Back Cover: Supramolecular adhesive hydrogels based on α‐cyclodextrin (αCD) capped decyl group‐modified Alaska pollock gelatin and poly(ethylene) glycol‐based crosslinker are designed. The resulting adhesive hydrogel can close the cerebral dura mater and has excellent anti‐swelling properties. These properties are attributed to the release of αCD from hydrogel after curing and the subsequent assembly of decyl groups. This is reported by Tetsushi Taguchi and co‐workers in article number 2300097.

Adhesives/sealants are used after suturing to prevent leakage of cerebrospinal fluid from an anastomotic site. Commercial adhesives/sealants have been used to close the cerebral dura. However, swelling of the cured adhesives/sealants induces increased intracranial pressure and decreases the strength of the seal. In the present study, tissue adhesive hydrogels with improved swelling property using inclusion complex composed of 𝜶-cyclodextrin (𝜶CD) and decyl group (C10)-modified Alaska pollock-derived gelatin (C10-ApGltn) with a high degree of substitution (DS) (>20 mol%) are developed. Viscosity of C10-ApGltn with a high DS solution remarkably decreased by the addition of 𝜶CD. The resulting 𝜶CD/C10-ApGltn adhesive hydrogel composed of 𝜶CD/C10-ApGltn inclusion complexes and poly(ethylene glycol) (PEG)-based crosslinker showed improved swelling property after immersion in saline. Also, the resulting adhesive has a significantly higher burst strength than fibrin-based adhesives and is as strong as a PEG-based adhesive. Quantitative analysis of 𝜶CD revealed that the improved swelling property of the resulting adhesive hydrogels is induced by the release of 𝜶CD from cured adhesive, and the subsequent assembly of decyl groups in the saline. These results suggest that adhesives developed using the 𝜶CD/C10-ApGltn inclusion complex can be useful for closing the cerebral dura mater.

Injectable hydrogels are promising carriers for cell delivery in regenerative medicine. However, injectable hydrogels composed of crosslinked polymer networks are often non-porous and prevent biological communication with host tissues through signals, nutrients, oxygen, and cells, thereby limiting graft survival and tissue integration. Here we report injectable hydrogels with liquid-liquid phase separation-induced microcapillary networks as stem cell-delivering scaffolds. The molecular modification of gelatin with hydrogen bonding moieties induced liquid-liquid phase separation when mixed with unmodified gelatin to form microcapillary networks structures in the hydrogels. Through spatiotemporally controlled covalent crosslinking and dissolution processes, porous microcapillary networks structures were formed in the hydrogels, which can enhance mass transport and cellular activity. The encapsulation of cells with injectable microcapillary networks hydrogels improved cellular adhesion, spreading, migration, and proliferation. Transplantation of mesenchymal stem cells with injectable microcapillary networks hydrogels enhanced graft survival and recovered hindlimb ischemia by enhancing material-tissue communication with biological signals and cells through microcapillary networks. This facile approach may serve as an advanced scaffold for improving stem cell transplantation therapies in regenerative medicine.