Mechanical-Enhanced Porous Silk-Based Cryogenic Microneedles for Cell Thawing/Revival in the Gastric Wall

Cell therapies for gastric disorders lack minimally invasive delivery platforms that preserve cell viability during storage and enable effective tissue penetration, owing to the high toughness and harsh environment of the gastric wall. Herein, we developed a mechanically reinforced, porous silk-based cryogenic microneedle (silk-cryoMN) platform for in situ cell delivery to the gastric wall. The optimized 1.5% (w/v) silk scaffolds exhibited interconnected pores (24.4 ± 7.9 μm, ~81% porosity), a compressive strength (422.8 ± 73.4 MPa), and a 3.4-fold increase in β-sheet content. The silk-cryoMNs showed greater thermal stability than H₂O-cryoMNs, maintaining structural integrity for over 60 s at room temperature. With a cryopreservation medium containing 100 mM sucrose and 2% DMSO, post-thaw cell viability exceeded 80% after 11 days of freezing, and most cells were released within 1 h. Furthermore, ex vivo studies confirmed penetration of porcine gastric tissue to depths of 422-448 μm within 30 s. These results suggest that the platform may address several translational barriers, including tissue penetration, handling stability, and cell viability preservation. Further in vivo studies and long-term safety evaluations are needed before clinical translation can be considered.