Limitations in transplantation of astroglia-biomatrix bridges to stimulate corticospinal axon regrowth across large spinal lesion gaps

Regrowth of injured axons across rather small spinal cord lesion gaps and subsequent functional recovery has been obtained after many interventions. Long-distance regeneration of injured axons across clinically relevant large spinal lesion gaps is relatively unexplored. Here, we aimed at stimulating long-distance regrowth of the injured corticospinal (CS) tract. During development, an oriented framework of immature astrocytes is important for correct CS axon outgrowth. Furthermore, a continuous growth promoting substrate may be needed to maintain a CS axon regrowth response across relatively large spinal lesion gaps. Hence, we acutely transplanted poly(D,L)-lactide matrices, which after seeded with immature astrocytes render aligned astrocyte-biomatrix complexes (R. Deumens, et al. Alignment of glial cells stimulates directional neurite growth of CNS neurons in vitro. Neuroscience 125 (3) (2004) 591-604), into 2-mm long dorsal hemisection lesion gaps. In order to create a growth promoting continuum, astrocyte suspensions were also injected rostral and caudal to the lesion gap. During 2 months, locomotion was continuously monitored. Histological analysis showed that astrocytes injected into host spinal tissue survived, but did not migrate. None of the astrocytes on the biomatrices survived within the lesion gap. BDA-labeled CS axons did not penetrate the graft. However, directly rostral to the lesion gap, 120.9 +/- 38.5% of the BDA-labeled CS axons were present in contrast to 12.8 +/- 3.9% in untreated control animals. The observed anatomical changes were not accompanied by locomotor improvements as analyzed with the BBB and CatWalk. We conclude that although multifactorial strategies may be needed to stimulate long-distance CS axon regrowth, future studies should focus on enhancing the viability of cell/biomatrix complexes within large spinal lesion gaps

In-Situ Observation of Crystallization and Growth in High-Temperature Melts Using the Confocal Laser Microscope

This review discusses the innovative efforts initiated by Emi and co-workers for in-situ observation of phase transformations at high temperatures for materials. By using the high-temperature confocal laser-scanning microscope (CLSM), a robust database of the phase transformation behavior during heating and cooling of slags, fluxes, and steel can be developed. The rate of solidification and the progression of solid-state phase transformations can be readily investigated under a variety of atmospheric conditions and be correlated with theoretical predictions. The various research efforts following the work of Emi and co-workers have allowed a deeper fundamental understanding of the elusive solidification and phase transformation mechanisms in materials beyond the ambit of steels. This technique continues to evolve in terms of its methodology, application to other materials, and its contribution to technology