Macrophage Depletion Reagents Clodrosome®
Clodrosome® is a multilamellar liposome suspension in which clodronate is encapsulated in the aqueous compartments of the liposomes. Encapsome® is formulated and prepared identically to Clodrosome® except that clodronate is not added to the liposomes. The liposomes are filtered through 2 μm polycarbonate membranes to ensure that the larger particles, which may be toxic to animals, are removed from the suspension. Both are prepared and packaged under sterile conditions. When animals or cells are treated with Clodrosome®, phagocytic cells recognize the liposomes as invading foreign particles and proceed to remove the liposomes from the local tissue or serum via phagocytosis. The liposomes then release clodronate into the cytosol, resulting in cell death. Non-encapsulated clodronate cannot cross the cell membrane to initiate cell death.
Control liposomes (Encapsome®) are recognized and phagocytosed by the same mechanism as Clodrosome®. Since the control liposomes do not contain clodronate, the phagocytic cells are not killed. However, phagocytes do respond to the ingestion of control liposomes by cytokine secretion, temporary suspension of phagocytic activity and other responses described in the literature.
Fluorescent liposomes (Fluoroliposome®) suitable for macrophage targeting and tracking are available containing five different fluorescent dyes (DiI, DiO, DiD, DiA and DiR) that covers the entire spectrum. Fluorescent liposomes come in standard and mannosylated form. For more information see here.
m-Clodrosome® and m-Encapsome® are mannosylated reagents that are specifically formulated to efficiently target macrophages in central nervous systems and macrophages that contain more mannose receptors.
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*When animals or cells are treated with Clodrosome®, phagocytic cells recognize the liposomes as invading foreign particles and proceed to remove the liposomes from the local tissue or serum via phagocytosis. The liposomes then release clodronate into the cytosol resulting in cell death. Unencapsulated clodronate cannot cross the cell membrane to initiate cell death.
*Encapsome® control liposomes are recognized and phagocytosed by the same mechanism as Clodrosome®. Since the control liposomes do not contain clodronate, the phagocytic cells are not killed. However, phagocytes do respond to the ingestion of the control liposomes by cytokine secretion, temporary suspension of phagocytic activity and other responses described in the literature.
*The product must be removed from the vial using sterile technique. Do not use if sterility is compromised. This is particularly important if a single vial is accessed multiple times over several weeks. The product should not be used more than 60 days after receipt, even if unopened.
*Liposomes may settle when left undisturbed for more than a few hours. Immediately prior to use, in order to ensure a homogeneous liposome suspension, slowly invert the vial several times until the suspension appears homogeneous by visual inspection. Vigorous or erratic shaking will not damage the liposomes but may induce foaming and bubble formation making it more difficult to accurately measure the desired dosage.
*If the personnel performing intravenous injections are not experienced in or familiar with, precautions for injecting larger volumes (~10% animal weight in ml), viscous liquids or particulate suspensions, consider having extra animals available in case serious injection-related adverse events occur. Dose control animals first to become familiar with large volume injections.
*Within hours after systemic administration of Clodrosome®, animals begin to lose important components of their immune system. Standard animal handling and housing protocols are not suitable for immunocompromised animals. Even when such precautions are taken, monitor the general health of each animal for opportunistic infections unrelated to the experimental protocol. There is no inherent toxicity to the product at the recommended dose levels.
*If research involves the in vivo administration of Clodrosome® to immunodeficient mice, such as NCG and SCID mice, a high mortality rate (often more than 50%) is to be expected. In order to have statistically meaningful results, using a larger pool size of mice is recommended.
*When dosing intravenously, use standard precautions for dosing larger volumes to animals including the following: a) warm product to room temperature prior to dosing; b) ensure that all air bubbles are removed from the syringe prior to dosing. Intravenous injection of air bubbles may result in air emboli which can kill or seriously injure animals; c) inject product at a slow, steady rate of no more than 1 ml/min; d) decrease infusion rate if animals display any atypical reactions such as unusual agitation.
*Infusion-related adverse reactions usually involve the animal gasping for air or other seizure-like movements. Animals often recover with no apparent permanent injury, but any potential effects on experimental results must be assessed by the researcher.
*Liposomes should be kept at 4°C and NEVER be frozen.