Dynamic zwitterionic degradable hydrogel niche for efficient stem cell expansion and recovery

During two-dimensional (2D) culture, stem cells gradually lose their proliferative activity and multipotency due to various physicochemical conditions, which significantly hinder the large-scale clinical applications of stem cell therapy. In recent years, three-dimensional (3D) cell culture has been increasingly utilized in the field of stem cell expansion owing to its unique advantages. The superhydrophilicity of zwitterionic hydrogels ensures the maintenance of stem cells' stemness during their expansion. This study aims to address a key challenge in the large-scale culture of stem cells in vitro: how to sustain their proliferative capacity and multipotency while achieving efficient cell recovery. To this end, we have designed a novel zwitterionic degradable hydrogel based on host-guest interactions as a 3D carrier for the in vitro culture of adipose-derived stem cells (ADSCs). We synthesized the copolymer poly(sulfobetaine-co-cyclodextrin) (p(SBMA-co-CD)) and adamantane-grafted hyaluronic acid (HA-Ada), and a stable hydrogel was rapidly formed by simply mixing solutions of these two polymers. Leveraging the antifouling properties of zwitterionic groups, this hydrogel effectively maintained the long-term stemness expression of ADSCs during culture. More importantly, we utilized the reversibility of host-guest interactions to disrupt the cross-linked structure of the hydrogel by adding competitive monomers, enabling efficient recovery of stem cells under gentle conditions. This process not only achieved a high recovery rate of stem cells but also avoided the damage to cells caused by traditional cell recovery methods. In summary, this study creatively introduced host-guest interactions into a zwitterionic hydrogel and successfully applied it to the 3D culture and recovery of stem cells in vitro. This hydrogel demonstrates functional plasticity in stem cell proliferation, culture, and harvest, holding promise for providing more reliable and efficient solutions in the fields of stem cell therapy and tissue engineering.