PLATELET CONCENTRATES FOR TRANSFUSION - METABOLIC AND STORAGE ASPECTS

Transfusion of platelets concentrated from donated blood is an establi shed therapeutic modality in clinical medicine. Over the past 25 years much effort has gone into optimising the conditions for the collectio n, preparation and storage of platelets for transfusion. Despite signi ficant advances, platelet production is still a costly process requiri ng a dedicated environment and the use of specially formulated plastic storage containers. A progressive lesion over storage limits the shel f life and the availability of donated platelets, while the need to st ore platelets in the donor's autologous plasma also results in a loss of valuable fresh plasma for fractionation. Recent studies have addres sed the issues of platelet quality and plasma economy by examining the possibility of storing platelets in a synthetic medium. Platelets sto red in a variety of crystalloid solutions have been shown to retain in vitro and in vivo properties equivalent or superior to platelets stor ed in autologous donor plasma. Some additional insight has been gained on the metabolic patterns of stored platelets. In particular, studies have shown that, under these conditions, platelets are unable to oxid ise dextrose to any significant extent, and that dextrose is invariabl y broken down to lactate, irrespective of the oxygen tensions in the p latelet's environment. This in turn leads to the metabolic lesion of p latelet storage, whereby low pH results in loss of platelet viability. Platelets stored in synthetic dextrose-free media are capable of main taining aerobic ATP generation, and acetate-a component of many media studied-has been shown to be metabolised by platelets. Similarly, plat elets prepared from blood collected into a dextrose-free anticoagulant have satisfactory properties both when suspended in autologous plasma or in a dextrose-free synthetic medium. The requirements for storage in special, high gas-permeable, containers, and for constant agitation during storage, were both found to be unnecessary when dextrose was e xcluded from the platelet's environment. These developments suggest th at manipulation of the platelet's metabolic pattern during blood bank storage may allow significant benefits in plasma economy as well as in decreasing the cost of platelet delivery to patients.