title: Theoretical optimization of the removal of cryoprotective agents using a dilution-filtration system.
abstract: BACKGROUND
  In the cryopreservation of blood, removing cryoprotectants from the cryopreserved blood safely and effectively is always being focused on. In our previous work, a dilution-filtration system was proposed to achieve the efficient clearance of cryoprotectants from the cryopreserved blood.
  
  
  METHODS
  In this study, a theoretical method is presented to optimize the diluent flow rate in the system to further reduce the osmotic damage to red blood cells (RBCs) and shorten the washing time necessary to remove cryoprotective agents (CPAs), based on a discrete mass transfer concept. In the method, the diluent flow rate is automatically adjusted by a program code in each cycle to maximize the clearance of CPAs, whereas the volume of RBCs is always maintained below the upper volume tolerance limit.
  
  
  RESULTS
  The results show that the optimized diluent flow rate can significantly decrease the washing time of CPAs. The washing time under the optimized diluent flow rate can be reduced by over 50%, compared to the one under the fixed diluent flow rate. In addition, the advantage of our method becomes more significant when the blood flow rate is lower, the dilution region volume is larger, the initial CPA concentration is higher, or the cell-swelling limit set by the system is smaller.
  
  
  CONCLUSIONS
  The proposed method for the dilution-filtration system is an ideal solution for not only guaranteeing the volume safety of RBCs but also shortening the washing time of CPAs. In practice, the optimization strategies provided here will be useful in the rapid preparation of cryopreserved blood for clinical use.
authors.forename: Heyuan
authors.initials: H
authors.lastname: Qiao
authors.affiliation: Center for Biomedical Engineering, University of Science and Technology of China, Hefei, Anhui 230027, China. wpdings@ustc.edu.cn.
authors.forename: Weiping
authors.initials: W
authors.lastname: Ding
authors.forename: Sijie
authors.initials: S
authors.lastname: Sun
authors.forename: Liangquan
authors.initials: L
authors.lastname: Gong
authors.forename: Dayong
authors.initials: D
authors.lastname: Gao
mesh_terms: D001793:Blood Preservation / Q000379:methods; D015925:Cryopreservation / Q000379:methods; D003451:Cryoprotective Agents / Q000302:isolation & purification*; D004912:Erythrocytes / Q000737:chemistry; D006801:Humans; D008962:Models, Theoretical; D044967:Serum / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry
chemical_list: D003451:Cryoprotective Agents; D012996:Solutions