Wound healing patterns of vocal cord acute injuries in rats and the protective effect of pentoxifylline in the progress

1. SUMMARYWOUND HEALING PATTERNS OF VOCAL CORD ACUTE INJURIES INRATS AND THE PROTECTIVE EFFECT OF PENTOXIFYLLINE IN THEPROGRESSMurat Belgi, M.D.Scar formation is the major cause of dysphonia following the vocal cord surgery.Lamina propria consists of extracellular matrix (ECM) and cells producing the componentsof the matrix. Components of ECM determines the biomechanical properties of the vocalcord. A balanced distrubition of this components provides an ideal viscoelasticity to vocalcord. Lamina propria is the basic part of the glottic structure for the generation of voice andthe benign vocal cord lesions generally originate in this region. The benign non-neoplasticlesions such as polyps or cysts cause dysphonia by disturbing closure of the vocal cords andthe mucosal wave generation. Surgical excisions of this sort of lesions are not fully efficientto tolerate the functional incompetance. Within the wound healing process, fibrotic tissuereplaces the original tissue. Changes in the composition of ECM disturbs the vocal cordfunction by impeding the mucosal wave movement.A well known healing and scar formation process enables to improve the effectivetreatment regimes. Different substances have been studied to assess this subject.Pentoxifiylline is a reliable drug with its low side effect profile and proven antiproliferative,antiinflammatory and antifibrotic effects, that has clinical indications on circulatorydisturbances. Its investigatory effects on wound healing process was shown on many tissuesbut hasn?t studied on vocal cords yet.Twenty Wistar rats was used in the study. Stripping of the vocal cord performed on 10of the rats as a surgical procedure and muscle defect created on the rest of the animals. Fiverats followed without treatment while 100 mg/kg/day pentoxifylline was givenintraperitoneally for 14 days in the rest of groups. Surgical procedures was performed to theleft vocal cords while the opposite cords remained intact as control subjects. The ratssacrificed and the laryngeal specimens obtained on the 14 th day of follow up period. Sectionswere stained with Hematoxylin-Eosin and inflammation and vascular proliferation scoresobtained on light microscopic examination. Tissue sections were stained with Sirius-Red tovisualize the collagen matrix and the whole images were examined with image analyseprogram to rationale the percentage of collagen density in terms of pixels on the stained area.It?s shown that pentoxifylline suppresses the inflammation which arouse as a responseto the tissue damage in both groups S+P and K+P. Although a more intense inflammatoryresponse was seen in group S than group K, no significant difference between collagen matrixlevels was detected. As collagen matrix levels compared between two groups, the levels werefound significantly lower in group K+P than group K. Collagen levels were found to belower in group S+P than group S, but no statistically significant difference were detected. Theamount of collagen matrix was measured significantly higher in group K+P and S+P thancontrol levels.In the study; it is undoubtly shown that pentoxifylline has an antiinflammatory andantifibrotic effect in the wound healing of the vocal cord tissue as it has on the other tissuesites. However new clinical studies needed to provide the effect of the findings to thefunctional outcomes.