A simplified method for monitoring cytokines in wound fluid

Cytokines in wound fluid are used as surrogates for wound healing in clinical research. The current methods used to collect and process wound fluid are noninvasive but not optimal. The aim of this prospective study was to evaluate a method (NovaSwab) by which wound fluid is collected by a surface swab and eluted in a physiological buffer for subsequent cytokine analysis. Wound fluid from 12 patients with leg ulcers was assessed by NovaSwab at the start (Day 0) and at the end of a 23-h collection period of wound fluid retained by foam oblates beneath an occlusive film dressing (Day 1). GM-CSF, IL-1α, IL-1β, IL-6, IL-8, PDGF-AA, TNF-α and VEGF levels were measured by multiplex and electrochemiluminescence assays. IL-1α (2.4×), IL-1β (2.0×) and IL-8 (1.8×) levels increased from Day 0 to Day 1 as detected by NovaSwab, indicating local production of these polypeptides in the wounds. On Day 1, the NovaSwab method yielded higher levels of IL-1α (4.0×), IL-1β (2.7×) and IL-6 (2.7×), and 35% lower levels of VEGF than those in wound fluid accumulated for 23 h in foam oblates (on average, 5 ml of wound fluid). In vitro experiments showed that the investigated cytokines in cell-free wound fluid were recovered in a quantitative manner by the NovaSwab method. We conclude that the method presented here is a promising research tool to study the kinetics of soluble cytokines over the course of wound healing. More studies are needed to determine the interobserver variation and reproducibility of the NovaSwab method.

Gene Expression Linked to Reepithelialization of Human Skin Wounds

Our understanding of the regulatory processes of reepithelialization during wound healing is incomplete. In an attempt to map the genes involved in epidermal regeneration and differentiation, we measured gene expression in formalin-fixed, paraffin-embedded standardized epidermal wounds induced by the suction-blister technique with associated nonwounded skin using NanoString technology. The transcripts of 139 selected genes involved in clotting, immune response to tissue injury, signaling pathways, cell adhesion and proliferation, extracellular matrix remodeling, zinc transport and keratinocyte differentiation were evaluated. We identified 22 upregulated differentially expressed genes (DEGs) in descending order of fold change (MMP1, MMP3, IL6, CXCL8, SERPINE1, IL1B, PTGS2, HBEGF, CXCL5, CXCL2, TIMP1, CYR61, CXCL1, MMP12, MMP9, HGF, CTGF, ITGB3, MT2A, FGF7, COL4A1 and PLAUR). The expression of the most upregulated gene, MMP1, correlated strongly with MMP3 followed by IL6 and IL1B. rhIL-1β, but not rhIL-6, exposure of cultured normal human epidermal keratinocytes and normal human dermal fibroblasts increased both MMP1 mRNA and MMP-1 protein levels, as well as TIMP1 mRNA levels. The increased TIMP1 in wounds was validated by immunohistochemistry. The six downregulated DEGs (COL7A1, MMP28, SLC39A2, FLG1, KRT10 and FLG2) were associated with epidermal maturation. KLK8 showed the strongest correlation with MKI67 mRNA levels and is a potential biomarker for keratinocyte proliferation. The observed gene expression changes correlate well with the current knowledge of physiological reepithelialization. Thus, the gene expression panel described in this paper could be used in patients with impaired healing to identify possible therapeutic targets.

Corrigendum: Biomarkers of Skin Graft Healing in Venous Leg Ulcers

Abstract is missing (Corrigendum)

Biomarkers of Skin Graft Healing in Venous Leg Ulcers

There is a need for biomarkers that predict the success of transplantation of venous leg ulcers (with autologous split-thickness skin grafts). The primary objective of this exploratory study was to investigate the association between split-thickness skin graft healing in venous leg ulcers and candidate wound fluid biomarkers representing inflammatory cell and endogenous proteinase activities, and bioactivity. A secondary objective was to compare biomarker levels of the 17 venous leg ulcers with sterile split-thickness skin graft donor-site wounds in another 10 patients with venous leg ulcers. Wound fluids were collected for 24 h using a validated method. The concentration of pre-operative matrix metalloproteinase-9 in wound fluid was higher in venous leg ulcers showing good healing (n = 10) than in venous leg ulcers showing poor healing (n = 7) 12 weeks after transplantation with meshed split-thickness skin grafts. The diagnostic value of matrix metalloproteinase-9 was good according to receiver-operating characteristic curve analysis. Matrix metalloproteinase activity in wound fluids from split-thickness skin graft donor-site wounds increased as a function of time and healing, but was still lower than matrix metalloproteinase activity in venous leg ulcer wound fluids, which showed increased levels of most biomarkers except for matrix metalloproteinase-9 and matrix metalloproteinase-2. In conclusion, wound fluid matrix metalloproteinase-9 concentration is a potential predictive biomarker of split-thickness skin graft healing in venous leg ulcers.

