Wharton’s jelly

Hyaluronan was identified by Karl Meyer11 in 1938 as a hexuronic acid-containing material that also provided the turgor for the vitreous of the eye. The name hyaluronic acid was proposed from the Greek hyalos (glassy, vitreous) and uronic acid. It required 20 years however before the chemical structure of HA was established.12 It was later found to be a present in virtually every vertebrate tissue, the highest concentrations occurring in the vitreous of the eye, in the synovial fluid in the joint capsule, and in the umbilical cord as Wharton s jelly. However, over 50% of total body HA is present in skin.13... 

Hyaluronan, despite the simplicity of its structure, has a surprisingly wide range of functions. In high concentrations, as found in the ECM of the dermis, it regulates water balance, osmotic pressure, functions as an ion exchange resin, and regulates ion flow. It functions as a sieve, to exclude certain molecules, to enhance the extracellular domain of cell surfaces, particularly the luminal surface of endothelial cells.28 It can also function as a lubricant and as a shock absorber. Hyaluronan can also act as a structural molecule, as in the vitreous of the eye, in joint fluid, and in Wharton s jelly. 

A major difference may exist between HA in vivo and HA chains that are extricated from the in situ situation. Very little is known about the properties of the HA within the narrow confines of the ECM or the restricted volume of the intercellular space. However, when HA undergoes aqueous extraction from major sources, such as from the mucoid layer of the rooster comb, from joint fluid, the perivascular space of the umbilical cord (Wharton s jelly), or from bacterial capsules, the extraction fluid has very high viscoelasticity. Such HA is in a random coil conformation. However, HA is unlikely to be in such a conformation in vivo, and little is known about the state of the HA within tight tissue spaces. It is probably much more structured, and probably has many additional functions that are unknown and lost when examined in vitro [15]. 

Wharton s jelly found in the umbilical cord is one of the major sources of vertebrate HA. The HA occurs in the perivascular space surrounding the three umbilical vessels. The abundance of HA in that structure and its associated enormous volume of water serves perhaps as a protective mechanism against ties and strictures of the cord. The HA may have evolved as a selective mechanism, as a survival technique protecting against strangulation of the fetus. 

One effective regenerative therapy for AD is to replace the substantial loss of cholinergic neurons commonly observed in Alzheimer s diseased brains. One promising strategy is to directly differentiate stem cells into cholinergic-like neurons (Fig. 5). Human umbilical cord mesenchymal stem cells derived from Wharton s jelly could be differentiated into cells of bulbous morphology. 

Chao KC, Chao KF, Fu YS, Liu SH. Islet-like clusters derived from mesenchymal stem cells in Wharton s Jelly of the human umbilical cord for transplantation to control type 1 diabetes. PLoS ONE. 2008 Jan 16 3(l) el451... 

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