Increase in wound breaking strength in rats in the presence of positively charged dextran beads correlates with an increase in endogenous transforming growth factor-β1 and its receptor TGF-βRI in close proximity to the wound

We have previously shown that positively charged beads (DEAE A25) increase wound breaking strength in linear incisions in rats and nonhuman primates at days 10-14 post-wounding. The increased wound strength may result in part from a stimulation of cells adjacent to the DEAE A25 beads to produce growth factors important for wound healing. In this report, we investigate this hypothesis by comparing the relative expression levels of transforming growth factor-beta1 and its receptor transforming growth factor-beta receptor type I in DEAE A25-treated and contralateral untreated rat linear incisions. DEAE A25-treated incisions were stronger than untreated control wounds at 3 days post-wounding, and the difference in breaking strength reached statistical significance at days 5, 7 and 10. Immunohistochemical analysis revealed a significant increase in transforming growth factor-beta1 and transforming growth factor-beta receptor type I expression in DEAE A25-treated incisions, up to 7 days post-wounding, as compared to untreated control wounds. FACS analysis revealed that macrophage cell lines exposed to DEAE A25 in vitro upregulate transforming growth factor-beta1 and transforming growth factor-beta receptor type I expression by 2-3 fold. Therefore, the increase in expression of transforming growth factor-beta1 and transforming growth factor-beta receptor type I in DEAE A25-treated incisions may be due to an increase in the concentration of macrophages adjacent to DEAE A25 beads, as well as the stimulation of individual macrophages to produce greater amounts of transforming growth factor-beta1 and transforming growth factor-beta receptor type I. This study also supports the significance of transforming growth factor-beta1 in wound healing.     

Raxofelast, a hydrophilic vitamin E-like antioxidant, stimulates wound healing in genetically diabetic mice

BACKGROUND. Impaired wound healing is a well-documented phenomenon in experimental and clinical diabetes. Emerging evidence favors the involvement of free radicals in the pathogenesis of diabetes-related healing deficit. This study assessed the effect of systemic administration of raxofelast, a protective membrane antioxidant agent, on wound healing by using healing-impaired (db/db) mice. METHODS. The wound healing effect of raxofelast was investigated by using an incisional skin-wound model produced on the back of female diabetic C57BL/KsJ db+/db+ mice and their healthy littermates (db+/+m). Animals were then randomized to the following treatment: raxofelast (15 mg/kg/d intraperitoneally) or its vehicle (dimethyl sulfoxide/sodium chloride 0.9%, 1:1, vol/vol). The animals were killed on different days, and the wounded skin tissues were used for histologic evaluation and for analysis of malondialdehyde (MDA) level and myeloperoxidase (MPO) activity, wound breaking strength, and collagen content. RESULTS. Diabetic mice showed delayed wound healing together with low collagen content, breaking strength, and increased MDA levels and MPO activity when compared with their healthy littermates. The administration of raxofelast did not modify the process of wound repair in healthy (db/+) mice, but significantly improved impaired wound healing in diabetic mice through the stimulation of angiogenesis, reepithelialization, synthesis, and maturation of extracellular matrix. Furthermore, raxofelast treatment significantly reduced MDA levels, MPO activity, and increased the breaking strength and collagen content of the wound. CONCLUSIONS. The current study provides evidence that raxofelast restores wound healing to nearly normal levels in experimental diabetes-impaired wounds and suggests that an increased lipid peroxidation in diabetic mice may have a role in determining a defect of wound repair.     

Preliminary Study of the Protective Effect of the Calcium Channel Blocker,Nifedipine, on Adriamycin-Induced Tissue Injury

The effect of nifedipine, an oral calcium-channel blocker, on adriamy cin-induced wound healing was studied. Nifedipine was administered to animals prior to treating with adriamycin. The healing strengths of cecal, fascial, and skin anatomoses were measured. Animals treated with adriamycin alone had significant decreases in healing strength compared to controls: for cecum at postoperative days (POD) 7 and 14; for skin at PODS 14, 21, and 28; for fascia at POD 28. Overall, nifedipine reduced the impact of adriamycin injury on the strength of healing incisional anastomoses. Nifedipine also appeared to protect collagen synthesis at anastomotic sites from adriamycin-induced impairment.     

