2023 AIChE Annual Meeting

Engineered Artificial Human Neutrophils Exhibit Mature Functional Performance

Neutrophils are a key innate immune component in the body, serving as powerful effector leukocytes by mediating opposing effects on tumor progression and ameliorating pathogen infections. They are the most prevalent leukocyte in the body but have a limited clinical application due to their short lifespan, resistance to genetic modification, and complex purification process. The ability to mimic neutrophil function in the tumor microenvironment (TME) holds promise for cancer therapeutics and presents an important challenge. An approach to optimizing the potential of neutrophils in the TME is the design of artificial neutrophils.

Artificial cells are built to mimic the function, shape, morphology, or behavior of naturally occurring cells and provide the ability to have greater control over cell behavior. Here, we combined genetic engineering technology with a nanodrug system and constructed artificial neutrophils that display similar functions as native neutrophils. K562 and HL60 human leukemia cells were used as the platform for construction of artificial cells because of their longer lifespans and ease of genetic editing.

Our artificial neutrophils strove to emulate neutrophil chemotaxis and bacterial phagocytosis. G-protein coupled receptors (GPCRs) play an essential role in neutrophil chemotaxis and serve as a chemoattractant receptor. Our study aims to demonstrate success of mimicking neutrophil chemotaxis in the artificial cells through targeting modified GPCR receptors that regulate the Gi signaling pathway, specifically the hM4Di receptor. GPCRs can also be engineered to be activated solely by a synthetic ligand, such as small molecule clozapine-N-oxide (CNO). These engineered GPCRs hold great potential to redirect the migration of modified cells under a controllable manner with CNO treatment.

As compared to the parental cells, engineered hM4Di-K562 and hM4Di-HL60 cells exhibited excellent chemotaxis ability towards clozapine-N-oxide (CNO) and superior bacteria phagocytic behavior. The antibacterial ability of the hM4Di-K562 cells was further enhanced by loading them with the glycopeptide vancomycin via mesoporous silica nanoparticles (Nano@Van), resembling the granule proteins of native neutrophils. Engineered hM4Di-K562 cells were able to effectively phagocytize the vancomycin-SiO2 nanoparticle complex and migrate to target bacteria in a CNO-responsive manner, reminiscent of many aspects of native neutrophils.

Our proposed artificial cell engineering platform provides a new avenue to investigate the physiological properties of neutrophils. By engineering these cells to recognize and respond to specific antigens, pathogens, or cancer cells, they can effectively simulate the immune system's response. Enhancing the immunomodulatory capabilities of artificial immune cells can lead to breakthroughs in disease treatment and prevention.