Effect of Stabilized Hypochlorous Acid on Re-epithelialization and Bacterial Bioburden in Acute Wounds: A Randomized Controlled Trial in Healthy Volunteers

The aim of this randomized controlled trial was to evaluate the wound-healing effect and antimicrobial properties of a novel stabilized hypochlorous acid solution on acute wounds, using a suction blister wound model. One suction blister was raised and de-roofed on each forearm in 20 healthy volunteers. Stabilized hypochlorous acid/control (sterile 0.9% NaCl) solutions were assigned to either wound by randomization. Wounds were irrigated and treated on days 0, 2 and 4. Re-epithelialization was assessed blindly by digital planimetry, and bacterial growth was assessed as the number of colony-forming units cultured from surface swabs. Hypochlorous acid solution increased the degree of re-epithelialization on day 4 by 14% compared with the control solution (95% confidence interval (CI) 6.8–20%, p = 0.00051) and was not inferior (p < 0.0001) to the control solution on day 10 (0.3%, 95% CI –1.3–1.9%). Median bacterial counts were lower with stabilized hypochlorous acid compared with control and were further reduced after irrigation and treatment of both groups on day 4, but remained lower in the stabilized hypochlorous acid group compared with the control group. This study demonstrates immediate and durable antimicrobial action and a beneficial effect on acute wound healing after irrigation and treatment with a stabilized hypochlorous acid formulation.

[Research trends in wound care]

Advanced wound care strategies are emerging, but more robust clinical data are needed such as identification of precise biomarkers for point-of-care diagnostics and 24/7 data. This will aid in the implementation of effective therapies in relevant patients. Increased knowledge among health care providers, health literacy improvement as well as patient involvement are also important in this process. In this review we focus on current research trends in compression therapy, modulation of inflammation and growth factors, the proteolytic microenvironment and microbiology.

The wound healing effect of local leukocyte platelet-rich plasma after total hip arthroplasty: A randomized controlled trial

Rapid wound closure is important after arthroplasty procedures to prevent postoperative complications. Platelets are rich in growth factors and leukocytes contribute to innate immunity. We hypothesized that topical leukocyte platelet-rich plasma (L-PRP) derived from the blood of patients would be beneficial to wound healing. In this randomized controlled trial, patients subjected to elective total hip arthroplasty (THA) were assigned by concealed allocation either L-PRP application onto the sutured fascia or no application (control) after the THA intervention. In addition, all patients received 1.5 g protein/kg, 5 g L-arginine, 500 mg vitamin C and 44 mg zinc daily over the 4-week postoperative period to obtain optimal nutrition. The primary endpoint was complete healing of the skin incision. The secondary endpoints were blood transfusions, length of hospital stay, pain and wound infections. Sixteen patients in the L-PRP group and 17 patients in the control group completed the trial. L-PRP treatment accelerated complete wound healing after 3 weeks (seven in the L-PRP group vs. zero in the control group, p = 0.003) and after 4 weeks (12 in the L-PRP group vs. six in the control group, p = 0.037). No postoperative superficial wound infections occurred within 4 weeks, and there were no significant differences in the other secondary outcomes. L-PRP generated in 10 sex-matched healthy volunteers revealed increased concentrations of platelets (5.8-fold) and leukocytes (2.3-fold) compared with those in whole blood. Furthermore, the concentration of keratinocyte mitogen epidermal growth factor in L-PRP (380 ± 130 pg/ml, mean ± SD) was higher (p < 0.001) than that in serum (130 ± 26 pg/ml). In conclusion, a single intraoperative local application of L-PRP promoted wound healing after THA, possibly mediated by EGF receptor agonists.

A Human Cellular Model for Colorectal Anastomotic Repair: The Effect of Localization and Transforming Growth Factor-β1 Treatment on Collagen Deposition and Biomarkers

Anastomotic leakage (AL) is a devastating complication after colorectal surgery, possibly due to the loss of stabilizing collagen fibers in the submucosa. Our aim was to assess the formation of collagen in the colon versus the rectum with or without transforming growth factor (TGF)-β1 exposure in a human cellular model of colorectal repair. Primary fibroblasts were isolated by an explant procedure from clinically resected tissue rings during anastomosis construction in 19 consecutive colorectal patients who underwent laparoscopy. The cells, identified as fibroblasts by morphologic characteristics and flow cytometry analysis (CD90⁺), were cultured for 8 days and in 12 patients in the presence of 1 ng/mL TGF-β1. Total collagen deposition was measured colorimetrically after Sirius red staining of fixed cell layers, and type I, III, and VI collagen biosynthesis and degradation were specifically determined by the biomarkers PINP, PRO-C3, PRO-C6, and C3M in conditioned media by competitive enzyme-linked immunosorbent assays. Total collagen deposition by fibroblasts from the colon and rectum did not significantly differ. TGF-β1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-β1 treatment increased COL1A1 and ACTA2 (encoding α-smooth muscle actin), and decreased COL6A1 and MMP2 mRNA levels in colorectal fibroblasts. In conclusion, we found no effect of anatomic localization on collagen production by fibroblasts derived from the large intestine. TGF-β1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.

