Effects of Poly(β-Amino Ester) Networks on Macrophage Response In Vitro

Poly(β-amino ester) or PBAE-based polymer networks are promising degradable biomaterials. This work investigated PBAEs formed from PBAE-diacrylate (PBAE-dA) macromers to assess how network chemistry and structure impact macrophages. PBAE-dAs were synthesized by an Aza-Michael type reaction between a diacrylate (butanediol diacrylate, diethylene glycol diacrylate or poly(ethylene glycol) diacrylate) and benzhydrazide to produce B6, α6, and A6, respectively. B6 PBAE-dA, α6 PBAE-dA, and mixtures thereof have similar molecular weights while α6 and A6 PBAE-dA have the same chemistry, but different molecular weights, allowing investigation into network chemistry and structure, respectively. B6 networks were the least hydrophilic and slowest degrading, while A6 was the most hydrophilic and fastest degrading under accelerated degradation conditions. RAW-Blue™ and primary murine macrophages were pre-activated to mimic the in vivo phenotype and cultured on PBAE networks without and with pre-adsorbed plasma. Macrophage response was assessed by NF-κB activation, inflammatory markers for gene expression (Il1b, Tnfa, Nos2) and cytokine production (IL-6, TNF-α, and IL-18). Comparing across PBAE networks, NF-κB activation was elevated in α6 and A6 but this did not translate to downstream pro-inflammatory cytokine response where there were minimal PBAE-dependent effects. Pre-adsorbed plasma attenuated macrophage activation on B6, α6, and co-polymers thereof but had no effect on A6 PBAE. While the most hydrophilic A6 PBAE induced a greater response across all PBAEs, it was lower compared to the hydrophobic polystyrene control. Collectively, this study further supports PBAEs for in vivo applications because their material properties and degradation rates are readily tunable while minimally affecting macrophage response.