Physiology of the Chronic Wound

Prospective and randomised evaluation of the protease-modulating effect of oxidised regenerated cellulose/collagen matrix treatment in pressure sore ulcers

In chronic wounds, excess levels and activity of proteases such as elastase and plasmin have been detected. Oxidised regenerated cellulose/collagen matrix (ORC/collagen matrix) has been reported to ameliorate the wound microenvironment by binding and inactivating excess proteases in wound exudates. In this study, the levels and activity of elastase and plasmin in wound exudates of pressure sore ulcers were measured to determine the beneficial effect of ORC/collagen matrix treatment compared with control treatment with a foam dressing. A total of 33 patients with pressure sores were enrolled in the study and were followed up for 12 weeks after treatment. Ten control patients were treated with a foam hydropolymer dressing (TIELLE^® , Systagenix), and the remaining 23 patients were treated with ORC/collagen matrix plus the foam dressing (TIELLE^® , Systagenix) on top. Wound assessments were carried out over 12 weeks on a weekly basis, with dressing changes twice a week. Ulcers were photographed and wound exudates were collected on admission and at days 5, 14 and then every 14 days to provide a visual record of any changes in appearance of the ulcer and healing rate and for biochemical analysis of the wound. The levels and activity of elastase and plasmin were measured in wound exudates. Statistical analysis was performed using ANOVA and Bonferroni's post hoc test with P-values <0·05 considered to be significant. Compared with controls, ORC/collagen matrix-treated pressure sore wounds showed a significant faster healing rate, which positively correlated with a decreased activity of elastase and plasmin in wound exudates. No signs of infection or intolerance to the ORC/collagen matrix were observed.

Bioactive glasses beyond bone and teeth: emerging applications in contact with soft tissues

The applications of bioactive glasses (BGs) have to a great extent been related to the replacement, regeneration and repair of hard tissues, such as bone and teeth, and there is an extensive bibliography documenting the role of BGs as bone replacement materials and in bone tissue engineering applications. Interestingly, many of the biochemical reactions arising from the contact of BGs with bodily fluids, in particular the local increase in concentration of various ions at the glass-tissue interface, are also relevant to mechanisms involved in soft tissue regeneration. An increasing number of studies report on the application of BGs in contact with soft tissues, aiming at exploiting the well-known bioactive properties of BGs in soft tissue regeneration and wound healing. This review focuses on research, sometimes involving preliminary in vitro studies but also in vivo evidence, that demonstrates the suitability of BGs in contact with tissues outside the skeletal system, which includes studies investigating vascularization, wound healing and cardiac, lung, nerve, gastrointestinal, urinary tract and laryngeal tissue repair using BGs in various forms of particulates, fibers and nanoparticles with and without polymer components. Potentially active mechanisms of interaction of BGs and soft tissues based on the surface bioreactivity of BGs and on biomechanical stimuli affecting the soft tissue-BG collagenous bonding are discussed based on results in the literature.

Temporal expression of IL-1β and IL-10 in rat skin, muscle, small bowel, and colon wounds: a correlative study

BACKGROUND

Cytokines play a major role in coordinated wound healing events. We hypothesized that rapid intestinal healing is due to an early upregulation of the pro-inflammatory cytokine interleukin-1β (IL-1β), followed by increases in the expression of the anti-inflammatory cytokine IL-10.

METHODS

We characterized the time course of IL-1β and IL-10 release at four wounds (skin, muscle, small bowel, and colonic anastomosis) after surgery on 38 juvenile male Sprague-Dawley rats. The tissue samples of each site were harvested at 0 (control), 1, 3, 5, 7, and 14 days postoperatively (n=6-8 per group) and analyzed by enzyme-linked immunosorbent assay kits for IL-1β and IL-10.

RESULTS

IL-1β expression peaked at days 5 and 7 in small bowel and colonic wounds when compared to skin or muscle. Similarly, IL-10 showed high expression in these time points in small bowel and colonic wounds. However, IL-10 showed the same expression in all time points in muscle and skin tissues except at day 1.

CONCLUSIONS

The high expression in IL-1β and IL-10 levels in small bowel and colon might explain the accelerated healing process in these wounds in comparison to skin and muscle tissues. Additional studies are required to determine whether IL-1β and IL-10 expression is the major factor defining site-specific differences in healing rates in different tissues. Understanding cytokine action in the wound healing process could lead to novel and effective therapeutic strategies.

Dental extraction in the neutropenic patient

PURPOSE

To identify risks of dental extraction in patients with mild, moderate, and severe neutropenia.

MATERIALS AND METHODS

The authors undertook an observational study of 116 patients diagnosed with neutropenia and undergoing dental extractions in the Mayo Clinic Division of Oral and Maxillofacial Surgery. Absolute neutrophil count (ANC) was no higher than 1,500/μL. Predictors were ANC, age, diagnosis, number of teeth removed, type and location of extraction, length of antibiotic use, presence and type of bacteremia at the time of consultation or extraction, reason for consultation, indication for extraction, and use of any granulocyte colony-stimulating factor (GCSF). Primary outcomes were total complications, surgical site infections, delayed healing, and prolonged postoperative pain. Descriptive and bivariate analyses were undertaken, with statistical significance set at a P value less than or equal to .05.

RESULTS

One hundred sixteen patients underwent extraction while neutropenic. The overall complication rate was 8.6% (n=10). All were minor complications requiring simple interventions, if any. Complications were delayed healing, surgical site infection, and prolonged postoperative pain. Delayed healing was not associated with ANC. GCSF and related medications did not appear to affect outcomes in these patients.

CONCLUSION

The results of this preliminary study suggest that extraction of teeth in patients at all stages of neutropenia can be conducted safely. Complications of extraction were few and should be easily controlled. Further studies are required to clarify and stratify risk for future patients.

A small peptide with potential ability to promote wound healing

Wound-healing represents a major health burden, such as diabetes-induced skin ulcers and burning. Many works are being tried to find ideal clinical wound-healing biomaterials. Especially, small molecules with low cost and function to promote production of endogenous wound healing agents (i.e. transforming growth factor beta, TGF-β) are excellent candidates. In this study, a small peptide (tiger17, c[WCKPKPKPRCH-NH2]) containing only 11 amino acid residues was designed and proved to be a potent wound healer. It showed strong wound healing-promoting activity in a murine model of full thickness dermal wound. Tiger17 exerted significant effects on three stages of wound healing progresses including (1) the induction of macrophages recruitment to wound site at inflammatory reaction stage; (2) the promotion of the migration and proliferation both keratinocytes and fibroblasts, leading to reepithelialization and granulation tissue formation; and (3) tissue remodeling phase, by promoting the release of transforming TGF-β1 and interleukin 6 (IL-6) in murine macrophages and activating mitogen-activated protein kinases (MAPK) signaling pathways. Considering its easy production, store and transfer and function to promote production of endogenous wound healing agents (TGF-β), tiger17 might be an exciting biomaterial or template for the development of novel wound-healing agents.

