Standardization and Comparative Characterization of Platelet-Rich Plasma Preparation Systems: A Methodological Study with Clinical Applicability Assessment

Background/Objectives: Platelet-rich plasma (PRP) is widely used in regenerative med-icine, but its clinical applicability is hindered by the variability of preparation methods. This study aimed to optimize and standardize PRP production in open systems under good manufacturing practice-compatible conditions, compare it with closed commercial systems, and characterize the products obtained. Methods: A prospective, intra-subject study was conducted in patients with degenerative knee pathology. Four experimental open methods and three closed commercial systems were evaluated. Complete blood count parameters were recorded for quality control; comparative analyses focused on platelet concentration, reproducibility, leukocyte modulation, and volumetric efficiency. Results: Twenty-one patients were included. All methods yielded platelet concentrations above baseline. Closed systems achieved the highest mean concentration with an en-richment factor of 2.9 ± 2.1 but demonstrated substantial variability (CV ~69%). Open methods showed superior reproducibility, particularly single-centrifugation protocols (CV 28-29%). Open methods allowed predictable modulation of leukocyte content: F1 and F2 achieved significant depletion (42% and 62% respectively), while F3 and F4 maintained or enriched leukocyte populations depending on centrifugation parameters. For a standard 1×10⁹ platelet dose, required PRP volumes were ~3.2mL (F1), 3.3mL (F2), 2.9mL (F3), 2.8mL (F4) vs 2.0mL (Commercial), with higher between-patient variability in the commercial system, corresponding to blood volumes of 15.6–38.4mL for open methods. Conclusions: Both open and closed systems concentrate platelets, but they differ significantly in reproducibility, leukocyte modulation capability, and volumetric yield. Open protocols demonstrated superior consistency and flexibility for personalized therapeutic applications. The choice of preparation method should be based on prede-fined therapeutic objectives, with standardized characterization ensuring reproducibility for clinical implementation.