Preliminary study of the protective effect of the calcium channel blocker, nifedipine, on adriamycin-induced tissue injury

The effect of nifedipine, an oral calcium-channel blocker, on adriamycin-induced wound healing was studied. Nifedipine was administered to animals prior to treating with adriamycin. The healing strengths of cecal, fascial, and skin anatomoses were measured. Animals treated with adriamycin alone had significant decreases in healing strength compared to controls: for cecum at postoperative days (POD) 7 and 14; for skin at PODs 14, 21, and 28; for fascia at POD 28. Overall, nifedipine reduced the impact of adriamycin injury on the strength of healing incisional anastomoses. Nifedipine also appeared to protect collagen synthesis at anastomotic sites from adriamycin-induced impairment.     

Effect of Allopurinol on Adriamycin-Induced Impairment of Wound Healing

Use of antineoplastic drugs perioperatively requires an understanding of their potential effects on healing wounds. Adriamycin is an antineoplastic drug with a wide range of antitumor activity. Prior studies have demonstrated that adriamycin impairs skin wound healing but these studies have offered limited explanations for the mechanism of action of the drug vis à vis impairment of healing wounds. In this study we investigated the effect of a xanthine oxidase inhibitor, allopurinol. on adriamycin-induced tissue injury to determine the role oxyradicals might play in reducing wound-breaking strength. Sixty-four Buffalo rats were studied. Eight animals were used to establish drug tolerances. Fifty-six animals were divided into four experimental groups: saline control (2 mL IP). allopurinol control (4.3 mg/kg PO), allopurinol-adriamycin (4.3 mg/kg PO + 6 mg/kg IV, respectively), and adriamycin (6 mg/kg IV). Animals treated with adriamycin alone had significantly reduced weight at postoperative day (POD) 7 compared to control groups (p <. 025). Bowel-bursting strength (BBS) of the animals treated with adriamycin alone was also significantly decreased at POD 7, compared to controls (p <. 025), and by POD 14 the animals treated with adriamycin alone had a significantly decreased fascial tensile strength, compared to the saline control (p <. 05). At no point did the animals treated with both allopurinol and adriamycin show a significantly decreased weight. BBS, or fascial tensile strength compared to control animals. Allopurinol appeared to protect against adriamycin toxicity on healing wounds. These results suggest that xanthine oxidase and possibly superoxide radicals play an important role in mediating adriamycin toxicity on healing wounds.     

Effect of allopurinol on adriamycin-induced impairment of wound healing

Use of antineoplastic drugs perioperatively requires an understanding of their potential effects on healing wounds. Adriamycin is an antineoplastic drug with a wide range of antitumor activity. Prior studies have demonstrated that adriamycin impairs skin wound healing but these studies have offered limited explanations for the mechanism of action of the drug vis á vis impairment of healing wounds. In this study we investigated the effect of a xanthine oxidase inhibitor, allopurinol, on adriamycin-induced tissue injury to determine the role oxyradicals might play in reducing wound-breaking strength. Sixty-four Buffalo rats were studied. Eight animals were used to establish drug tolerances. Fifty-six animals were divided into four experimental groups; saline control (2 mL IP), allopurinol control (4.3 mg/kg po), allopurinol-adriamycin (4.3 mg/kg po + 6 mg/kg IV, respectively), and adriamycin (6 mg/kg IV). Animals treated with adriamycin alone had significantly reduced weight at postoperative day (POD) 7 compared to control groups (p less than .025). Bowel-bursting strength (BBS) of the animals treated with adriamycin alone was also significantly decreased at POD 7, compared to controls (p less than .025), and by POD 14 the animals treated with adriamycin alone had a significantly decreased fascial tensile strength, compared to the saline control (p less than .05). At no point did the animals treated with both allopurinol and adriamycin show a significantly decreased weight, BBS, or fascial tensile strength compared to control animals. Allopurinol appeared to protect against adriamycin toxicity on healing wounds. These results suggest that xanthine oxidase and possibly superoxide radicals play an important role in mediating adriamycin toxicity on healing wounds.     

