Resumo

In spinal cord injury the primary damage is followed by events that expand the initial injury. The exacerbated inflammatory response is responsible for demyelinaton and neuronal apoptosis, which contributes to the formation of a microenvironment non-permissive to axonal regeneration. In previous studies, we described that hyperlaminin (HypLM) was capable of increasing neuritogenesis in vitro. In addition, the application of these polymers to the injured cord led to a significant functional recovery as early as 24 hours post-lesion, which suggests containment of the inflammatory damage. In order to confirm such anti-inflammatory effect of the polymers, Wistar rats were subjected to partial transection and received 10µl injections of acidic buffer or HypLM immediately after lesion. Animals that received HypLM showed infiltrates of activated ED1-positive macrophages only at the lesion epicenter, while the control group displayed ED1 staining all over the cord extension. Furthermore, the serum levels of C reactive protein, a marker of the acute inflammatory process, was reduced in 50% in the first 24 hours. In the same period, the number of neutrophils in the lesion epicenter was 61% reduced in the HypLM treated group (27.3+-4.5 vs. 10.6 +-1.7). In addition, one day after lesion the levels of the pro-inflammatory cytokines IL-1 β and TNF- α were also significantly diminished in the cord tissue of the HypLM group (6.8+-1.9 vs 1.7+-0.6 and 4.3+-0.7 vs. 1.4 +-0.3, respectively). Our data suggest that HypLM has an immunomodulatory effect, helping to preserve the nervous parenchyma.Neuroprotection probably facilitates the regenerative processby inducing alternative activation of macrophages/microglia.