Are Platelet Volume, Density, and the Homeostatic Blueprint the Missing Link in Platelet-Rich Plasma Therapies? An Evidence-Based Narrative Review.

Background/Objectives: Platelet-rich plasma (PRP) has been extensively used in clinical practice to treat musculoskeletal (MSK) and spinal maladies. PRP applications and preparation methods focus on variables such as delivery technique, formulation, and device performance. Few PRP preparation methods consider the variability in the biological status of the individual patient following a comprehensive homeostatic tissue repair response. In recent years, more information has become available for addressing the efficacy of PRP devices and preparation methods. Furthermore, the impact of the PRP dose and bioformulation on different pathoanatomical tissues and patient outcomes has been more widely discussed. This review aims to examine different variables in the optimization of PRP preparation methods, focusing on several platelet indices that influence hematopoiesis, subsequent to homeostasis and neuronal regulation, and how this relates to the release of platelets with variable densities, the mean platelet volume (MPV), platelet distribution width (PDW), and ultimately platelet concentration. Methods: A literature review was conducted using the PubMed, Medline, and Cochrane databases. Results: The literature indicates that the overall physiological platelet dynamics, from bone marrow megakaryocytes to peripheral blood release, differ continuously between health and disease. This study demonstrates that variations in platelet density, as indicated by mean platelet volume (MPV), and platelet count are associated with deviations in the total platelet distribution width. Conclusions: Incorporating platelet indices (PIs) into platelet-rich plasma (PRP) preparation protocols and methodologies is recommended to optimize the recovery of denser, more reactive, and regenerative platelets inherent in peripheral blood, which are integral to the patient's homeostatic tissue repair mechanisms. Pre-procedural assessment of the patient's platelet biological status allows for the preservation of an optimal platelet profile within PRP preparations, potentially enhancing clinical efficacy.