High amounts of nicotinamide phosphoribosyltransferase (NAMPT) were found in human seminal plasma. This enzyme influences energy metabolism and apoptosis and is essential for the regulation of cellular nicotinamide adenine dinucleotide (NAD) levels in somatic cells. NAD is required as a co-substrate for dehydrogenases, which are potentially important for spermatogenesis. The functional significance of intra- and extracellular NAMPT in human reproduction, however, has not been defined yet. The objectives of the study were therefore to determine NAMPT protein expression in human spermatozoa and testes, the secretion of NAMPT by spermatozoa depending on their maturation stage and the impact of NAMPT enzymatic function on sperm viability, motility, fertilisation capacity and induction of apoptosis. Firstly, we detected NAMPT protein in different cell types of human testes. NAMPT protein was also detected in spermatozoa, with significantly higher amounts in immature than in mature ejaculated spermatozoa. Additionally, NAD levels were significantly higher in immature than in mature spermatozoa. Secondly, NAMPT was released into the supernatant of human spermatozoa, with significantly higher NAMPT levels in supernatant of immature spermatozoa compared with mature cells. Finally, the specific inhibition of the enzyme by FK866 did not influence motility, capacitation or apoptosis signalling. In summary, NAMPT is produced in human spermatozoa in a maturation-dependent manner.

BACKGROUND:The umbilical cord contains stem and progenitor cells in vast amounts. Therefore, a long-term storage of this tissue for future therapies seems reasonable. OBJECTIVE:The aim of this study was a systematic comparison of mesenchymal stromal cells from fresh and cryopreserved umbilical cord tissue to demonstrate the feasibility of cryopreservation of tissues for later cell isolation. Furthermore, we tested the cultivation of these cells in GMP-compliant human AB serum, as a substitute for FCS, and subjected the expanded cells to karyotype analysis. METHODS: We applied limiting dilution analysis for evaluation of fibroblastoid colony-forming units and flow cytometric analysis of surface markers. Additionally we analyzed adipogenic and osteogenic differentiation potential. RESULTS: High numbers of viable MSC were isolated from cryopreserved umbilical cord tissue and a proportion of these cells showed clonal proliferation. The cells expressed the classic mesenchymal stromal cell surface markers, and effectively differentiated into osteocytes and adipocytes. Culture expansion of the mesenchymal stromal cells in medium supplemented with human AB serum did not change the surface marker profile. Moreover, karyotype analysis revealed genetic stability of mesenchymal stromal cells during expansion. CONCLUSIONS: Cryopreservation of umbilical cord tissue represents an auspicious approach for long-term storage of umbilical cord tissue and therefore a valuable tool for autologous stem cell applications.