Transforming PRP into a shelf-stable therapy: Lyophilization preserves angiogenic and regenerative properties.

Objectives: Platelet-rich plasma (PRP) is widely used in regenerative medicine due to its high concentration of bioactive growth factors; however, its short shelf life limits its clinical applicability. Lyophilization has been proposed to extend PRP stability, but its impact on biological efficacy remains unclear. This study evaluated whether lyophilization alters the biochemical composition and regenerative function of PRP derived from expired platelet units unsuitable for transfusion.

Materials and methods: Pooled isogroup PRP was processed as either liquid PRP or lyophilized PRP. Growth factors (FGF-1, PDGF, VEGF) and endotoxin levels were quantified. Biological activity was assessed in human dermal fibroblasts (HDFs) and human umbilical vein endothelial cells (HUVECs) using MTT assays, in vitro wound closure, gene expression analysis (MMP-1, MMP-3, Ang1, PDGFR), and CD31 immunocytochemistry at 5% and 10% concentrations, with fetal bovine serum (FBS) as a control.

Results: Lyophilization resulted in moderate reductions in FGF-1, PDGF, and VEGF relative to Liquid-PRP (P<0.05), while endotoxin levels remained acceptable. In HDFs, liquid-PRP induced higher MMP-1 and MMP-3 expression, whereas lyophilized-PRP promoted lower but sufficient expression, consistent with controlled extracellular matrix remodeling, with comparable wound-closure outcomes between PRP groups. In HUVECs, lyophilized PRP preserved cell viability, migration, and CD31 expression, comparable to liquid PRP and FBS. Angiogenic gene expression showed a concentration-dependent response, with maximal activation at 5% PRP, and no functional impairment after lyophilization (P<0.05).

Conclusion: Despite a moderate reduction in growth factors, lyophilized PRP retained regenerative efficacy, supporting lyophilization as a viable strategy for the stable, sustainable reuse of PRP.