Intracellular hydrogelation preserves fluid and functional cell membrane interfaces for biological interactions

Abstract

Cell membranes are an intricate yet fragile interface that requires substrate support for stabilization. Upon cell death, disassembly of the cytoskeletal network deprives plasma membranes of mechanical support and leads to membrane rupture and disintegration. By assembling a network of synthetic hydrogel polymers inside the intracellular compartment using photo-activated crosslinking chemistry, we show that the fluid cell membrane can be preserved, resulting in intracellularly gelated cells with robust stability. Upon assessing several types of adherent and suspension cells over a range of hydrogel crosslinking densities, we validate retention of surface properties, membrane lipid fluidity, lipid order, and protein mobility on the gelated cells. Preservation of cell surface functions is further demonstrated with gelated antigen presenting cells, which engage with antigen-specific T lymphocytes and effectively promote cell expansion ex vivo and in vivo. The intracellular hydrogelation technique presents a versatile cell fixation approach adaptable for biomembrane studies and biomedical device construction.

Cell-based biocomposite engineering directed by polymers

“…The polymer chains with fluorescent signals produced in living cells enable long-term cell labeling, 41 while the hydrogel network can serve as a reinforced framework to support the cell morphology and cell membrane. 18 To sum up, the direct coupling of cells with polymers creates new possibilities for developing cell-based biocomposites.…”

“…5c). 18 In their report, the poly(ethylene glycol) diacrylate monomer (PEG-DA) and 2-hydroxyl-4′-(2-hydroxyethoxy)-2-methylpropiophenone photoinitiator (I2959) were chosen as reactive reagents to achieve cell hydrogelation. Both the monomer and initiator exhibited high cytoplasmic permeation and low reactivity to proteins, which could effectively form intracellular crosslinking as well as minimize the damage of cell interior components and the formation of cell-surface masking.…”

“…Such an artificial polymer network could also support the phospholipid bilayer and retain the membrane fluidity and membrane order in the gelated cells to preserve the bioactivity. 18 Relying on this intracellular hydrogelation strategy, the gelated murine and human primary dendritic cells were transformed into robust and modular artificial antigen-presenting systems, which could be stored by freezing and lyophilization, as well as functionalized with cytokine-releasing carriers for T-cell modulation. The biomimetic materials with robust stability and remarkable biological functionality improved the anticancer efficacy in mice by adoptive T-cell therapy.…”

“…For example, through biotechnologies such as genetic engineering and metabolic engineering, living cells can be modified to produce drugs and bioenergetic molecules as living biofactories. 10 Moreover, with robust physical or chemical techniques, cells can be transformed into structured carbonized, 11–13 silicified, 11,14,15 metallized, 16,17 or polymeric 18,19 biocomposites.…”

“…In the past two decades, extensive efforts have been devoted to the design and manufacture of cell-based biocomposites through the assistance of polymeric materials. 17,18,23,25,26,32,33,36–41 The combination of cells and polymers results in specific physiochemical and biological properties of the integrated biocomposites. On the one hand, natural cells grant the cell-based biocomposites potential bioactivities and biostructures, which can hardly be obtained by artificial synthesis.…”