Spatial expression of metallothionein, matrix metalloproteinase-1 and Ki-67 in human epidermal wounds treated with zinc and determined by quantitative immunohistochemistry: A randomised double-blind trial

Reepithelialisation is fundamental to wound healing, but our current understanding largely relies on cellular and animal studies. The aim of the present randomised double-blind three-arm controlled trial was to correlate genuine epidermal wound healing with key proteins and topical zinc treatment in humans. Sixty wounds were produced using deroofed suction blisters in 30 healthy volunteers and randomised to topical zinc sulphate (n = 20), placebo (n = 20), or control (n = 20) treatment for 4 days. All wounds with perilesional skin were processed for automatic immunostaining of paraffin tissue sections with monoclonal antibodies against Ki-67, metallothionein (MT) and matrix metalloproteinase (MMP)-1. Protein expression was quantified by automated digital image analysis. Epidermal Ki-67 and MT labelling indices were increased in keratinocytes in the neoepidermis (∼1.1 mm) and at the wound edge (0.5 mm) compared to normal skin. Increased MMP-1 immunostaining was restricted to the neoepidermis. MT was robustly upregulated in the upper dermis of the wounds. Zinc treatment enhanced MMP-1 expression beneath the neoepidermis via paracrine mechanisms and MT under the neoepidermis and in the nonepithelialised wound bed via direct actions of zinc as indicated by the induction of MT2A mRNA but not MMP-1 mRNA in cultured normal human dermal fibroblasts by zinc sulphate. The present human study demonstrates that quantitative immunohistochemistry can identify proteins involved in reepithelialisation and actions of external compounds. Increased dermal MT expression may contribute to the anti-inflammatory activities of zinc and increased MMP-1 levels to promote keratinocyte migration.

Staphylococcus aureus Augments Release of Matrix Metalloproteinase-8 from Human Polymorpho-nuclear Leukocytes

is missing (Short communication).

Zinc Oxide Inhibits Axillary Colonization by Members of the Genus Corynebacterium and Attenuates Self-perceived Malodour: A Randomized, Double-blind, Placebo-controlled Trial

Malodour from the axilla is commonly caused by specific microbes, and may be inhibited by zinc oxide. The aim of this study was to determine the effects of zinc oxide on the axillary microbiota, odour and pH in a randomized, double-blind, placebo-controlled trial in 30 healthy volunteers. In each participant 1 axilla was treated with zinc oxide and the other with a placebo for 13 days. The microbiota and pH were analysed before and during treatment. At the final visit, the participants judged their own axillary odour for comparison. With zinc oxide treatment total bacterial growth and, specifically, that of odour-producing Corynebacterium spp. and Staphylococcus hominis, decreased (p < 0.05), despite an increase (p < 0.0005) in skin-surface pH. Compared with the placebo, zinc oxide treatment reduced (p = 0.005) self-perceived malodour. In vitro, Corynebacterium spp. (19 isolated strains) survival was reduced (p < 0.0005) at pH 5.0 compared with pH 6.0; growth inhibition by zinc oxide occurred at ≤ 400 mg/l, and cell death occurred at ≤ 10,000 mg/l for 12 (63%) of the strains. In conclusion, application of zinc oxide reduced malodour and the counts of causative bacteria, but increased the pH of the axilla.

Matrix Metalloproteinases: How Much Can They Do?

Zinc-dependent matrix metalloproteinases (MMPs) belong to metzincins that comprise not only 23 human MMPs but also other metalloproteinases, such as 21 human ADAMs (a disintegrin and metalloproteinase domain) and 19 secreted ADAMTSs (a disintegrin and metalloproteinase thrombospondin domain). The many setbacks from the clinical trials of broad-spectrum MMP inhibitors for cancer indications in the late 1990s emphasized the extreme complexity of the participation of these proteolytic enzymes in biology. This editorial mini-review summarizes the Special Issue, which includes four review articles and 10 original articles that highlight the versatile roles of MMPs, ADAMs, and ADAMTSs, in normal physiology as well as in neoplastic and destructive processes in tissue. In addition, we briefly discuss the unambiguous involvement of MMPs in wound healing.

Multinutrient Supplementation Increases Collagen Synthesis during Early Wound Repair in a Randomized Controlled Trial in Patients with Inguinal Hernia

BACKGROUND

Inguinal hernia disease is associated with an imbalanced collagen metabolism. Surgical stress has a negative impact on nutrients important for collagen synthesis.

OBJECTIVE

We hypothesized that supplementation with a combination of nutrients would enhance collagen biosynthesis in inguinal hernia disease patients when undergoing hernia repair.

METHODS

In this exploratory randomized controlled trial, 21 men (age: 55.2 ± 2.8 y; BMI: 25.0 ± 0.7 kg/m2) scheduled for Lichtenstein inguinal hernia repair were assigned to multinutrient supplementation (n = 10; multinutrient group) or no multinutrient supplementation (n = 11; control group). The multinutrient group received 14 g l-arginine, 14 g l-glutamine, 1250 mg vitamin C, and 55 mg zinc daily starting 14 d before surgery and ending 14 d after surgery. The multinutrient and control groups received high-quality protein to ensure a daily intake of 1.5 g protein/kg. Collagen biosynthesis was measured by the biomarkers type I procollagen propeptide (CICP), type III procollagen propeptide (PRO-C3), and type V procollagen propeptide (PRO-C5) in the sera on days -14, 0, and 1, and in the wound fluids on postoperative days 1 and 2. Compliance was recorded after the 28-d intervention period.

