Repair of the injured spinal cord by implantation of a synthetic degradable block copolymer in rat

The present study is designed to assess the properties of a new degradable PLA-b-PHEMA block copolymer hydrogel and its therapeutic effectiveness after implantation following a thoracic spinal cord hemisection on rats. Degradable characteristics and porous aspect of the scaffold are respectively analyzed by the evaluation of its mass loss and by electron microscopy. The biomaterial toxicity is measured through in vitro tests based on motoneuron survival and neurite growth on copolymer substrate. Functional measurements are assessed by the Basso, Beattie and Bresnahan (BBB) and the Dynamic Weight Bearing (DWB) tests during 8 weeks post-surgery. Histological analyses are achieved to evaluate the presence of blood vessels and axons, the density of the glial scar, the inflammatory reaction and the myelination at the lesion site and around it. The results indicate that the synthetic PLA-b-PHEMA block copolymer is a non-toxic and degradable biomaterial that provides support for regenerating axons and seems to limit scar tissue formation. Additionally, the implantation of the porous PLA-b-PHEMA scaffold enhances locomotor improvement. The observed functional recovery highlights the potential benefits of plain tissue engineering material, which can further be optimized by bioactive molecule functionalization or transplanted cell encapsulation.