Wound healing modulators in a tracheoplasty canine model

Treatment with Hyaluronic Acid and Collagen-Polyvinylpyrrolidone Improves Extracellular Matrix Assembly for Scarring after Tracheal Resection

Treatment of tracheal stenosis is occasionally performed in combination with wound healing modulators to manipulate new extracellular matrix (ECM) formation and prevent fibrosis. Hyaluronic acid (HA) and collagen-polyvinylpyrrolidone (collagen-PVP) decrease fibrosis in experimental tracheal healing. However, they have not been used clinically as their effect on ECM components, which modify tracheal scarring, has not been described. Objective. To evaluate the effect of the application of HA, collagen-PVP, a mixture of HA and collagen-PVP (HA+collagen-PVP), and mitomycin C on the expression of decorin, matrix metalloproteinase 1 (MMP1), and MMP9, as well as the type of collagen and deposits formed in the scar after resection and end-to-end anastomosis (REEA) of the cervical trachea using an experimental model. Materials and Methods. Thirty dogs underwent REEA of the cervical trachea and were treated with different wound healing modulators: group I (n = 6), control; group II (n = 6), HA; group III (n = 6), collagen-PVP; group IV (n = 6), HA+collagen-PVP; and group V (n = 6), mitomycin C. The dogs were evaluated clinically and endoscopically for 4 weeks. Subsequently, macroscopic and microscopic changes, expression of ECM proteins, and collagen deposition in tracheal scars were analysed. Results. Groups II, III, and IV showed reduced endoscopic, macroscopic, and microscopic inflammation, improved neovascularization, high decorin expression (p < 0.01, analysis of variance (ANOVA)), and moderate expression of MMP1 (p < 0.003, ANOVA) and type I and III collagen (p < 0.05, Kruskal–Wallis). Groups IV and V developed fewer collagen deposits (p < 0.001, ANOVA). Conclusion. Treatment with HA and collagen-PVP improved post-REEA healing by increasing neovascularization, stimulating the expression of decorin, and regulating the expression of MMP1, as well as type I and III collagen and their deposition.

[Etiopathogenetic factors of wound healing in chronic post-intubation cicatricial stenosis of the larynx and trachea]

Despite the existing modern high-tech methods of examination and a variety of surgical treatment methods, the problem of diagnosis, treatment and rehabilitation of patients with chronic post-intubation cicatricial stenosis of the larynx and trachea still requires further study. Improving the understanding and correction of cellular, molecular genetic and biochemical disorders in a chronic wound is a key condition for increasing the efficiency of diagnosis, individual prognosis of the clinical course and the conduct of adequate therapeutic and preventive measures for post-intubation cicatricial laryngotracheal stenoses. In this regard, it seemed appropriate to analyze the existing etiopathogenetic factors of pathological wound healing in chronic post-intubation cicatricial stenosis of the larynx and trachea. Our attempt to summarize the available literature data demonstrated that laryngotracheal scars are a fibro-proliferative disease caused by aberrant wound healing after a damaging effect on the tissues of the larynx and trachea. The article describes the most pathogenetically significant healing, repair, and scarring factors in post-intubation laryngotracheal stenoses, including transforming growth factor β1, vascular growth factor A, type I and III collagen, and matrix metalloproteinases. An assessment of the features of the diagnostic and prognostic significance of these markers will increase the effectiveness of the treatment of patients with chronic cicatricial stenosis of the larynx and trachea, and will also serve as a prerequisite for the development of strategies for diagnostic, treatment, prophylactic and rehabilitation measures that will improve the quality of medical care and the quality of life of patients with chronic cicatricial stenosis of the larynx and trachea.

Effects of Pirfenidone and Collagen-Polyvinylpyrrolidone on Macroscopic and Microscopic Changes, TGF-β1 Expression, and Collagen Deposition in an Experimental Model of Tracheal Wound Healing

Tracheal stenosis (TS) is a fibrosis originated by prolonged inflammation and increased transforming growth factor beta 1 (TGF-β1) expression and collagen deposition (CD) in the tracheal wound. Several wound-healing modulators (WHMs) have been used to modulate the tracheal healing process and prevent TS, but they have failed, justifying the need to evaluate alternative WHM. The pirfenidone (PFD) and collagen-polyvinylpyrrolidone (Collagen-PVP) decrease inflammation and fibrosis. This study assessed the effect of PFD administration and Collagen-PVP topical application on macroscopic and microscopic changes, TGF-β1 expression, and CD in an experimental model of tracheal wound healing. Forty Wistar rats underwent cervical tracheoplasty, were divided into 4 groups (n = 10), and were treated with different WHM: group I, saline solution (SS); group II, Collagen-PVP; group III, mitomycin C (MMC); and group IV, 40 mg/kg PFD. Four weeks after surgery, the macroscopic and microscopic changes, in situ TGF-β1 expression, and CD in posttracheoplasty scars were evaluated. The animals treated with Collagen-PVP and PFD developed less inflammation and fibrosis than animals in the other study groups (p < 0.05, Kruskal-Wallis) and, moreover, showed lower TGF-β1 expression and CD than animals in group I (p < 0.05, ANOVA and Tukey's test). In conclusion, PFD and Collagen-PVP decrease inflammation, fibrosis, TGFβ-1 expression, and CD in the posttracheoplasty rats' scar.

Effects of middle ear packing with collagen polyvinylpyrrolidone and hyaluronic acid in guinea pigs

OBJECTIVE

The aim of this study was to evaluate otoscopic and microscopic changes produced on the healthy mucosa of the middle ear (ME) and tympanic membrane (TM) of guinea pigs after packing with a collagen polyvinylpyrrolidone (CPVP) sponge soaked in hyaluronic acid (HA).

