Decrease in expression of histamine H₂ receptors by human amniotic epithelial cells during differentiation into pancreatic beta-like cells

Abstract

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.