Histological and biochemical evaluation of plasma rich in growth factors treatment for grade II muscle injuries in sheep.

The purpose of this study was to perform a histological and biochemical evaluation of the influence of plasma rich in growth factors (PRGF) on muscle regeneration process after a surgically induced grade II muscle laceration. A randomized, single blind, controlled experimental research was conducted including twenty-one adult healthy sheep, randomly divided in three groups (n = 7). A grade II surgical section was performed in the biceps femoris muscle of both hindlimbs. After two days (basal time), intralesional infiltration of autologous PRGF or Saline solution was randomly administered in both hindlimbs. Treatment was repeated once a week. Animal groups were euthanized at 1 (T1), 2 (T2) or 4 (T4) weeks. Histological assessment showed that PRGF intralesional injection induced a significant decrease of inflammatory cells density, significant higher centrally nucleated fibers percentage and significantly smaller fibrotic areas compared to Saline-treated muscles at T1, T2 and T4. Also, lower vascular density, with lower capillaries cross-sectional area, in PRGF group compared to Saline was observed. Biochemical analysis revealed a significant higher expression level of MYOD1, MYF5 and MYOG genes in PRGF groups at T1 compared to Saline treated muscles. At ultrastructural level, PRGF groups presented scarce edema and loss of connective tissue structure, as well as higher mitochondrial density adequately associated to the sarcomere unit in contrast to the Saline group. In conclusion, histological, biochemical, and ultrastructural results showed that PRGF treatment improved muscle regeneration process leading to more mature histological aspect in newly formed muscle tissue after a surgically induced grade II muscle injury.

Cartilage regeneration using a novel autologous growth factors-based matrix for full-thickness defects in sheep.

PURPOSE: To investigate the chondrogenic-regenerative properties of a novel autologous-made matrix composed of hyaline cartilage chips combined with a growth factors-based clot for full-thickness defects in sheep. METHODS: A full-thickness, 8-mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in 6 sheep. Treatment consisted of surgical implantation of an autologous-based matrix of hyaline cartilage chips combined with a clot of plasma poor in platelets and intraarticular injection of plasma rich in growth factors. Outcome measures at 1, 3 and 6 months included macroscopic International Cartilage Repair Society (ICRS) score, histological and immunohistochemical analysis for collagen expression, and transmission electron microscopy study. RESULTS: The 6-month macroscopic evaluation showed nearly normal (11.1 ± 0.7) cartilage repair assessment. The ICRS score was significantly higher at 6 months compared to 3 months (5.5 ± 1.3; p < 0.0001) and 1 (1.1 ± 0.4; p < 0.0001) month. At 6 months, hyaline cartilage tissue filling the defect was observed with adequate integration of the regenerated cartilage at the surrounding healthy cartilage margin. At 6 months, mature chondrons and cartilage matrix contained collagen fibers with masked fibrillary structure, and the expression of collagen in the newly formed cartilage was similar in intensity and distribution pattern compared to the healthy adjacent cartilage. CONCLUSIONS: This novel treatment enhanced chondrogenesis and regenerated hyaline cartilage at 6 months with nearly normal macroscopic ICRS assessment. Histological analysis showed equivalent structure to mature cartilage tissue in the defect and a collagen expression pattern in the newly formed cartilage similar to that found in adjacent healthy articular cartilage. The present technique may have clinical application for chondral injuries in humans because this procedure is cheap (no need for allograft, or expensive instrumentation/biomaterials/techniques), easy and fast-performing through a small arthrotomy, and safe (no rejection possibility because the patients' own tissue, cells, and plasma are used).