RESULTS

Serum PRO-C5 concentrations decreased (P < 0.05) postoperatively in the control but not the multinutrient group. Neither CICP nor PRO-C3 serum concentrations differed significantly between the 2 groups. In wound fluid, the CICP concentrations increased (P < 0.05) from days 1 to 2 in the multinutrient group and were 49% higher (P = 0.10) than those in the control group on day 2. Wound fluid concentrations PRO-C3 and PRO-C5 showed no significant time or group differences. The 28-d compliance was similar (P = 0.27) in the 2 groups.

CONCLUSION

Oral supplementation with arginine, glutamine, vitamin C, and zinc augment collagen synthesis during the first 2 d after inguinal hernia repair. This trial was registered at clinicaltrials.gov as NCT03221686.

Matrix Metalloproteinase-3 is Key Effector of TNF-α-Induced Collagen Degradation in Skin

Inflammatory processes in the skin augment collagen degradation due to the up-regulation of matrix metalloproteinases (MMPs). The aim of the present project was to study the specific impact of MMP-3 on collagen loss in skin and its interplay with the collagenase MMP-13 under inflammatory conditions mimicked by the addition of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). Skin explants from MMP-3 knock-out (KO) mice or from transgenic (TG) mice overexpressing MMP-3 in the skin and their respective wild-type counterparts (WT and WTT) were incubated ex vivo for eight days. The rate of collagen degradation, measured by released hydroxyproline, was reduced (p < 0.001) in KO skin explants compared to WT control skin but did not differ (p = 0.47) between TG and WTT skin. Treatment with the MMP inhibitor GM6001 reduced hydroxyproline media levels from WT, WTT and TG but not from KO skin explants. TNF-α increased collagen degradation in the WT group (p = 0.0001) only. More of the active form of MMP-13 was observed in the three MMP-3 expressing groups (co-incubation with receptor-associated protein stabilized MMP-13 subforms and enhanced detection in the media). In summary, the innate level of MMP-3 seems responsible for the accelerated loss of cutaneous collagen under inflammatory conditions, possibly via MMP-13 in mice.

Uncontrolled gelatin degradation in non-healing chronic wounds

OBJECTIVE

To compare matrix metalloproteinase (MMP)-9 and the antiproteinase tissue inhibitor of metalloproteinases (TIMP)-1 in wound fluids and sera from patients with chronic non-healing or acute healing wounds. In addition, the functional consequences on MMP-9 activity and general gelatinase activity were assessed.

METHOD

In this observational study, samples were collected from patients with venous leg ulcers (VLUs), patients with type 2 diabetes with neuropathic foot ulcers (DFUs), and from another cohort of VLU patients with sterile split-thickness skin graft donor sites after autologous skin grafting, serving as healing control wounds. MMP-9 and TIMP-1 concentrations were determined by enzyme-linked immunosorbent assays. MMP-9 and gelatinase activities were determined in wound fluids in subsets of the patients.

RESULTS

A total of 24 patients took part in the study. No significant differences in MMP-9 wound fluid levels were found among the three groups. TIMP-1 levels were markedly and significantly lower in the two chronic wound groups resulting in a severely unbalanced MMP-9/TIMP-1 ratio, especially notable in the VLU group and possibly in the elevated endogenous MMP-9 activity (p<0.01) compared with the acute wound fluids. At least 20% of the chronic wound fluids displayed atypical patterns on gelatin zymography and showed high general gelatinase activity that was not inhibited by either TIMP-1 or by a gelatinase inhibitor (AG3340). MMP-9 levels were higher in the sera of the patients with type 2 diabetes.

CONCLUSION

We hypothesise that non-MMP proteinases contribute to matrix destruction in a significant number of chronic wounds. Blocking the excessive MMP-9 activity may be insufficient to normalise wound healing. The reasons and effects of the very low TIMP-1 levels in chronic wounds need further clarification.

Acellular Fish Skin Grafts and Pig Urinary Bladder Matrix Assessed in the Collagen-Induced Arthritis Mouse Model

It is vital that cellular- and tissue-based products (CTPs) used for wound treatment do not provoke autoimmunity. In this study, the immunogenic response to extracts of 2 CTPs of piscine and porcine origin was assessed in the collagen-induced arthritis model. Male DBA/1J mice were divided into 4 groups, each composed of 7 to 9 animals. Each animal was injected with one of following to assess their immune responses: (1) bovine type II collagen (100 µg) in Freund's adjuvant, (2) extract of piscine skin (100 µg) in Freund's adjuvant, (3) extract of porcine urinary bladder matrix (100 µg) in Freund's adjuvant, or (4) Freund's adjuvant alone (control) at the beginning of the experiment and 3 weeks later. Clinical signs of arthritis were assessed from week 5 onwards, and anti-type II and anti-type I collagen antibody immunoglobulin G (IgG) serum levels were measured before injections and 8 weeks after exposure using enzyme-linked immunosorbent assays. Only the mice exposed to bovine type II collagen developed clinical arthritis accompanied by very high anti-type II collagen IgG serum levels. Anti-type II collagen IgG serum levels were also detected in the porcine group but were undetectable in the piscine skin and control groups after 8 weeks. There were no significant differences in anti-type I collagen IgG serum levels among the groups. The results showed that piscine skin did not provoke systemic autoimmunity against type II collagens in DBA/1J mice.

