cell dose for transplanting the 75‐kg recipient. These numbers were obtained by processing approximately 10 L of whole blood, and most centers now process 15–20 L. Other reports involving processing of 15–20 L of blood for each cytapheresis procedure suggest that larger numbers of CD34+ cells are obtained [114]. Thus, currently for most donors, one or two procedures result in a dose of cells suitable for transplantation.
Storage of peripheral blood stem cells
Because of the variability in the number of cells that may be obtained, the strategy for using the cells for transplantation cannot always be the same. If the dose needed for transplantation can be obtained with one procedure, the cells can be transfused immediately. However, if two or three apheresis procedures are necessary, it may be desirable to freeze the concentrates and transfuse them all at once. However, the freezing and thawing may alter the composition of the PBSC concentrates, and so some transplant physicians give the cells fresh each day until the desired dose is obtained. Alternatively, the concentrate collected on the first day is stored in the liquid state and transfused with the concentrate collected on the second day. It appears that PBSCs can be preserved satisfactorily in Plasmalyte A, Normosol or STM‐Sav for 24 hours at room temperature [125]. A more extensive discussion of hematopoietic stem cell preservation is provided in Chapter 19.
Figure 6.3 CD34+ cell yield in peripheral blood concentrates collected from normal donors.
(Source: Reproduced with permission from Stroncek DF, Clay ME, Smith J, et al. Composition of peripheral blood progenitor cell components collected from healthy donors. Transfusion 1997; 37:411–417. © 1997 John Wiley & Sons. Reproduced with permission of John Wiley & Sons.)
6.7 Donor selection and complications of cytapheresis in normal donors
Because donation of blood components by apheresis is fundamentally different from whole blood donation, there are some donor eligibility requirements and complications that are unique to apheresis donors. This chapter focuses on the donation procedures and the products. Donor selection and complications are discussed in Chapter 4.
6.8 Plasmapheresis and source plasma
The plasma collection and fractionation industry in the United States developed during the 1960s using manual plastic bag methods for plasma collection by plasmapheresis. Today, virtually all source plasma collected in the United States for fractionation into derivatives (see Chapters 2 and 5) is obtained by semiautomated instrument plasmapheresis. It has been estimated [126] that about 28 million liters of plasma are fractionated annually in the world (see Chapter 2). Most plasma used as fresh frozen plasma (FFP) is obtained from whole blood, but the increasing flexibility of some apheresis instruments makes it possible to obtain plasma for FFP as a by‐product of platelet or red cell apheresis. There are no data on the number of plasma products produced in this manner. Apheresis plasma contains greater activities of factor V, factor VIII, factor IX, and factor XI, prothrombin fragments 1 and 2, and platelet factor IV compared with recovered plasma (see Chapter 4 and Burnouf [126] and Runkel et al. [127]). Thus, apheresis appears to produce plasma with a higher quality, although the clinical significance of this is not established.
Source plasma is the starting material for the further manufacture of some diagnostics and plasma “derivatives.” Derivatives are described in more detail in Chapter 2, and the selection and medical evaluation of plasma donors are described in Chapter 4. Plasmapheresis was done using sets of multiple plastic bags and involved separation of the blood from the donor such that there was a chance for return of red cells to the incorrect donor. Source plasma is now collected by semiautomated instruments that require less operator involvement, while producing larger amounts of plasma at a reasonable cost. Usually one venipuncture is used, and the system can be set up in about 5 minutes. This includes loading the disposable plastic set into the instrument, connecting the anticoagulant and solution bags, recording appropriate data, and placing the collection bags. The venipuncture area is prepared as for whole blood collection (see Chapter 4), and the venipuncture is done using the needle integral with the disposable plastic set used for the procedure. The operator then activates the instrument, and blood flow is initiated by the pumps in the instrument. Anticoagulant is metered into the blood flowing into the instrument in the proper ratio, and the centrifuge bowl is filled until the optical sensor detects the red cell interface and stops the inflow of blood. During this filling phase of the cycle, the plasma has been diverted into the collection bag. After the plasma–cell interface has reached the detector, the blood flow is reversed and the red cells are pumped from the bowl back to the donor. The cycle is then repeated until the desired amount of plasma is obtained. Usually about 500 mL of plasma can be obtained in about 30 minutes [128]. These instruments might be used to produce FFP but are not used extensively to produce source plasma.
The Fresenius Kabi Autopheresis C (Auto‐C) and Aurora plasmapheresis instruments operate on a different principle from the Haemonetics devices. The Autopheresis C combines filtration and centrifugation to separate blood in a smaller chamber (and possibly more efficiently). The instrument setup and donor preparation are the same as described for the Haemonetics systems and for whole blood collection. In these systems, blood is withdrawn from the donor into a closed, disposable plastic set with a total extracorporeal volume of about 165 mL. Blood separation occurs in a small, 7‐mL (Auto C or Aurora) or 15‐mL (Aurora Xi) cylinder that is part of the system. A magnet causes rotation of the cylinder inside a larger compartment. The cylinder is composed of a membrane, and as the cylinder rotates, plasma moves peripherally through the membrane, thus providing the filtration part of the separation system. The system does not operate in a continuous‐flow manner; blood is returned intermittently to the donor through the single venipuncture and the process is repeated. The Auto‐C system collects about 500 mL of plasma in about 30 minutes [129, 130]. The Aurora Xi is slightly more efficient; however, both systems are used extensively for the production of source plasma for further manufacture of plasma derivatives.
References
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2 2. Kliman A, Gaydos LA, Schroeder LR, Freireich EJ. Repeated plasmapheresis of blood donors as a source of platelets. Blood 1961; 18:303–309.
3 3. McCullough J. Introduction to apheresis donations including history and general principles. In: McLeod B, Price T, Weinstein R, eds. Apheresis: Principles and Practice, 2nd edn. Bethesda, MD: AABB Press, 2003, pp. 29–48.
4 4. Tullis JL, Tinch RJ, Baudanza P, et al. Plateletpheresis in a disposable system. Transfusion 1971; 11:368–377.
5 5. Graw RG, Herzig GP, Eisel RJ, Perry S. Leukocyte and platelet collection from normal donors with the continuous flow blood cell separator. Transfusion 1971; 11:94–101.
6 6.
