Phosphatidylcholine and L-acetyl-carnitine-based freezing medium can replace egg yolk and preserves human sperm function

Fernanda Sicchieri; Aline Bomfim Silva; Viviane Paiva Santana; Maria Aparecida Carneiro Vasconcelos; Rui Alberto Ferriani; Alessandra Aparecida Vireque; Rosana Maria Dos Reis

doi:10.21037/tau-20-1004

Phosphatidylcholine and L-acetyl-carnitine-based freezing medium can replace egg yolk and preserves human sperm function

Transl Androl Urol. 2021 Jan;10(1):397-407. doi: 10.21037/tau-20-1004.

Authors

Fernanda Sicchieri¹, Aline Bomfim Silva¹, Viviane Paiva Santana¹, Maria Aparecida Carneiro Vasconcelos¹, Rui Alberto Ferriani^{1

2}, Alessandra Aparecida Vireque³, Rosana Maria Dos Reis^{1

2}

Affiliations

¹ Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
² National Institutes of Hormones and Woman's Health, CNPq, Brazil.
³ Invitra - Assisted Reproductive Technologies Ltd., Supera Innovation and Technology Park, Ribeirão Preto, São Paulo, Brazil.

Abstract

Background: Conventional cryopreservation methods induce chemical and mechanical damage to the sperm membranes. The cryoprotectant potential of phospholipids of vegetal origin as soybean lecithin has been investigated as a substitute for egg yolk in diluents used for the cryopreservation of human spermatozoa. Therefore, the objective of this study was comparing the efficacy of a synthetic cryoprotectant supplemented with L-α-phosphatidylcholine (PC) and L-acetyl-carnitine (ANTIOX-PC) and the standard egg-based TEST-yolk buffer (TYB) in preserving sperm motility and chromatin quality in cryopreserved semen samples.

Methods: Prospective experimental study in which semen samples from 63 men with normal sperm motility and 58 men with low sperm motility were included and analyzed both before and after cryopreservation using ANTIOX-PC or TYB freezing media. Sperm quality was evaluated by routine semen analysis and DNA fragmentation index using the Terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

Results: Differences in the post-thaw progressive motility and DNA fragmentation index were not detected between TYB and ANTIOX-PC cryoprotectants in both normal and low sperm motility groups (P>0.05). However, ANTIOX-PC medium retained higher non-progressive motility and lower percentage of immotile sperm when compared to TYB medium, resulting in a greater total motile sperm count (P<0.05), regardless baseline values of motility characteristic of the normospermic or asthenozoospermic samples.

Conclusions: ANTIOX-PC medium was effective to protect human sperm during a freeze-thaw cycle compared to the TYB medium. A clinically relevant advantage in better preserving kinetic parameters as higher total motility and lower immotile post-thawed sperm from ANTIOX-PC, in normal and low motility semen samples, demonstrated the positive impact of phospholipid and antioxidant treatment on sperm cryotolerance with high potential for egg yolk lipids replacement and biosafety.

Keywords: DNA fragmentation index; L-acetyl-carnitine; Lα-Phosphatidylcholine; Sperm cryopreservation; progressive motility.