Effects of L-carnitine and pentoxifylline on long-term preservation of the human sperms: An experimental study.

Background: In infertility clinics, long-time preserving high-quality spermatozoa is a challenging problem.

Objective: The present study aimed to prolong preserving of the human spermatozoa by adding pentoxifylline (PT) and L-carnitine (LC) without using high-cost freezing techniques.

Materials and methods: In this experimental study, semen samples of 26 normozoospermia men aged between 28-34 yr, were firstly prepared using the swim-up technique, and each sample was divided into the following 3 aliquots: untreated control group, the LC, and PT-treated groups. The samples were stored for up to 12 days at 4-6 C, and sperm motility was assessed. The percentages of the sperms with double-stranded DNA, apoptotic, and acrosomal interacted sperms were evaluated by sperm chromatin structure assay, AnnexinV-PI staining, and peanut agglutinin, respectively.

Results: On day 7, 26.83% $\pm$ 4.26 of sperms were motile in the PT group which was significantly more than LC (6.67% $\pm$ 0.61) and control (0.83 $\pm$ 0.17) groups (p $<$ 0.001). At day 12, while all sperms lost their motility in LC and control groups, adding PT led to 3.17% $\pm$ 0.47 sperms remaining motile (p $<$ 0.001). Moreover, on day 12, the percent of apoptotic sperms in the PT-treated group (8% $\pm$ 0.20) was significantly lower than in LC-treated group (5.9% $\pm$ 0.28, p = 0.03). None of the additives positively affected the number of sperms with double-stranded DNA (p $>$ 0.05). LC could also maintain acrosomal integrity over a storage time of up to 12 days.

Conclusion: Despite PT's improved sperm motility, LC was more efficient in preventing apoptosis and acrosomal reactions. However, DNA was resistant to denaturation regardless of the treatments.