Topical Neuropeptide Y for Ischemic Skin Wounds.

Our objective was to investigate the effects of topically applied neuropeptide Y (NPY) on ischemic wounds. Initially, the animal model for ischemic wound healing was validated using 16 male Sprague Dawley albino rats. In the intervention study, an additional 28 rats were divided into three groups: NPY (0.025%), the positive control insulin-like growth factor-I (IGF-I, 0.0025%), and the hydrogel carrier alone (control). The hydrogel was selected due to its capacity to prolong NPY release (p < 0.001), as demonstrated in a Franz diffusion cell. In the animals, an 8 mm full-thickness wound was made in a pedunculated dorsal ischemic skin flap. Wounds were then treated and assessed for 14 days and collected at the end of the experiment for in situ hybridization analysis (RNAscope®) targeting NPY receptor Y2R and for meticulous histologic examination. Wound healing rates, specifically the percentage changes in wound area, did not show an increase with NPY (p = 0.907), but there was an increase with rhIGF-I (p = 0.039) compared to the control. Y2R mRNA was not detected in the wounds or adjacent skin but was identified in the rat brain (used as a positive control). Light microscopic examination revealed trends of increased angiogenesis and enhanced inflammatory cell infiltration with NPY compared to control. An interesting secondary discovery was the presence of melanophages in the wounds. Our findings suggest the potential of NPY to enhance neovascularization under ischemic wound healing conditions, but further optimization of the carrier and dosage is necessary. The mechanism remains elusive but likely involves NPY receptor subtypes other than Y2R.

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-1ß, IL-6, IL-8, PDGF-AA, TNF-α and VEGF levels were measured by multiplex and electrochemiluminescence assays. IL-1α (2.4×), IL-1ß (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-1ß (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.

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.

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 preoperative 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.

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-1ß, 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.

Cytokines and Venous Leg Ulcer Healing-A Systematic Review.

Venous leg ulcers (VLUs) are the most common type of leg ulcers with a significant socioeconomic burden due to slow healing. Cytokines may be involved in the pathogenesis of VLUs. In this systematic review, our objective was to investigate the association between cytokine levels, including growth factors, with the healing of VLUs. PubMed, Embase, Web of Science and Cochrane Library were searched from their inception to August 2021. We retrieved 28 articles investigating 38 different cytokines in 790 patients. Cytokines were most commonly investigated in wound fluid and less frequently in biopsies and serum. The studies were judged as having a moderate to high risk of bias, and the results were often inconsistent and sometimes conflicting. A meta-analysis was not performed due to clinical and methodological heterogeneities. We found weak evidence for elevated IL-1α, IL-6, IL-8, TNF-α and VEGF levels in non-healing VLUs, an elevation that declined with healing. TGF-ß1 levels tended to increase with VLU healing. Other cytokines warranting further investigations include EGF, FGF-2, GM-CSF, IL-1ß, IL-1Ra and PDGF-AA/PDGF-BB. We conclude that non-healing VLUs may be associated with an elevation of a palette of pro-inflammatory cytokines, possibly reflecting activated innate immunity in these wounds. There is a paucity of reliable longitudinal studies monitoring the dynamic changes in cytokine levels during wound healing.

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-ß1 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)-ß1 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-ß1. 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-ß1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-ß1 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-ß1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.

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.

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.

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.

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)-ß1 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-ß1 levels (rS = 0.540, P = 0.006). Although TGF-ß1 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.

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.

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.

Noninvasive measurement of reepithelialization and microvascularity of suction-blister wounds with benchmarking to histology.

We explored use of the suction-blister wound model in the assessment of not only epidermal regeneration but also pain, the microvascular response and bacteriology. The effects of topical zinc sulfate were studied to articulate the methodologies in this double-blind trial. One epidermal suction blister (10 mm) was induced on each buttock in 30 healthy volunteers (15 females:15 males) and deroofed on day 0. The wounds were randomized to daily treatment with 1.4% zinc sulfate shower gel (n = 20), placebo (n = 20) or control (n = 20). Digital photography coupled with planimetry, transepidermal water loss (TEWL) measurement and optical coherence tomography (OCT) was benchmarked to the gold standard of histology of 60 full-thickness wound biopsies on day 4. Pain increased after application of the shower gels. Microvessel density, determined from OCT images, increased from day 0 to day 2 in the three groups but increased more with the placebo than with the zinc shower gel (p = 0.003) or the control treatment (p = 0.002) and correlated (rS = 0.313, p = 0.015) with the inflammatory response on day 4, as determined by histology. Coagulase-negative staphylococci were more common in wounds compared with skin (p = 0.002) and was reduced (p = 0.030) with zinc sulfate treatment. Planimetric analysis of digital wound images was not biased (p = 0.234) compared with histology, and TEWL measurements showed no correlation (rS = 0.052, p = 0.691) with epithelialization. Neoepidermal formation, determined by histology, did not differ (p = 0.290) among the groups. Zinc sulfate reduced (p = 0.031) the release of lactate dehydrogenase from cultured gel-treated keratinocytes isolated from the blister roofs. Therefore, combination of the standardized suction-blister wound model with noninvasive planimetry and OCT is a useful tool for assessing wound therapies. Zinc sulfate transiently dampened inflammation and reduced bacterial growth.

Selective matrix metalloproteinase inhibition increases breaking strength and reduces anastomotic leakage in experimentally obstructed colon.

PURPOSE: Colonic obstruction causes loss of collagen and impairment of anastomotic integrity by matrix metalloproteinases (MMPs). Unexpectedly, pharmacological MMP inhibition increased anastomotic leakage (AL) in obstructed colon possibly due to the non-selective nature of these compounds and the experimental model applied. We therefore studied the effects of selective MMP inhibition on the healing of anastomoses in colon obstructed by a novel laparoscopic technique. METHODS: Left colon was obstructed in 38 male Sprague-Dawley rats (226-284 g). After 12 h, stenoses were resected and end-to-end anastomoses constructed. Baseline breaking strength was determined in 6 animals on day 0. The remaining 32 rats were randomized to daily treatment with the selective MMP-8, MMP-9, and MMP-12 inhibitor AZD3342 (n = 16) or vehicle (n = 16). On day 3, anastomoses were evaluated for AL and breaking strength. Isolated anastomotic wound tissue was analyzed on total collagen and pepsin-insoluble and pepsin-soluble collagen by hydroxyproline. The soluble collagens were further differentiated into native, measured by Sircol, and fragmented forms. RESULTS: Baseline breaking strength was maintained with AZD3342 but decreased by 25% (P = 0.023) in the vehicle group. The anastomotic breaking strength of AZD3342-treated rats was 44% higher (P = 0.008) than the vehicle-treated rats. Furthermore, the AL rate was reduced (P = 0.037) with AZD3342 compared with vehicle treatment. AZD3342 treatment influenced neither the total or insoluble collagen concentrations nor the degree of fragmentation of the soluble collagen triple helices. CONCLUSION: Selective MMP inhibition increased anastomotic breaking strength and reduced AL after resection of colonic obstruction.