Feasibility study of autologous blood-derived eye drops: comparison of autologous serum (AS) preparations versus plasma rich in growth factor (PRGF) preparations

Purpose
To evaluate the feasibility of autologous blood-derived eye drops needed by the ophthalmology department to treat drug-resistant severe dry eye.

Materials and methods
State the art of the practices of French University Hospitals (questionnaire survey), and from a literature review to compare autologous serum eye drops with PRGF preparations.

Results and discussion
26 University Hospitals were contacted among which 10 centers (9 hospital pharmacies and 1 cell therapy laboratory) out of the 12 producing autologous serum eye drops answered. 15 articles were found.
A search for viruses contaminations is carried out in 80% of cases every 6.5months (SD=2.95, range 3-12), and the patient’s consent is collected in 50% of cases.
The blood sample is taken by a nurse in the hospital ward, every 15weeks (SD=9, range 3-24). The number of tubes per patient is 12.17 (SD=3.43) with a total volume of 73.86mL (SD=24.58, range 40-120). In a French Blood Establishment, preparation is made from a blood donation of 200mL. The tubes are left to settle (70% of cases), for 4.83h (SD=9.39) at 17.80°C (SD=7.10, range 4-21) before centrifugation with 3500rpm (SD=2566) for 11.88min (SD=5.30) at 9.80°C (SD=7.79, range 4-21).
Preparation: serum was mostly filtered and diluted to 20% with Balanced Salt Serum. Sterility checks are performed on a sample of the preparation. Then eye droppers are usually delivered each 2 weeks (range 2-12). They are stored in pharmacy at -20°C until use for a maximum of 6 months, kept by patients at +4°C and mostly used for 7 consecutive days.
The eye droppers have a capacity of 4.2mL (SD=1.48, range 2-6). The conditioning is made of opaque white polyethylene or tinted glass.
According to the literature, the PRGF eye drops are produced from 19 blood collection tubes per patient, i.e. 171mL. Samples are centrifuged at 580g for 8min at room temperature. The supernatant is incubated at 37°C for 1h, and then heat treated at 56°C for 60min. The plasma supernatants are filtered, aliquoted and can be stored during 3 months at -20°C. Patients must keep them at +4°C and each vial is used during 3 days. Only 3 hospitals performed tests with the medical device ENDORET^®. According to their feedback, it is an unsecured (use of needles) and unsecure system: lack of reproducibility of the volumes distributed in the conditioning vials.

Conclusions
The great variability of SA eye drops preparation practices in France requires standardization. As for ENDORET^®, a system for automating the manufacture of PRGF eye drops, it is difficult at this stage to say, given the framework of learning a new technique, whether the non-reproducibility is due to an optimal number of manipulations not being reached, or inherent to the system.

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