Characterization of incisional wound healing in inducible nitric oxide synthase knockout mice

BACKGROUND: Excisional wound healing in inducible nitric oxide synthase knockout (iNOS-KO) mice has been previously shown to be impaired compared with their background strain controls. Incisional wounds were created in this experiment in both types of animals and paradoxically were found to heal with the same rapidity and breaking strength in both groups. METHODS: Dorsal 2.5 cm incisional wounds were created in iNOS-KO mice, as well as their parental strain controls (C57BL/6J). Standardized polyvinyl alcohol sponges were implanted in the wounds to allow for measurement of collagen deposition. Animals were harvested on postoperative days (PODs) 3, 5, 7, 10, 14, and 28, and their wounds subjected to tensiometric breaking strength analysis. Nonisotopic in situ hybridization quantitative analysis for iNOS, endothelial NOS (eNOS), basic fibroblast growth factor (bFGF), transforming growth factor-beta1 (TGF-beta1), vascular endothelial growth factor (VEGF), and interleukin-4 (IL-4) expression in the wounds was performed. Hydroxyproline levels were quantitated in the harvested polyvinyl alcohol sponges. Data were analyzed with the Students t test. RESULTS: No significant differences were found in breaking strengths or levels of hydroxyproline (and thus collagen) in iNOS-KO versus wild-type wounds at all tested time points. Flawed iNOS expression levels in iNOS-KO animals were similar to (functional) iNOS expression in wild-types. eNOS and bFGF expression nearly doubled on POD 7 in iNOS-KO incisions (P =.002, and.002), respectively and remained 200% to 300% elevated thereafter. TGF-beta1 expression was increased approximately 50% to 100% in iNOS-KO wounds on PODs 5 and 7 (P =.006 and.01, respectively). VEGF and IL-4 expression was elevated by 25% to 100% in wild-type compared with iNOS-KO animals at all time points (P <.01). CONCLUSIONS: The overexpression of TGF-beta1 and eNOS may represent mechanisms in iNOS-KO mice to compensate for their loss of functional iNOS, resulting in incisional wound healing equivalent to controls. Their impaired expression of VEGF and IL-4, on the other hand, may partially explain the delayed excisional wound healing noted in these animals.     

A Multitargeted Receptor Tyrosine Kinase Inhibitor,SU6668, Does Not Affect the Healing of Cutaneous Full-Thickness Incisional Wounds in SKH-1 Mice

Disturbances of angiogenesis have been suggested to result in the impaired healing of skin wounds. Using a murine incisional wound model, we evaluated the effects of SU6668, an inhibitor of the receptors for vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF), on the healing of skin wounds. Mice were administered vehicle, SU6668 (100 or 400 mg/kg/day, b.i.d.), or dexamethasone (1 mg/kg/day, b.i.d.), and wound healing was monitored histologically and using a tensiometer. SU6668 at a fully efficacious dose of 100 mg/kg/day had no significant effect on the healing process, while at a supratherapeutic dose of 400 mg/kg/day, there were subtle transient histologic changes and slight decreases in tensile strength, suggesting a slight delay in the wound healing process. In conclusion, these data indicate that inhibition of the receptors for VEGF, PDGF, and FGF at levels necessary to inhibit tumor growth in mouse xenograft models does not affect the healing of incisional wounds in mice. Redundant pathways likely compensate for inhibition of VEGF, PDGF, and FGF signaling pathways in the skin healing process.     

A multitargeted receptor tyrosine kinase inhibitor, SU6668, does not affect the healing of cutaneous full-thickness incisional wounds in SKH-1 mice.

Disturbances of angiogenesis have been suggested to result in the impaired healing of skin wounds. Using a murine incisional wound model, we evaluated the effects of SU6668, an inhibitor of the receptors for vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF), on the healing of skin wounds. Mice were administered vehicle, SU6668 (100 or 400 mg/kg/day, b.i.d.), or dexamethasone (1 mg/kg/day, b.i.d.), and wound healing was monitored histologically and using a tensiometer. SU6668 at a fully efficacious dose of 100 mg/kg/day had no significant effect on the healing process, while at a supratherapeutic dose of 400 mg/kg/day, there were subtle transient histologic changes and slight decreases in tensile strength, suggesting a slight delay in the wound healing process. In conclusion, these data indicate that inhibition of the receptors for VEGF, PDGF, and FGF at levels necessary to inhibit tumor growth in mouse xenograft models does not affect the healing of incisional wounds in mice. Redundant pathways likely compensate for inhibition of VEGF, PDGF, and FGF signaling pathways in the skin healing process.     

