thickness burn wounds of the face in an intensive care unit setting. It enables extended time intervals between dressing changes without an increased risk for complications.

Enzymatic Debridement of Porcine Burn Wounds via a Novel Protease, SN514.

Necrotic tissue generated by a thermal injury is typically removed via surgical debridement. However, this procedure is commonly associated with blood loss and the removal of viable healthy tissue. For some patients and contexts such as extended care on the battlefield, it would be preferable to remove devitalized tissue with a nonsurgical debridement agent. In this paper, a proprietary debridement gel (SN514) was evaluated for the ability to debride both deep-partial thickness (DPT) and full-thickness burn wounds using an established porcine thermal injury model. Burn wounds were treated daily for 4 days and visualized with both digital imaging and laser speckle imaging. Strip biopsies were taken at the end of the procedure. Histological analyses confirmed a greater debridement of the porcine burn wounds by SN514 than the vehicle-treated controls. Laser speckle imaging detected significant increases in the perfusion status after 4 days of SN514 treatment on DPT wounds. Importantly, histological analyses and clinical observations suggest that SN514 gel treatment did not damage uninjured tissue as no edema, erythema, or inflammation was observed on intact skin surrounding the treated wounds. A blinded evaluation of the digital images by a burn surgeon indicated that SN514 debrided more necrotic tissue than the control groups after 1, 2, and 3 days of treatment. Additionally, SN514 gel was evaluated using an in vitro burn model that used human discarded skin. Treatment of human burned tissue with SN514 gel resulted in greater than 80% weight reduction compared with untreated samples. Together, these data demonstrate that SN514 gel is capable of debriding necrotic tissue and suggest that SN514 gel could be a useful option for austere conditions, such as military multi-domain operations and prolonged field care scenarios.

T5 Preliminary Analysis of a Phase 3 Open-label, Controlled, Randomized Trial Evaluating the Efficacy and Safety of a Bioengineered Regenerative Skin Construct in Patients with Deep Partial-thickness Thermal Burns

Abstract Introduction Autograft (AG) is the standard of care for treatment of severe burns. While AG provides effective wound closure (WC), the procedure creates a donor-site wound prone to dyspigmentation, infection, scarring, and pain. In a phase 1b trial, no deep partial-thickness (DPT) wound treated with a bioengineered regenerative skin construct (BRSC) required AG by Day 28 and WC at the BRSC site was achieved in 93% of patients by Month 3 (Holmes et al 2019). This phase 3 study evaluated the efficacy and safety of this BRSC in patients with DPT burns. Methods This phase 3 study (NCT03005106) enrolled patients aged ≥18 years with 3–49% total body surface area (TBSA) thermal burns on the torso or extremities. In each patient, two DPT areas (≤2,000 cm2 total) deemed comparable following excision were randomized to treatment with either cryopreserved BRSC or AG. Coprimary endpoints were 1) the difference in percent area of BRSC treatment site and AG treatment site autografted at 3 months and 2) the proportion of patients achieving durable WC of the BRSC treatment site without AG at 3 months. Safety assessments were performed in all patients. Efficacy was analyzed at 3 months and safety and scar follow-up continues to one year. Results A total of 71 patients were enrolled (mean [SD] age 44 [16] years; mean [SD] %TBSA 12.0 [8.4]). By Month 3, 4.3% (SD 21.6%) of all BRSC-treated area required AG compared with an additional regrafting of 2.1% of all AG-treated area (total 102.1% SD 13.1%; P&amp;lt; .0001). Three patients subsequently required AG at their BRSC site, 2 of whom also required it at their AG sites; Durable WC without autografting at the BRSC treatment site was achieved at Month 3 in 83% of patients compared with 86% of patients at the AG site. The most common BRSC-related adverse event (AE) was pruritus, occurring in 11 (15%) patients. All BRSC-related AEs were mild or moderate in severity. Conclusions This phase 3 study achieved both coprimary endpoints, including significant autograft sparing and durable WC in DPT burns. This BRSC may offer a new treatment for severe burns to reduce or eliminate the need for AG. Applicability of Research to Practice This BRSC has shown clinical benefit in patients with DPT thermal burns, potentially mitigating donor site morbidity. External Funding Stratatech, a Mallinckrodt Company; Funding and technical support for the Phase 3 clinical study were provided by the Biomedical Advanced Research and Development Authority (BARDA), under the Assistant Secretary for Preparedness and Response, within the U.S. Department of Health and Human Services, under Project BioShield Contract No. HHSO100201500027C.

