System and method for obtaining a cellular sample enriched with defined cells such as platelet rich plasma (PRP)

A method for obtaining plasma enriched in platelets, comprising:

• filling a collection tube containing an anticoagulant and a gel polymer based on polyolefin with a specific gravity in a range of 1.04 to 1.09 g/cm3, and having at least one stopper for maintaining said collection tube closed to the atmosphere, with whole blood;
• separating the whole blood in the collection tube by centrifugation to obtain a first fraction of red blood cells, sediment and granulocytes;
• a second fraction of the gel;
• a third fraction of plasma enriched in platelets;
• and a fourth fraction of plasma depleted in platelets;
• collecting with a first collection syringe a portion of the fraction of plasma depleted in platelets;
• discarding the portion collected with the first collection syringe;
• resuspending the third fraction of plasma enriched in platelets;
• and
• extracting the plasma enriched in platelets with a second collection syringe while said collection tube remains closed to the atmosphere;
• wherein
• said plasma enriched in platelets contains white blood cells at a concentration less than 50% of the concentration in the whole blood.