L-arginine improves wound healing after trauma-hemorrhage by increasing collagen synthesis

BACKGROUND: Several studies indicate impaired wound healing after trauma and shock. Wound immune cell dysfunction seems to be responsible for altered wound healing after trauma-hemorrhage (T-H). In this respect, administration of the amino acid L-arginine normalized wound immune cell function under those conditions. It remains unknown, however, whether L-arginine improves impaired wound healing after T-H. METHODS: To study this, male C3H/HeN mice were subjected to a midline laparotomy (i.e., soft tissue trauma induced), and polyvinyl sponges were implanted subcutaneously at the wound site before hemorrhage (35 +/- 5 mm Hg for 90 minutes) or were subjected to sham operation. During resuscitation, mice received 300 mg/kg body weight L-arginine or saline (vehicle). Seven days thereafter, hydroxyproline (OHP), a metabolite of collagen synthesis, was measured in the wound fluid using high-performance liquid chromatography. Collagen types I and III were determined in the wound by Western blot analysis. In addition, wound breaking strength was measured 10 days after T-H or sham operation. RESULTS: The results indicate that OHP was significantly decreased in T-H mice. L-arginine, however, restored depressed OHP in the wound fluid in the T-H animals. Similarly, L-arginine treatment prevented a significant depression of collagen I synthesis after T-H. Collagen III was not significantly affected by T-H or L-arginine. Most important, L-arginine increased maximal wound breaking strength after severe blood loss. Therefore, L-arginine improves wound healing after T-H by increasing collagen synthesis. CONCLUSION: Because L-arginine improves wound healing, the results suggest that L-arginine might represent a novel and useful adjunct to fluid resuscitation for decreasing wound complications after trauma and severe blood loss.     

Angiogenesis inhibitor TNP-470 inhibits murine cutaneous wound healing

BACKGROUND. TNP-470 (AGM-1470) is a potent inhibitor of angiogenesis with potential therapeutic applications in neoplastic and angio-proliferative diseases. This study evaluated its effect on cutaneous wound healing in a murine dorsal excisional wound model. MATERIALS AND METHODS. Full-thickness wounds (1.60 cm2) were created on the dorsum of homozygous/hairless mice (7 to 9 weeks). Wound areas were measured on alternate days for 16 days. Experimental groups consisted of (1) TNP-470 administered in doses of 0.05, 0.5, and 5.0 mg/kg on Days 0, 2, and 4 or Days 0 through 6; (2) TNP-470 (5.0 mg/kg) coadministered with minocycline (4.0 and 10 mg/kg) on Days 0, 2, and 4; and (3) TNP-470 (5.0 mg/kg on Days 0, 2, and 4) coadministered with topical basic fibroblast growth factor (bFGF) 1. 0 microg/wound on Days 0, 1, and 2. Hematoxylin and eosin staining was used to compare experimental and control wounds. RESULTS. TNP-470 administration significantly decreased wound healing in a dose-dependent manner versus controls (P <.05). The 5.0 mg/kg concentration yielded the greatest effect by maintaining an average wound area 20.4% greater than controls and a marked delay in wound healing on H&E staining. Alternate-day dosing was as effective as consecutive day administration. Minocycline did not augment the wound healing inhibition of TNP-470. Coadministration of TNP-470 and bFGF eliminated any rate-altering effect of TNP-470 upon wound healing and resulted in wound areas similar to controls. CONCLUSION. Therapy with TNP-470 induces a significant delay in murine cutaneous wound healing. This effect may be exploited for use in situations where wound healing is excessive and debilitating. Topical application of bFGF can overcome TNP-470-induced wound healing inhibition.     

In vivo characterization of interleukin-4 as a potential wound healing agent

Interleukin-4 increases the synthesis of extracellular matrix proteins, including types I and III collagen and fibronectin, by both human and rat fibroblasts. Because fibroblasts are the final common effector cells of most phases of tissue repair, this study set out to investigate the effects of interleukin-4 on the healing of three different types of wounds. Acute excisional and chronic granulating wounds inoculated with Escherichia coli and incisional wounds in streptozotocin-induced diabetic Sprague-Dawley rats were used. Recombinant murine or human interleukin-4 was applied topically to the open wounds at doses of 0.1, 1.0, or 10.0 microg/cm(2)/wound for 5 or 10 days. Incisional wounds received the same doses once-at the time of wounding. The time taken to achieve wound closure or wound breaking strength measurements of wounds was recorded and compared with relevant untreated control groups. Wound contraction was impaired in the presence of bacteria, and this was reversed by all doses of recombinant murine interleukin-4. Recombinant murine interleukin-4 had no effect on the wound closure of noncontaminated wounds; it reduced wound breaking strength in acute excisional wounds, except in a contaminated setting when wounds were treated with 1.0 pg/cm(2)/wound. Recombinant interleukin-4 (1.0 microg) improved breaking strength of both diabetic and normal incisional wounds. The apparent pleiotropic effect of interleukin-4 on wound breaking strength under different wound conditions may be related not only to the activity of the fibroblast but also the ratio of cross-linked collagen/total collagen content of wounds. This study suggests that interleukin-4 may be a useful agent for accelerating closure of wounds, particularly where healing is impaired.     

