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-ß (TGF-ß1), 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 °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 °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-ß1, PDGF-AB, and albumin remained stable over the 4 weeks at 4 °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 °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 °C or after 1, 3, 6, or 9 months at -20 °C. CONCLUSIONS: Long-term storage of autologous serum eyedrops at -20 °C does not affect the concentration of GF, simplifies clinical logistics, and reduces the frequency of blood extractions from the patients.

Autologous serum eye drops diluted with sodium hyaluronate: clinical and experimental comparative study.

PURPOSE: To assess the efficacy of sodium hyaluronate as vehicle for diluting autologous serum. METHODS: The concentration and temporal stability of EGF, TGF-ß, PDGF-AB and albumin in fresh and frozen samples of autologous serum diluted with sodium hyaluronate and saline solution, as well as the pH, osmolarity and density was studied. In parallel, the clinic effects of autologous serum diluted to 20% with sodium hyaluronate were compared with another solution of autologous serum diluted to 20% with saline in a prospective, comparative, randomized and double-blind study in 26 patients (52 eyes) with Sjögren syndrome. Patients underwent a complete ophthalmic assessment including tear film evaluation and corneal and conjunctival impression cytology at the beginning of the study and 2 months later. RESULTS: The growth factor (GF) concentration remained stable during 1 month at 4°C both in fresh and defrosted samples without any differences being found between both preparations. No differences were found related to osmolarity, pH and density between these preparations before and after frosting. Autologous serum diluted with sodium hyaluronate caused a significant improvement of the tear film stability, fluorescein and rose Bengal stain, break-up time, corneal and conjunctival squamous metaplasia as well as in the patient subjective perception. CONCLUSIONS: Sodium hyaluronate is an excellent vehicle for diluting autologous serum due to the gradual release of GF and increasing their duration and effect on the ocular surface. Preparations diluted with sodium hyaluronate are better tolerated by patients and require a lower number of drops administrations.