The effect of gender on early colonic anastomotic wound healing

PURPOSE

Clinically, male patients subjected to colorectal surgery are more prone to develop anastomotic leakage than female patients by unknown mechanisms. Our aim was to investigate the impact of gender on anastomotic wound healing using an experimental model.

METHODS

One-layer colonic anastomosis was constructed in 8-week-old 28 male and 32 female Sprague-Dawley rats. Animals of one group (n = 30) were sacrificed immediately after surgery day 0 and the other group (n = 30) on postoperative day 3. Anastomotic breaking strength, total collagen (hydroxyproline), soluble collagen (Sircol), matrix metalloproteinase (MMP)-9, and transforming growth factor (TGF)-β1 were measured.

RESULTS

The anastomotic breaking strength decreased from day 0 to day 3 with no significant gender differences either in the extent of decline (P = 0.122) or absolute day 3 strengths (P = 0.425). Analogously, total collagen concentration in the anastomotic wounds decreased postoperatively and were lower (P = 0.043) in the male compared with the female rats on day 3. MMP-9 levels increased in the anastomoses postoperatively, but they did not differ (P = 0.391) between male and female animals. Soluble collagen levels were lower in the day-3 anastomoses of male versus female rats (P = 0.015) and correlated positively with total TGF-β1 levels (r_S = 0.540, P = 0.006). Although TGF-β1 tended to be lower in male compared with the female rats, the differences did not reach statistical significance.

CONCLUSION

Our findings point towards a less favorable collagen metabolism in colonic anastomoses of male compared with female rats during early wound healing.

Type V Collagen is Persistently Altered After Inguinal Hernia Repair

BACKGROUND AND AIMS

Hernia formation is associated with alterations of collagen metabolism. Collagen synthesis and degradation cause a systemic release of products, which are measurable in serum. Recently, we reported changes in type V and IV collagen metabolisms in patients with inguinal and incisional hernia. The aim of this study was to determine if the altered collagen metabolism was persistent after hernia repair.

MATERIAL AND METHODS

Patients who had undergone repairs for inguinal hernia (n = 11) or for incisional hernia (n = 17) were included in this study. Patients who had undergone elective cholecystectomy served as controls (n = 10). Whole venous blood was collected 35-55 months after operation. Biomarkers for type V collagen synthesis (Pro-C5) and degradation (C5M) and those for type IV collagen synthesis (P4NP) and degradation (C4M2) were measured by a solid-phase competitive assay.

RESULTS

The turnover of type V collagen (Pro-C5/C5M) was slightly higher postoperatively when compared to preoperatively in the inguinal hernia group (P = 0.034). In addition, the results revealed a postoperatively lower type V collagen turnover level in the inguinal hernia group compared to controls (P = 0.012). In the incisional hernia group, the type V collagen turnover was higher after hernia repair (P = 0.004) and the postoperative turnover level was not different from the control group (P = 0.973).

CONCLUSION

Patients with an inguinal hernia demonstrated a systemic and persistent type V collagen turnover alteration. This imbalance of the collagen metabolism may be involved in the development of inguinal hernias.

Bacterial Aggregates Establish at the Edges of Acute Epidermal Wounds

Objective: The bacterial composition and distribution were evaluated in acute standardized epidermal wounds and uninjured skin by a molecular in situ technology benchmarked to conventional culturing. This was done to reveal whether bacterial biofilm is present in acute wounds. Approach: On the buttock of 26 healthy volunteers, 28 suction blisters were made and de-roofed. Four wounds were biopsied immediately after wounding, whereas the remaining 24 wounds were treated daily with sterile deionized water and covered with a moisture-retaining dressing. On day 4 post-wounding, swabs were obtained for culturing from the wounds and adjacent skin, and the wounds including adjacent skin were excised. Tissue sections were stained with peptide nucleic acid (PNA) fluorescence in situ hybridization (FISH) probes, counterstained by 4',6-diamidino-2-phenylindole, and evaluated by confocal laser scanning microscopy (CLSM). Results: No bacterial aggregates were detected at day 0. At day 4, coagulase-negative staphylococci (CoNS) were the sole bacteria identified by CLSM/PNA-FISH and culturing. CoNS was isolated from 78% of the wound swabs and 48% of the skin swabs. Bacterial aggregates (5-150 μm) were detected by PNA-FISH/CLSM in the split stratum corneum and fibrin deposits at the wound edges and in the stratum corneum and the hair follicles of the adjacent skin. The bacterial aggregates were more common (p = 0.0084) and larger (p = 0.0083) at wound edges than in the adjacent skin. Innovation: Bacterial aggregates can establish in all wound types and may have clinical significance in acute wounds. Conclusion: Bacterial aggregates were observed at the edges of acute epidermal wounds, indicating initiated establishment of a biofilm.

