Comparison of bioactive substances in novel-developed freeze-dried platelet-rich plasma (PRP) and activated normal PRP, and investigation of bioactive substance levels after long-term storage

Introduction: In recent years, biotherapy in orthopedics has become widespread, and platelet-rich plasma (PRP) has been readily used to treat sports injuries and osteoarthritis. Production of freeze-dried PRP (PRP-FD) results in PRP that is in powder form, allowing it to be stored for long periods at room temperature. Using this technology, we have developed Valuable Platelet-Derived Factor Concentrate Freeze Dry (VFD). However, whether VFD contains sufficient levels of bioactive substances (BS) remains unknown and retains the same levels of BS during long-term storage. In this study, we examined whether VFD contains sufficient amounts of BS and whether they retain these BS levels during long-term storage. Methods: Peripheral blood was collected from 10 healthy men (mean +/- SD: 46.5 +/- 15 years old) and various BS, including transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), tissue inhibitors of metalloproteinases-1 (TIMP-1), interleukin-1 receptor antagonist (IL-1ra), matrix metallopeptidase-9 (MMP-9), and interleukin-6 (IL-6), were compared between VFD and normal PRP samples, including both leukocyte-rich PRP (LR-PRP) and leukocyte-poor PRP (LP-PRP). VFD was prepared using two rounds of centrifugation. LP-PRP and LR-PRP were activated by freezing and thawing before measurement. To evaluate the effects of long-term storage, the BS of VFD purified from five professional football players was compared between baseline and 1 year after storage. Results: In terms of the growth factors, the TGF-beta and EGF levels were higher in LR-PRP than in VFD and LP-PRP (p < 0.05), while the bFGF levels were higher in VFD than in the LR-PRP and LP-PRP groups (p < 0.01). In terms of anti-inflammatory cytokines, the TIMP-1 level was lower in VFD than that in the other groups (p < 0.01), whereas the IL-1ra levels were higher in VFD than those in LP-PRP (p < 0.05) and lower than those in LR-PRP (p < 0.01). In terms of inflammatory enzymes and cytokines, the IL-1ra level was higher in VFD than that in LP-PRP (p < 0.05) and lower than that in LR-PRP (p < 0.01), whereas the IL-6 levels did not differ among the groups. Furthermore, the TGF-beta, bFGF, TIMP-1, and IL-1ra levels were 5.61 -> 3.38 (x10(3) pg/mu L), 61.0 -> 63.0 (pg/mu L), 3.4 -> 2.7 (x10(5) pg/mu L), and 14.9 -> 14.5 (x10(3) pg/mu L) at baseline and 1 year later, respectively. No significant differences in the BS levels were observed between baseline and 1 year after storage. Conclusions: The VFD samples prepared in this study exhibited higher levels of anti-inflammatory cytokines than LP-PRP and contained growth factor levels similar to LP-PRP and LR-PRP. In addition, the BS levels in VFD samples were maintained after one year of storage. These results suggest that VFD can be prepared and stored and may serve as a novel treatment strategy for sports injuries in high-risk groups, such as athletes. (c) 2024, The Japanese Society for Regenerative Medicine. Production and hosting by Elsevier B.V. All rights reserved. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).