Molecular events in the Wharton’s jelly and blood vessels of human umbilical cord
The umbilical cord is seen as the main junction between the developing embryo or fetus and placenta. We studied the antimicrobial response, the presence of undifferentiated cells and TGF-α, as well as tissue degeneration and compensatory remodelling processes in the cells of human umbilical cord.
Seven umbilical cord tissue samples obtained during premature and full term births were stained with hematoxylin and eosin and by immunohistochemistry for human beta defensin 2 (hBD-2), hematopoietic progenitor cell antigen CD34, matrix metalloproteinase 2 (MMP-2), the tissue inhibitor of matrix metalloproteinase 2 (TIMP-2), nestin and transforming growth factor alpha (TGF-α). The intensity of staining was graded semiquantitatively.
Antimicrobial response was more prominent in the Wharton’s jelly – we found numerous hBD-2-containing cells, while hBD-2 positive cells in the walls of arteries and vein varied from moderate to abundance. Numerous cells in the Wharton’s jelly contained CD34, while in the walls of blood vessels few to moderate stained positive for CD34. MMP-2, TIMP-2 and nestin positive cells were found in all the tissue samples and varied from numerous in the walls of blood vessels to abundance in the Wharton’s jelly and the inflammation region. The abundance of TGF-α-containing cells was found in Wharton’s jelly and moderate to numerous cells of blood vessels contained TGF-α.
Conclusions: The human umbilical cord possesses antimicrobial activity and shows the presence of undifferentiated cells. The striking distribution and the expression of MMP-2, TIMP-2 and nestin suggest their role in the very effective and extensive tissue degeneration and compensatory remodelling processes. TGF-α seems to be an important growth factor for extra-embryonic tissue development.