Adding pace to the 1mm/day paradigm



Peripheral nerves connect peripheral tissues to the brain and spinal cord. Disruption to these connections, from injury or chronic diseases, often leads to loss of functions such as movement disorders, and sometimes paralysis. Regaining the lost functions depends on how well the injured nerves regenerate and reestablishes the necessary connections. Unfortunately, peripheral nerves regenerate at a much slower growth rate of 1mm/day and, more terribly the re-growth doesn’t even sustain for couple of weeks. So the maximum re-growth injured nerves could achieve at normal circumstances fall short to 7-14mm which in turn do not allow these nerves to re-innervate their proper targets. Misdirected growth complicates the process further. What is left finally is an overall functional deficit. Is there a way out?

Well, many research labs across the world address peripheral nerve regeneration. Adding pace to the re-growth, providing clearer paths, and improving directionality to the re-growing nerves are the broader approaches employed. Many interesting results were presented this year at SFN. Our group led by Dr.Zochodne showed the impact of sweeping away tumor suppressor molecules, from the regeneration milieu, on peripheral nerve regeneration. Dr.Clifford’s group from Harvard presented on in vitro generated human neurons as a tool to screen therapeutics that facilitates neuroregeneration. Seeding cultured primary neurons to injured nerves as a way to tackle the situation was discussed by Dr.Cullen’s group. Adding to the various approaches, Dr.Chan’s group demonstrated how electrical stimulation is helpful to improve regeneration.

Immune cells, particularly macrophages, play important roles in the peripheral nervous system. Their multifaceted roles on neuroregeneration, degeneration, and inflammation were discussed over the past five days of SFN. A general consensus on exploring macrophage biology as a potential approach to improve regeneration was emerged.

Overall, studies on peripheral nervous system and its connections are fascinating. Rigorous experimental approaches are underway to tease out ways to bring affected individuals back to regular life.