Transient changes in permeability in HeLa and L cells during detachment from a substrate

Area of Science:

• Cell biology
• Membrane transport
• Biochemistry

Background:

• Sodium-potassium (Na+/K+) gradients are crucial for cell function.
• Cell detachment from substrates can alter cellular physiology.
• Understanding membrane permeability changes is vital for cellular research.

Purpose of the Study:

• To investigate the changes in Na+ and K+ gradients in HeLa cells after enzymatic detachment.
• To explore the factors affecting the recovery of these ion gradients.
• To assess the potential for increased cell permeability during detachment for molecular delivery.

Main Methods:

• HeLa cells were detached using trypsin and other enzymes (EDTA, pronase E, dispase).
• Sodium (Na+) and potassium (K+) gradients were monitored.
• Effects of ouabain, cold, bumetanide, and CO2 acidification were tested.
• Cell permeability to molecules up to 5000 molecular weight (e.g., inulin) was assessed.

Main Results:

• Detachment caused Na+ and K+ gradients to approach medium levels, followed by recovery within 15 minutes.
• Recovery was inhibited by ouabain and cold but not bumetanide.
• Similar effects were observed with different detachment enzymes and in cells without intercellular connections or with acidified interiors.
• Increased permeability allowed entry of molecules up to 5000 Da.
• Reduced effect was noted in already rounded cells.

Conclusions:

• Cell detachment induces a transient increase in cell membrane leakiness, possibly due to foot detachment.
• This transient permeability can be exploited for introducing large molecules into cells.
• The findings suggest a novel method for cellular molecular delivery.