PFA is superior to glyoxal in preserving oocyte, embryo, and stem cell proteins evidenced by super-resolution microscopical surveys of epitopes

• Published in: Journal of assisted reproduction and genetics 2020-02, Vol.37 (2), p.369-384
• Main Authors: Celikkan, Ferda Topal, Mungan, Ceren, Sucu, Merve, Uysal, Fatma, Kahveci Hayme, Selda, Hayme, Serhat, Kuscu, Nilay, Ozkavukcu, Sinan, Celik-Ozenci, Ciler, Can, Alp
• Format: Article
• Language: English
• Subjects: Animals; Embryo, Mammalian - drug effects; Embryo, Mammalian - immunology; Embryos; Epitopes; Epitopes - drug effects; Epitopes - immunology; Female; Fixatives; Fixatives - pharmacology; Formaldehyde - pharmacology; Glyoxal - pharmacology; Gynecology; Human Genetics; Humans; Immunocytochemistry; Immunohistochemistry; Immunoreactivity; Localization; Measuring techniques; Medicine; Medicine & Public Health; Mesenchyme; Mice; Microscopy; Oocytes; Oocytes - drug effects; Oocytes - growth & development; Oocytes - immunology; Polymers - pharmacology; Proteins; Reproductive Medicine; Somatic cells; Stem cells; Stem Cells - drug effects; Stem Cells - immunology; Stromal cells; Technological Innovations; Umbilical cord
• ISSN: 1058-0468; 1573-7330
• DOI: 10.1007/s10815-019-01666-9

Purpose Chemical fixation is a critical step to retaining cellular targets as naturally as possible. Recent developments in microscopy allow sophisticated detection and measuring techniques with which spatio-temporal molecular alterations are conceivable. In this study, we compare two members of aldehyde fixatives [i.e., glyoxal (Gly) and paraformaldehyde (PFA)] to determine whether Gly, a less toxic dialdehyde fixative that is considered to retain immunoreactivity could provide a successful and consistent cell fixation in favor of PFA in various cell preparations and types. Methods We document the fixation competence of Gly and PFA side-by-side (with or without Triton X-100 permeabilization) in live- and fixed-cell preparations in mouse oocytes, embryos, and human somatic cells (human umbilical cord-derived mesenchymal stromal cells) using protein quantification by Western blot assay and super-resolution microscopy. Results Although Gly seemed to act faster than PFA, catastrophic consequences were found not acceptable, especially in oocytes and embryos. Due to cell lysate and immunocytochemistry surveys, it was obvious that PFA is superior to Gly in retaining cellular proteins in situ with little/no background staining. In many samples, PFA revealed more reliable and consistent results regarding the protein quantity and cellular localization corresponding to previously defined patterns in the literature. Conclusion Although the use of Gly is beneficial as indicated by previous reports, we concluded that it does not meet the requirement for proper fixation, at least for the tested cell types and proteins. However, PFA alone with no addition of TX displayed a significant cytoplasmic loss by generating membrane blebs during fixation.