Mechanical Properties Affect Primary T Cell Activation in 3D Bioprinted Hydrogels

Abstract

T cells play a critical role in the adaptive immune response of the body, especially against intracellular pathogens and cancer. In vitro, T cell activation studies typically employ planar (two-dimensional, 2D) culture systems that do not mimic native cell-to-extracellular matrix (ECM) interactions, which influence activation. The goal of this work was to study T cell responses in a cell line (EL4) and primary mouse T cells in three-dimensional (3D) bioprinted matrices of varied stiffness. Cell-laden hydrogels were 3D bioprinted from gelatin methacryloyl (GelMA) using a digital light processing (DLP)-based 3D bioprinter operated with visible light (405 nm). Mechanical characterization revealed that the hydrogels had pathophysiologically relevant stiffnesses for a lymph node-mimetic tissue construct. EL4, a mouse T cell lymphoma line, or primary mouse T cells were 3D bioprinted and activated using a combination of 10 ng/mL of phorbol myristate acetate (PMA) and 0.1 μM of ionomycin. Cellular responses revealed differences between 2D and 3D cultures and that the biomechanical properties of the 3D bioprinted hydrogel influence T cell activation. Cellular responses of the 2D and 3D cultures in a soft matrix (19.83 ± 2.36 kPa) were comparable; however, they differed in a stiff matrix (52.95 ± 1.36 kPa). The fraction of viable EL4 cells was 1.3-fold higher in the soft matrix than in the stiff matrix. Furthermore, primary mouse T cells activated with PMA and ionomycin showed 1.35-fold higher viable cells in the soft matrix than in the stiff matrix. T cells bioprinted in a soft matrix and a stiff matrix released 7.4-fold and 5.9-fold higher amounts of interleukin-2 (IL-2) than 2D cultured cells, respectively. Overall, the study demonstrates the changes in the response of T cells in 3D bioprinted scaffolds toward engineering an ex vivo lymphoid tissue-mimetic system that can faithfully recapitulate T cell activation and unravel pathophysiological characteristics of T cells in infectious biology, autoimmunity, and cancers.

Crosstalk between T lymphocyte and extracellular matrix in tumor microenvironment

“…Primary mouse T cells activated with PMA and ionomycin exhibited 1.35 times more active cells in soft substrates compared to those in hard substrates. This demonstrated variations in T cell responses within the 3D bioprinting scaffold, faithfully reproducing T cell activation and revealing the pathophysiological characteristics of T cells in infectious biology, autoimmune diseases, and cancer ( 164 ).…”

“…Research into T cell activation often utilizes two-dimensional (2D) culture systems, which do not replicate the interactions between naturally activated cells and the ECM that affect activation ( 162 , 163 ). Mechanical characterizations suggest that hydrogels have pathophysiologically relevant stiffness, mimicking the structure of lymph node tissues ( 164 , 165 ). Joseph et al.…”

“…Joseph et al. found that using a mouse T cell lymphoma line EL4 or primary mouse T cells in 3D bioprinting, and activating them with a combination of 10ng/mL phorbol myristate acetate (PMA) and 0.1μM ionomycin, resulted in a 1.3-fold increase in the ratio of active EL4 cells in soft substrates compared to those in hard substrates ( 164 ). Primary mouse T cells activated with PMA and ionomycin exhibited 1.35 times more active cells in soft substrates compared to those in hard substrates.…”

Trends in Photopolymerizable Bioinks for 3D Bioprinting of Tumor Models

“…Immune cells and other stromal cells play crucial roles in TME regulation . Understanding the mechanisms of cancer cell evasion from immune cell surveillance and their ability to modulate immune cell functions can provide novel approaches to target the TME.…”

“…Immune cells and other stromal cells play crucial roles in TME regulation. 130 Understanding the mechanisms of cancer cell evasion from immune cell surveillance and their ability to modulate immune cell functions can provide novel approaches to target the TME. Henrich et al prepared a mini-brain tumor model by encapsulating GL261 glioblastoma cells and glioblastoma-associated macrophages (GAMs) in 3D bioprinted GelMA hydrogels.…”