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

in Wound Repair & Regeneration : Official Publication of the Wound Healing Society and the European Tissue Repair Society (2012), 20(5), 748-756

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 ... [more ▼]

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 5 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 mRNA level of type III collage, matrix metalloproteinase 2, 3 and 9 was similar in the 2 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 tendons healing and results in an ultimate stronger mechanical resistance. [less ▲]

Effects of platelet-rich plasma on the healing of tendons: animal model

in Biomedica 2012 (2012, April)

Introduction: Platelet-Rich Plasma (PRP) contains lot of growth factors which could enhance the healing process of different tissues. We aimed to determine if a single injection of PRP could improve the ... [more ▼]

Introduction: Platelet-Rich Plasma (PRP) contains lot of growth factors which could enhance the healing process of different tissues. We aimed to determine if a single injection of PRP could improve the cicatrisation of ruptured Achilles tendons of rats. Material and Methods: A 5mm defect was surgically made in the Achilles tendon of 120 rats. A few hours after surgery, 45 rats received a PRP or PBS injection in situ. After 5, 15 and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were immediately submitted to a biomechanical tensile strength test until rupture using a “cryo-jaw” device. After, theses samples were used for transcriptomic analyses. Histological and biochemical analyses were performed on the five remained tendons in each group. Results: Tendons in the PRP group were more resistant to rupture at 15 and 30 days than those in the control group. The transverse area of tendons in the PRP group was significantly higher at day 5 and 15. The constraint was significantly increased in tendons of the PRP group in the late phase of the healing (day 30). Histological and immunohistological analysis showed an increased staining for fibrillar collagen at day 5 confirmed by a biochemical analysis showing an increased collagen concentration in the callus. The expression of tenomodulin, a tenocyte differentiation marker, was significantly higher in the PRP-treated tendons at day 5. No significant difference in terms of mRNA for type III collagen and matrix metalloproteinase 9 was observed at any time between the 2 groups. Conclusion: A single injection of PRP in sectioned Achilles tendon of rats few hours after surgery influences the early phase of tendons healing, resulting in an ultimate stronger mechanical resistance. [less ▲]

Evaluation of the use of VEGF111 for the treatment of tendon lesions.

Poster (2011, May 20)

Alterations of tendons are common pathologies resulting from repetitive or abnormal mechanical sollicitations. Very frequently lesions become chronic and may even lead to rupture. As there is no current ... [more ▼]

Alterations of tendons are common pathologies resulting from repetitive or abnormal mechanical sollicitations. Very frequently lesions become chronic and may even lead to rupture. As there is no current efficient treatment for curing this type of diseases, new therapeutic approaches are being tested and developed. Injection of platelet-rich plasma (PRP) seems to be a promising treatment by local release of growth factors. Among these factors, VEGF-A is known to induce positive effects on vascular functions and angiogenesis, and could be implicated in the healing process of tendons. Several isoforms of VEGF-A have been described in literature, including VEGF165 and 121. VEGF111 is encoded by exons 1-4 and 8a. The lack of exon 5 enables VEGF111 to resist to proteolytic degradation and the absence of exons 6 and 7 reduces its affinity for several macromolecules present on the cell surface and in the extracellular matrix. In vivo, it has been shown to be highly proangiogenic and diffusible. A 5mm defect was surgically performed in the Achilles tendon of 60 rats. Two hours after closure of the fascia and the skin, an injection within the wound was performed with PBS alone (n=30) or with PBS containing 100 ng of VEGF111 (n=30). 10 rats of each group were sacrificed at days 5, 15 and 30. The operated tendon was then carefully removed and collected for either immunohistochemical analyses or mechanical testing. At each time point, the section and the overall appearance of the repairing tendons were similar for PBS and VEGF111-injected tendon. As compared to controls, injection of VEGF111 seemed to promote a faster angiogenesis, although the number of samples was at this stage too low for performing reliable statistical analysis. Mechanical resistance to rupture of the repairing tendons was also measured. No difference between the two groups was observed after 5 or 15 days. By contrast, increased tensile strength was clearly evidenced in the VEGF-treated group after 30 days. These preliminary data seem to indicate a positive effect of a single VEGF111 injection for restoring the mechanical properties of tendons after their section. Additional experiments are planned for confirmation purposes and for further characterizing the model. It includes a “dose- response” analysis, the use of VEGF165 as an additional control and a study evaluating the effect of several injections. [less ▲]