MATERIAL AND METHODS

In 24 guinea pigs, myringotomy on the right side was created and the ME was packed as follows: Group I (n = 6): Absorbable gelatin sponge (AGS) soaked in saline solution; Group II (n = 6): AGS sponge soaked in HA, Group III (n = 6): CPVP sponge soaked in saline solution, Group IV (n = 6): CPVP sponge soaked in HA. Four weeks after miringotomy, the ME and TM integrity and residual packing material were evaluated otoscopically. Histologically, we evaluated inflammatory changes on the ME mucosa.

RESULTS

All animals in Groups I and II showed residual packing material (p < .001 ANOVA, TUKEY). Histologically, more inflammation was observed in Groups I, II, and III than in Group IV (p < .001 ANOVA, TUKEY). Group IV showed greater fibroblastic reaction (p < .02, ANOVA, TUKEY) versus other groups.

CONCLUSION

The CPVP sponge soaked in HA used as ME packing material is biocompatible and nontoxic, because it produces minimal inflammatory changes on the healthy mucosa of the ME and TM of guinea pigs. However, more research with injured mucosa is needed to validate its usefulness in otosurgery.

Tracheal resection and anastomosis in a red-tailed black cockatoo (Calyptorhynchus banksii banksii)

Tracheal stricture is an uncommon sequel to tracheitis in birds. We describe a case in a red-tailed black cockatoo that was attributed to a bacterial tracheitis associated with inhaled plant material and was successfully resolved by surgical resection and anastomosis of the trachea.

Polymerized type I collagen reduces chronic cyclosporine nephrotoxicity

BACKGROUND

Polymerized type I collagen (P-collagen) has been successfully used to reduce human hypertrophic scars due to its anti-fibrotic and anti-inflammatory properties. We therefore carried out a study to determine if P-collagen reduces functional and structural injury in chronic cyclosporine [cyclosporine A (CsA)] nephropathy.

METHODS

Four groups of six male Wistar rats fed with a low sodium diet were treated with vehicle, P-collagen (0.8 mg/day, i.p.), CsA (15 mg/kg) or CsA + P-collagen for 15 days. Mean arterial pressure, renal blood flow and glomerular filtration rate were measured in all groups. Structural injury such as arteriolopathy, tubulo-interstitial fibrosis (TI-fibrosis) and positive apoptotic cells were quantified. The mRNA expression levels of transforming growth factor-beta (TGF-beta), kidney injury molecule (Kim-1), alpha-smooth muscle actin (alpha-SMA), glutathione peroxidase, catalase and Cu/Zn superoxide dismutase (SOD) as well as MnSOD were assessed. Antioxidant enzyme activity, renal lipoperoxidation and urinary excretion of oxygen peroxide (UH(2)O(2)V) were determined.

RESULTS

Cyclosporine produced renal dysfunction and induced the development of arteriolopathy, TI-fibrosis and tubular apoptosis. These alterations were associated with increases in TGF-beta, Kim-1 and alpha-SMA mRNA levels as well as with a significant increase of oxidative stress and a reduction of SOD activity. P-Collagen partially ameliorated CsA-induced renal dysfunction and structural injury and prevented both tubular apoptosis and increased oxidative stress. This renoprotective effect was found to be associated with a reduction of TGF-beta, Kim-1 and alpha-SMA mRNA levels.

CONCLUSIONS

This study has therefore demonstrated that P-collagen appears to have anti-fibrotic and anti-apoptotic properties and highlights the possibility that the compound might be useful in a strategy to reduce chronic CsA nephrotoxicity.

Aerosolized polymerized type I collagen reduces airway inflammation and remodelling in a guinea pig model of allergic asthma

Collagen-polyvinylpyrrolidone (Collagen-PVP) has been demonstrated to elicit immunomodulatory properties in different chronic inflammatory diseases. Nevertheless, its effects on asthma are still unknown. We have evaluated whether collagen-PVP could modulate airway inflammation and remodelling in a guinea pig model of allergic asthma. Sensitized guinea pigs were challenged with the allergen (ovalbumin) six times (at 10-day intervals). From the third challenge on, animals were treated every 5 days with saline aerosols containing 0.16, 0.33, or 0.66 mg/ml of collagen-PVP (n = 5, respectively). Some guinea pigs, sensitized and challenged with saline as well as treated with 0 or 0.66 mg/ml collagen-PVP, were included in the study as control (n = 7) and sham groups (n = 5), respectively. From the first challenge on, ovalbumin induced a transient airway obstruction, measured by barometric plethysmography, which was not modified by collagen-PVP treatments. After the last allergen challenge, guinea pigs were anesthetized to obtain bronchoalveolar lavage (BAL) and the left lung caudal lobe. As expected, BAL cell count from allergen-challenged guinea pigs showed abundant neutrophils and eosinophils, as well as numerous tumor necrosis factor (TNF)-alpha-expressing granulocytes and macrophages in airway wall (determined by immunohistochemical assay). Neutrophilia and TNF-alpha-expressing leukocytes, from collagen-PVP treated animals, diminished from 0.16 mg/ml, and eosinophilia from 0.66 mg/ml of collagen-PVP doses. Histological changes induced by allergen challenges include thickening of connective tissue below airway epithelium and vascular wall widening of airway adjacent vessels; these changes were reduced by collagen-PVP treatment. Collagen-PVP seems to have anti-inflammatory and antifibrotic properties in this guinea pig asthma model.