[Three-dimensional culture of T cells based on droplet hydrogel microspheres]

The T cell therapy has become an effective approach for treating tumors or immune diseases. The current in vitro expansion of T cells is usually carried out in suspension culture systems, which takes a long time and is prone to causing problems such as decreased cell functions and T cell exhaustion. This study aims to explore the preparation method of calcium alginate hydrogel cell microspheres based on microfluidic chips, and uses Jurkat cells as the model cells to evaluate the improvement effect of this three-dimensional culture system on the in vitro expansion efficiency and functional maintenance of T cells. In this study, a flow-focusing droplet microfluidic chip was fabricated via soft lithography. Through the cross-shaped microfluidic chip, droplets with controllable size and cell encapsulation rate conforming to Poisson distribution could be stably generated. CaCl₂ (5%) could cause rapid cross-linking and solidification of sodium alginate hydrogel microspheres. The Jurkat cells encapsulated in the hydrogel microspheres could achieve three-dimensional culture, with a cell viability rate of over 95%, comparable to that of plate culture. The cell proliferation rate was increased by 8.8% compared with that of the plate culture group. The secretion levels of cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in the hydrogel microspheres were 14.3% and 4.3%, respectively, higher than those in the plate culture group. When Jurkat cells were co-encapsulated with interleukin-2 (IL-2) in the hydrogel microspheres, the secretion levels of effector factors IFN-γ and TNF-α were 39.8% and 40.7%, respectively, higher than those in the plate culture group. This study provides a new strategy for optimizing the in vitro expansion culture system of T cells. The constructed three-dimensional co-culture technology of cell microspheres has potential application in T cell therapy.