Purpose To compare the expression profiles of Tektin 2 and CatSper 2 motility proteins in the spermatozoa of normozoospermic and oligoasthenozoospermic men and determine its correlation with sperm motility, fertilization rate, embryo quality and pregnancy rate. Methods Tektin 2 and CatSper 2 protein expression was studied using Western Blotting and immunofluorescence. Tektin 2 and CatSper 2 protein levels were quantified by ELISA. Results Oligoasthenozoospermic men were found to have lower fertilization rates, poor embryo quality and lower pregnancy rates as compared to normozoospermic men.The levels of Tektin 2 and CatSper 2 are significantly lower in spermatozoa of oligoasthenozoospermic men as compared to normozoospermic controls; the levels were also lower in immotile fraction as compared to motile fraction of spermatozoa obtained from normozoospermic individuals. The levels of Tektin 2 and CatSper 2 were higher in individuals demonstrating sperm motility >60 % as compared to sperm motility <30 %. Tektin 2 but not CatSper 2 levels were positively associated with fertilization rate, embryo quality and pregnancy rate. Conclusion Levels of Tektin 2 and CatSper 2 proteins are positively associated with sperm motility parameters. Measurements of Tektin 2 levels can be correlated with the clinical outcome of ICSI.

The urge to have one’s own biological child supersedes any desire in life. Several options have been used to obtain gametes including pluripotent stem cells (embryonic ES and induced pluripotent iPS stem cells); gonadal stem cells (spermatogonial SSCs, ovarian OSCs stem cells), bone marrow, mesenchymal cells and fetal skin. However, the field poses a huge challenge including inefficient existing protocols for differentiation, epigenetic and genetic changes associated with extensive in vitro manipulation and also ethical/regulatory constraints. A tremendous leap in the field occurred using mouse ES and iPS cells wherein they were first differentiated into epiblast-like cells and then primordial germ cell-like cells. These on further development produced sperm, oocytes and live offspring (had associated genetic problems). Evidently differentiating pluripotent stem cells into primordial germ cells (PGCs) remains a major bottleneck. Against this backdrop, we propose that a novel population of pluripotent stem cells termed very small embryonic-like stem cells (VSELs) may serve as an alternative, potential source of autologus gametes, keeping in mind that they are indeed PGCs surviving in adult mammalian ovaries and testes. Both VSELs and PGCs are pluripotent, relatively quiescent because of epigenetic modifications of parentally imprinted genes loci like Igf2-H19 and KCNQ1p57, share several markers like Stella, Fragilis, Mvh, Dppa2, Dppa4, Sall4, Blimp1 and functional receptors. VSELs are localized in the basement membrane of seminiferous tubules in testis and in the ovary surface epithelium. Ovarian stem cells from mouse, rabbit, sheep, marmoset and humans (menopausal women and those with premature ovarian failure) spontaneously differentiate into oocyte-like structures in vitro with no additional requirement of growth factors. Thus a more pragmatic option to obtain autologus gametes may be the pluripotent VSELs and if we could manipulate them in vivo – existing ethical and epigenetic/genetic concerns associated with in vitro culture may also be minimized. The field of oncofertility may undergo a sea-change and existing strategies of cryopreservation of gametes and gonadal tissue for fertility preservation in cancer patients will necessitate a revision. However, first the scientific community needs to arrive at a consensus about VSELs in the gonads and then work towards exploiting their potential.

HSP90 levels are downregulated in oligoasthenozoospermia, and its functional inhibition attenuates progesterone-mediated sperm motility and acrosome reaction.

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