Density Gradient Medium for Cell Separation


PluriSelect offers ready-to-use density gradient media for the specific isolation of different populations of blood cells via single-step density gradient centrifugation. PBMC-Spin® with a density of 1.077 g/ml at room temperature is used for the isolation of PBMCs (peripheral blood mononuclear cells, containing lymphocytes and monocytes) from fresh sample material within 12 hours. Leuko Spin is optimized for the enrichment of all leukocytes from fresh sample material.

If you have to work with blood older than 12 or even 24 hours, we recommend using our PBMC24+ Spin, which is optimized for these conditions to reduce granulocyte contamination. For the isolation of monocytes or platelets from human blood, take a look at our Monocyte Spin and PLT Spin. Isn’t there the one for you? No problem! If you need a specific gravity for the isolation of animal blood or similar sample material, use our set of MSDS and DDM centrifugation media to mix any density between 1.0 and 1.1 g/mL.

How is cell density related to cell health and viability?

Cellular health is frequently measured with a variety of stains that interact with cells in different physiological states. For example, trypan blue is often used to distinguish living cells from dead cells. Trypan blue interacts with intracellular proteins in the cytoplasm of dead cells, giving them a dark blue appearance. However, trypan blue is excluded from living cells, which are observed to have clear cytoplasm easily distinguishable from dead cells.

Cells that are viable can be separated from those that have been damaged and are undergoing apoptosis, although not yet dead, by using markers. Scientists can assess the status of individual cells using a protein (Annexin V) that binds to exposed phosphatidylserine on the cell surface for apoptosis or dyes for DNA replication (ethidium monoazide or propidium iodide (PI)). which are indicative of cell division/proliferation.

What is the difference between cell mass and cell volume, the ratio of which makes up cell density?

Cell mass is the amount of matter that makes up a cell. Water makes up the bulk of a cell’s mass at about 70%. Cells are generally classified based on their content of organic macromolecules (lipids, carbohydrates, proteins, nucleic acids), which make up the majority of a cell’s weight. The organic macromolecule composition of a cell determines its basic chemistry and ultimately defines its structure and function and how it interacts with the outside world. While the inorganic ions of a cell are the least abundant in the 1% or less of the cell mass, they play an important role in cell metabolism and overall cell function.

Cell volume is a cellular characteristic defined as the amount of space a cell occupies. A balance between intracellular osmolarity and extracellular tonicity determines the volume of a cell that is controlled by the inflow/outflow of water for homeostatic function. Cell volume can define not only cell shape, but also modulate other cell functions such as cell proliferation, migration, and death. Apoptosis is related to volume contraction and changes in cell deformability.

How does cellular osmotic stress affect cell density and therefore cell function?

Regulation of cell volume is a critical function of cells. When cells are exposed to osmotically active environments, the normal cellular function is to maintain equilibrium through the regulation of osmotic stress. The movement of water by osmosis (in or out) alters the concentrations of intracellular macromolecules. These changes in extracellular osmolarity alter cell volume and therefore cell density. The inability to respond to an osmotic challenge can result in impaired function of a cell.

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