Proteoglycans contribute to the structure and hydration of connective tissue throughout the body, including cartilage, skin and the matrix inside the umbilical cord. This is general structural biology, studied long before any specific tissue product existed, and applies across many tissue types beyond cord matrix alone.
Wharton's jelly is rich in hyaluronic acid, collagens and growth factors. Whether a specific product's documentation itemizes proteoglycan content separately from those other components is something to confirm with the supplier rather than assume from general tissue biology.
Supplier documentation may describe matrix composition qualitatively, by naming the component categories present, rather than publishing an exact proteoglycan quantity for a given product. If a quantitative figure matters to your evaluation, confirm with the supplier whether that data exists for the specific lot and request the documentation rather than assuming a number applies across lots.
Knowing the term helps a buyer read matrix-composition language in supplier literature accurately instead of mistaking structural protein content for a functional claim.