Microglia encapsulation in nanozyme-loaded hydrogels: response to oxidative stress and inflammation

To investigate the role of hydrogel composition and nanozymes incorporation on the inflammatory response of encapsulated murine microglia.

Sodium alginate (SA) hydrogels containing i) hyaluronic acid (HA) of low-100 kDa or high-1 MDa molecular weight and ii) Mn₃O₄ nanoparticles (Mn₃O₄-NPs) were prepared and characterized. The inflammatory response of encapsulated microglia was assessed.

HA enhanced cell-biomaterial interactions and reduced cell aggregation. Under normal culture conditions, HA induced a pro-inflammatory response, particularly with high-MW HA, with a 7-fold increase in IL-6 expression and a 2.2-fold increase in TNF-α secretion. Under prolonged LPS stimulation, HA promoted an anti-inflammatory shift, with a 2-fold decrease in IL-1β expression and restored IL-4 expression to basal levels. Mn₃O₄‑NP-loaded hydrogels showed strong H₂O₂ scavenging capability, protecting cells from oxidative stress. This effect may be partially counterbalanced by ^•OH generation at high Mn₃O₄‑NP concentrations. Under short-term LPS stimulation, Mn₃O₄ promoted a slight pro-inflammatory response, with a 1.3-fold and 1.2-fold increase in IL-1β and TNF-α expression. However, prolonged LPS exposure reflected an anti-inflammatory scenario, with increased IL-4 and a 2.4-fold increase in Arg-1 expression.

SA hydrogels are promising carriers for antioxidant nanozymes and microglia, modulating cell response under prolonged inflammation while protecting cells from oxidative stress.