Salvianolic acid B in vitro inhibited matrix metalloproteinases-1, -2, and -9 activities

OBJECTIVE

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases, which as a group can degrade essentially all extracellular matrix components. The proteolytic property of the MMPs is important during wound healing to remove debris and facilitate cell migration. Targeting towards the decreased MMPs activities is a new treatment strategy for healing chronic wounds. Salvia miltiorrhiza is a popular Chinese herb that could promote chronic ulcers healing for topical use. Salvianolic acid B (Sal B) is the most abundant bioactive component in Salvia miltiorrhiza. The research was designed to explore the inhibitory effects of Sal B on MMP-1, MMP-2 and MMP-9 activities.

METHODS

Pure human interstitial collagenase (MMP-1) or gelatinase A (MMP-2) was activated by p-aminophenylmercuric acetate (APMA), and was incubated with Sal B for 1 h. The activities were observed by quenched fluorescent substrate. Gelatinase B (MMP-9) is rich in polymorphonuclear neutrophils (PMN), so the rat PMN was used as a source of MMP-9 for MMPs activity assays. In vitro MMP-9 from rats' PMN lysate was incubated with Sal B for 1 h, and its activity was tested by gelatin zymography.

RESULTS

Sal B dose-dependently inhibited the human MMP-1 and MMP-2 activities in the range of 0.002 4 to 0.3 g/L, with 50% inhibiting concentration (IC(50)) of (0.090<0.015) g/L and (0.080<0.005) g/L respectively. In the range of 0.003 to 0.3 g/L, Sal B could inhibit the MMP-9 activity (P<0.01).

CONCLUSION

The broad-spectrum inhibitory effects of Sal B on MMPs may reveal one of the mechanisms for the effects of Salvia miltiorrhiza on chronic wounds.

Upregulation of the proinflammatory cytokine-induced neutrophil chemoattractant-1 and monocyte chemoattractant protein-1 in rats' intestinal anastomotic wound healing--does it matter?

BACKGROUND

The proinflammatory cytokines and growth-promoting factor are essential components of the wound healing process. We hypothesized that under healthy conditions, faster healing of intestinal anastomotic wound is due to an early upregulation of proinflammatory cytokines, cytokine-induced neutrophil chemoattractant-1 (CINC-1) that is followed by a quicker upregulation of homeostatic chemokine, monocyte chemoattractant protein-1 (MCP-1) and late upregulation of transforming growth factor (TGF-β).

METHODS

We characterized the time course of CINC-1, MCP-1 and TGF-β release at four wounds (skin, muscle, small bowel, and colonic anastomosis) after surgery on 38 juvenile male Sprague Dawley rats. The tissue samples of each site were harvested at 0 (control), 1, 3, 5, 7 and 14 days postoperatively (n = 6-8/group) and analyzed by ELISA kits for CINC-1, MCP-1 and TGF-β.

RESULTS

CINC-1 expression peaked earlier in muscle and colonic wounds when compared to skin and small bowel. MCP-1 levels were elevated early in skin and muscle wounds, but later expression of MCP-1 was shown in colonic wounds. TGF-β levels were unchanged in all wound sites.

CONCLUSION

An earlier peak in CINC-1 levels and later expression of MCP-1 were seen in colonic wounds, but no significant increase in TGF-β levels was observed. These findings support the early healing process in intestinal anastomotic wounds.

Clinical and economic benefit of enzymatic debridement of pressure ulcers compared to autolytic debridement with a hydrogel dressing

OBJECTIVE

The purpose of this study was to determine the cost-effectiveness of enzymatic debridement using collagenase relative to autolytic debridement with a hydrogel dressing for the treatment of pressure ulcers.

METHODS

A 3-stage Markov model was used to determine the expected costs and outcomes of wound care for collagenase and hydrogel dressings. Outcome data used in the analysis were taken from a randomized clinical trial that directly compared collagenase and hydrogel dressings. The primary outcome in the clinical trial was the proportion of patients achieving a closed epithelialized wound. Transition probabilities for the Markov states were estimated from the clinical trial. A 1-year time horizon was used to determine the expected number of closed wound days and the expected costs for the two alternative debridement therapies. Resource utilization was based on the wound care treatment regimen used in the clinical trial. Resource costs were derived from standard cost references and medical supply wholesalers. The economic perspective taken was that of the long-term care facility. No cost discounting was performed due to the short time horizon of the analysis. A deterministic sensitivity analysis was conducted to analyze economic uncertainty.

RESULTS

The number of expected wound days for the collagenase and hydrogel cohorts are estimated at 48 and 147, respectively. The expected direct cost per patient for pressure ulcer care was $2003 for collagenase and $5480 for hydrogel debridement. The number of closed wound days was 1.5-times higher for collagenase (317 vs 218 days) than with the hydrogel. The estimated cost/closed wound day was 4-times higher for the hydrogel ($25) vs collagenase ($6).

CONCLUSIONS

In this Markov model based on a randomized trial of pressure ulcer care in a long-term care setting collagenase debridement was economically dominant over autolytic debridement, yielding better outcomes at a lower total cost. Since it was a single institution study with a small sample size, the results should be interpreted with caution. Specifically, the findings may not necessarily be generalized to other hydrogel dressings, healthcare settings, age groups, or to wounds of other etiologies.

PEGylated human plasma fibronectin is proteolytically stable, supports cell adhesion, cell migration, focal adhesion assembly, and fibronectin fibrillogenesis

Delayed wound healing in many chronic wounds has been linked to the degradation of fibronectin (FN) by abnormally high protease levels. We sought to develop a proteolytically stable and functionally active form of FN. For this purpose, we conjugated 3.35 kDa polyethylene glycol diacrylate (PEGDA) to human plasma fibronectin (HPFN). Conjugation of PEGDA to HPFN or HPFN PEGylation was characterized by an increase of approximately 16 kDa in the average molecular weight of PEGylated HPFN compared to native HPFN in SDS-PAGE gels. PEGylated HPFN was more resistant to α chymotrypsin or neutrophil elastase digestion than native HPFN: after 30 min incubation with α chymotrypsin, 56 and 90% of native and PEGylated HPFN respectively remained intact. PEGylated HPFN and native HPFN supported NIH 3T3 mouse fibroblast adhesion and spreading, migration and focal adhesion formation in a similar manner. Fluorescence microscopy showed that both native and PEGylated HPFN in the culture media were assembled into extracellular matrix (ECM) fibrils. Interestingly, when coated on surfaces, native but not PEGylated HPFN was assembled into the ECM of fibroblasts. The proteolytically stable PEGylated HPFN developed herein could be used to replenish FN levels in the chronic wound bed and promote tissue repair.

