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Electron microscopic studies on tissue distribution of lipid microspheres used as drug delivery carriers
Y Shoji1, Y Mizushima, A Yanagawa
1First Department of Internal Medicine, St. Marianna University, Kawasaki, Japan.
Abstract:
The tissue distribution of lipid microspheres (LMs), drug carriers for targeting therapy of anti-inflammatory drugs, was morphologically studied by electron microscope. In areas of inflammation in rats and mice, LMs were taken up by macrophages and accumulated around endothelial cells of blood vessels, and were observed to penetrate to the outer layer of blood vessels. LMs were also observed in reticuloendothelial cells such as Kupffer cells and splenic macrophages. Furthermore, the uptake of LMs by polymorphonucleocytes (PMNs) in areas of inflammation was enhanced 2-3 fold when LMs were coated with homogeneous IgG. These findings are in agreement with the tissue distribution results previously reported by the authors in studies using radioisotope-labelled LMs. The present and previous reports indicate that LMs could be used as a novel drug carrier, similarly to liposomes, in a drug delivery system specific for areas of inflammation and reticuloendothelial systems.
Insights
Lipid microspheres (LMs) accumulate in inflamed tissues, particularly within macrophages and around blood vessels. Coating LMs with IgG enhances their uptake by immune cells, suggesting potential for targeted anti-inflammatory drug delivery.
Area of Science:
- Biomedical Engineering
- Pharmacology
- Immunology
Background:
- Lipid microspheres (LMs) are investigated as drug carriers for targeted anti-inflammatory therapies.
- Understanding the tissue distribution of LMs is crucial for optimizing drug delivery systems.
Purpose of the Study:
- To morphologically investigate the tissue distribution of lipid microspheres (LMs) in inflamed tissues.
- To evaluate the effect of IgG coating on LM uptake by immune cells in inflammatory sites.
Main Methods:
- Electron microscopy was used to study LM distribution in inflamed tissues of rats and mice.
- Comparison of LM uptake in tissues with and without IgG coating on the microspheres.
Main Results:
- LMs were observed within macrophages and around blood vessels in inflamed areas.
- LMs penetrated the outer layer of blood vessels and were found in reticuloendothelial cells (Kupffer cells, splenic macrophages).
- IgG-coated LMs showed a 2-3 fold enhanced uptake by polymorphonucleocytes (PMNs) in inflammatory sites.
Conclusions:
- LMs demonstrate specific tissue distribution in inflamed areas and reticuloendothelial systems.
- IgG coating significantly enhances LM uptake by immune cells at inflammatory sites.
- LMs show promise as novel drug carriers for targeted drug delivery systems, similar to liposomes.