Since tendon injuries and tendinopathy are a growing problem, sometimes requiring surgery, new strategies that improve conservative therapies are needed. Platelet-rich plasma (PRP) seems to be a good candidate by virtue of its high content of growth factors, most of which are involved in tendon healing. This study aimed to evaluate if different concentrations of platelets in PRP have different effects on the biological features of normal human tenocytes that are usually required during tendon healing. The different platelet concentrations tested (up to 5 × 106 plt/µL) stimulated differently tenocytes behavior; intermediate concentrations (0.5 × 106, 1 × 106 plt/µL) strongly induced all tested processes (proliferation, migration, collagen, and MMPs production) if compared to untreated cells; on the contrary, the highest concentration had inhibitory effects on proliferation and strongly reduced migration abilities and overall collagen production but, at the same time, induced increasing MMP production, which could be counterproductive because excessive proteolysis could impair tendon mechanical stability. Thus, these in vitro data strongly suggest the need for a compromise between extremely high and low platelet concentrations to obtain an optimal global effect when inducing in vivo tendon healing.

Level II, prospective cohort study.

Haemostatic alterations in dogs naturally infected by ehrlichiosis and/or leishmaniasis were studied. Platelet count, ADP and collagen-induced platelet aggregation, prothrombin time, activated partial thromboplastin time (APTT) and plasma fibrinogen concentration were measured. An evident reduction of platelet aggregation response was shown for Leishmania-Ehrlichia co-infected dogs where platelet aggregation was lower in comparison with control and leishmaniotic dogs (ADP and collagen, P < or = 0.01) and ehrlichiotic dogs (ADP 10 and 7.5 microm, P < or = 0.05). Moreover, a significant increase in APTT as well as a reduction of the albumin/globulin rate (A/G) for leishmaniotic and co-infected dogs versus control and ehrlichiotic dogs was detected. The hypothesis of a synergism between leishmaniosis and ehrlichiosis in altering platelet function by different pathways is discussed.

No abstract