en عمومى General مقالات اصيل Original Article BACKGROUND Autologous platelet concentrate has been used to improve the function and regeneration of injured tissues. Tendinopathies are common in clinical practice, although long-term treatment is required. On the basis of lead time, we compared the effect of using platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) in repairing rat Achilles tendon. METHODS The effectiveness of using PRP and PRF was evaluated after 14 and 28 postoperative days by histological analysis. The quantification of collagen types I and III was performed by Sirius red staining. Qualitatively, the data were verified with hematoxylin-eosin (H&E) staining. RESULTS In Sirius red staining, no significant treatment differences were found between groups. Statistical difference was observed only between PRP (37.2% collagen) and the control group (16.2%) 14 days after treatment. Intra-groups compared twice showed a difference for collagen I (27.8% and 47.7%) and III (66.9% and 46.0%) in the PRF group. The control group showed differences only in collagen I (14.2% and 40.9%) and no other finding was observed in the PRP group. In H&E staining, PRF showed a better cellular organization when compared to the other groups at 28 days. CONCLUSION Our study suggests that PRF promotes accelerated regeneration of the Achilles tendon in rats, offering promising prospects for future clinical use. Healing, Platelet-rich fibrin, Achilles tendon, Platelet-rich plasma 101 109 http://wjps.ir/browse.php?a_code=A-10-111-1&slc_lang=en&sid=1 Franciele Dietrich francidi05@gmail.com 10031947532846001083 10031947532846001083 Yes Laboratory of Medical Abilities and Surgical Research, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Gustavo Lançanova Duré gustavo.l.dure@gmail.com 10031947532846001084 10031947532846001084 No Laboratory of Medical Abilities and Surgical Research, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Caroline Peres Klein carolpkl@gmail.com 10031947532846001085 10031947532846001085 No Laboratory of Medical Abilities and Surgical Research, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Vinícius Faccin Bampi vfbampi@gmail.com 10031947532846001086 10031947532846001086 No Laboratory of Medical Abilities and Surgical Research, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Alexandre Vontobel Padoin alexandre@padoin.med.br 10031947532846001087 10031947532846001087 No Service of Hand Surgery and Reconstructive Microsurgery, São Lucas Hospital, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Vinícius Duval da Silva vinids@pucrs.br 10031947532846001088 10031947532846001088 No Service of Pathology Anatomy and Cytopathology, São Lucas Hospital, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Jefferson Braga Silva jeffmao@terra.com.b 10031947532846001089 10031947532846001089 No Service of Hand Surgery and Reconstructive Microsurgery, São Lucas Hospital, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS)