| The therapeutic principle of hemorrhagic shock after injury is to perform blood transfusion as soon as possible,to prevent the failure of coagulation due to the dilution of coagulation factors.The red blood cells needed for blood transfusion,in addition to fresh blood from the donor,mostly come from the cryogenically stored blood in the blood bank.Either stored in fridge or cryopreserved,the red blood cells undergo storage damage,which leads to the quality reduction and aging of red blood cells,resulting in increasing the risk of death after clinical blood transfusion.The storage damage of red blood cell can be evaluated by measurement of the deformability of red blood cells.The deformability of red blood cells refers to the ability to use their own deformation during flow through narrow blood vessels.Focusing on the great demand of quality control of long-term storaged red blood cells and safety of blood transfusion,this study established an optical method to detect the deformability of red blood cells stored in vitro,which provided technical solutions for the screening of red blood cell storage conditions and for the quality monitoring of long-term storage of red blood cells.The content of this thesis can be summarized as the following parts:introduction of the basic principles of optical tweezers technology;building of a single-trap optical tweezers system,including the optical system design,key components selection,hardware control and system integration;calibration of the tweezers system,including the precise measurement of displacement,calibration of trap stiffness and measurement of tiny force;establishment of an optical-tweezers based dual-handle method and its application to the measurement of shear modulus of red blood cells.The red blood cells were stored in vitro for 5 weeks at 4?or with cryopreservation at-80?.For fresh erythrocytes and those stored at 4?for 1,2,3,4and 5 weeks,the shear modulus H of erythrocyte membranes was 8.4,10.76,11.35,11.46,11.85,and 12.25?N*m-1,respectively;design and establishment of the microfluidic-optical tweezers combining technique,and its application to the measurement of the long axis deformation index(?)of erythrocytes stored in vitro at4?for 5 weeks or at-80?with cryopreservation and rehydration.For fresh red blood cells and those stored at 4?for one to five weeks,the(?)was 11.68,11.02,8.31,8.17,8.04,and 8.33,respectively;the relation between deformability and the storage condition/time.The aging process of stored red blood cells was assessed.The measurement results of the two methods are in good agreement,providing a new reference technology for the screening of red blood cell storage conditions and the quality monitoring of long-term storage of red blood cells.The deformation of red blood cells was detected by optical tweezers with double handles,and the shear modulus of membranes of red blood cells after both storage at4°C and cryopreservation and rehydration was measured.In this technique,we focused on the changes in the amount of biconcave disc shaped cell membranes in RBCs stored in vitro.Our experiment results show that the changes in RBC moduli were mainly related to the morphology of RBCs in appearance.The shape of concave erythrocytes is similar to that of fresh erythrocytes,so there is a certain difference in the moduli of fresh erythrocytes and stored erythrocytes,but the difference is not linear.Our results strongly prove that the biconcave disc-shaped red blood cells stored for many weeks have similar membrane shear modulus and deformability to fresh erythrocytes and have a relatively close physiological state or physiological age.By establishing the optical tweezers-microfluidic combining technology,the deformability of ex vivo stored red blood cells can be characterized.Using this combined technique,the deformation index(?)of the long axis of cells after storage at 4°C and after cryopreservation and rehydration was compared,and the relation between this index and the deformability of stored erythrocytes was established.This technology is an important breakthrough in the high-throughput deformability detection of single red blood cells.Moreover,it is valuable to explore the combined technology for the detection of cryopreserved red blood cells.After the rehydration of cryopreserved cells,there is still a lack of in-depth research on the morphological changes and deformability of red blood cells. |
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