RESUMO
PURPOSE: To analyze the biological stability of autologous serum eyedrops after lyophilization. DESIGN: Prospective, comparative experimental study. METHODS: This was a comparative study with serum obtained from 12 healthy volunteers. The concentrations of different epitheliotropic factors (eg, transforming growth factor-ß [TGF-ß1], epidermal growth factor [EGF], platelet-derived growth factor AB [PDGF-AB], and albumin) were measured in fresh and lyophilized serum. The samples were studied after serum preparation (fresh serum) and immediately after saline solution reconstitution of lyophilized serum (0), 15, and 30 days later. The biological effects of both serum samples were also compared on conjunctival and corneal cell cultures. The pH, osmolarity, and serum density were also determined. RESULTS: No significant differences were found in the concentration of growth factors between fresh serum and re-dissolved serum samples after lyophilization. The concentration of growth factors remained stable during 1 month at 4°C in re-dissolved lyophilized form with saline solution. No differences were found related to osmolarity, pH, and density between fresh and lyophilized serum. In addition, no differences were found on the conjunctival and corneal cells proliferation and differentiation in cells cultures between either serum preparation. CONCLUSIONS: The properties of autologous serum remain after lyophilization. The lyophilized serum can be easily stored without temperature restrictions and easily reconstituted for preparation of eyedrops for standard clinical use.