Percoll

Percoll is a tool for more efficient density separation in biochemistry that was first formulated by Pertoft and colleagues.[2] It is used for the isolation of cells, organelles, and/or viruses by density centrifugation. Percoll consists of colloidal silica particles of 15–30 nm diameter (23% w/w in water) which have been coated with polyvinylpyrrolidone (PVP). Percoll is well suited for density gradient experiments because it possesses a low viscosity compared to alternatives, a low osmolarity, and no toxicity towards cells and their constituents.

Concentration of Plasmodium falciparum-infected erythrocytes by discontinuous density gradient centrifugation in Percoll.[1]

Percoll is a registered trademark of GE Healthcare.

Past use in artificial reproduction

Percoll was previously used in assisted reproductive technology (ART) to select sperm from semen by density gradient centrifugation, for use in techniques such as in vitro fertilization or intrauterine insemination. However, in 1996, Pharmacia sent out a letter to laboratories stating that Percoll should be used for research purposes only, not clinical. Pharmacia had not marketed it as a sperm preparation product; it had been repackaged and sold as such by third-party manufacturers. The FDA Warning Letter was due to concerns that PVP might cause damage to sperm (an unknown issue), and also that some batches of Percoll contained high levels of endotoxin (a known issue). The latter concern also applies to the use of Percoll with any other cells that might be injected back into a patient, since endotoxin can cause severe inflammation and fever. Since then it has been replaced with other colloids in the ART industry.[3]

References
  1. Rüssmann L, Jung A, Heidrich HG (1982). "The use of percoll gradients, elutriator rotor elution, and mithramycin staining for the isolation and identification of intraerythrocytic stages of Plasmodium berghei". Zeitschrift für Parasitenkunde. 66 (3): 273–280. doi:10.1007/BF00925344. PMID 6177116.
  2. Pertoft, H.; Laurent, T.C.; Laas, T.; Kagedal, L. (1978). "Density gradients prepared from colloidal silica particles coated by polyvinylpyrrolidone (Percoll)". Analytical Biochemistry. 88 (1): 271–282. doi:10.1016/0003-2697(78)90419-0.
  3. Mortimer, D (May–June 2000). "Sperm preparation methods". Journal of Andrology. 21 (3): 357–66. PMID 10819443. Retrieved 5 May 2010.
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