Comparison of the effects of platelet rich plasma (PRP) and dexamethasone injection on scar formation after vocal fold injury in rabbits

Treatment of vocal fold scar is difficult and costly. The effects of many molecules and biomaterials on wound healing are investigated in animal experiments in which vocal fold damage is induced. Although Platelet Rich Plasma (PRP) has been used in different clinical disciplines due to its regeneration and enhancing the healing effects in recent years, its effects on the healing process after vocal fold injury are not fully identified yet. Although dexamethasone injection is frequently used in clinical practice to prevent scar formation after vocal fold injury, the results obtained are controversial. In this study, an animal experiment was planned to investigate whether PRP injection would make more histopathological contribution to the prevention of scar formation after vocal fold injury, as compared to dexamethasone injection. Electrocautery was applied to damage the right and left vocal folds of 12 New Zealand rabbits. PRP obtained from the rabbits' own blood was injected into the right vocal fold, and dexamethasone was injected into the left vocal fold. After 8 weeks, the experimental animals were euthanized, and the levels of inflammatory cell infiltration, vascularization, collagen, elastin, and hyaluronic acid were compared in histopathological evaluation. In statistical comparison of histopathological data obtained; in terms of plasma cell infiltration, vascularization, edema, and vascularization parameters in fibrosis, statistically significant results were obtained in favor of the PRP group. Complications such as foreign body reaction and necrosis were not observed after PRP and dexamethasone injection. Although the difference between collagen and elastin molecules, which are critical in vocal fold scar healing, was more positive in favor of PRP, no statistically significant result was revealed in the statistical evaluation. Conclusion: PRP injection in rabbits with vocal fold damage is at least as useful as dexamethasone injection in preventing scar formation by regulating the reactions taking place during the wound healing phase. Although it does not show a distinct advantage in the comparison, there are histopathological results showing that certain doses may positively affect the formation of healthy tissue in damaged areas of the vocal fold. PRP injection after vocal fold injury provided more anti-inflammatory response from dexamethasone. However, this effect did not have as great an effect as expected on the levels of collagen and elastin, which are the main molecules involved in vocal fold scar formation. There is a need for new studies in which PRP is applied at different doses and times after vocal fold injury, and its effects on different molecules involved in the vocal fold injury phase are questioned.