单核细胞集落刺激因子缺失对小鼠创面愈合与新生血管化的影响

目的观察单核细胞集落刺激因子(GMCSF)缺失对创面愈合率和创面愈合过程中新生血管化程度的影响,并分析其机理。方法取GMCSF基因缺失小鼠(GMCSF-/-)和野生小鼠(WT)各30只,麻醉后背部致创(0.8cm×0.8cm),伤后在不同时相点摄像并取创面标本。通过计算机图像处理系统计算创面愈合率,用免疫组织化学方法通过测定创面CD31的阳性表达来计算新生血管数目。结果GMCSF基因缺失的小鼠创面愈合率从伤后3d起就明显低于野生小鼠。伤后第7天起,GMCSF-KO组小鼠CD31的阳性率明显低于WT组。结论GMCSF基因缺失影响创面的新生血管化能力,进而影响创面的愈合。     

Significance of T-lymphocytes in wound healing

To determine the importance of T-lymphocytes in wound healing, we examined the effect of T-lymphocyte depletion on the healing of surgical wounds. Thirty Balb/c mice were injected intraperitoneally with 1 mg of rat anti-mouse (IgG2b) cytotoxic monoclonal antibody (30H12) against the Thy1.2 (all T) determinant. Twenty-four hours later animals showed a greater than 95% depletion of Thy1.2 cells in peripheral blood and spleen. Thirty control mice received nonspecific rat immunoglobulin (1 mg). Twenty-four hours after treatment mice underwent a 2.5 cm dorsal skin incision with subcutaneous placement of polyvinyl alcohol sponges. Injections were repeated at weekly intervals. Wound healing was assessed at 2, 3, and 4 weeks by the breaking strength of wound strips and by the hydroxyproline content of sponge granulomas (an index of wound reparative collagen deposition). Thy1.2 depletion at death was 95% to 57% in peripheral blood and 86% to 68% in the spleen. Both groups gained weight equally. We found that T cell depletion significantly impairs wound breaking strength and wound collagen deposition at all times studied. The data strongly suggest that T-lymphocytes modulate fibroblast activity during normal wound healing.     

皮肤伤口愈合生物力学测定的实验研究

用 1NSTRON4300材料实验机对小鼠不同愈合时间皮肤伤口断裂力进行测定的结果表明:3、4天无明显差别,5～21天呈急剧上升,21～28天上升缓慢,28天以后趋于平稳。7天时伤口强度为正常皮肤的14％,28天时为80％。由此,将伤口愈合过程分为粘着期(1～4天),纤维愈合期(5～28天)和纤维改建期(28天以后)。可供临床判定最佳拆线时间及伤后功能锻炼开始时间参考。     

A comparison between cyclosporin A and methylprednisolone plus azathioprine on bronchial healing following canine lung autotransplantation

The effects of two low-dose immunosuppressive therapies upon the healing of the bronchial anastomosis and skin wounds following lung autotransplantation were evaluated. Autotransplantation was performed in three groups of dogs: Group 1 (nine dogs) received no immunosuppression, Group 2 (seven dogs) received postoperative immunosuppression with methylprednisolone (2 mg/kg) and azathioprine (1.5 mg/kg), and Group 3 (four dogs) received postoperative immunosuppression with cyclosporin A (20 mg/kg/day). Skin incisions 7 cm in length were made in the dorsal region of each dog. Dogs were put to death 23 days postoperatively, and the breaking strength of the bronchial anastomoses and skin wounds was evaluated with the Instron Universal Testing Machine, with a cross-head speed of 0.5 cm/min. Bronchial breaking strengths were similar in Groups 1 and 3 and significantly higher than in Group 2 (p less than 0.001). Skin breaking strengths were similar in Groups 1 and 3 and significantly higher than in Group 2 (p less than 0.001). Scanning electron microscopic (SEM) studies of both skin and bronchial wounds showed normal formation of collagen bundles in Groups 1 and 3 but a disorganized pattern in Group 2. Our results suggest that low-dose immunosuppression with methylprednisolone and azathioprine significantly affects wound healing and breaking strength of both bronchial anastomoses and healed skin incisions following canine lung autotransplantation. Immunosuppression with cyclosporin A had no adverse effect on either bronchial or skin healing.     