Reconstruction of abdominal wall of a chronically infected postoperative wound with a rectus abdominis myofascial splitting flap

BACKGROUND

If a chronically infected abdominal wound develops, complications such as peritonitis and an abdominal wall defect could occur. This could prolong the patient's hospital stay and increase the possibility of re-operation or another infection as well. For this reason, a solution for infection control is necessary. In this study, surgery using a rectus abdominis muscle myofascial splitting flap was performed on an abdominal wall defect.

METHODS

From 2009 to 2012, 5 patients who underwent surgery due to ovarian rupture, cesarean section, or uterine myoma were chosen. In each case, during the first week after operation, the wound showed signs of infection. Surgery was chosen because the wounds did not resolve with dressing. Debridement was performed along the previous operation wound and dissection of the skin was performed to separate the skin and subcutaneous tissue from the attenuated rectus muscle and Scarpa's fascial layers. Once the anterior rectus sheath and muscle were adequately mobilized, the fascia and muscle flap were advanced medially so that the skin defect could be covered for reconstruction.

RESULTS

Upon 3-week follow-up after a rectus abdominis myofascial splitting flap operation, no major complication occurred. In addition, all of the patients showed satisfaction in terms of function and esthetics at 3 to 6 months post-surgery.

CONCLUSIONS

Using a rectus abdominis myofascial splitting flap has many esthetic and functional benefits over previous methods of abdominal defect treatment, and notably, it enabled infection control by reconstruction using muscle.

Glucose toxic effects on granulation tissue productive cells: the diabetics' impaired healing

Type 2 diabetes mellitus is a metabolic noncommunicable disease with an expanding pandemic magnitude. Diabetes predisposes to lower extremities ulceration and impairs the healing process leading to wound chronification. Diabetes also dismantles innate immunity favoring wound infection. Amputation is therefore acknowledged as one of the disease's complications. Hyperglycemia is the proximal detonator of systemic and local toxic effectors including proinflammation, acute-phase proteins elevation, and spillover of reactive oxygen and nitrogen species. Insulin axis deficiency weakens wounds' anabolism and predisposes to inflammation. The systemic accumulation of advanced glycation end-products irreversibly impairs the entire physiology from cells-to-organs. These factors in concert hamper fibroblasts and endothelial cells proliferation, migration, homing, secretion, and organization of a productive granulation tissue. Diabetic wound bed may turn chronically inflammed, procatabolic, and an additional source of circulating pro-inflammatory cytokines, establishing a self-perpetuating loop. Diabetic fibroblasts and endothelial cells may bear mitochondrial damages becoming prone to apoptosis, which impairs granulation tissue cellularity and perfusion. Endothelial progenitor cells recruitment and tubulogenesis are also impaired. Failure of wound reepithelialization remains a clinical challenge while it appears to be biologically multifactorial. Ulcer prevention by primary care surveillance, education, and attention programs is of outmost importance to reduce worldwide amputation figures.

An audit to assess the perspectives of U.S. wound care specialists regarding the importance of proteases in wound healing and wound assessment

Chronic wounds represent an aberrant biochemistry that creates a toxic proteolytic milieu which can be detrimental to the healing process. Rebalancing the wound microenvironment and addressing elevated protease activity (EPA) could therefore help facilitate healing. To understand how clinicians currently diagnose and manage excessive proteolytic activity, 183 survey responses from US wound specialists were collated and analysed to find out their perceptions on the role of proteases. The majority of respondents (>98%) believed proteases were important in wound healing and that a point-of-care (POC) protease test could be useful. This study yielded a low response rate (7.1%, n = 183); however, there were adequate data to draw significant conclusions. Specialists perceived that fibrin, slough, granulation tissue and rolled wound edges could indicate EPA. About 43% of respondents, however, failed to give a correct response when asked to review photographs to determine if excessive protease activity was present, and the perceived visual signs for EPA did not correlate with the wounds that had EPA; no statistical differences between professions were observed. Respondents chose debridement, wound cleansing and advanced therapies as important in reducing excessive protease activity. It was concluded that specialists have a need for POC diagnostic tests. On the basis of the responses to wound photos, it was determined that there were no visual cues clinicians could use in determining excessive protease activity. Additional research is recommended to evaluate the efficacy of a POC diagnostic test for protease activity and the treatments and therapies applied when EPA is found.

Harnessing growth factors to influence wound healing

Cutaneous wound healing is a dynamic process with the ultimate goal of restoring skin integrity. On injury to the skin, inflammatory cells, endothelial cells, fibroblasts, and keratinocytes undergo changes in gene expression and phenotype, leading to cell proliferation, migration, and differentiation. Cytokines and growth factors play an essential role in initiating and directing the phases of wound healing. These signaling peptides are produced by a variety of cells and lead to a concerted effort to restore the skin barrier function.

Experimental pig model of clinically relevant wound healing delay by intrinsic factors

The intrinsic factors associated with delayed wounds are ischaemia, infection, the presence of necrotic tissue and the presence of foreign bodies. This study was designed to create adaptable intrinsic factors induced delayed wound healing model in the pig, similar to clinical conditions. Four pigs were used in this study. Ten 4 × 4 cm fresh full-thickness skin defect wounds were made on the back of each pig. Double-flanged blocks made of silicon, a material that induces foreign body reactions, tissue ischaemia and causes local wound infection, were inserted into half of the wounds (n = 5) and removed at weeks 1, 2 or 3. The other wounds (n = 5) were left open for control purposes. Biopsies were obtained at weeks 1-4 for histological examinations and to evaluate inflammatory cytokines, which included tumour necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6. A Periscan PIM 3 Laser was used to measure degrees of ischaemia. A Visitrak Digital(®) device was used to measure the sizes of unhealed wounds. After 3 weeks, unhealed mean wound sizes were 30·72 ± 3·36 and 2·91 ± 1·51 cm(2) , in the experimental and control groups, respectively. Laser Doppler showed limited perfusion at wound margins in wounds containing silicone blocks. Histological findings corresponding to the severity of chronic inflammation were markedly higher and persisted until week 3 in the experimental group. The levels of IL-1 and TNF-α in the third week were statistically significantly higher in the model group. Also, in the fourth week, the level of TNF-α in the model group was significantly higher. Epithelialisation was not complete at the end of the fourth week despite removing silicone blocks in the experimental group. On the basis of macroscopic and histological evaluations and molecular assessments, the described wound model has the characteristics of wound ischaemia and necrosis and persistent inflammation, which are very similar to delayed wounds of patients.

