Platelet Concentrates in an Additive Solution Prepared from Pooled Buffy Coats

Abstract

A new method for the preparation of platelet concentrates (PCs) is described. The source material is buffy coat (BC), prepared after keeping standard CPD whole-blood units at room temperature for 6-12 h, followed by centrifugation at 3,500 rpm for 10 min (first series) or 4,000 rpm for 12.5 min (second series). BC, separated from plasma and red cells, was kept at room temperature for a further 8-12 h without agitation. Pools of 6 (first series) and 4 (second series) BCs were prepared using a sterile docking device and suspended in a platelet-additive solution (PAS) containing sodium/potassium chloride, citrate, phosphate, and mannitol. After gentle centrifugation, the platelet-rich supernatant was expressed to and stored in one (first series) or two (second series) 1-liter polyolefine (PL-732) containers. In the first series, the total number of platelets was 316 ± 59 x 10(9) per PC (yield 65%). However, when the method was applied at a routine scale, the yield varied considerably and was shown to be strongly dependent on the hematocrit of the BCs. A number of steps were taken to standardize the technique which resulted in an improved yield (77.3 ±8.7%) with 316± 52x10(9) platelets (mean ± SD, range 203-490, n = 134), obtained from 4 BC pools and lower leukocyte contamination than before, 18 ± 17xl0(6) per preparation (range 1-73, microscopic counting, n = 38). The storage medium consisted of a mixture of plasma and PAS. Standardization of the hematocrit and volume of the BCs is essential, both for improvement of the yield and for providing a sufficient amount of glucose and bicarbonate to the platelets throughout storage. The method is particularly suitable in combination with automated techniques for blood component preparation which include BC removal. Blood gases, pH and adenosine triphosphate were maintained at satisfactory levels; the release of platelet factor 4 and lactate dehydrogenase was not different from traditional PC preparation and storage. However, the content of glucose was exhausted in many PC units towards the end of a storage of 6 days. When whole blood and BC are stored for such a long period, and when the gas permeability of their containers is poor, it is important, in order to avoid early loss of swirling, that the surface-to-volume ratio and the gas permeability of the PC containers is sufficiently large to allow good gas exchange.

Storage of pools of six and eight platelet concentrates

“…The platelet counts were reduced by less than 5 percent during the storage of the pools and the single units (Day 1 through Day 5). For pools manufactured with 8 units, the mean platelet count was reduced from 6.38 (+ 0.82) to 6.22 ( 2 0.86) x 10".…”

The quality of platelets after storage for 7 days

“…However, in a recent multicentre study of pathogenreduced PCs, in the control arm, PCs were a mix of those stored in plasma or PASII, yet there was no significant difference in 1 or 24 h CCI between PC storage media used (van Rhenen et al, 2003). CCIs following transfusion of 5-day-old PCs to thrombocytopenic patients are reported to be similar for PCs stored in plasma or PASI, although in this study, the type of PCs differed between groups (Eriksson et al, 1993). The data on PCs stored in PAS are therefore mixed, and it is unclear whether they are as good or more efficacious than plasma for extended storage.…”

Apheresis‐induced platelet activation:comparison of three types of cell separators

“…Upon ADP stimulation, PCs from the Amicus (90-min) and the Spectra showed reduced response, from 25 (range, 22-27) and 28 (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) percent aggregates in whole blood to 11 (9-15) and 14 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) percent aggregates in PCs (p = 0.004 and p = 0.016), respectively, whereas PCs from the MCS+ responded at the same level as did platelets in whole blood: 27 (24-29) versus 28 (20-42) percent aggregates. The Amicus PC component after 45 minutes' harvest time also showed reduced ADP response, from 27 (22)(23)(24)(25)(26)(27)(28)(29)(30) to 14 (7-31) percent aggregates, although this difference was not significant. Upon strong platelet agonist (TRAP) stimulation, only platelets from the Amicus 90-minute apheresis procedures showed reduced response, from 33 (31-35) percent aggregates in whole blood to 24 (14-31) percent aggregates in PCs (p = 0.003).…”

“…It is surprising that single-donor apheresis PCs harvested on the Amicus for 90 minutes showed as much platelet degranulation as did PCs produced from four buffy coats. 28 Moreover, the platelet degranulation responses to in vitro ADP and TRAP stimulation were measured. The Amicus (90-min) PC component showed reduced response as compared to both preapheresis values and values in the other PC groups, with regard both to α-granule release (Fig.…”