Zeta potential vs apoptotic marker: which is more suitable for ICSI sperm selection?

Purpose: Selection of appropriate sperm is considered as a decision making point in the ICSI procedure. Canonically, sperm selection is based on morphology and motility. Recent advances in this field, have shown that, this procedure can be assisted by further selection based on membrane surface charge (Zeta potential) and surface apoptotic marker (phosphatidylserine externalization) using magnetic activated cell sorter (MACS). Based on the literature, both these procedures improve quality of selected sperm population. Therefore, this study aims to compare the efficiency of these two procedures.
Methods: Semen samples were collected from 36 fertile and infertile (teratozoospermic and /or asthenozoospermic) individuals. Sperm DNA fragmentation, protamine deficiency and morphology were assessed by TUNEL, CMA3 and papanicolaou staining in unprocessed, MACS and Zeta processed samples.
Results: Although both MACS and Zeta were able to separate a higher percentage of sperm with normal morphology, and lower DNA fragmentation and protamine deficiency compared to unprocessed, MACS procedure could significantly isolate, a greater percentage of sperm with normal acrosome and protamine content compared to Zeta procedure.
Conclusion: Both MACS and Zeta procedures improve the quality of the selected spermatozoa for ICSI. However, MACS procedure is more efficient in individuals with severe male factor infertility to select sperm with normal acrosome and protamine content but concern regarding transfer of MACS beads into the oocyte remains to be resolved.