Engineering the dynamics of biophysical cues in supramolecular hydrogels to facile control stem cell chondrogenesis for cartilage regeneration

Hydrogel systems have been widely used to engineer biomimetic niches that capture microenvironments cues to steer cell fate; however, challenges remain in inducing mesenchymal stromal cells (MSCs)'s differentiation into chondrocytes remains a challenge due to natural extracellular matrix (ECM)'s complex composition. Herein, we designed double network (DN) hydrogels with tunable viscoelastic properties that recapitulated the biophysical cues of ECM to guide MSCs chondrogenesis. DN hydrogels were formed through the combination of supramolecular guest-host (GH) hyaluronic acid (HA) and poly (γ-glutamic acid) (γ-PGA) networks with covalent networks by the crosslinking of thiolated γ-PGA and PEG diacrylate. By adjusting GH concentration, the biophysical properties (e.g., viscoelasticity) of DN hydrogel could be tailored on-demand to investigate the effect of viscoelasticity in three dimensions (3D). The DN hydrogel with increased GH concentration showed viscoelastic matrices, enhanced ECM secretion, and chondrogenesis of encapsulated MSCs, as evidenced by upregulated expression of key biomarkers (e.g., aggrecans, collagen II). We further showed that DN hydrogel with viscoelastic behavior promoted cartilage-specific matrix deposition and regeneration of articular cartilage through in vivo studies. Our results have provided valuable insights into the design of viscoelastic DN hydrogel with an ECM-mimicking 3D microenvironment for efficient chondrogenesis for cartilage regeneration therapies.