Safety evaluation of silver-ion dressings in a porcine model of deep dermal wounds: A GLP study

IntroductionSilver ion has strong antimicrobial properties and is used in a number of wound dressings. In burn models, silver-nylon dressings produce elevated silver levels in the wound along with minimal systemic effect. We evaluated systemic toxicity in a non-burn wound model to see if a similar pattern of silver ion distribution would occur. MethodsEight deep partial-thickness wounds each were created on the dorsum of 40 Gottingen minipigs using a Er-YAG Laser. Half were treated with a 21-day course of silver-nylon dressings (Silverlon®) and half were treated with moist gauze dressings. Wound, blood, liver and kidney silver levels, along with blood chemistry and hematology data were obtained at appropriate intervals. ResultsAll wounds healed well with healing enhanced by silver-nylon dressings. Silver ion was demonstrable in all wounds treated with silver-nylon at day 21 and after 14 days of no further treatment. Silver ion was not detected in blood, liver or kidney of any animal treated with silver-nylon or control dressings. Liver and kidney function remained normal in all animals. ConclusionA 21-day application of silver-nylon dressings to a non-burn dermal wound produces no systemic or local toxicity in Gottingen minipigs.

Preclinical evaluation of a novel silver gelling fiber dressing on Pseudomonas aeruginosa in a porcine wound infection model.

The wound environment is a fertile ground for biofilm forming pathogens. Once biofilms form within the wound, they can be very challenging to eradicate. The purpose of this study was to examine the effect of a gelling fiber dressing with silver using a well-established porcine wound biofilm model. Deep partial thickness wounds were inoculated with Pseudomonas aeruginosa ATCC 27312 and covered with a polyurethane film dressing to promote biofilm formation. Wounds were then divided into treatment groups: gelling fiber dressing with silver, gelling fiber dressing without silver, hydrofiber dressing with silver, benzethonium chloride and ethylenediaminetetraacetic acid and compared to untreated control. Microbiological, biofilm, and histological wound assessments were performed on days 3, 5, and 7 postinfection. Treatment with gelling fiber dressing with silver resulted in significant reduction of P. aeruginosa biofilm when compared to all other treatment groups on every assessment time point. In addition, gelling fiber dressing with silver treatment resulted in detachment of biofilm from the wound, while wounds treated with gelling fiber dressing with and without silver showed more granulation tissue formation on day 3. Our data show that a new gelling fiber dressing with silver was effective in reducing biofilm associated P. aeruginosa in vivo. This study may have important clinical implications especially for wounds heavily colonized with gram-negative biofilm-forming bacteria.

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.

Effectiveness of a polyhexanide irrigation solution on methicillin-resistant Staphylococcus aureus biofilms in a porcine wound model.

Irrigation and removal of necrotic debris can be beneficial for proper healing. It is becoming increasingly evident that wounds colonized with biofilm forming bacteria, such as Staphylococcus aureus (SA), can be more difficult to eradicate. Here we report our findings of the effects of an irrigation solution containing propyl-betaine and polyhexanide (PHMB) on methicillin-resistant Staphylococcus aureus (MRSA) biofilms in a porcine wound model. Thirty-nine deep partial thickness wounds were created with six wounds assigned to one of six treatment groups: (i) PHMB, (ii) Ringer's solution, (iii) hypochlorous acid/sodium hypochlorite, (iv) sterile water, (v) octenidine dihydrochloride, and (vi) octenilin. Wounds were inoculated with MRSA and covered with a polyurethane dressing for 24 hours to allow biofilm formation. The dressings were then removed and the wounds were irrigated twice daily for 3 days with the appropriate solution. MRSA from four wounds were recovered from each treatment group at 3 days and 6 days hours after initial treatment. Irrigation of wounds with the PHMB solution resulted in 97·85% and 99·64% reductions of MRSA at the respective 3 days and 6 days assessment times when compared to the untreated group. Both of these reductions were statistically significant compared to all other treatment groups (P values <0·05).

Noninvasive Techniques for the Determination of Burn Severity in Real Time.

Visual diagnosis of second-degree burns has proven inadequate for determining the appropriate treatment regimen. Although multiple noninvasive imaging techniques have shown promise for providing information about burn wound severity, the ideal technology to aid burn wound excision would provide real-time readouts. Herein, the authors examine a high-resolution infrared (IR) camera (thermography) and a multiprobe adapter system (MPAS-6; transepidermal evaporative water loss, colorimetry) to assess their usefulness in predicting burn severity. Contact burn wounds of increasing severity were created in a porcine model. Wounds were assessed for 4 days with an IR camera and MPAS-6. In addition, each day, the burn wounds were biopsied for histological analysis to determine burn depth for correlation with noninvasive measures. Surface temperatures decreased with increasing burn severity, which was associated with increasing transepidermal evaporative water loss. Melanin content correlated with the depth of collagen coagulation and was bimodal, with superficial and full-thickness burns having higher values than deep partial thickness wounds. Erythema content was highest in superficial burns and negatively correlated with necrosis (high-mobility group box protein 1 expression). Importantly, surface temperature taken on every single day after injury was predictive of all histologically determined measurements of burn depth (ie, collagen coagulation, apoptosis, necrosis, vascular occlusion). The results indicate that IR imaging and skin quality probes can be used to support the diagnosis of burn severity. Most importantly, IR measurements gave insight into both the zone of coagulation and the zone of stasis on every postburn day studied.