皮肤伤口愈合生物力学测定的实验研究

用ＩＮＳＴＲＯＮ４３００材料实验机对小鼠不同愈合时间皮肤伤口断裂力进行测定的结果表明：３、４天无明显差别，５～２１天呈急剧上升，２１～２８天上升缓慢，２８天以后趋于平稳。７天时伤口强度为正常皮肤的１４％，２８天时为８０％。由此，将伤口愈合过程分为粘着期（１～４天），纤维愈合期（５～２８天）和纤维改建期（２８天以后）。可供临床判定最佳拆线时间及伤后功能锻炼开始时间参考。     

Inhibition of matrix metalloproteinases enhances breaking strength of colonic anastomoses in an experimental model

BACKGROUND: The breaking strength of colonic anastomoses declines after operation to a minimum at days 3-4, with a subsequent risk of anastomotic dehiscence. The mechanism is thought to be collagen degradation by matrix metalloproteinases (MMPs). This study examined the pathogenic role of MMPs on the mechanical strength of colonic anastomoses by giving the synthetic broad-spectrum MMP inhibitor BB-1101 systemically. METHODS: Forty-eight male Sprague-Dawley rats were treated daily for 7 days with BB-1101 30 mg/kg or vehicle alone (control) starting 2 days before operation. The breaking strength of standardized left-sided colonic anastomoses was measured on postoperative days 1, 3 and 7. RESULTS: Serum BB-1101 levels were increased at 100 nmol/l in BB-1101-treated rats. The anastomotic breaking strength was 48 per cent higher (P = 0.02) in BB-1101-treated animals compared with controls on postoperative day 3. Neither collagen accumulation nor infiltration of neutrophils in the anastomotic area was influenced by BB-1101 treatment. Net deposition of new collagen in subcutaneous sponges was unaffected by the BB-1101. CONCLUSION: The enhanced breaking strength of colonic anastomoses during the critical early postoperative phase found after administration of a broad-spectrum MMP inhibitor implies that MMPs might increase the risk of anastomotic dehiscence. Presented in part to the third joint meeting of the European Tissue Repair Society and the Wound Healing Society in Bordeaux, France, 24-28 August 1999, and published in abstract form in Wound Repair Regen 1999; 7: A321     

Changes in abdominal wounds following treatment with sirolimus and steroids in a rat model

Wound healing complications have been observed in patients receiving sirolimus (SLR). This study examined the degree and duration of delayed healing in various protocols using SLR. Sprague-Dawley rats underwent a standard midline abdominal incision and wound closure. Groups of 6 rats each were randomized to receive different doses of SLR (2 and 5 mg/kg) with or without loading dose (10 mg/kg x3 days), and with or without steroids (20 mg/kg x3 days followed by 5 mg/kg for 2 weeks). Rats were humanely killed on postoperative days 5, 10, or 15. Wound breaking force was measured using the EHMI BIAX-II instrument and tensile strength was calculated. Wounds in control animals had gradual increase in tensile strength during the 15-day observation. In contrast, high and loading doses of SLR caused reduction in wound strength until day 10, but the wounds' tensile strength became equivalent to control by day 15. The addition of steroids prolonged wound recovery with low doses of SLR until day 15 and had very profound effects on healing in high-dose SLR-treated animals (>50% reduction) that continued beyond the 2 weeks of observation. Low doses of SLR in non-steroid-treated animals had a short-term (5-day) impact on wound healing; high dose and loading doses delayed healing for 10 to 15 days. The addition of steroids had a synergistic effect on delayed wound healing, particularly in animals receiving high-dose SLR, which demonstrated prolonged wound weakness. These results may provide practical guidelines for postoperative introduction of SLR in the context of various clinical protocols.