Inflammatory pathways in spinal cord injury

Injury to the spinal cord results in direct damage to axons, neuronal cell bodies, and glia that cause functional loss below the site of injury. In addition, the injury also triggers an inflammatory response that contributes to secondary tissue damage that leads to further functional loss. Reducing inflammation after spinal cord injury (SCI) is therefore a worthy therapeutic goal. Inflammation in the injured spinal cord is a complex response that involves resident cells of the central nervous system as well as infiltrating immune cells, and is mediated by a variety of molecular pathways and signaling molecules. Here, we discuss approaches we have used to identify novel therapeutic targets to modulate the inflammatory response after SCI to reduce tissue damage and promote recovery. Effective treatments for SCI will likely require a combination of approaches to reduce inflammation and secondary damage with those that promote axon regeneration.

Protein degradation and protection observed in the presence of novel wound dressing components

Chronic wounds typically have excessive levels of matrix metalloproteinases (MMPs) and proinflammatory cytokines that impair healing. Reducing these detrimental proteins may be key to healing chronic wounds. Proprietary protease blends were formulated specifically to degrade excessive amounts of proinflammatory factors that could prevent wound healing. Applications of protease-containing wound dressings to acute and chronic wounds have been observed clinically to resolve inflammation and appear to aid healing. The purpose of this study was to test in vitro a deliberate blend of proteases for the ability to deactivate or activate known proteins associated with inflammation or healing. Purified human target proteins were incubated with test and control solutions and samples removed at various time points. Blinded samples were tested using a novel infrared protein multiplex sandwich-ELISA-type array technique. Many proinflammatory proteins such as MMPs, cytokines and chemokines were susceptible to degradation. Many proteins such as growth factors, cytokines and TIMP1 were resistant to degradation. Not all proinflammatory proteins were deactivated. Family protein structure did not appear to affect susceptibility to degradation or deactivation. These results suggest that specific protease containing wound dressings appear to reduce multiple detrimental components which may disrupt their deleterious effects on the wound bed and microenvironment. By improving the wound microenvironment through the use of definitive proteases, these novel wound dressings may help transition wounds into the subsequent phase of healing.

Novel use of platelet-rich plasma to augment curative diabetic foot surgery

Autologous platelet-rich plasma (PRP) may enhance wound healing through the formation of a platelet plug that provides both hemostasis and the secretion of biologically active proteins, including growth factors such as platelet-derived growth factor, transforming growth factor (TGF)-β, TGF-β2, and epidermal growth factor. The release of these growth factors into the wound may create an environment more conducive to tissue repair and could accelerate postoperative wound healing. To our knowledge, there are no reports of combining the use of PRP with curative diabetic foot surgery. This article provides a summary of the literature regarding PRP and wound healing and presents a case of a 49-year-old man with diabetes and a three-month history of a deep, nonhealing plantar hallux wound in which PRP was combined with a first metatarsophalangeal joint arthroplasty. Through the use of the PRP and bioengineered tissue to supplement curative diabetic foot surgery, the patient healed uneventfully at seven weeks.

Intra-lesional injections of recombinant human epidermal growth factor promote granulation and healing in advanced diabetic foot ulcers: multicenter, randomised, placebo-controlled, double-blind study

A multicenter, double-blind, placebo-controlled trial was carried out to evaluate the intra-lesional infiltration of recombinant epidermal growth factor (EGF) in Wagner's grade 3 or 4 diabetic foot ulcers (DFUs). Subjects (149) were randomised to receive EGF (75 or 25 microg) or placebo, three times per week for 8 weeks and standard good wound care. The main endpoint was granulation tissue covering > or = 50% of the ulcer at 2 weeks. It was achieved by 19/48 controls versus 44/53 in the 75 microg group [odds ratio (OR): 7.5; 95% confidence interval (CI): 2.9-18.9] and 34/48 in the 25 microg group (OR: 3.7; 1.6-8.7). Secondary outcome variables such as end-of-treatment complete granulation response (28/48 controls, 46/53 with 75 microg and 34/48 with 25 microg EGF), time-to-complete response (controls: 5 weeks; both EGF dose groups: 3 weeks), and wound closure after follow-up (25/48 controls, 40/53 with 75 microg and 25/48 with 25 microg EGF) were also treatment dependent. Multivariate analyses yielded that they were significantly enhanced by 75 microg EGF treatment and neuropathic versus ischemic ulcers. Most adverse events were mild and no drug-related severe adverse reactions were reported. It was concluded that recombinant human EGF (rhEGF) local injections offer a favourable risk-benefit balance in patients with advanced DFU.

Dynamic changes in matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 levels during wound healing in diabetic rats

BACKGROUND

We investigated the mechanism of delayed would healing caused by diabetes and measured the dynamic changes in matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels. We noted differences in the ratio of MMP-9 to TIMP-1 in the wounds of diabetic and nondiabetic rats.

METHODS

Forty-two Sprague-Dawley rats weighing 250 g were randomly assigned to either the control group or the streptozotocin-induced diabetes group. Then, full-thickness excision wounds were created on the middle of the back of each animal. Skin biopsy specimens were obtained on days 0, 3, 7, and 14 after incision. The content of collagen was quantified by Masson's staining and the macrophage marker, and CD68 was detected by immunohistochemical analysis. Messenger RNA and protein expression of MMP-9 and TIMP-1 was measured by reverse transcriptase-polymerase chain reaction and Western blot, respectively.

RESULTS

Diabetic rats exhibited slower wound healing than control animals (P < .05). On days 3, 7, and 14 after incision, higher levels of MMP-9 messenger RNA and protein expression were detected in the diabetic group compared with the control group (P < .05), and expression of TIMP-1 messenger RNA and protein was significantly decreased. In addition, the ratio of MMP-9 to TIMP-1 was stable in controls, whereas there was a marked increase in the ratio in diabetic skin wounds.

CONCLUSIONS

The balance between MMP-9 and its inhibitor, TIMP-1, is disturbed in diabetic skin tissue after injury, which may lead to histologic abnormality of diabetic skin and delayed wound healing.

