Researchers, using two different kinds of stem cells in rats, were able to regenerate oligodendrocytes — myelin-producing brain cells that are defective in multiple sclerosis (MS). They were also able to grow adult neural stem cells (NSCs, immature cells of the nervous system) in laboratory cultures and prod them to develop into oligodendrocytes.
The study, titled “Human mesenchymal factors induce rat hippocampal- and human neural stem cell dependent oligodendrogenesis,” was published in the journal Glia.
The exact cause of MS is unknown — including what triggers attacks on myelin — but the loss of oligodendrocytes seen in the disease is known to play a role in its progression.
Nerve cells in the brain send their signals through their axons, long arm-like structures that extend out from the centers of the nerve cells. The signals are electrical pulses transmitted along the length of an axon. Oligodendrocytes provide the insulation — called myelin — that wraps around axons, speeding up the transmission of electrical signals through the nerve cells.
Loss or malfunction of oligodendrocytes means that signaling in the brain is impaired. It is this slowing of signaling that is thought to cause MS symptoms.
Stem cells are immature cells that give rise to differentiated cells — cells with a specific function, such as oligodendrocytes.
Adult neural stem cells can divide and produce nerve cells and other brain cells, including oligodendrocytes. However, in normal circumstances, the regeneration of cells that take place in the human brain is not enough to repair the damage seen in MS.
The researchers set out to find conditions that would promote the differentiation of adult human NSCs into oligodendrocytes. They discovered that another type of stem cell, mesenchymal stem cells (MSCs), could provide the signals required.
First they tested their system in rats, and found that by using factors produced by human MSCs, they could induce the growth of new oligodendrocytes in the animals.
Then they grew adult NSCs in the laboratory, and using the same factors from human MSCs were able to promote the establishment of oligodendrocytes in the cultured cells.
“Stimulation with human MSC factors was observed to equally promote rat stem cell oligodendrogenesis, axonal wrapping and tissue integration,” the team wrote.
“We also show for the first time that dominant pro-oligodendroglial factors derived from human fetal MSCs can instruct human induced pluripotent stem cell-derived NSCs to differentiate into … oligodendrocytes,” the researchers concluded.