Surface-Based Total Blood Volume Calculation for Platelet and Extracellular Vesicle-Rich Plasma and Gel Preparation by Us-ing a Mathematical Model

Platelet- and extracellular vesicle-rich plasma (PVRP) and platelet- and extracellular vesicle-rich gel (PVRG) are blood-derived products gaining attraction in regenerative medicine. However, despite their reported good efficacy, their preparation protocols are too time-consum-ing. Moreover, patient-tailored preparation protocols are desired to optimise platelet and extra-cellular vesicle (EV) count in PVRP and PVRG. This scientific contribution presents a clinical implementation of mathematical model for calculation of the desired total blood volume for PVRG preparation. PVRG was prepared according to previously derived mathematical model of blood cell and EV sedimentation during centrifugation based on the patient's erythrocyte sedi-mentation rate (ESR) (Božič et al., 2021). We estimated the volume of blood required for the treat-ment of the surface area of the individual patient, prepared the PVRG accordingly and applied it to the patient’s wound. After six applications of 13 mL to 65 mL of PVRG, the osteoradi-onecrotic surface area decreased from 46 cm2 to 18 cm2, and infection was eradicated. The math-ematical modelling of total blood volume needed to prepare PVRG proved useful to prepare the therapeutic amount of PVRG and also optimized time for the PVRG preparation protocol. Keywords: Extracellular vesicles; Platelet-rich plasma; Regenerative medicine; Osteitis; Osteora-dionecrosis; Osteomyelitis; Temporal bone