gms | German Medical Science

Objectives/Interrogation: Peripheral nerves injuries are common lesions than cause loss of function and poor outcome. In case of severe nerve gap (>50mm), the gold standard remains the autologous graft. The limits are: functional damage at the donor site, double surgical access and the lack of large amounts of grafts. In response to injury, Schwann cells (SC), take advantage to extracellular matrix (ECM) connection, proliferates in organized structures than guiding axons during regeneration.

Methods: Researchers focused two main areas of investigation: the role of the interaction between cells with the extracellular membrane (ECM) and the forces acting during axonal elongation.

Results and Conclusions: Regarding the contact between cells (nervous and glial) and physical stimuli arising from the ECM, the tissue engineering build artificial surfaces than reproduce the topographical signals of the ECM (Micro and Nano size spur). The influence of micro and nano-topography on cells behaviour is explored both in vitro and in vivo. SC quit on the anisotropic substrate aligning preferably along the axis of the topographical signal, while cells cultured on flat surfaces show a random orientation. In reference to the forces acting during axonal elongation in 1984 Bray demonstrated in vitro that the application of a mechanical tension by micro-needles of glass inserted in the growing cones, helped the axon's elongation, without reducing the diameter. Riggio et all proposed to use, in vitro, nervous Rat PC12 Cells cultured with magnetisable nanoparticles (MNPs) (1-100mgml-1), "assimilated" by cells by endocytosis. Subsequently, an external magnetic field was applied. The association of the nanoparticles and an external magnetic field, generating a tension force in order of pN, virtually able to guiding axonal growing and orienting cells along the direction of the magnetic force(4). The Author investigated the early step of in vivo application of this technique and used an experimental model of the median nerve injury in rats. The data show that did not hinder with the nerve regeneration (one week after injury, it is evident the presence of Schwann cells migrated from the proximal to the distal stump). The MNPs were endocited by Schwann cells, but also within the same nerve fibres.

Finally, in case of severe nerve gap the gold standard remain the autologous nerve graft, however the technique could be overcome in the future by different and alternatives solutions.