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A rush to standardize PRP protocols could prevent researchers from critical discoveries found only through overcoming clinical obstacles that may defy established norms. For example, a definition of PRP in 2001 proposed an optimal clinical healing concentration of 1,000,000 platelets/µL in a 5-mL volume of plasma for bone.¹⁴⁹ But in 2008, a platelet gel study concluded that a concentration of about 1.5 × 10⁶ plt/mL appeared to be optimal for proliferation, migration, and invasion of endothelial cells, showing that higher concentrations of growth factors can adversely affect wound healing for soft tissues.¹⁵⁰

Despite the general similarity in the protocols for preparing PRP, a number of variables affect whole blood centrifugation for platelet concentration and volume: platelet size, anatomical differences of patients, hematocrit variability, the amount and location of autologous blood drawn, the centrifugal forces and number/duration of spins, and temperature variants (including a refrigerated centrifuge; Table 1-1).^151–157

Compounding the problems of standardization are variations in centrifugation terminology (for example, rotation-per-minute versus g-force), centrifuge rotor radius, patient age and sex,¹⁵⁸ activating or not activating PRP before application,^159,160 using noncommercial PRP kits, needle bore size, and types of anticoagulants or lack thereof.

The variety of methods for delivering PRP to a wound site demonstrates the evolving and sometimes competing techniques for applying PRP and other biologics in wound healing; however, reliable clinical results often require replicable delivery methods in addition to standard production methods. For example, hydrogels, sponges, and nanofiber scaffold fabrication can be used for treating bone defects with PRP.¹⁵⁹

So clinicians must be wary about too-rigid standardization of the principles and technologies of platelet sequestration, the nomenclature and classification of platelet-rich products, and the application of those products for wound healing. The dynmaic and often contradictory nature of PRP derivations and clinical applications across the medical spectrum may in fact represent opportunities for greater scientific and medical understanding and advancement.