Platelet-rich plasma (PRP) and tendon healing: comparison between fresh and frozen-thawed PRP.

Platelet-rich plasma (PRP) is increasingly used in the treatment of musculoskeletal diseases. Its preservation by freezing it for the realization of multiple injections in clinical use has never been discussed. Calcaneal tendons of rats were surgically sectioned. Platelet concentration of the PRP was 2.5 x 106/µl with autologous plasma of rats. Frozen-thawed PRP was prepared by performing two cycles of freezing and thawing on PRP aliquots. Both platelet preparations were injected in the lesion. Biomechanical and histological evaluations were carried out after 7, 20 or 40 days post surgery. After 7 and 40 days, no significant difference was observed between the PRP and the frozen-thawed PRP group. There is however a difference 20 days after surgery: the ultimate tensile strength (UTS) was greater in the fresh PRP group. No obvious difference with histological aspect was observed between the two groups. In conclusion, fresh PRP and frozen-thawed PRP injections can lead to similar results in the healing process of section calcaneal tendons of rats. Improvements with fresh PRP are slight. PRP could thus be frozen to be preserved if multiple injections are needed (e.g. osteoarthritis).

Gastrointestinal effects of general anaesthesia in horses undergoing non abdominal surgery: focus on the clinical parameters and ultrasonographic images.

The ultrasonographic images of the gastrointestinal tract in horses can be influenced by fasting and sedation but the proper effect of general anaesthesia (GA) on them has not been determined yet. This study aimed to evaluate the effects of GA on ultrasonographic images of the gastrointestinal tract in horses and to compare these effects with a clinical evaluation. Twenty horses undergoing non-abdominal surgeries were evaluated by ultrasonography before and 4 times within 24 h after GA. Each ultrasonographic exam focused on the stomach, the duodenum and on 5 locations on the jejunum. The four-quadrant auscultation and the postoperative faecal output were also recorded. Pre and post anaesthetic values were compared using linear mixed effects models. None of the horses presented colic signs or reduced faecal output. During the first 2 post anaesthetic evaluations, the gut sounds were significantly decreased and, when taking all jejunal locations together, the jejunal diameter and visualisation frequency significantly increased. No intestinal loop appeared thickened and most of their diameters remained within the normal range. Our results suggest that the effects of GA on the ultrasonographic images of the small intestine are mild and of short duration and can therefore be differentiated from a pathological process.

Effects of platelet-rich plasma (PRP) on the healing of Achilles tendons of rats.

Platelet-rich plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. In conclusion, an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance.