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A study carried out by researchers at the Kyoto University School of Medicine and published in the current issue of CELL TRANSPLANTATION (Vol.16 No. 8) has shown that when transplanted bone marrow cells (BMCs) containing adult stem cells are protected by a 15mm silicon tube and nourished with bio-engineered materials, they successfully help regenerate damaged nerves. The research may provide an important step in developing artificial nerves.
"We focused on the vascular and neurochemical environment within the tube," said Tomoyuki Yamakawa, MD, the study's lead author. "We thought that BMCs containing adult stem cells, with the potential to differentiate into bone, cartilage, fat, muscle, or neuronal cells, could survive by obtaining oxygen and nutrients, with the result that rates of cell differentiation and regeneration would improve."
Nourished with bioengineered additives, such as growth factors and cell adhesion molecules, the BMCs after 24 weeks differentiated into cells with characteristics of Schwann cells - a variety of neural cell that provides the insulating myelin around the axons of peripheral nerve cells. The new cells successfully regenerated axons and extended their growth farther across nerve cell gaps toward damaged nerve stumps, with healthier vascularity.
"The differentiated cells, similar to Schwann cells, contributed significantly to the promotion of axon regeneration through the tube," explained Yamakawa. "This success may be a further step in developing artificial nerves." Grafting self-donated (autologous) nerve cells to damaged nerves has been widely practiced and considered the "gold standard." However, autologous cells for transplant are in limited supply. Allologous cells, donated by other individuals, require the host to take heavy immunosuppressant drugs. Artificial nerves, cultured from a variety of cells and transplanted to nerve damaged areas, have been considered as alternatives to nerve grafting. However, prior to this research, cells cultured for this purpose have generally not been very successful in regenerating axons with sufficient vascularity or length to bridge nerve gaps.
"This technique for implanting BMCs containing adult stem cells at damaged nerve sites as employed by the Kyoto researchers has opened up new possibilities for nerve regeneration, " said Paul Sanberg, PhD, D.Sc., Distinguished Professor at University of South Florida Health and co-editor-in- chief of Cell Transplantation.