Early Subcellular Hepatocellular Alterations in Mice Post Hydrodynamic Transfection: An Explorative Study

Area of Science:

• Molecular Biology
• Hepatology
• Cell Biology

Background:

• Hydrodynamic transfection (HT) is a key method for delivering plasmid genes into rodent livers.
• While HT facilitates gene delivery, the precise mechanism of plasmid incorporation into hepatocytes remains unclear.
• The technique involves rapid injection of DNA solutions, causing cardiac congestion and liver influx, primarily in acinus zone 3.

Purpose of the Study:

• To investigate the cellular mechanisms underlying plasmid uptake in hepatocytes following hydrodynamic transfection (HT).
• To elucidate the early cellular events and ultrastructural changes in liver cells after HT using electron microscopy.

Main Methods:

• Anesthetized C57BL/6J/129Sv mice received hydrodynamic tail vein injections of either an empty transposon vector or saline.
• Liver tissues were collected at various time points (1 minute to 48 hours) post-injection.
• Ultrastructural analysis was performed on fixed liver tissues using electron microscopy (EM).

Main Results:

• Electron microscopy revealed cytoplasmic membrane-bound vesicles in hepatocytes near central venules within 1 minute of HT.
• These vesicles enlarged into vacuoles, often near the nucleus, and appeared optically empty.
• Most hepatocytes showed normal ultrastructure, with some exhibiting minor damage; findings were similar in vector and saline groups.

Conclusions:

• Vacuole formation following HT is interpreted as nonspecific endocytosis.
• The study suggests that direct interaction at the plasma membrane is not the primary mechanism for plasmid incorporation during HT.
• Further research is needed to fully understand the intracellular trafficking and integration of plasmids post-transfection.