Alginate attenuates reactive microglia in vivo

Alginate is a marine polysaccharide commonly used in the form of hydrogel in different biomedical applications due to its biocompatibility, low toxicity and immunogenicity, and its ability to mimic the extracellular matrix. In vitro studies demonstrated that alginate exerts anti-inflammatory properties, which could be exploited for targeting brain pathologies characterized by elevated levels of tissue inflammation. The present study aimed to evaluate alginate’s effects on immune cells in vivo using the ibotenic-induced brain lesion model and the pilocarpine model of mesial temporal lobe epilepsy. The administration of calcium alginate (prepared by using the magnesium salt of alginate and calcium chloride) resulted in reduced ibotenic-associated microglial reactivity in rat brains. As a subsequent step, to enhance the translational potential of the hydrogel, lesioned epileptic rats were treated with neural stem cells and alginate; our results showed that alginate was capable of reversing the increase in Iba1 cell body size induced by neural stem cell injection, confirming that alginate exerts a modulatory effect on microglial activity.