Clinical Implementation of Platelet- and Extracellular Vesicle-Rich Product Preparation Protocols

Extracellular vesicles (EVs) are considered essential mediators of regenerative roles of autologous platelet- and extracellular vesicle-rich plasma (PVRP) and platelet- and extracellular vesicle-rich gel (PVRG). PVRP and PVRG are novel blood-derived products gaining attraction in regenerative medicine. However, despite their reported good efficacy, their preparation protocols are too time-consuming. Moreover, patient-tailored preparation protocols are desired to optimize platelet and EV count in PVRP and PVRG. This article presents the clinical implementation of one-step, patient-tailored erythrocyte sedimentation rate (ESR)-based, PVRP and PVRG preparation protocols through the presentation of three cases: (1) large chronic tympanic membrane (TM) perforation, (2) osteoradionecrosis of the lateral skull base, and (3) cerebrospinal fluid (CSF) leak in the sphenoid sinus. These were treated with PVRP and PVRG, prepared according to our preclinically constructed mathematical sedimentation model of cells and EVs based on the patient's ESR. (1) TM healed completely after the treatment with 3.6 mL of PVRP and PVRG (high platelet and EV protocol). The speech discrimination score and air conduction pure tone average improved from 75% to 95% and from 65 to 25 dB, respectively. (2) The osteoradionecrotic surface area decreased from 46 to 18 cm², and infection was eradicated after six applications of 13-65 mL of PVRG ("half-volume" protocol). (3) No CSF leak recurrence was detected after surgical closure with 30 mL of PVRG postoperatively. Reproducible preparation protocols proved effective, safe, fast, and straightforward enough for the surgical staff to prepare PVRP and PVRG intraoperatively. To alleviate preparation, a calculator is provided. This pilot study presents a sound basis for further studies, which are needed to assess the therapeutic effect of PVRP and PVRG. Impact statement We introduce a clinical implementation of a patient-tailored, erythrocyte sedimentation rate-based platelet- and extracellular vesicle-rich plasma (PVRP) and gel (PVRG) preparation protocol based on a mathematical model. Products proved beneficial in wound healing and were, to our knowledge, used for the first time in the treatment of osteoradionecrosis of the lateral skull base. Furthermore, this reproducible preparation protocol is fast and straightforward to implement in clinical practice. A calculator is provided to alleviate PVRP and PVRG preparation for various clinical scenarios.