Methods and apparatus for isolating platelets from blood

Abstract

A platelet collection device comprising a centrifugal spin-separator container with a cavity having a longitudinal inner surface. A float in the cavity has a base, a platelet collection surface above the base, an outer surface. The float density is below the density of erythrocytes and above the density of plasma. The platelet collection surface has a position on the float which places it below the level of platelets when the float is suspended in separated blood. During centrifugation, a layer of platelets or buffy coat collects closely adjacent the platelet collection surface. Platelets are then removed from the platelet collection surface. Movement of a float having a density greater than whole blood through the sedimenting erythrocytes releases entrapped platelets, increasing the platelet yield.

Description

BACKGROUND [0001] 1. Field [0002] The present invention concerns apparatuses and methods for rapid fractionation of blood into erythrocyte, plasma and platelet fractions. Each fraction may be put to use or returned to the blood donor. Useful high concentration platelet fractions have platelet concentrations in excess of two times the concentration in anti-coagulated whole blood before processing of greater than 2×106 platelet / μL. The invention has particular value for rapid preparation of autologous concentrated platelet fractions to help or speed healing. [0003] 2. Description of the Prior Art [0004] Blood may be fractionated and the different fractions of the blood used for different medical needs. For instance, anemia (low erythrocyte levels) may be treated with infusions of erythrocytes. Thrombocytopenia (low thrombocyte (platelet) levels) may be treated with infusions of platelet concentrate. [0005] Under the influence of gravity or centrifugal force, blood spontaneously sedime...

AI Technical Summary

Benefits of technology

[0036] The present invention is directed to methods and apparatuses for simple and fast preparation of autologous platelet concentrates from whole anti-coagulated blood.

[0039] A further aspect of the invention is the use of a float having a density less than the density of the erythrocytes and greater than that of whole blood which rises through the mixture as the erythrocyte sediment during centrifugation, gently disrupting the erythrocytes to free trapped platelets, thus greatly increasing the platelet yield.

[0040] Another aspect of the present invention is that the apparatuses may be completely automated and require no user intervention between, first, loading and actuating the device and, second, retrieving the platelet concentrate.

[0042] Another aspect of the present invention is that bloods of different hematocrits and different plasma densities may be processed by the same apparatus.

[0045] Another aspect of the present invention is that the processing is rapid.

[0047] In one embodiment, the device includes a flexible inner tube, and a float is positioned within the flexible inner tube. The float has an outer surface in sealing engagement with the inner surface of the flexible tube in a neutral pressure condition, the sealing engagement preventing movement of fluid between the outer surface of the float and the inner surface of the flexible tube in the neutral pressure condition. The outer surface of the float disengages from contact with the inner surface of the flexible tube in an elevated pressure condition, thus enabling movement of fluid between the outer surface of the float and the inner surface of the flexible tube in the elevated pressure condition as well as free movement of the float within the tube. The float has a platelet receptor cavity positioned to be at the position of platelets in separated blood after centrifugation. The float has a channel communicating with the platelet receptor cavity for removing separated platelets therefrom after centrifugation. In one configuration, the float comprises a proximal segment having a distal surface and a distal segment having a proximal surface opposed to the distal surface, the distal surface and the proximal surfaces defining the platelet receptor cavity. Preferably, the outer container includes a port for introducing blood into the inner tube at the beginning of a platelet separation process and for removing platelets from the platelet cavity within the inner tube at the end of the platelet separation process. Optionally, the port includes a syringe coupling Luer locking device. The outer container can have an inner surface for restraining expansion of the inner tube during centrifugation.

Problems solved by technology

Platelets are the most difficult to isolate and purify.

It is believed that centrifugation can damage the platelets by sedimenting the platelets against a solid, non-physiological surface.

The packing onto such a surface induces partial activation and may cause physiological damage, producing “distressed” platelets which partially disintegrate upon resuspension.

Such long times are not considered to be practical and economical for intra-operative autologous applications.

In this first attempt complete separation between the different cellular components could not be achieved, at least not in one step because of considerable overlap in the presence of platelets, leukocytes and erythrocytes in the fractions collected after different centrifugation times and speed.

It was shown the white cells negatively affect platelet storage and may induce adverse effects after transfusion due to cytokine formation.

Removal of leukocytes (leukoreduction) from PRP and PC is a major problem because non-self leukocytes (allogeneic leukocytes) and the cytokines they produce can cause a violent reaction by the recipient's leukocytes.

Therefore, much of the prior art focuses on leukoreduction of platelet concentrates because non-autologous leukocytes excite deleterious immune reactions.

The use of autologous platelets obviates the requirement for time-consuming screening tests.

The autotransfusion equipment used to make autologous platelet concentrates requires a skilled operator and considerable time and expense.

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