Wharton's jelly mesenchymal stem cells: a concise review of their secretome and prospective clinical applications

Abstract

Accumulating evidence indicates that most primary Wharton's jelly mesenchymal stem cells (WJ-MSCs) therapeutic potential is due to their paracrine activity, i.e., their ability to modulate their microenvironment by releasing bioactive molecules and factors collectively known as secretome. These bioactive molecules and factors can either be released directly into the surrounding microenvironment or can be embedded within the membrane-bound extracellular bioactive nano-sized (usually 30-150 nm) messenger particles or vesicles of endosomal origin with specific route of biogenesis, known as exosomes or carried by relatively larger particles (100 nm-1 μm) formed by outward blebbing of plasma membrane called microvesicles (MVs); exosomes and MVs are collectively known as extracellular vesicles (EVs). The bioactive molecules and factors found in secretome are of various types, including cytokines, chemokines, cytoskeletal proteins, integrins, growth factors, angiogenic mediators, hormones, metabolites, and regulatory nucleic acid molecules. As expected, the secretome performs different biological functions, such as immunomodulation, tissue replenishment, cellular homeostasis, besides possessing anti-inflammatory and anti-fibrotic effects. This review highlights the current advances in research on the WJ-MSCs' secretome and its prospective clinical applications.

Keywords: EVs; WJ-MSCs; Wharton’s jelly mesenchymal stem cells; exosome; extracellular vesicles; secretome.

FIGURE 1

Umbilical cord WJ-MSCs and secretome. (A) Anatomical illustration of a cross section of umbilical cord depicting Wharton’s jelly, the process of WJ-MSCs mechanical and enzymatic isolation, culturing and secretome collection which contains both soluble and exosome fractions. (B) Schematic image for the exosome components. (C) Prospective functional roles of the secretome that influence cell function and system homeostasis.