Objective: To identify an optimal back-flush solution for leukocyte-depleted filters that maximizes peripheral blood mononuclear cell (PBMC) recovery with high viability, long-term storage stability, and sterility of the harvested residues, thereby providing a clinically translatable strategy. Methods: Three sterile bag-packaged solutions—Saline, Solvent, and Hanks' balanced salt solution (HBSS)—were used to back-flush randomly assigned leukocyte-depleted filters. Nucleated cell recovery rate and viability of the harvested residues were compared. The optimal solution identified was applied to an expanded sample set. PBMC viability and yield were evaluated after 1h vs 48h storage of the residues. PBMCs isolated from the residues were cryopreserved in liquid nitrogen for 1 month, followed by post-thaw comparisons of viability and T-cell expansion capacity. Results: The Solvent group achieved the highest and most consistent nucleated cell recovery rate. Post-flush recovery rate from filters after 400 mL whole blood processing was (21.3±1.6)% for the Solvent group, significantly higher than Saline group (19.2±6.3)% and HBSS group (11.2±5.0)%, with residues from all groups maintaining viability >90%. No biologically significant difference in residue viability was observed between 48h vs 1h storage groups (93.3±2.3)% vs (95.7±1.8)%). PBMC recovery rates from residues showed no statistical difference between 48h vs 1h storage groups [(48.2%±9.5%)vs (40.41%±8.35%), P>0.05], with (17.7±2.6)×10 cells. After 1-month cryopreservation and 10-day expansion, PBMCs isolated from 48-hour-stored residues retained (91.2±3.2)% viability and achieved a (61.9±15.9)-fold expansion. Conclusion: The bag-packaged Solvent, as a back-flush solution, enables sterile acquisition of leukocyte-depleted filter residues through closed-system tubing connections. These residues maintained PBMC viability and recovery rates after 48h storage at 2℃-8℃, with post-cryopreservation (1-month liquid nitrogen) viability and expansion capacity remaining stable. This protocol complies with blood bank regulatory criteria, addresses the concerns about the infectious window period in cell therapy raw materials, and provides a clinically translatable strategy for PBMC-based applications.

【Objective】 To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue, so as to provide reference for future major events. 【Methods】 A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted. Ten emergency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones. The blood temperature during the drone flight were monitored, the cold chain control during drone flight was evaluated, and the application of drone flight was reviewed. 【Results】 During the Hangzhou Asian Games, a total of 14 drones were used for blood delivery. The delivery time(min) by drone from the blood station to one of the designated hospitals was 11.83±0.09, and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land delivery (P<0.05), meanwhile was 17.50±0.08, 24.50±3.27 and 26.57±3.23 respectively to the other hospital(P<0.05). Compared with land emergency blood delivery and routine blood delivery, blood delivery time by drone was much shorter, demonstrating better timeliness and stability. The temperature monitoring during the drone delivering showed that the suspended red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃, with a temperature difference of 0.5-0.9 ℃ and 0.2-1.0℃ between takeoff and landing respectively, demonstrating that the blood cold chain was under control, and the delivery ran safely and smoothly. 【Conclusion】 During major events, the use of drones for emergency blood delivery ensures the quality of the blood, with good timeliness, feasibility and operability, and is worthy of promotion and application.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.

Objective To explore the application of drones in blood emergency support during the 19th Asian Games Hangzhou in Shaoxing venue,so as to provide reference for future major events.Methods A retrospective analysis of drone delivery of emergency blood to two designated rescue hospitals in Shaoxing for the Asian Games was conducted.Ten emer-gency and 30 routine land blood delivery records from two designated hospitals in 2023 were randomly selected to compare with the blood delivery using drones.The blood temperature during the drone flight were monitored,the cold chain control during drone flight was evaluated,and the application of drone flight was reviewed.Results During the Hangzhou Asian Games,a total of 14 drones were used for blood delivery.The delivery time(min)by drone from the blood station to one of the designated hospitals was 11.83±0.09,and 20.80±3.29 by emergency land delivery and 23.23±3.54 by routine land de-livery(P＜0.05),meanwhile was 17.50±0.08,24.50±3.27 and 26.57±3.23 respectively to the other hospital(P＜0.05).Compared with land emergency blood delivery and routine blood delivery,blood delivery time by drone was much shorter,demonstrating better timeliness and stability.The temperature monitoring during the drone delivering showed that the suspen-ded red blood cells and platelets were in a range of 3.8-6.8℃ and 21.8-22.8℃,with a temperature difference of 0.5-0.9℃ and 0.2-1.0℃ between takeoff and landing respectively,demonstrating that the blood cold chain was under control,and the delivery ran safely and smoothly.Conclusion During major events,the use of drones for emergency blood delivery ensures the quality of the blood,with good timeliness,feasibility and operability,and is worthy of promotion and applica-tion.