Artificial activation of sperm motility in vitro.

AIM: The sperm activation method is a modern methodological approach that is used more and more often in practice. The number of studies focused on methods of artificial activation of human sperm motility are constantly increasing. Standard sperm selection methods can fail in some cases, among other things, because very young sperm are isolated that have not yet completed their development. In these cases, artificial stimulation of their movement can have a positive effect and greatly facilitate and faster the process of selecting suitable sperm. Methylxanthines are most often used as activating agents. However, opinions on the safety of using these substances on sperm are not uniform. The aim of the thesis is to present current knowledge about artificial activation of sperm motility for in vitro fertilization and subsequent embryonic development. METHODOLOGY: Research of relevant literature in Web of Science, Scopus, PubMed/Medline databases. RESULTS AND CONCLUSION: The literature analysis shows that this method is safe and effective in the selection of immotile spermatozoa. Scientific studies have been conducted to verify the safety and reliability of this method. The conclusion of these studies is the positive impact of this method of selection, especially in cases of sperm obtained from testicular tissue after method testicular sperm extraction. In these cases, the method of artificial sperm activation facilitated and accelerated the selection of sperm before intracytoplasmic sperm injection. Undamaged spermatozoa, which are immobile due to incomplete maturation, were activated.

Human cells with osteogenic potential in bone tissue research.

Bone regeneration after injury or after surgical bone removal due to disease is a serious medical challenge. A variety of materials are being tested to replace a missing bone or tooth. Regeneration requires cells capable of proliferation and differentiation in bone tissue. Although there are many possible human cell types available for use as a model for each phase of this process, no cell type is ideal for each phase. Osteosarcoma cells are preferred for initial adhesion assays due to their easy cultivation and fast proliferation, but they are not suitable for subsequent differentiation testing due to their cancer origin and genetic differences from normal bone tissue. Mesenchymal stem cells are more suitable for biocompatibility testing, because they mimic natural conditions in healthy bone, but they proliferate more slowly, soon undergo senescence, and some subpopulations may exhibit weak osteodifferentiation. Primary human osteoblasts provide relevant results in evaluating the effect of biomaterials on cellular activity; however, their resources are limited for the same reasons, like for mesenchymal stem cells. This review article provides an overview of cell models for biocompatibility testing of materials used in bone tissue research.

Assisted oocyte activation.

OBJECTIVE: Currently, there is a rapid increase in studies on assisted oocyte activation, which can significantly improve the process of in vitro fertilization. Fertilization of oocytes by conventional methods and by intracytoplasmic sperm injection can be affected by insufficient activation of the oocyte. The reason is mainly deviations in the enzymatic equipment of sperm or oocytes or a non-functional activation cascade. In many cases, fertilization can be achieved using artificial oocyte activation by applying calcium ion donors to the oocytes after sperm microinjection. However, opinions on the safety and reliability of this method are not uniform. The aim of the thesis is to present current knowledge about assisted oocyte activation and its impact not only on in vitro fertilization, but also on subsequent embryonic and fetal development. METHODOLOGY: Research of relevant literature in Web of Science, PubMed/Medline and Scopus databases. RESULTS AND CONCLUSIONS: Based on the literature data and the authors' own experience, it follows that this method is effective and safe from the point of view of further development of the embryo, fetus and postnatal development. Extensive meta-analyses focused on this method were carried out, which did not find a negative impact not only on the embryonic and fetal development of the individual, but this method did not have associated with a negative impact on the psychosomatic development of the children.

Epigenetic and non-epigenetic mode of SIRT1 action during oocyte meiosis progression.

BACKGROUND: SIRT1 histone deacetylase acts on many epigenetic and non-epigenetic targets. It is thought that SIRT1 is involved in oocyte maturation; therefore, the importance of the ooplasmic SIRT1 pool for the further fate of mature oocytes has been strongly suggested. We hypothesised that SIRT1 plays the role of a signalling molecule in mature oocytes through selected epigenetic and non-epigenetic regulation. RESULTS: We observed SIRT1 re-localisation in mature oocytes and its association with spindle microtubules. In mature oocytes, SIRT1 distribution shows a spindle-like pattern, and spindle-specific SIRT1 action decreases α-tubulin acetylation. Based on the observation of the histone code in immature and mature oocytes, we suggest that SIRT1 is mostly predestined for an epigenetic mode of action in the germinal vesicles (GVs) of immature oocytes. Accordingly, BML-278-driven trimethylation of lysine K9 in histone H3 in mature oocytes is considered to be a result of GV epigenetic transformation. CONCLUSIONS: Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocytes, which can be readily switched from the epigenetic to non-epigenetic mode of action depending on the progress of meiosis.