Preparation of porous GelMA microcarriers by microfluidic technology for Stem-Cell culture

Gelatin methacrylamide porous microcarriers (GelMA PMS), one of the most promising three-dimensional cell culture scaffolds, are limited in large-scale applications due to lack of ideal preparation method, unclear regulation of pore size on cell behavior and a lack of research on the entire cell culture process. Herein, combining microfluidic synchronous photo-crosslinking and ice-templating method, a low-cost, easy-assembly and suitable for scalability method is proposed to prepare GelMA PMS for bone marrow mesenchymal stem cells (BMSCs) expansion. The pore size of GelMA PMS can be controlled by adjusting the freezing temperature (-20 ℃, −60 ℃, −196℃). As a result, PMS 60 (frozen at −60 ℃) with the optimized pore size of 25.3 ± 3.2 μm exhibited the highest cell attachment ratio (90.2%) and the largest cell spreading area (0.516 mm2/MS). More importantly, PMS 60 displayed higher cell attachment efficiency, proliferation rate, adipogenic, osteogenic, and chondrogenic differentiation potential than commercial microcarriers Cytodex-1. Furthermore, BMSCs not only achieved bead-to-bead transfer on PMS 60 but also exhibited potent proliferation rate after transfer to new blank microcarriers. Cultured BMSCs were efficiently harvested from PMS 60 without damaging cell viability. In addition, the cryopreservation and thawing process did not affect the PMS 60 to support cell proliferation, while cells loaded on Cytodex-1 could not continue to proliferate. Therefore, GelMA PMS fabricated in this work shows great potential application and provides insights for MSCs culture.