Platelet Rich Plasma (PRP) is recognised as a therapeutic field with scarce evidence of efficacy. This is difficult to get because the heterogeneity of the PRP used, and the lack of agreement to define its standard quality features.
PRP efficacy could be modified by several factors along the preparation procedure. (Table 1), but growth factor or platelet content as its surrogated, are probably the most relevant.
The study published recently by Reurink et al. (NEJM 370;26. June 26; 2014) on acute muscle injury, is welcome as offer a well methodological design to improve knowledge on this controversial field, but the study do not evaluated PRP quality parameters of the products injected, being difficult to compare their results to other studies or generalise their conclusions to different scenarios where the PRP product used were different, compromising the external validity of the study.
PRP denomination includes a broad range of products with heterogenic quality parameters, and probably with different therapeutically effect. The consideration of those parameters in the PRP studies is desirable to get unbiased evidences.
Table 1. Factors that could modify PRP efficacy. Most relevant in bold.
|Blood cell concentrations||Specially platelets|
|Blood collection||Venopucture technic|
|Blood container||Tube (plastic or glass), Plastic bag|
|Anticoagulant||With or without.|
|EDTA , heparin, ACD-A;|
|Time and Temperature from collection to processing|
|PRP separation technic from the other blood components|
|PRP quality parameters||Growth factors content|
|Platelet total content|
|Storage (if feasible)||Temperature|
|GF release from platelets (Activaton)||Chemical or physical||Thrombin, calcium, epinephrine; ADP…|
|Clot or not.|
|Therapheutical use||Time from the activation|
|Other products simultaneous used.|
|System sterility||Open or close system|
José Luis Bueno MD