Capacitation is the natural process occuring in the female’s Fallopian tubes during which spermatozoa undergo the final steps necessary for fertilization. Proteins, steroid hormones and cell-to-cell signaling from the female control this process, which can be replicated in part by incubating sperm under the right conditions for at least several hours in vitro. Our research shows that a critical step in capacitation is the loss of membrane cholesterol, facilitated by Cholesterol ester Transfer Protein (CETP or LTP-1). CETP is found in the Fallopian tubes of all mammals we have studied, and is an active contaminant in some human serum albumin preparations.
Capacitating sperm change in their motility pattern, surface charge, distribution of membrane lipids and proteins, internal calcium and pH, phosphorylation of tyrosine amino acids, activation of signaling cascades and in other ways still under investigation. Some of these changes may be used to detect capacitation and to diagnose capacitation defects.
Spiraling motility and Hyperactivation are detected by computerized analysis of motility.
Acrosome reaction, which may be considered an end-point of capacitation, is an established sperm function test. Membrane changes include the migration of lipid rafts containing ganglioside GM1; a test for this is performed by Androvia Life Sciences (CapScore ™). Our lab offers a portal to Androvia’s test, which may be combined with other in-house tests for capacitation.
