Opioid receptors and opioid peptides in the cardiomyogenesis of mouse embryonic stem cells.

The stimulation of myocardium repair is restricted due to the limited understanding of heart regeneration. Interestingly, endogenous opioid peptides such as dynorphins and enkephalins are suggested to support this process. However, the mechanism-whether through the stimulation of the regenerative capacity of cardiac stem cells or through effects on other cell types in the heart-is still not completely understood. Thus, a model of the spontaneous cardiomyogenic differentiation of mouse embryonic stem (mES) cells via the formation of embryoid bodies was used to describe changes in the expression and localization of opioid receptors within cells during the differentiation process and the potential of the selected opioid peptides, dynorphin A and B, and methionin-enkephalins and leucin-enkephalins, to modulate cardiomyogenic differentiation in vitro. The expressions of both κ- and δ-opioid receptors significantly increased during mES cell differentiation. Moreover, their primary colocalization with the nucleus was followed by their growing presence on the cytoplasmic membrane with increasing mES cell differentiation status. Interestingly, dynorphin B enhanced the downregulation gene expression of Oct4 characteristic of the pluripotent phenotype. Further, dynorphin B also increased cardiomyocyte-specific Nkx2.5 gene expression. However, neither dynorphin A nor methionin-enkephalins and leucin-enkephalins exhibited any significant effects on the course of mES cell differentiation. In conclusion, despite the increased expression of opioid receptors and some enhancement of mES cell differentiation by dynorphin B, the overall data do not support the notion that opioid peptides have a significant potential to promote the spontaneous cardiomyogenesis of mES cells in vitro.

Stabilization of hyaluronan-based materials by peptide conjugation and its use as a cell-seeded scaffold in tissue engineering.

New materials based on molecules naturally occurred in body are assumed to be fully biocompatible and biodegradable. In our study, we used hyaluronic acid (HA) modified with peptides, which meet all this criterion and could be advantageously used in tissue engineering. Peptides with RGD, IKVAV or SIKVAV adhesive motif were attached to HA-based fiber or non-woven textile through ester bond in the term of solid phase peptide synthesis. A linker between HA and peptide containing three glycine or two 6-aminohexanoyl units was applied to make peptides more available for cell surface receptors. Dermal fibroblasts adhered readily on this material, preferentially to RGD peptide with 6-aminohexanoyl linker. Contrary, the absence of adhesive peptide did not allow the cell attachment but maintained the material stability.