Novel Approaches of Sperm Selection for ART: The Role of Objective Biochemical Markers of Nuclear and Cytoplasmic Integrity and Sperm Function

Abstract

With the technological advancements in assisted reproduction treatment, it is now feasible to cause fertilization and pregnancy by injection of a single spermatozoon into the oocyte via the ICSI method. The ultimate goal in this respect is the selection of a spermatozoon that has genetic and cellular attributes comparable to those sperm that interact with the zona pellucida under physiological or conventional IVF fertilization conditions. In light of this aim, this review focuses largely on objective biochemical markers within the nuclear and cytoplasmic compartment of spermatozoa, which define and reflect sperm developmental and genetic characteristics that are optimal for fertilization as well as for paternal contribution to the developing embryo. The ICSI sperm selection methods, including those based on hyaluronic acid binding and high-magnification visualization, are discussed along with the research evidence that supports the interrelated developmental and genetic integrity of the selected sperm. Furthermore, the review examines the use of other sperm diagnostics which may guide us in the treatment of male factor infertility patients. The diagnostic techniques examined include those focusing on the sperm nuclear integrity, in particular the Sperm Chromatin Structure Assay (SCSA). The fundamental information being generated from more molecular and biochemical-based analysis of sperm will create a basis for identifying key deficiencies in spermatozoa that might be implicated in the defective sperm function observed in a significant proportion of infertile males and may aid in both diagnosis and treatment.