Inflammatory biomarkers in combat wound healing

BACKGROUND

Modern war ballistics and blast injuries inflict devastating extremity injuries, violating soft tissue, bone, and neurovascular structures. Despite advances in complex wound management, appropriate timing of war wound closure remains subjective. In addition, the pathophysiology of acute wound failure is poorly defined.

METHODS

Patients with penetrating extremity wounds sustained during combat were prospectively studied and followed for 30 days after definitive wound closure. The primary outcome was wound healing. Wound dehiscence was defined as spontaneous partial or complete wound disruption after closure. Serum, wound effluent, and wound bed tissue biopsy were collected at each surgical wound debridement. Serum and wound effluent were analyzed with a multiplex array of 22 cytokines and chemokines, and wound tissue for corresponding gene transcript expression.

RESULTS

Fifty-two penetrating extremity war wounds in 33 male patients were investigated. Nine (17%) wounds dehisced. Concomitant vascular injury, increased wound size, and higher injury severity score correlated with wound dehiscence. Both serum and wound effluent cytokine and chemokine protein profiles were statistically associated with healing outcome at various time points. Wound biopsy gene transcript expression demonstrated increased tissue inflammation associated with wound failure. Multiple protein and gene transcript biomarkers predictive of wound healing were identified.

CONCLUSIONS

The cytokine and chemokine protein and gene transcript expression patterns demonstrate a condition of inflammatory dysregulation associated with war wound failure. A molecular biomarker panel may predict combat wound healing outcome and warrants prospective validation.

The Role of Doxycycline as a Matrix Metalloproteinase Inhibitor for the Treatment of Chronic Wounds

Many chronic wounds fail to heal with conventional therapy, resulting in disability and impaired quality of life. New technologies using recombinant growth factors, autologous growth factors, or bioengineered skin—tissue substitutes have been shown to be effective, but these treatments are costly. An effective, low-cost treatment to improve healing of chronic wounds is needed. The molecular environment of chronic wounds, like many other chronic inflammatory diseases, contains abnormally high levels of proinflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-1β]) and matrix metalloproteinases (MMPs), which impair normal wound healing. In animal models and clinical studies of ulcerative diseases, doxycycline, an inexpensive and Food and Drug Administration (FDA)-approved antibiotic, appears to inhibit members of the MMP superfamily like MMPs and TNF-α-converting enzyme (TACE). This article provides an overview of the roles of MMPs and intrinsic tissue inhibitors of metalloproteinases (TIMPs) in wound healing and the damaging effects of chronically elevated levels of MMPSs in chronic wounds. It also explores the use of topical doxycycline, a synthetic MMP inhibitor (MMPI), to enhance healing of chronic wounds.

Accelerated wound closure of pressure ulcers in aged mice by chitosan scaffolds with and without bFGF

Pressure ulcers are a significant healthcare concern, especially for elderly populations. Our work served to ameliorate the chronicity of these ulcers by addressing ischemia-reperfusion injury mediated by neutrophils and the concomitant loss of vasculature in these wounds. To this end, chitosan scaffolds loaded with basic fibroblast growth factor (bFGF) contained in gelatin microparticles were developed and tested for clinical relevance in an aged mouse model. Pressure ulcers were induced in aged mice, and efficacy of treatment was assessed. On days 3 and 7, both chitosan and chitosan-bFGF scaffolds significantly accelerated wound closure compared to gauze control. By day 10, all wounds achieved similar closure. Delivery and angiogenic function of bFGF was verified through ELISA and histology. Elevated neutrophil levels were observed in chitosan and chitosan-bFGF groups. Since neutrophil elastase contributes to the proteolytic environments of pressure ulcers, the effect of chitosan on elastase was assessed. In vitro, chitosan inhibited elastase activity. In vivo, elastase protein levels in wounds were reduced with chitosan-bFGF scaffolds by day 10. These results suggest that chitosan is an effective material for growth factor delivery and can help to heal chronic ulcers. Collectively, our data show that chitosan-bFGF scaffolds are effective in accelerating wound closure of pressure ulcers in aged animals.

Intracellular adenosine triphosphate delivery enhanced skin wound healing in rabbits

Small unilamellar lipid vesicles were used to encapsulate adenosine triphosphate (ATP-vesicles) for intracellular energy delivery. This technique was tested in full-thickness skin wounds in 16 adult rabbits. One ear was rendered ischemic by using a minimally invasive surgery. The other ear served as a normal control. Four circular full-thickness wounds were created on the ventral side of each ear. ATP-vesicles or saline was used and the wounds were covered with Tegaderm (3M, St. Paul, MN). Dressing was changed and digital photos were taken daily until all the wounds were healed. The mean healing times of ATP-vesicles-treated wounds were significantly shorter than that of saline-treated wounds on ischemic and nonischemic ears. Histologic study indicated better-developed granular tissue and reepithelialization in the ATP-vesicles-treated wounds. The wounds treated by ATP-vesicles exhibited extremely fast granular tissue growth. More CD31 positive cells were seen in the ATP-vesicles-treated wounds. This preliminary study shows that direct intracellular delivery of ATP can accelerate the healing process of skin wounds on ischemic and nonischemic rabbit ears. The extremely fast granular tissue growth was something never seen or reported in the past.

The pro-inflammatory environment in recalcitrant diabetic foot wounds

Lower extremity ulceration is one of the serious and long-term diabetic complications rendering a significant social burden in terms of amputation and quality-of-life reduction. Diabetic patients experience a substantial wound-healing deficit. These lesions are featured by an exaggerated and prolonged inflammatory reaction with a significant impairment in local bacterial invasion control. Experimental and clinical evidences document the deleterious consequences of the wound's pro-inflammatory phenotype for the repair process. From a biochemical standpoint, hyperinflammation favours wound matrix degradation, thus, amplifying a pre-existing granulation tissue productive cells' invasiveness and recruitment deficit. Tumour necrosis factor perpetuates homing of inflammatory cells, triggers pro-apoptotic genes and impairs reepithelialisation. Advanced glycation end-products act in concert with inflammatory mediators and commit fibroblasts and vascular cells to apoptosis, contributing to granulation tissue demise. Therapeutic approaches aimed to downregulate hyperinflammation and/or attenuate glucolipotoxicity may assist in diabetic wound healing by dismantling downstream effectors. These medical interventions are demanded to reduce amputations in an expanding diabetic population.

Biofilms and chronic wound inflammation

In contrast to the commonly accepted hypothesis of host-centred pathology, it is possible that surface bacteria, not host dysfunction, cause the chronicity and perpetual inflammation associated with chronic non-healing wounds.

