Objective and design
Considering the role of histaminergic pathway in the differentiation of stem cells, we compared expression patterns of H1 and H2 receptors in the human amniotic epithelial cells (HAEC) culture at different stages of nicotinamide-induced differentiation into PBLC with the control HAEC.
Material and methods
HAEC isolated after term pregnancies (N = 12) were cultured in vitro. Altogether, 72 cultures were established. The culture medium in the studied group was supplemented on Day 5 with nicotinamide (10 mM). C-peptide concentration in the medium collected every 3 days for 15 days was determined immunoenzymatically as a marker of differentiation. At the same intervals the cultures were formalin-fixed and paraffinembedded for H1 and H2 receptors immunostaining. Quantitative immunohistochemistry was applied for evaluation of H1 and H2 expression.
Results
C-peptide was detected on Day 6 and the levels were kept gradually increased until Day 12, then stayed at almost the same level, 3.7-fold higher than initially. Expression of H2 was unchanged until Day 9 after nicotinamide addition, then was significantly (p < 0.05) decreased and amounted (mean % value for the measurements performed on Day 12 and Day 15, ±SEM) 49.73 ± 11.03 of the reference value obtained in control HAEC.
Conclusion
Variable expression of H2 during nicotinamide-induced differentiation of HAEC into PBLC may define a time-point, indicating involvement of histamine at the earlier stages.
