How to select healthy sperm for intracytoplasmic sperm injection in samples with high sperm DNA fragmentation?

 How to select healthy sperm for intracytoplasmic sperm injection in samples with high sperm DNA fragmentation?

Authors: Garrido et al. 

Panminerva Medica 2023 June;65(2):148-58
DOI: 10.23736/S0031-0808.23.04870-X

Preamble:

Selection of ICSI-viable sperm: a challenge?
High sperm DNA fragmentation (SDF) negatively impacts natural fertility and assisted reproduction conditions. It reduces fertilization rates, implantation, pregnancy, and live birth rates in in-vitro fertilization (IVF). Although SDF has no adverse impact on fertilization or pregnancy rates in intracytoplasmic sperm injection (ICSI), it is correlated with poor embryo quality and a higher risk of miscarriage. Techniques like magneticactivated cell sorting, intracytoplasmic morphologically selected sperm injection, physiologic ICSI, and microfluidic sperm sorters are used to select sperm with intact DNA for ICSI.
ICSI treatment is mainly optimized by the prior spermatozoa selection with intact DNA. However, long-term complications like sperm DNA fragmentation are unclear due to defective packaging during spermiogenesis, apoptosis, and oxidative stress. Sperm preparation procedures can reduce SDF rates, increasing spermatozoa with normal chromatin structure.

CAPSULE: 

This article reviews several methods used in sperm selection in cases with high SDF to be used in ART techniques.

Contributors: Alayman Hussein, MBBCH, MSc, MD, AF (Egypt) and Cesar Rojas-Cruz, MD, FECSM (Germany)

Magnetic-activated cell sorting MACS for non-apoptotic spermatozoa:
This technique excludes apoptotic sperm cells which express phosphatidyl-serine in their membrane using a column filter and exposition to a magnetic field after addition of annexin V coated with metallic microparticles. The result is a ready to use sample rich in non-apoptotic sperm. Suggested indication is infertile patients with high SDF, more than 2 failed ICSI trials and/or more than 2 miscarriages with an unknown female factor. Multiple studies have shown heterogeneous results with the use of MACS. The accumulated evidence does not support its clinical use.

IMSI (intracytoplasmic morphologically selected sperm injection):
Conventionally sperm to be injected for ICSI are selected based on motility and typical morphology using 200x to 400x optical magnification. More than 2 decades ago and alternative approach using ultra high magnification (6000X) was described. It allows selection based on subcellular organelles such acrosome, post acrosomal lamina, mid piece mitochondria, tail, and nucleus. A correlation has been described with the presence of sperm vacuoles and SDF. A great body of research has not shown clinically relevant differences using this selection technique.

Physiological ICSI (PICSI):
Studies evaluating use of selected sperm with Hyaluronic acid for ICSI have improved embryo quality and live birth rates. Hyaluronan-selected sperm has lower levels of SDF and aneuploidy. Recent studies have shown a possible effect on miscarriage using this approach.

Microfluidics:
Trying to mimic the natural shape of female reproductive tract, different systems of chambers and filters are used for sperm selection. This technique avoids the detrimental effects of conventional centrifugation which has been related with higher levels of SDF and ROS in the pellets.
Microfluidic based sperm selection devices have shown reduced amounts of SDF. Clinical impact has been evaluated with conflicting results.

Electrophoresis:
Using a membrane based electrophoretic purification technique sperm with low SDF could be isolated. The impact in clinical results had been discouraging.

Birefringence:
Using an inverted microscope with high power differential interference contrast optics sperm can be assessed. A total pattern of human sperm head birefringence is associated with higher SDF.

Testicular vs Ejaculate sperm:
Testicular sperm has lower SDF compared with ejaculated sperm (ES). It has been reported in observational studies that improved ICSI outcomes with testicular sperm compared with ES. TESE may be recommended for couples with repeated ICSI failures and high SDF, however, the quality of evidence is very low.

In conclusion, the current ability of these techniques to improve ICSI outcomes is suboptimal. Focused future research will probably give effective additional tools for the study and treatment of this subset of infertile couples with high SDF sperm.

Acknowledgment:
This commentary was co-authored by Professor Alayman Hussein (Egypt) and Dr. Cesar Rojas-Cruz (Germany).
We gratefully acknowledge the time and effort invested by them in summarizing this article.

Contributors profile:
Alayman Hussein, MBBCH, MSc, MD, AF
Professor and Chairman of Urology Department,
Minia University, Minia, Egypt
President of the Andrology Section of the Egyptian
Urological Association
www.alaymanclinic.com

Cesar Rojas-Cruz, MD, FECSM
Urologist/ Andrologist
Urology Department,
University of Rostock
Germany
www.cesarrojascruz.com