Treatment with bone marrow-derived stromal cells accelerates wound healing in diabetic rats

Bone marrow stem cells participate in tissue repair processes and may have a role in wound healing. Diabetes is characterised by delayed and poor wound healing. We investigated the potential of bone marrow-derived mesenchymal stromal cells (BMSCs) to promote healing of fascial wounds in diabetic rats. After manifestation of streptozotocin (STZ)-induced diabetic state for 5 weeks in male adult Sprague-Dawley rats, healing of fascial wounds was severely compromised. Compromised wound healing in diabetic rats was characterised by excessive polymorphonuclear cell infiltration, lack of granulation tissue formation, deficit of collagen and growth factor [transforming growth factor (TGF-beta), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor PDGF-BB and keratinocyte growth factor (KGF)] expression in the wound tissue and significant decrease in biomechanical strength of wounds. Treatment with BMSC systemically or locally at the wound site improved the wound-breaking strength (WBS) of fascial wounds. The improvement in WBS was associated with an immediate and significant increase in collagen levels (types I-V) in the wound bed. In addition, treatment with BMSCs increased the expression of growth factors critical to proper repair and regeneration of the damaged tissue moderately (TGF-beta, KGF) to markedly (EGF, VEGF, PDGF-BB). These data suggest that cell therapy with BMSCs has the potential to augment healing of the diabetic wounds.

Extracorporeal shock wave therapy for management of chronic ulcers in the lower extremities

Management of chronic ulcers in the lower extremities is still a challenge for patients and health providers. Recent studies showed extracorporeal shock waves (ESW) as effective in stimulating growth factors, inducing angiogenesis and healing of fractures and injuries. This study was planned to investigate the opportunity of introducing the ESW in the treatment of chronic wounds. Thirty consecutive patients with chronic posttraumatic, venous and diabetic ulcers, unresponsive to conservative or advanced dressing treatments, were counseled about the use of ESW as alternative treatment for their wounds. Thirty-two wounds were treated and 16 wounds healed completely within six sessions of ESW. In all of the nonhealed wounds, decrease of the amount of exudates, increased percentage of granulation tissue compared with fibrin/necrotic tissue and decrease of wounds' size were statistically significant after four to six sessions of ESW (p < 0.01). Significant decrease of pain was reported (p < 0.001). Comparison with a control group of 10 patients with chronic ulcer treated on the basis of regular dressings confirmed the statistical significant improvement in the healing process (p < 0.01). ESW therapy seems to be a safe, feasible and cost-effective treatment for chronic ulcers in the lower extremities. Further research and clinical trials are necessary to evaluate dose and time intervals of sessions to standardize a protocol of treatment in the management of chronic wounds.

Effect of oxidised regenerated cellulose/collagen matrix on proteases in wound exudate of patients with chronic venous ulceration

Oxidised regenerated cellulose/collagen matrix (ORC/collagen matrix) modifies wound microenvironments by binding and inactivating excess levels of proteases such as elastase, plasmin and gelatinases in wound exudates. To compare levels of the gelatinases matrix metalloproteinase 2 (MMP-2), elastase and plasmin in wound exudates collected from chronic venous insufficiency patients with venous leg ulcers treated with either an ORC/collagen matrix or a standard control therapy. During a 12-week treatment period, wound exudate samples were obtained from a control group of 10 patients treated with a hydrocolloid dressing and a treatment group of 17 patients treated with a combination of ORC/collagen matrix and hydrocolloid dressing. On admission and days 5, 14 and every subsequent 14th day, ulcers were photographed to determine healing rate and changes in ulcer appearance, and MMP-2 concentration and the gelatinase, elastase and plasmin activities were analysed from wound exudates. The patients treated with ORC/collagen matrix showed a significant decrease in elastase, plasmin and gelastinase activity as compared with the control group, with no significant difference in the MMP-2 concentrations between the two groups. The results show a significant and immediate reduction in protease activity in wound exudates from venous leg ulcers treated with ORC/collagen.

Negative pressure wound therapy with instillation: a pilot study describing a new method for treating infected wounds

This data review reports the results of 15 patients who were treated with Vacuum-Assisted Closure (VAC) negative pressure therapy system in addition to the timed, intermittent delivery of an instilled topical solution for management of their complex, infected wounds. Prospective data for 15 patients treated with negative pressure wound therapy (NPWT)-instillation was recorded and analysed. Primary endpoints were compared to a retrospective control group of 15 patients treated with our institution's standard moist wound-care therapy. Culture-specific systemic antibiotics were prescribed as per specific patient need in both groups. All data were checked for normality of distribution and equality of variance and appropriate parametric and non parametric analyses were conducted. Compared with the standard moist wound-care therapy control group, patients in the NPWT-instillation group required fewer days of treatment (36.5 +/- 13.1 versus 9.9 +/- 4.3 days, P < 0.001), cleared of clinical infection earlier (25.9 +/- 6.6 versus 6.0 +/- 1.5 days, P < 0.001), had wounds close earlier (29.6 +/- 6.5 versus 13.2 +/- 6.8 days, P < 0.001) and had fewer in-hospital stay days (39.2 +/- 12.1 versus 14.7 +/- 9.2 days, P < 0.001). In this pilot study, NPWT instillation showed a significant decrease in the mean time to bioburden reduction, wound closure and hospital discharge compared with traditional wet-to-moist wound care. Outcomes from this study analysis suggest that the use of NPWT instillation may reduce cost and decrease inpatient care requirements for these complex, infected wounds.

Correlation of procalcitonin and cytokine expression with dehiscence of wartime extremity wounds

BACKGROUND

Despite technological advances in the treatment of severe extremity trauma, the timing of wound closure remains the subjective clinical decision of the treating surgeon. Traditional serum markers are poor predictors of wound-healing. The objective of this study was to evaluate the cytokine and chemokine profiles of severe extremity wounds prior to closure to determine if wound effluent markers can be used to predict healing.

METHODS

Serum and effluent (exudate) samples were collected prospectively from adult volunteers with multiple high-energy penetrating extremity wounds sustained during military combat. Samples were collected prior to definitive wound closure or flap coverage. Wounds were followed clinically for six weeks. The primary clinical outcome measures were wound-healing and dehiscence. Control serum samples were collected from normal age and sex-matched adult volunteers. All samples were analyzed for the following cytokines and chemokines: procalcitonin; eotaxin; granulocyte macrophage colony stimulating factor; interferon (IFN)-gamma; interleukin (IL)-1 through 8, 10, 12, 13, and 15; IFN-gamma inducible protein-10; monocyte chemotactic protein-1; macrophage inflammatory protein-1alpha; the protein regulated on activation, normal T expressed and secreted (RANTES); and tumor necrosis factor (TNF)-alpha.