Impaired collagen synthesis in the rectum may be a molecular target in anastomotic leakage prophylaxis

The underlying molecular mechanisms for anastomotic leakage (AL) after colorectal surgery are unknown and there are no therapeutics for AL prevention. Our aim was to correlate endogenous matrix metalloproteinase (MMP) activity, collagen concentration, and collagen/MMP/cytokine mRNA levels with anatomic location in human colorectal tissue. We enrolled 22 patients in this prospective study: 7 underwent elective laparoscopic sigmoid resection and 15 underwent low anterior resection for colorectal cancer. Full-thickness intestinal tissue rings from anastomoses constructed with a circular stapler were used for the determination of the MMP activity, tissue collagen concentration and mRNA levels. COL1A1 (p = 0.017) and COL3A1 (p = 0.0013) mRNA levels were lower in rectal tissue than in colonic samples. Neither MMP activities nor collagen concentrations differed significantly between the two anatomic locations. By elucidating the factors responsible for the decreased collagen production we may identify specific molecular targets in AL prophylaxis.

Therapeutic improvement of colonic anastomotic healing under complicated conditions: A systematic review

AIM: To identify therapeutic agents for the prophylaxis of gastrointestinal anastomotic leakage (AL) under complicated conditions.

METHODS: The PubMed and EMBASE databases were searched for English articles published between January 1975 and September 2014. Studies with the primary purpose of improving anastomotic healing in the colon or rectum under complicated preoperative and/or intraoperative conditions were included. We excluded studies investigating the adverse effects or risk assessment of an active intervention. Furthermore, investigations of biophysical materials, sealants, electrical stimulation and nutrients were excluded. The primary study outcome was biomechanical anastomotic strength or AL. The meta-analysis focused on therapeutic agents that were investigated in one animal model using the same outcome by at least three independent research groups.

RESULTS: The 65 studies included were divided into 7 different complicated animal models: Bowel ischemia, ischemia/reperfusion, bowel obstruction, obstructive jaundice, peritonitis, chemotherapy and radiotherapy. In total, 48 different therapeutic compounds were examined. The majority of investigated agents (65%) were reported as beneficial for anastomotic healing. Twelve of the agents (25%) were tested more than once in the same model, whereas 13 (27%) of the agents were tested in two or more models of complicated healing. Two therapeutic agents met our inclusion criteria for the meta-analysis. Postoperative hyperbaric oxygen therapy significantly increased anastomotic bursting pressure in ischemic colon anastomoses by a mean of 28 mmHg (95%CI: 17 to 39 mmHg, P < 0.00001). Granulocyte macrophage-colony stimulating factor failed to show a significant increase in anastomotic bursting pressure (95%CI: -20 to 21 mmHg, P = 0.97) vs controls in experimental chemotherapeutic models.

CONCLUSION: This systematic review identified potential therapeutic agents, but more studies are needed before concluding that any of these are useful for AL prophylaxis.

Abdominal wall hernias-A local manifestation of systemically impaired quality of the extracellular matrix

BACKGROUND

Throughout life, inguinal hernia develops in approximately every fourth man, some of whom develop multiple hernias. If patients at risk of developing multiple hernias could be identified by a serologic biomarker, treatment might be able to be tailored and improved. Evidence suggests that abdominal wall hernia formation is associated with altered collagen metabolism. The aim of this study was to evaluate biomarkers for type IV and V collagen turnover in patients with multiple hernias and control subjects without hernia.

METHODS

Venous blood was collected from 88 men (mean age, 62 years) with a history of more than 3 hernia repairs and 86, age-matched men without hernias. Biomarkers for synthesis of collagen type IV (P4NP) and type V (P5CP) as well as breakdown (C4M and C5M) were measured in serum by validated, solid-phase, competitive assays. Collagen turnover was indicated by the ratio between the biomarker for synthesis and breakdown.

RESULTS

Type IV collagen turnover was 1.4-fold increased in patients with multiple hernias compared to control subjects (P < .001), whereas type V collagen turnover was 1.7-fold decreased (P < .001). Diagnostic power of P5CP was 0.83 (95%C.I.:0.77-0.89), P < .001.

CONCLUSION

Patients with multiple hernias exhibit increased turnover of type IV collagen and a decreased turnover of type V collagen, demonstrating systemically altered collagen turnover. Biomarkers for type V collagen turnover may be used to identify patients at risk for or with multiple hernias.

GM6001 Increases Anastomotic Leakage following Colonic Obstruction Possibly by Impeding Epithelialization

BACKGROUND

Emergency operations performed on an obstructed colon are accompanied by an increased risk of anastomotic insufficiency. Tissue-destructive matrix metalloproteinase (MMP) activity is elevated in the obstructed colon and contributes to a loss of suture-holding submucosal collagen, which may be mediated by tumor necrosis factor (TNF)-α. Our aim was to study the effect of the non-selective MMP and TNF-α converting enzyme (TACE) inhibitor GM6001 (30 mg/kg) on anastomosis repair in obstructed left colon. GM6001 has been proved to be highly efficacious in elective anastomosis rodent models.

METHODS

A partial obstruction of the distal colon was induced in male Sprague-Dawley rats. After 4 d the obstructed colonic segment was resected, and an end-to-end anastomosis was constructed. Seven days later, the anastomoses were evaluated for clinical leakage. Histopathological and immunohistochemical assessments were also performed. Finally, the direct effect of GM6001 on epithelialization was studied in cultured colonic epithelial cells.

