Human cells helpful in repairing spinal cord injuries

Houston: Human astrocyte cells, the major support cells in the central nervous system, have been found to help repair spinal injury, according to a new study.

Scientists at the University Of Colorado School Of Medicine and the University Of Rochester Medical Center have found an effective way to restore locomotors function through repairing a damaged nervous system with a type of astrocyte cell found in the brain and spinal cord.

The research indicated that transplanting stem cells wasn`t nearly as effective as creating and modifying a specific type of cell before transplanting them.

The team created two types of human astrocytes and transplanted them into rats.

One type of astrocyte, bone morphogenetic protein (BMP), gave as much as a 70 per cent increase in the protection of neurons in the spinal cord in rats with spinal cord injuries than the other type of astrocyte, ciliary neurotic factor (CNFT).

The study is different from any other research ever conducted in that it showed that even though cells are derived from the exact same group of original cells, they can have completely different effects when it comes to use and treatment.

Chris Proschel, PhD, lead study author and assistant professor of Genetics at the University of Rochester Medical Center says, "We`ve shown in previous research that the right types of rat astrocytes are beneficial, but this study brings it up to the human level, which is a huge step.

"What`s really striking is the robustness of the effect. Scientists have claimed repair of spinal cord injuries in rats before, but the benefits have been variable and rarely as strong as what we`ve seen with our transplants."

The study is unique, says Stephen Davies, PhD, first author and associate professor in the Department of Neurosurgery at the University of Colorado School of Medicine, because it showed that astrocytes derived from the same human cell precursors have entirely different functions and produced different results for repairing injured spinal cords.

The researchers say transplanting stem cells directly into the spinal cord and hoping that they will be useful, may not be the best approach– something they found when they tried it on the rats.

Instead, they isolated human glial precursor cells then exposed them to two different signalling molecules, that encouraged the cells to differentiate into BMP (bone

morphogenetic protein) or CNTF (ciliary neurotrophic factor).

When scientists transplanted the BMP human astrocytes, they found significant improvement in the injured rats` movement, measured by their ability to cross a ladder-like track.

"Clearly, not all human astrocytes are equal when it comes to promoting repair of the central nervous system," Davies said.

The BMP astrocytes provided the most benefits for protecting injured neurons in the spinal cord.

Jeanette Davies, PhD, assistant professor at the University of Colorado School of Medicine and co-lead author of the study explains, "It is estimated that astrocytes make up the vast majority of all cell types in the human brain and spinal cord, and provide multiple different types of support to neurons and other cells of the central nervous system.

"These multiple functions are likely to all be contributing to the ability of the right human astrocytes to repair the injured spinal cord."

The study is promising for treating patients with spinal cord injuries.

Jason Huang, MD, associate professor of Neurosurgery at the University of Rochester Medical Center and Chief of Neurosurgery at Highland Hospital notes the significant clinical implications of the findings.

Modifying human astrocytes that are the major support cells in the central nervous system boosted protection of spinal cord neurons 70 per cent compared to using undifferentiated astrocytes, allowing rats with spinal cord injury to regain movement.

The next step say the scientists is to test the effect of transplanted astrocytes derived from human stem cells in more complex models of severe early and late spinal cord injury.