Sara Martín-Colomo

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.

Bioresorbable nanopatterned scaffolds functionalized with polydopamine (PDA) and graphene oxide (GO) have been shown to promote the differentiation of murine neural stem cells (mNSCs) toward neural and glial lineages. Herein, we aim to evaluate the compatibility of these scaffolds for the culture and differentiation of both human embryonic (hESCs) and induced pluripotent (hiPSCs) stem cells. Our results indicate that PDA and GO scaffolds support the topographic alignment of hESCs and hiPSCs cultures, while preserving their pluripotency characteristics. Upon differentiation, PDA and GO scaffolds guide cell specification toward the neuroectoderm germ layer and the neural crest. This promotes enhanced differentiation into both neural and supportive glial cells of the central nervous system (CNS), as well as Schwann cells of the peripheral nervous system (PNS). Moreover, nanopatterned scaffolds also support the differentiation of hESCs and hiPSCs toward endothelial precursors. These findings establish a novel culture platform that enables combined differentiation pathways, potentially relevant for applications in personalized medicine and regenerative cell therapy.

The mechanics of the extracellular matrix (ECM) determine cell activity and fate through mechanoresponsive proteins including Yes-associated protein 1 (YAP). Rigidity and viscous relaxation have emerged as the main mechanical properties of the ECM steering cell behavior. However, how cells integrate coexisting ECM rigidity and viscosity cues remains poorly understood, particularly in the high-stiffness regime. Here, we have exploited engineered stiff viscoelastic protein hydrogels to show that, contrary to current models of cell-ECM interaction, substrate viscous energy dissipation attenuates mechanosensing even when cells are exposed to higher effective rigidity. This unexpected behavior is however readily captured by a pull-and-hold model of molecular clutch–based cell mechanosensing, which also recapitulates opposite cellular response at low rigidities. Consistent with predictions of the pull-and-hold model, we find that myosin inhibition can boost mechanosensing on cells cultured on dissipative matrices. Together, our work provides general mechanistic understanding on how cells respond to the viscoelastic properties of the ECM.