RESULTS

Unlike the robust beneficial effect on anastomosis under uncomplicated conditions, here GM6001 had a negative impact on anastomotic wound healing following colonic obstruction and substantially (p=0.004) more rats in the GM6001 group (75%) than in the control group (11%) had developed anastomotic leakage. In the anastomotic wounds, the myofibroblast abundance and cell proliferation were similar in the two groups. Histologically, GM6001 treatment resulted in wider and minimally epithelialized wounds that were commonly necrotic on the luminal side and infiltrated with numerous granulocytes. In vitro, GM6001 also delayed (p=0.026) epithelialization of denuded intestinal epithelium grown on type I collagen.

CONCLUSIONS

Non-selective MMP/TACE inhibition with GM6001 increased the anastomotic complications following colon obstruction. Inhibition of epithelialization is one possible mechanism responsible for the increased leakage following GM6001 treatment.

Expression and inhibition of matrix metalloproteinase (MMP)-8, MMP-9 and MMP-12 in early colonic anastomotic repair

PURPOSE

Submucosal collagen is paramount for colonic anastomotic integrity. Matrix metalloproteinases (MMPs) mediate collagen degradation that increases the risk of wound dehiscence. Although broad-spectrum MMP inhibitors are beneficial for anastomotic strength, they can cause adverse reactions. Knowledge of specific MMPs responsible for the weakening of anastomoses can be used to optimise MMP inhibition therapy. We aimed to quantify transcript and protein levels of multiple MMPs in colonic anastomoses and evaluate the effect of inhibiting the MMPs that displayed the highest expression levels on anastomotic repair.

METHODS

Left-sided colonic anastomoses were made in male Sprague-Dawley rats. After 3 days when biomechanical strength is lowest, MMP mRNA and protein levels were measured by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assays and gelatin zymography. The effects of the MMP-8, MMP-9 and MMP-12 synthetic inhibitor AZD3342 was also studied.

RESULTS

MMP-8, MMP-9 and MMP-12 gene and protein expression increased profoundly (p < 0.01), and MMP-13 mRNA and MMP-2 mRNA and protein modestly (p < 0.001) in the anastomoses. MMP-3 mRNA levels were not up-regulated significantly compared with adjacent uninjured colon. Increased anastomotic MMP-12 levels paralleled macrophage infiltration by immunohistochemical analyses. AZD3342 (50 mg/kg) treatment increased the anastomotic breaking strength by 29% (p = 0.015) day 3 compared with vehicle. Improved anastomotic strength was not accompanied with alterations of type I or type III procollagen mRNA but was possibly due to inhibition of the concerted digestive action on the existent submucosal collagens by the targeted MMPs.

CONCLUSION

The present findings justify the concept of selective MMP inhibition to enhance anastomotic strength in colon.

Zinc, copper, and selenium tissue levels and their relation to subcutaneous abscess, minor surgery, and wound healing in humans

Trace element involvement in wounds left to heal by secondary intention needs clarification. We have previously reported faster healing of wounds following acute surgery compared with elective excision of pilonidal sinus disease. The effect of topical zinc on the closure of the excisional wounds was mediocre compared with placebo. In contrast, parenteral zinc, copper, and selenium combined appear effective for wound healing in humans. We have investigated zinc, copper, and selenium with respect to (a) impact of acute versus chronic pilonidal sinus and (b) regional concentrations within granulating wounds treated topically with placebo or zinc in 42 (33 males) pilonidal disease patients. Baseline serum and skin concentrations of copper correlated (r S = 0.351, p = 0.033, n = 37), but not of zinc or selenium. Patients with abscesses had elevated serum C-reactive protein (CRP) and copper levels (+29 %; p < 0.001) compared with the elective patients consistent with the strong correlation between serum copper and CRP (r S = 0.715, p < 0.0005, n = 41). Seven days after elective surgery, serum CRP and copper levels were elevated (p = 0.010) versus preoperative values. The copper concentration in wound edges was higher than in periwound skin (p < 0.0005) and wound base (p = 0.010). Selenium levels were increased in wound edge compared to wound base (p = 0.003). Topical zinc oxide treatment doubled (p < 0.050) zinc concentrations in the three tissue localizations without concomitant significant changes of copper or selenium levels. In conclusion, copper and selenium are mobilized to injured sites possibly to enhance host defense and early wound healing mechanisms that are complementary to the necessity of zinc for matrix metalloproteinase activity.

Rapid morphological changes and loss of collagen following experimental acute colonic obstruction

PURPOSE

Anastomosis of an acutely obstructed colon is associated with an increased risk of dehiscence. In experimental models, acute obstruction decreases collagen in the colonic wall, but the time course and propagation along the colon of the biochemical changes are unknown. Furthermore, there is a paucity of information on the correlation between these biochemical changes and histological features.

METHODS

Forty male Sprague Dawley rats were subjected to partial obstruction by placing a silicone ring around the left colon 30 mm above the reflection. Obstruction was maintained for 0, 1, 2, 3 or 4 days. Samples from five different locations along the colon were analysed on circumference, tissue water content, collagen concentration and histomorphology. Neutrophil and macrophage infiltration was characterized immunohistochemically.

