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Stem cells obtained from amniotic fluid, the umbilical cord (UC), and placenta are gaining in popularity. Stem cells from the umbilical cord offer several advantages, including: non-invasive collection procedures, more hearty and steady growth than bone-marrow derived stem cells (they can maintain a steady doubling time (DT) over up to 10 passages), higher differentiation capability, and faster self-renewal. These cells express low levels of major histo-compability complex (MHC) class I, and generally lack MHC class II and its co-stimulatory ligands like CD40, CD80, and CD86. Thus, they are characterized with low immunogenicity. The umbilical cord, which starts developing in the fifth week of gestation, contains different compartments where stem cells originate: the cord lining, Wharton’s jelly, and perivascular region. UC mesenchymal cells derived from Wharton’s jelly are the most studied and offer more stable and better osteogenic and adipogenic differentiation potentials. The cells are extracted by either the explant or the enzymatic digestion method, though neither method has been characterized as the ‘standard’ thus far. The explant method requires manual mincing of the tissue fragments and results in an inconsistent number of extracted MSCs. In contrast, the enzymatic digestion method uses enzymes to break down the non-required cell fragments, and results in more consistent cell numbers. Regardless of extraction method, the cells are usually expanded in vitro in laboratories using culture systems and bioreactors. The cord lining of the UC is generally isolated with the explant method -- resulting in two kinds of MSCs: cord lining mesenchymal stem cells (CLMC), which are used to aid in burn and diabetic ulcer wound healing, and cord lining epithelial stem cells (CLEC), which are used for persistent corneal epithelial defects and skin improvements. Currently many companies are creating their own version of these stem cells, one of which is by Aspire, who are creating a version named ACT-20.
Stem cells obtained from amniotic fluid, the umbilical cord (UC), and placenta are gaining in popularity. Stem cells from the umbilical cord offer several advantages, including: non-invasive collection procedures, more hearty and steady growth than bone-marrow derived stem cells (they can maintain a steady doubling time (DT) over up to 10 passages), higher differentiation capability, and faster self-renewal. These cells express low levels of major histo-compability complex (MHC) class I, and generally lack MHC class II and its co-stimulatory ligands like CD40, CD80, and CD86. Thus, they are characterized with low immunogenicity. The umbilical cord, which starts developing in the fifth week of gestation, contains different compartments where stem cells originate: the cord lining, Wharton’s jelly, and perivascular region. UC mesenchymal cells derived from Wharton’s jelly are the most studied and offer more stable and better osteogenic and adipogenic differentiation potentials. The cells are extracted by either the explant or the enzymatic digestion method, though neither method has been characterized as the ‘standard’ thus far. The explant method requires manual mincing of the tissue fragments and results in an inconsistent number of extracted MSCs. In contrast, the enzymatic digestion method uses enzymes to break down the non-required cell fragments, and results in more consistent cell numbers. Regardless of extraction method, the cells are usually expanded in vitro in laboratories using culture systems and bioreactors. The cord lining of the UC is generally isolated with the explant method -- resulting in two kinds of MSCs: cord lining mesenchymal stem cells (CLMC), which are used to aid in burn and diabetic ulcer wound healing, and cord lining epithelial stem cells (CLEC), which are used for persistent corneal epithelial defects and skin improvements. Currently many companies are creating their own version of these stem cells, one of which is by Aspire, who are creating a version named ACT-20.
General theories of therapeutic action postulate that HUCMSCs can replace damaged cells, inhibit immunological functions through paracrine actions, and promote proliferation of endogenous stem cells through cell-cell communication. HUCMScs are thought to alter immune function through inhibition of Natural Killer Cell, T-cell, and B-cell proliferation along with redirecting monocytes and dendritic cells to less mature states. HUCMSCs are currently investigated for specific cell-based therapies, as they can be differentiated and engrafted for various disease states with low immunogenicity. Such applications include neurodegenerative diseases, spinal cord injury, stroke, and even liver disease. Certain factors secreted by HUCMSCs, such as oxidative stress pathways, are also thought to inhibit tumor growth and even lymphoma cell growth. These therapies are currently being considered for the treatment of COVID-19.
