CULTIVATING HUMAN SCHWANN CELLS FOR GRAFTING
Patrick M. Wood, Ph.D. • Richard P. Bunge, M.D.

Schwann cells, the nerve growth- and function-supporting cells of peripheral nerves, are prime candidates for strategies to bridge areas of spinal cord injury. Stimulation of Schwann cells to divide will be needed to cultivate the large numbers of cells to be used in grafts to promote spinal cord regeneration. Past Miami Project studies have shown that populations of human Schwann cells can be stimulated to divide (expanded). Human-derived Schwann cells have not been observed to divide uncontrollably in the laboratory or form tumors after grafting. These encouraging findings suggest that expanded human Schwann cells could be safe for clinical applications. Still, before expanded Schwann cell populations can be safely tested in clinical trials, we need to understand how their proliferation is controlled.

Dr. Pat Wood and his colleagues showed that the cells divide more rapidly when there are fewer cells in the dish, an important observation that will lead to efficient cultivation of cells for future testing. Further, they showed that expanded human Schwann cells retain their natural capacity to regulate cell proliferation – they stop dividing when they contact other Schwann cells. This behavior in vivo helps prevent tumor formation. The scientists studied how the cells sense contact with other Schwann cells, and found that cells seem not to transmit long-distance signals. Instead, when they recognize a molecule known as contactinhibin on the surface of cells they touch, their division is inhibited. Though other molecules may also contribute to the control of division, this demonstration that normal regulatory processes are still in effect is an important advance toward using expanded human Schwann cells for clinical trials.