Effect of platelet rich fibrin on block, crushed anddiced cartilage

Introduction: In rhinoplasty, autologous cartilage grafts are commonly used as an ideal graft material for addressing weak nasal skeletal structure, contour deformities, and irregularities in various areas of the nose. The literature describes various methods of using cartilage, such as using it in block form, diced form, or crushed form. However, each method has its own advantages and disadvantages. Various procedures have been applied to enhance the viability, survival, and prevent resorption, as well as to reduce dispersion and migration of autologous cartilage grafts. However, the existing practices mentioned in the literature have not provided definitive solutions to potential risks and problems. This study aims to investigate the potential effects of thrombocyte-rich fibrin (PRF), a biological tissue product, on autologous cartilage grafts, determine the optimal combination with different forms of autologous cartilage grafts, and shed light on the biological and physiological mechanisms involved in this process. Methods: The study involved 24 New Zealand rabbits with an average weight of 3000 g (ranging from 2500 g to 3500 g) at the age of 4-6 months. Autologous cartilage grafts were obtained from the single ear of each subject and divided into six groups: block, crushed, and diced cartilage grafts were assigned to the control group, while block, crushed, and diced cartilage grafts combined with TZF were assigned to the study group. Autologous cartilage grafts combined with TZF, which were standardized and equally distributed, were implanted into subcutaneous pockets on the rabbits' backs at equal distances. After 8 weeks, the implanted subcutaneous pockets were dissected, and autologous cartilage grafts and TZF combination products were subjected to histopathological, immunohistochemical, and biochemical examinations. Viability, proliferation, and chondrogenic properties of cartilage tissues have been examined. The cartilage matrix molecules, collagen, and elastic fiber structures have been investigated. The biomarkers of extracellular molecules and growth factors have been evaluated. Angiogenesis, oxidative stress, and apoptosis markers which have not been studied previously regarding PRF and its effects on cartilage grafts were examined. The IBM SPSS Statistics 26.0 program was used for data analysis. Descriptive findings were presented as mean and standard deviation. One-way ANOVA test was used, and variance homogeneity was checked with the Levene test. Tukey and Games-Howell tests were employed as complementary post-hoc analyses to determine differences. The significance level was set at p < 0.05. Results: According to the biochemical analyses conducted in our study using ELISA, the levels of parameters such as CK-18 M30, TOS, and OSI were significantly lower in the groups combining PRF with crushed, block, and diced cartilage grafts compared to their respective controls (p < 0.001, p < 0.01, p < 0.01). On the other hand, the levels of parameters HYP, VEGF, GAG, TGF-β1, bFGF, HIF-1α, PDGF, COMP, TAS, and EGF were significantly higher in the groups combining PRF with crushed, block, and diced cartilage grafts compared to the control group (p < 0.001, p < 0.01, p < 0.01). Histopathological and immunohistochemical examination findings revealed that the groups combining PRF with crushed and block cartilage grafts exhibited intense peripheral proliferation areas and higher amounts of collagen, elastic fibers and cartilage extracellular matrix (ECM) proteoglycans. In the control group with crushed cartilage grafts, significant histopathological changes, decreased cell survival, high levels of degeneration and matrix damage in cartilage tissue, and the replacement of fibrotic connective tissue and ossification were observed. In intra- group comparisons, both the groups combining TZF and the control groups showed that autologous diced and block cartilage grafts had better cell survival, lower degeneration rates, and were richer in cartilage ECM matrix components compared to autologous crushed cartilage grafts. Conclusion: The results obtained from our study demonstrated that PRF has positive effects on the viability, cell survival, and cell proliferation processes of autologous cartilage grafts, increases the levels of factors involved in angiogenesis, plays a regulatory role on cartilage tissue ECM molecules, and reduces inflammation during the investigated time interval. We believe that the natural fibrin scaffold of TZF, which acts as a supportive structure for tissue regeneration, holding growth factors and stem cells together and allowing their slow and controlled release, significantly contributes to this process. Additionally, we believe that PRF plays a role in favor of cell survival in oxidative stress markers and apoptotic processes, which have not been previously investigated on autologous cartilage grafts. With this study, we suggest that PRF, as a biologic tissue product that is easily obtainable, cost-effective, has a gelatinous and membranous structure, and neither cause hypersensitivity reactions nor carry a high risk of infection, can be successfully used in combination with diced and block cartilage grafts to minimize complications and achieve more predictable outcomes in nasal surgeries.