Enhanced cutaneous wound healing by Senecio serratuloides (Asteraceae/Compositae) in a pig model

Senecio serratuloides (Asteraceae/Compositae) is a traditional herbal remedy used to treat skin wounds in South Africa. The plant contains hepatotoxic alkaloids and is responsible for the death of farm animals which have eaten the plant. Wound healing efficacy was determined by applying prepared plant material to deep partial-thickness wounds on a pig model and healing was compared to controls over 16days. Regrowth of the skin was monitored by measuring the increasing ratio of the epidermal thickness, relative to that of normal skin. The neo-epidermis of plant-treated wounds was significantly thicker on days 5 and 7 and was maximal on day 7, compared with day 9 for the controls. The pH of the treated wound surface was significantly lower than the controls on day 2. The presence of alkaloids was confirmed with Dragendorff's reagent on thin layer chromatography, but liver function enzymes were no different to that of the controls and no signs of liver toxicity were apparent on histology when the plant was applied topically to wounds. S serratuloides treatment accelerated the healing of deep partial thickness wounds and the epidermal thickness ratio was found to be a useful marker in monitoring the wound healing process. The significance of the lower wound surface pH remains to be fully determined.

Biphasic presence of fibrocytes in a porcine hypertrophic scar model.

The duroc pig has been described as a promising animal model for use in the study of human wound healing and scar formation. However, little is known about the presence and chronology of the fibrocyte cell population in the healing process of these animals. Wounds known to form scar were created on red duroc swine (3" x 3") with a dermatome to a total depth of either 0.06 inches or 0.09 inches. These wounds were allowed to heal completely and biopsies were done at scheduled time points during the healing process. Biopsies were formalin fixed and paraffin embedded for immunohistochemical analysis. Porcine reactive antibodies to CD-45 and procollagen-1 and a human reactive antibody to LSP-1 were used to detect the presence of fibrocytes in immunohistochemistry, an immunocytochemistry. Initial immunohistochemical studies showed evidence of a biphasic presence of fibrocytes. Pigs with 0.06 inches deep wounds showed positive staining for CD-45 and LSP-1 within highly cellular areas at days 2 and 4 after wounding. Additional animals with 0.09 inches deep wounds showed positive staining within similar areas at days 56, 70, and 113 after wounding. There was no immunohistochemical evidence of fibrocytes in skin biopsies taken at days 14, 28, or 42. Procollagen-1 staining was diffused in all samples. Cultured cells were stained for CD-45, LSP-1, and procollagen-1 by immunocytochemistry. These data confirm that fibrocytes are indeed present in this porcine model. We conclude that these cells are present after initial wounding and later during scar formation and remodeling. We believe that this is an evidence of a biphasic presence of fibrocytes, first as an acute response to skin wounding followed by later involvement in the remodeling process, prompted by continued inflammation in a deep partial thickness wound.

Effects of a topical aqueous oxygen emulsion on collagen deposition and angiogenesis in a porcine deep partial‐thickness wound model

A porcine deep partial-thickness wound model was used to evaluate the effects of a newly developed topical aqueous oxygen emulsion (TOE) on wound repair. The wounds were treated with TOE, which contains super-saturated oxygen or vehicle control. Semiquantitative immunofluorescent staining was performed to examine protein production for type I and type III collagen and vascular endothelial growth factor (VEGF). Immunofluorescent staining revealed higher protein levels of type I and type III collagen and VEGF in the TOE treatment group. Histological analysis also revealed improved angiogenesis and granulation tissue formation with topical TOE treatment and was consistent with the protein expression. In addition, the histology examination demonstrated faster epithelialization in wounds treated with TOE. The study suggests that sustained high levels of oxygen released by TOE may promote the process of wound repair through increasing collagen deposition and angiogenesis as well as stimulating epithelialization.

Keratin dressings speed epithelialization of deep partial‐thickness wounds

Keratin gene expression is regarded as a hallmark of epidermal biology. It demarcates the three keratinocyte phenotypes: basal (expressing KRT5 and KRT14), differentiating (expressing KRT1 and KRT10), and activated (wound healing), which is characterized by expression of KRT6, KRT16, and KRT17. Activated keratinocytes are among the first signals of epidermal wound healing. In addition, they are found deregulated in nonhealing chronic wounds. To examine keratins as a potential modality for wound-healing disorders, we evaluated two different keratin dressings, liquid or solid, and assessed their effects of epithelialization and closure using porcine partial-thickness wound-healing model in vivo. We found that both forms of keratin dressings accelerated closure and epithelialization, achieving statistically significant differences on day 5. Evidence suggesting early onset of epithelialization was corroborated further by gene expression analyses revealing induction of KRT6A, KRT16, and KRT17 by day 2 postwounding. The data suggest that keratin dressings may stimulate epithelialization by enhancing the activation of keratinocytes. We conclude that keratin-containing dressings can accelerate wound healing and closure. Further studies are needed to determine the molecular mechanisms of this activation.