RESULTS

The colonic circumference and water content increased (p < 0.001), while the collagen concentration decreased by 48 % (p < 0.01) proximal to the obstruction already after 1 day. The degree of dilation and collagen reduction did not change significantly over the subsequent 3 days of obstruction, whereas the water content normalized by day 3. Mucosal and submucosal oedema and the relative neutrophil infiltration were highest after 1 day in the colonic segment proximal to the stenosis while the macrophage population continued to increase to day 4. Muscular necrosis in addition to ganglionitis and neuritis in the nervous plexus increased with duration of obstruction.

CONCLUSIONS

The pronounced and rapid changes of the composition of cells and the extracellular matrix of the colonic wall following acute obstruction may be of guidance for present surgical treatments and future pharmacological interventions.

Collagen levels are normalized after decompression of experimentally obstructed colon

AIM

Our aim was to define the dynamics in collagen concentrations in the large bowel wall following decompression of experimental obstruction.

METHOD

Colonic obstruction was created in 28 male rats by the placement of a silicone ring around the distal colon. The ring was removed after 4 days to mimic endoscopical decompression by stent deployment. Colon circumference and collagen concentration were measured proximal to the obstructed segment immediately and at 3 and 10 days after decompression. The corresponding colonic sites of 23 sham-operated and eight nonoperated control animals were subjected to identical analyses.

RESULTS

Four days of obstruction resulted in a more than twofold increase in colonic circumference (20 vs 8 mm), with a concomitant 43% reduction (P = 0.001) in collagen concentration in the bowel wall proximal to the obstruction compared with sham animals. Three days after decompression, collagen concentrations remained reduced (P < 0.05), while there was no significant difference after 10 days with either sham-operated or nonoperated controls. Colonic circumference of the obstructed colon remained slightly distended (11 mm) on day 10 and tended to correlate (r(S) = 0.51, P = 0.053) with total matrix metalloproteinase activity.

CONCLUSION

The marked reduction in collagen concentration in an experimentally obstructed colon is normalized 10 days after decompression. These findings may have clinical implications for the timing of surgical resection.

Nonselective matrix metalloproteinase but not tumor necrosis factor-α inhibition effectively preserves the early critical colon anastomotic integrity

BACKGROUND

Increased matrix metalloproteinase (MMP) activity has been implicated in the pathogenesis of colorectal anastomotic leakage. Tumor necrosis factor-α (TNF-α) induces MMPs and may influence anastomosis repair.

METHODS

We assessed the efficacies of the nonselective hydroxamate MMP inhibitor GM6001, the selective hydroxamate MMP inhibitor AG3340 and a TNF-α antagonist with respect to anastomotic breaking strength of left-sided colon anastomoses in male Sprague-Dawley rats.

RESULTS

Systemic GM6001 treatment effectively blocked MMP activity and maintained the initial breaking strength day 0 of the anastomoses when administered subcutaneously as daily depositions (100 mg/kg) or continuously (10 mg/kg/day). In contrast, the anastomotic biomechanic strength was lowered by 55% (p < 0.001) in vehicle-treated rats on postoperative day 3. GM6001 treatment increased breaking strength by 88% (p < 0.0005) compared with vehicle-treated rats day 3 and reduced (p = 0.003) the occurrence of spontaneous anastomotic dehiscence. Histologically, the anastomotic wound was narrower (p < 0.05) in the longitudinal direction in GM6001-treated animals whereas GM6001 had no significant effect on inflammatory cell infiltration or epithelialization. AG3340 (10 mg/kg) increased (p < 0.012) breaking strength by 47% compared with vehicle on day 3 but did not significantly prevent the reduction of the initial breaking strength on day 0. Although the increased TNF-α levels in the wound were attenuated, the anastomotic breaking strength was not improved (p = 0.62) by the TNF-α (10 mg/kg) inhibitor given systemically.

CONCLUSIONS

Pharmacological nonselective MMP inhibition ought to be explored as a prophylactic regimen to reduce anastomotic complications following colorectal resection. The involvement of TNF-α was insignificant in anastomotic wound healing in an experimental model.

Effect of diclofenac on cyclooxygenase-2 levels and early breaking strength of experimental colonic anastomoses and skin incisions

BACKGROUND

Recently, there has been a focus on the effect of the nonsteroidal anti-inflammatory drugs on the anastomotic leakage rate after colorectal surgery.

METHODS

An experimental, randomized, placebo-controlled prospective study on 32 male Wistar rats was carried out. We examined the effect of diclofenac 4 mg/kg/day on the cyclooxygenase-2 (COX-2) enzyme in the anastomotic tissue and on the breaking strength of anastomotic and incisional wounds. The operation was performed with colonic resection and hand-sewn anastomosis. After 3 days, the rats were sacrificed and the breaking strength and the COX-2 content of the anastomosis were measured.

RESULTS

There was a significantly reduced level of COX-2 in the rats treated with diclofenac (p = 0.001); no significant differences in any of the breaking strength measurements and no significant correlation between COX-2 levels and breaking strength of the anastomotic or incisional wounds could be found (p = 0.073 and p = 0.727).

CONCLUSION

This study for the first time showed that a diclofenac dose of 4 mg/kg/24 h was sufficient to reduce the level of COX-2 enzymes in the anastomotic tissue in rats. This inhibition of the inflammatory response did not lead to reduced breaking strength of either anastomotic or incisional wounds. Whether there is a detrimental effect of COX inhibition on colorectal anastomoses in the clinical setting remains controversial.