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Interaction of intravenously injected liposomes with mouse liver mitochondria. A fluorescence and electron microscopy
Abstract:
Megamitochondria, resulting from cuprizone feeding of Swiss ICR mice, were fluorescent in hepatocytes after the intravenous injection to mice of a liposome-encapsulated acridine orange-DNA complex (AO-DNA). Flow cytofluorimetric analysis of isolated megamitochondria showed that the proportion of liposome-encapsulated AO-DNA which localized in megamitochondria increased from 0.02% of the dose injected per liver cell at 3 min after injection to an average of 0.34% at 1 h after injection. Megamitochondria showed negligible fluorescence by fluorescence activated cell sorting (FACS) analysis when free AO-DNA was intravenously injected. Transmission electron micrographs of mouse liver tissue after intravenous injection of liposomes encapsulating iron dextran showed an association of the liposomes with megamitochondria which appeared identical to liposome association with normal mitochondria. These results support and extend our earlier observation that a fraction of the liposomes injected intravenously into mice associate with mitochondria in the liver, and possibly deliver their aqueous contents there.
Insights
Liposomes efficiently deliver acridine orange-DNA (AO-DNA) to megamitochondria in mouse liver cells. This targeted delivery was confirmed using flow cytometry and electron microscopy, showing increased AO-DNA localization over time.
Area of Science:
- Cell Biology
- Biochemistry
- Drug Delivery
Background:
- Megamitochondria are enlarged mitochondria observed in certain pathological conditions.
- Cuprizone feeding is a known method to induce megamitochondria formation in mice.
- Liposomes are widely used as drug delivery vehicles.
Purpose of the Study:
- To investigate the targeted delivery of liposome-encapsulated acridine orange-DNA (AO-DNA) to megamitochondria.
- To quantify the localization of AO-DNA within megamitochondria over time.
- To confirm the association of liposomes with megamitochondria using electron microscopy.
Main Methods:
- Induction of megamitochondria in Swiss ICR mice via cuprizone feeding.
- Intravenous injection of liposome-encapsulated AO-DNA.
- Flow cytofluorimetric analysis of isolated megamitochondria.
- Fluorescence-activated cell sorting (FACS) analysis.
- Transmission electron microscopy (TEM) of liver tissue.
Main Results:
- Liposome-encapsulated AO-DNA showed significant fluorescence in hepatocytes containing megamitochondria.
- Flow cytometry revealed increased AO-DNA localization in megamitochondria from 0.02% at 3 min to 0.34% at 1 hour post-injection.
- Free AO-DNA showed negligible fluorescence in megamitochondria.
- TEM confirmed liposome association with megamitochondria, similar to normal mitochondria.
Conclusions:
- Liposomes effectively target and deliver their contents, such as AO-DNA, to megamitochondria in vivo.
- This study validates and extends previous findings on liposome-mitochondria association in the liver.
- Liposomes represent a promising strategy for delivering therapeutic agents to megamitochondria.