RESULTS

Fifty wounds were analyzed in twenty patients. Four of the fifty wounds dehisced. An increased rate of wound dehiscence was observed in patients with a concomitant closed head injury as well as in those with an associated arterial injury of the affected limb (p < 0.05). Among the serum chemokines and cytokines, only serum procalcitonin levels correlated with wound dehiscence (p < 0.05). Effluent analysis showed that, compared with wounds that healed, wounds that dehisced were associated with elevated procalcitonin, decreased RANTES protein, and decreased IL-13 concentrations (p < 0.05). No wound with an effluent procalcitonin concentration of <220 pg/mL, an IL-13 concentration of >12 pg/mL, or a RANTES protein concentration of >1000 pg/mL failed to heal.

CONCLUSIONS

Effluent procalcitonin, IL-13, and RANTES protein levels as well as serum procalcitonin levels correlate with wound dehiscence following closure of severe open extremity wounds. These preliminary results indicate that effluent biomarker analysis may be an objective means of determining the timing of traumatic wound closure.

MOC-PSSM CME article: Pressure sores

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand and describe the physiology of pressure sore development. 2. Understand and describe population risk factors. 3. Understand and describe examination and classification. 4. Understand and describe common surgical treatment algorithms. 5. Understand and describe strategies for prevention and postoperative recurrence.

SUMMARY

Pressure sores are ischemic damage to soft tissues resulting from unrelieved pressure, usually over a bony prominence. In both acute and chronic circumstances, a careful, structured multidisciplinary strategy is required from initial diagnosis to resolution. Mechanical issues, such as the relief of pressure, adequate surgical debridement, and flap coverage, are of little value if educational, nutritional, social, and resource-based issues are not in place. The authors discuss a range of topics, including etiology, physiology, classification, operative options, and strategies to prevent recurrence.

FACIT collagen (1alpha-chain) is expressed by hemocytes and epidermis during the inflammatory response of the ascidian Ciona intestinalis

Based on previous cloning and sequencing study, real-time PCR and in situ hybridization assays of the inflamed body wall of LPS-injected Ciona intestinalis showed the enhanced gene expression of a collagen with FACIT structural features (Ci-type IX-Col 1alpha-chain). By using specific antibodies raised against an opportunely chosen Ci-type IX-Col synthetic peptide, the fibroblast property of hemocytes challenged in vitro with LPS (at 4h) was displayed by flow cytometry, while immunocytochemistry identified hemocytes with large granules (morula cells) as collagen-producing cells. Hemocyte lysate supernatant analyzed in immunoblotting contained a 60 kDa band identifiable as 1alpha-chain-Ci-type IX-Col. Observations of body wall sections (immunohistochemistry method) supported the role of hemocytes and showed that epidermis expressed Ci-type IX-Col 1alpha-chain in the time course of the inflammatory reaction (within 24h). Transcript and protein were mainly found in the epidermis that outlined the proximal side of the tunic matrix (at 24h after LPS injection), in cells associated with the epidermis at 4 and 192 h. In conclusion, the C. intestinalis inflammatory response to LPS challenge appeared to be composed of a complex reaction set, and for the first time we showed in ascidians a granulation tissue with FACIT-collagen production that could participate in inflammation and wound healing. Like in vertebrates, C. intestinalis acute inflammatory reactions result in a regulated pattern of tissue repair with collagen expression during remodelling. Ci-type IX-Col could be involved in a network of non-fibril-forming collagens that participates in the organization of extracellular matrix and defense responses.

[Randomized comparative trial of a collagen/oxidized regenerated cellulose dressing in the treatment of neuropathic diabetic foot ulcers]

INTRODUCTION

Diabetic foot is a complication of diabetes mellitus that manifests with the development of ulcers that frequently precede amputation. Several studies have verified that the environment of the diabetic neuropathic foot ulcer contains a high concentration of metalloproteinases. The aim of the present study was to evaluate the efficacy of a protease-modulating dressing in the treatment of neuropathic diabetic foot ulcers.

MATERIAL AND METHOD

A randomized controlled trial was conducted in 40 patients with a 6-week or longer history of neuropathic diabetic foot ulcer. The patients were randomized to two groups: group 1 (n = 20) received treatment with the protease-modulating dressing while the control group (group 2; n = 20) received the treatment specified in the standardized protocol for good wound care. The patients were then followed-up for 6 weeks.

RESULTS

After 6 weeks, healing was achieved in 12 patients (63% of n = 19) in group 1 under treatment with the protease-modulating dressing versus three patients (15% of n = 19) in the control group (p < 0.03). The mean time to healing was 23.3 +/- 9.9 days in group 1 and 40.6 +/- 1.15 days in group 2 (p < 0.01).

CONCLUSIONS

The results confirm the hypothesis that the use of protease-modulating dressings in patients with neuropathic diabetic foot ulcers leads to better tissue regeneration than good wound care.

Synergistic action of protease-modulating matrix and autologous growth factors in healing of diabetic foot ulcers. A prospective randomized trial

This study tests the hypothesis that addition of a protease-modulating matrix enhances the efficacy of autologous growth factors in diabetic ulcers. Fifty-one patients with chronic diabetic foot ulcers were managed as outpatients at the Democritus University Hospital of Alexandroupolis and followed up for 8 weeks. All target ulcers were > or = 2.5 cm in any one dimension and had been previously treated only with moist gauze. Patients were randomly allocated in three groups of 17 patients each: Group A was treated only with the oxidized regenerated cellulose/collagen biomaterial (Promogran, Johnson & Johnson, New Brunswick, NJ), Group B was treated only with autologous growth factors delivered by Gravitational Platelet Separation System (GPS, Biomet), and Group C was managed by a combination of both. All ulcers were digitally photographed at initiation of the study and then at change of dressings once weekly. Computerized planimetry (Texas Health Science Center ImageTool, Version 3.0) was used to assess ulcer dimensions that were analyzed for homogeneity and significance using the Statistical Package for Social Sciences, Version 13.0. Post hoc analysis revealed that there was significantly greater reduction of all three dimensions of the ulcers in Group C compared to Groups A and B (all P<.001). Although reduction of ulcer dimensions was greater in Group A than in Group B, these differences did not reach statistical significance. It is concluded that protease-modulating dressings act synergistically with autologous growth factors and enhance their efficacy in diabetic foot ulcers.

