Methods for enriching CD34.sup.+ human hematopoietic progenitor cells

A method of enriching CD34.sup.+ cells from a cell mixture, comprising:

• layering a cell mixture containing fetal cells into a centrifuge tube, said tube containing a density gradient solution having an osmolality of 280.+-.10 mOsm/kg H.sub.2 O and a specific density of 1.0605.+-.0.0005 gr/ml;
• centrifuging said tube at a gravitational force sufficient to pellet cells having specific densities greater than 1.0610 gr/ml;
• and
• collecting an enriched population of CD34.sup.+ cells from an interface above the density gradient solution.

A centrifugation tube, comprising:

• a tube adapted for centrifugation having a first closed end defining an inner bottom wall and an opposite open end;
• an annular member disposed in said tube and defining an opening therethrough, wherein said opening has an area less than the area of a cross section of said tube, said annular member defining a lower portion of the tube extending between said
• member and the tube bottom wall and an upper portion above said annular member;
• and
• a density gradient solution having a density of 1.0605.+-.0.0005 gr/ml, and filling said lower portion and a part of said upper portion.

A centrifuge syringe comprising:

• a generally cylindrical container adapted for centrifugation, having an inner wall, a first end and a second end, said first end and second end each defining central orifices;
• a hollow needle secured to the first end by a detachable connection and communicating with said first end orifice;
• a plunger adapted to be slideably positioned within said container, said plunger comprising a cylindrical housing having a bottom wall and a top wall defining therebetween a fluid receiving space, said top wall formed by an annular member defining an opening;
• a circumferential seal around said cylindrical housing cooperating with said container inner wall to substantially prevent fluid passage therebetween;
• a handle removably connected to said plunger and adapted to move longitudinally through the central orifice of the second end of said container;
• and
• density gradient material having a density of 1.0605.+-.0.0005 gr/ml disposed within said fluid receiving space and extending above said annular member.

A method of extracting and centrifuging a fluid specimen utilizing a syringe including an outer container with an inner plunger having a bottom wall joined to a top wall defining therebetween a fluid space, said top wall formed by an annular member having an opening, and said bottom wall connected to a handle, comprising the steps of:

• filling said fluid space and syringe with a density gradient material having a density of 1.0605.+-.0.0005 gr/ml to a level above said top wall;
• drawing a sample into the container and on top of the density gradient material by pulling said handle;
• removing the handle from the plunger;
• placing the syringe in a centrifuge;
• applying centrifugal force to said syringe;
• and
• removing at least a portion of said sample remaining above the annular member after applying centrifugal force.