Long term stability of preservative-free and lyophilized PRGF eye drops stored at different temperature conditions: in vitro comparative study

Long-term stability of blood-derived eye drops is required to adapt the use of this treatment to prolonged clinical treatments and more green pharmacy. This study has been designed to assess the long-term storage life of freeze-dried plasma rich in growth factors (PRGF) eye drops, maintaining their biological content and activity. Thus, blood from five healthy donors was extracted and centrifuged for obtaining PRGF. The obtained PRGF eye-drops after platelet activation were freeze-stored or were lyophilized and then stored for 18 and 24 months at room temperature (RT) or at + 5 °C. Growth factor content and proliferative potential of PRGF eye drops on primary human keratocytes (HK) was evaluated at each storage time and condition. All growth factors maintained their levels at each time and storage condition. No differences were observed on the proliferative activity of keratocytes after treatment with freeze-dried PRGF eye-drops stored at RT or +5 °C for 18 or 24 months in comparison with fresh samples. No microbial contamination was observed in any of the PRGF eye-drops. Accepting the limitations of this study, it is observed that freeze-dried PRGF eye drops retain both key growth factors and biological activity when stored at room temperature or +5 °C for up to 18–24 months.