title: Histological study of the influence of plasma rich in growth factors (PRGF) on the healing of divided Achilles tendons in sheep.
abstract: BACKGROUND
  The use of plasma rich in growth factors (PRGF) has been proposed to improve the healing of Achilles tendon injuries, but there is debate about the effectiveness of this therapy. The objective of the present study was to evaluate the histological effects of PRGF, which is a type of leukocyte-poor platelet-rich plasma, on tendon healing.
  
  
  METHODS
  The Achilles tendons of twenty-eight sheep were divided surgically. The animals were randomly divided into four groups of seven animals each. The repaired tendons in two groups received an infiltration of PRGF intraoperatively and every week for the following three weeks under ultrasound guidance. The tendons in the other two groups received injections with saline solution. The animals in one PRGF group and one saline solution group were killed at four weeks, and the animals in the remaining two groups were killed at eight weeks. The Achilles tendons were examined histologically, and the morphometry of fibroblast nuclei was calculated.
  
  
  RESULTS
  The fibroblast nuclei of the PRGF-treated tendons were more elongated and more parallel to the tendon axis than the fibroblast nuclei of the tendons in the saline solution group at eight weeks. PRGF-treated tendons showed more packed and better oriented collagen bundles at both four and eight weeks. In addition to increased maturation of the collagen structure, fibroblast density was significantly lower in PRGF-infiltrated tendons. PRGF-treated tendons exhibited faster vascular regression than tendons in the control groups, as demonstrated by a lower vascular density at eight weeks.
  
  
  CONCLUSIONS
  PRGF was associated with histological changes consistent with an accelerated early healing process in repaired Achilles tendons in sheep after experimental surgical disruption. PRGF-treated tendons showed improvements in the morphometric features of fibroblast nuclei, suggesting a more advanced stage of healing. At eight weeks, histological examination revealed more mature organization of collagen bundles, lower vascular densities, and decreased fibroblast densities in PRGF-treated tendons than in tendons infiltrated with saline solution. These findings were consistent with a more advanced stage of the healing process.
  
  
  CONCLUSIONS
  Based on the findings in this animal model, PRGF infiltration may improve the early healing process of surgically repaired Achilles tendons.
authors: Department of Animal Medicine and Surgery, University of Córdoba, Campus de Rabanales, Ctra. Madrid - Km 396, 14014, Córdoba, Spain. v12fesaj@uco.es
authors: J Andrés
authors: JA
authors: Fernández-Sarmiento
authors: Juan M
authors: JM
authors: Domínguez
authors: María M
authors: MM
authors: Granados
authors: Juan
authors: J
authors: Morgaz
authors: Rocío
authors: R
authors: Navarrete
authors: José M
authors: JM
authors: Carrillo
authors: Rafael J
authors: RJ
authors: Gómez-Villamandos
authors: Pilar
authors: P
authors: Muñoz-Rascón
authors: Juana
authors: J
authors: Martín de Las Mulas
authors: Yolanda
authors: Y
authors: Millán
authors: Montserrat
authors: M
authors: García-Balletbó
authors: Ramón
authors: R
authors: Cugat
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000473:pathology / Q000601:surgery; D000818:Animals; D003094:Collagen / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D036341:Intercellular Signaling Peptides and Proteins; D053657:Platelet-Rich Plasma; D011897:Random Allocation; D012421:Rupture; D012756:Sheep; D014945:Wound Healing
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D003094:Collagen