Intralesional injections of Citoprot-P (recombinant human epidermal growth factor) in advanced diabetic foot ulcers with risk of amputation

To investigate the efficacy and safety of recombinant human epidermal growth factor (rhEGF) in advanced diabetic foot ulcers (DFU) A double-blind trial was carried out to test two rhEGF dose levels in type 1 or 2 diabetes patients with Wagner's grade 3 or 4 ulcers, with high risk of amputation. Subjects were randomised to receive 75 (group I) or 25 mug (group II) rhEGF through intralesional injections, three times per week for 5-8 weeks together with standardised good wound care. Endpoints were granulation tissue formation, complete healing and need of amputation. Safety was assessed by clinical adverse events (AEs) and laboratory evaluations. Forty-one patients were included. After 5-8 weeks of treatment, 83% patients in the higher dose group and 61% in group II achieved useful granulation tissue covering more than 98% of the wound area. At long-term assessment, 13 (56.5%) patients healed in group I and 9 (50%) in group II. The mean time to complete healing in group I was 20.6 weeks (95% CI: 17.0-24.2) and 19.5 weeks (16.3-22.7) in group II. After 1-year follow-up, only one patient relapsed. Amputation was not necessary in 65% and 66.7% of groups I and II, respectively. The AEs rates were similar. The most frequent were sepsis (33%), burning sensation (29%), tremors, chills and local pain (25% each). rhEGF local injection enhances advanced DFU healing and reduces the risk of major amputation. No dose dependency was observed.

Recent insights into the causes of chronic leg ulceration in venous diseases and implications on other types of chronic wounds

Venous ulceration represents the most prevalent form of difficult-to-heal wounds and these problematic wounds require a significant amount of healthcare resources for their treatment. In order to develop effective treatment regimens a clearer understanding of the underlying pathological processes that lead to skin breakdown is required. However, to date, most of these studies have tended to focus on describing the pathology of already-established ulcers. By bringing together relevant aspects of diverse disciplines such as inflammation, cardiovascular, and connective tissue biology, we aim to provide an insight into how circulatory abnormalities that are caused by the underlying disease etiology can induce local tissue inflammation resulting in tissue breakdown. Initially this results in internal tissue damage but if the underlying disease is not treated, the internal tissue damage can worsen and lead to open ulceration. This article discusses the cause-and-effect relationships between chronic venous insufficiency and venous ulceration, focusing particularly on the biological processes that lead from the underlying disease condition to overt ulceration. Available evidence also suggests that formation of pressure, diabetic foot and arterial ulcers, and ulcers as results of blood disorders, is also likely to share some of the same biological processes as venous ulcers.

Effects of topical glutathione treatment in rat ischemic wound model

Oxidative stress secondary to ischemia can cause physiopathologic changes that adversely affect wound healing. In this experimental study, we hypothesized that the topical use of esterified glutathione, a well-known antioxidant, can minimize the effects of oxidative stress by an increase in intracellular glutathione and accelerate wound healing by increasing the contraction capacity of fibroblasts and preventing keratinocytes from apoptosis in a rat ischemic wound model. Experimental models were divided into 3 groups as treatment, control, and healthy. Bipedicled flaps were elevated from the dorsum of the rats, and 6-mm punch wounds were created at the end of the first day when the ischemia is most apparent. Wounds were followed histopathologically and immunohistochemically, and matrix metalloproteinase (MMP)-1 and tissue inhibitors of metalloproteinase (TIMP-1) levels were measured by ELISA. Samples were collected at 0, 5, 8, 10, and 12 days. Histopathologic evaluation revealed significant extracellular matrix deposition and reepithelization every fifth day in treatment and healthy groups when compared with control group. Immunohistochemical evaluation revealed increased apoptosis in basal keratinocytes in the control group when compared with the other groups. The evaluation of the samples collected at 5 and 8 days revealed increased MMP-1 levels in treatment and control groups, but the increase in TIMP-1 levels was more significant than MMP-1 levels in treatment group. MMP-1/TIMP-1 ratio was significantly low in the treatment group.Our results showed that topical GSH treatment can reduce oxidative stress, and the reestablishment of the MMP-1/TIMP-1 ratio gives way to adequate and regular extracellular matrix production and reepithelization. It is concluded that esterified GSH, which is experimentally shown to be effective in ischemic wound healing, can be used clinically in ischemic wounds.

Bacterial profiling using skin grafting, standard culture and molecular bacteriological methods

OBJECTIVE

Wound healing can be delayed by the presence of colonising bacteria, and in polymicrobial wounds they may act synergistically to the further detriment of wound healing. In this pilot investigation, biopsy and swab samples were obtained as part of skin-graft operations performed on a chronic venous leg ulcer in order to study the spatial microbial diversity and to compare standard bacteriological and molecular biological techniques.

METHOD

The wound was sampled before excision, and sampling was undertaken at multiple locations across the wound. Swab samples and biopsies were subjected to culture analysis and 16S rRNA polymerase chain reaction (PCR), and to denaturing gradient gel electrophoresis (DGGE).

RESULTS

Within the wound samples, DGGE identified the major wound microflora components and established the extent of local differences in bacterial diversity.

CONCLUSION

This ongoing investigation has verified DGGE as a powerful tool for elucidating the clinical microbiology of a chronic disease state. It also suggests that skin graft operations are a novel way of obtaining multiple samples for in vivo bacteriology and for establishing the spatial distribution of bacteria in the complex micro-environment of chronic wounds.

Immediate tight sealing of skin incisions using an innovative temperature-controlled laser soldering device: in vivo study in porcine skin

BACKGROUND

A feedback temperature-controlled laser soldering system (TCLS) was used for bonding skin incisions on the backs of pigs. The study was aimed: 1) to characterize the optimal soldering parameters, and 2) to compare the immediate and long-term wound healing outcomes with other wound closure modalities.

MATERIALS AND METHODS

A TCLS was used to bond the approximated wound margins of skin incisions on porcine backs. The reparative outcomes were evaluated macroscopically, microscopically, and immunohistochemically.

RESULTS

The optimal soldering temperature was found to be 65 degrees C and the operating time was significantly shorter than with suturing. The immediate tight sealing of the wound by the TCLS contributed to rapid, high quality wound healing in comparison to Dermabond or Histoacryl cyanoacrylate glues or standard suturing.

CONCLUSIONS

TCLS of incisions in porcine skin has numerous advantages, including rapid procedure and high quality reparative outcomes, over the common standard wound closure procedures. Further studies with a variety of skin lesions are needed before advocating this technique for clinical use.