Novel method for the cryopreservation of testicular sperm and ejaculated spermatozoa from patients with severe oligospermia: a pilot study.

Objective: To investigate Volvox globator as an easy-to-handle vehicle and as a safe alternative for cryopreservation of functional motile sperm cells.

Design: Prospective, controlled, clinical pilot study.

Setting: Two in vitro fertilization (IVF) outpatient clinics for reproductive medicine.

Patient(s): Fifteen patients with severe male infertility (density <100 motile sperm per milliliter) who were recruited from two IVF programs. The sperm cells were not intended for clinical use after thawing.

Intervention(s): In each case, a predetermined number (n = 8) of motile and morphologically intact sperm cells were injected into each Volvox sphere and then cryopreserved. The quality of the sperm cells and the handling of the Volvox spheres were verified.

Main Outcome Measure(s): Postthaw recovery rate in cases of severe male infertility and the amount of motile sperm after thawing.

Result(s): The postthaw recovery rate was 100%. At least 60% of the sperm cells were motile after thawing.

Conclusion(s): The use of the spherical algae Volvox globator offers a promising, inexpensive, and easy approach to the cryopreservation of functional motile sperm cells. Volvox globator is an alternative in countries that prohibit the destructive use of oocytes, even after fertilization has failed.