Freeze-Dried Human Platelet-Rich Plasma Retains Activation and Growth Factor Expression after an Eight-Week Preservation Period

Abstract

Study DesignControlled laboratory study.PurposeThis study aimed to evaluate the efficacy of platelet-rich plasma (PRP) stored at room temperature (RT), frozen, or after freeze-drying.Overview of LiteraturePRP enriches tissue repair and regeneration, and is a novel treatment option for musculoskeletal pathologies. However, whether biological activity is preserved during PRP storage remains uncertain.MethodsPRP was prepared from blood of 12 healthy human volunteers (200 mL/person) and stored using three methods: PRP was stored at RT with shaking, PRP was frozen and stored at −80℃, or PRP was freeze-dried and stored at RT. Platelet counts and growth factor content were examined immediately after preparation, as well as 2, 4, and 8 weeks after storage. Platelet activation rate was quantified by flow cytometry.ResultsPlatelet counts were impossible to determine in many RT samples after 2 weeks, but they remained at constant levels in frozen and freeze-dried samples, even after 8 weeks of storage. Flow cytometry showed approximately 80% activation of the platelets regardless of storage conditions. Almost no growth factors were detected in the RT samples after 8 weeks, while low but significant expression was detected in the frozen and freeze-dried PRP. Over time, the mean relative concentrations of various growth factors decreased significantly or disappeared in the RT group. In the frozen group, levels were maintained for 4 weeks, but decreased significantly by 8 weeks (p <0.05). The freeze-dried group maintained baseline levels of growth factors for the entire 8-week duration.ConclusionsFreeze-drying enables PRP storage while maintaining bioactivity and efficacy for extended periods.

PRGF-Modified Collagen Membranes for Guided Bone Regeneration: Spectroscopic, Microscopic and Nano-Mechanical Investigations

“…Moreover, the main growth factor levels and cytokines were quantitatively assessed ( Table 2). The values presented in Table 2 are in agreement with previously reported data [19,[29][30][31][32][33]. These previous results demonstrated that different plasma formulations enhance proliferation and migration of fibroblast populations, protect and inhibit TGF-1-induced myofibroblast differentiation, and regulate the metabolic activity of mesenchymal stem cells [33].…”

“…On the other hand, the concept of PRGF and its related mechanism is that by increasing the concentration of growth factors and cytokines that are released by platelets, the healing process is accelerated [28]. The actual definition of protein rich plasma (PRP) (and related PRGF) is accepted as a minimum platelet concentration three times that of whole blood [18,19,29]. In our study, as presented in Table 1, the counted platelets are in agreement with this definition.…”

Freeze-Dried Platelet-Rich Plasma Induces Osteoblast Proliferation via Platelet-Derived Growth Factor Receptor-Mediated Signal Transduction

“…In conclusion, we showed that PDGF in FD-PRP is pharmacologically active in vitro after 4 weeks of storage. As concluded in previous reports [12,13], for the clinical application of FD-PRP after extended long-term storage, further investigations are required to determine the effects of FD-PRP on human bone fusion and soft tissue repair. If FD-PRP is shown to be clinically applicable, it could be useful to promote bone fusion after bone fracture surgical repair, induce interbody fusion, and provide the appropriate scaffolding for bone formation after spinal surgery without the need of intraoperative blood collection.…”

“…Thus, patients are required to donate a large amount of blood just before surgery for fresh PRP preparation. To overcome this limitation, we focused on freeze-dried PRP (FD-PRP) and confirmed that FD-PRP maintained baseline levels of GFs for the entire 8-week duration [12]. Furthermore, Shiga et al [13] showed that FD-PRP could achieve accelerated bone union in a rat PLF model even after 8-week storage.…”

Freeze-Drying of Platelet-Rich Plasma: The Quest for Standardization

“…Typically, PDGF, TGF, epidermal growth factor (EGF) and VEGF are involved in tissue repair and assessed in fresh versus FD-PRP. For example, Shiga et al [17] compared fresh-frozen (−80 ºC) PRP with FD-PRP. They established its stability, up to 8 weeks at room temperature, based on the quantification of PDGF, VEGF, TGF and EGF.…”