Ficoll

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Ficoll is a neutral, highly branched, high-mass, hydrophilic polysaccharide which dissolves readily in aqueous solutions. Ficoll radii range from 2-7 nm. It is prepared by reaction of the polysaccharide with epichlorohydrin.

Ficoll columns are used in biology to separate blood to its components (erythrocytes, leukocytes etc.) Ficoll is normally placed at the bottom of a column, and blood is then slowly layered above the ficoll. After being centrifuged, the following layers will be visible in the column, from top to bottom: plasma and other constituents, mono-nuclear cells (MNC), ficoll, and erythrocytes & granulocytes which should be present in pellet form. This separation allows easy harvest of MNC's. Note that some red blood cell trapping (presence of erythrocytes & granulocytes) may occur in the MNC or ficoll layer. Major blood clotting may sometimes occur in the MNC layer. Ethylene diamine tetra-acetate (EDTA) is commonly used in conjunction with ficol separation to prevent clotting.

Ficoll can also be used to separate islets of Langerhans from pancreatic tissue. The separated islets can then be used for transplantation into patients with type 1 diabetes

Because Ficoll layering is a very slow process, similar products which include a column containing a porous high-density polyethylene barrier or "frit" have been developed. These products allow blood to be layered on much more quickly without mixing the Ficoll-like polysaccharide and blood. An example of such a product is the "Accuspin System Histopaque-1077" sold by Sigma Aldrich. It is important to note that the cost of these products is significantly higher than basic Ficoll products.

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