Definition: A component derived from fresh whole blood that contains the most of the original platelet content in a therapeutically effective form.

Properties: Depending on the method of preparation, the platelet content per single unit equivalent will vary from 45 to 85 x 109 in 50 to 60 ml suspension medium. Leucocyte content will vary from 0.05 to 1 x 109 and red cells from 0.2 to 1 x 109 per SUE.

Methods of preparation:

1) Preparation of Platelet rich plasma: where a unit of fresh whole blood of not more than 24hrs, kept at +22 degrees celcius (+2 degrees celcius), is cryofuged so that an optimal number of platelets remain in plasma while the leucocytes and red cells are reduced to a minimum.

2) Preparation of platelets from Platelet rich plasma: Platelets in PRP are sedimented by hard spin centrifuge. The Platelet poor plasma (PPP)/supernatant is removed leaving only 50-70mls of PPP with the platelets concentration. The platelets are allowed to disaggregate and then resuspended.

3) Preparation of platelets from buffy coat: Whole blood stored between +20 degrees celcius to +24 degrees celcius for up to 24 hours is centrifuged so that platelets are sedimented in the buffy coat layer together with the leucocytes. A pool of same blood grouped buffycoats are further processed to seperate the platelets from the redcells and leucocytes, filtered and suspended in an additive nutrient solution.

Storage & Stability: Platelets must be stored in plastic bags intended for platelet storage having the characteristic of being permeable to gases for oxygen availability for platelets. During storage pH must remain between 6.8 to 7.4 and they must be continuously aggitated in an appropriate equipment, with a temperature of between +20 degrees celcius to +24 degrees celcius . Platelets can be stored for 5 days under the above parameters.