Stability of Growth Factors in Autologous Serum Eyedrops After Long-Term Storage

Purpose: The purpose of this study is to assess the stability of the growth factors (GF) in autologous serum eyedrops under different storage conditions. Methods: The concentration of epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta 1), platelet-derived growth factor AB (PDGF-AB), and albumin was measured in fresh and defrosted samples of autologous serum under different storage conditions. The fresh and defrosted samples were cooled at 4 degrees C, and they were studied immediately after preparation, or after defrosting, and after 1, 2, 3, and 4 weeks. The concentration of GF was also assessed after 1, 3, 6, and 9 months at -20 degrees C. We also investigated how the different storage conditions influence the biological effects of autologous serum on conjunctival and corneal cell cultures. Results: The concentration of EGF, TGF-beta 1, PDGF-AB, and albumin remained stable over the 4 weeks at 4 degrees C, both in fresh and in defrosted samples. Likewise, no statistically significant differences were found between the GF concentration in fresh samples and after 1, 3, 6, and 9 months of freezing at -20 degrees C. Moreover, no differences were found on the cell proliferation and differentiation between cultured cells with fresh or defrosted samples after 4 weeks at 4 degrees C or after 1, 3, 6, or 9 months at -20 degrees C. Conclusions: Long-term storage of autologous serum eyedrops at -20 degrees C does not affect the concentration of GF, simplifies clinical logistics, and reduces the frequency of blood extractions from the patients.