Macrophages play diverse and critical roles throughout the body — from immune defense to tissue repair. To better understand their specific functions within individual tissues and their contributions to disease progression, researchers often need to selectively deplete macrophages in vivo.
Among all available tools, clodronate liposomes stand out as one of the most effective, economical, and well-established methods for macrophage depletion. By choosing different administration routes — such as intravenous (tail vein) or intraperitoneal injection — researchers can achieve targeted clearance of macrophages in specific tissues.
This article marks the first lesson in our “Macrophage Clearance Classroom” series, where we’ll explore injection methods, dosing strategies, and experimental applications to help you design effective macrophage depletion studies.
1. Injection Methods Overview
Tail Vein Injection
Tail vein injection offers a rapid and efficient way to deplete macrophages in the blood, liver (Kupffer cells), spleen, and lungs. Maximal depletion is typically achieved within 24 hours after injection, so timing of sample collection is critical.
Key Steps:
- Gently restrain the mouse and expose the tail through a hole in an inverted container.
- Dilate the tail veins by wrapping the tail with gauze soaked in ~70 °C warm water or alcohol.
- Use a 1 mL syringe; insert the needle parallel to the vein (<30° angle) at the distal one-quarter of the tail.
- Inject slowly — no resistance or skin blanching should occur if the needle is in the vein.
- For repeated injections, start from the tail tip and gradually move toward the base to minimize vessel damage.
After injection, apply gentle pressure with cotton for 1–2 min to stop bleeding.
Intraperitoneal Injection
Intraperitoneal (IP) injection is another common route for macrophage depletion, especially for targeting peritoneal macrophages and systemic clearance. Maximal depletion occurs 48–72 hours post-injection.
Procedure:
- Hold the mouse in the dorsal position with the abdomen facing up; disinfect the injection site with 75% ethanol.
- Inject at a site approximately 0.5 cm lateral to the midline of the lower abdomen, level with the thigh roots.
- Insert the needle at a 45° angle and advance 2–3 mm; resistance decreases once the needle penetrates the peritoneum.
- Aspirate slightly — if no blood or fluid appears, inject the liposome suspension slowly.
- Gently rotate and withdraw the needle to prevent leakage.
Other Routes
Depending on the research goal, other administration methods may be used — including subcutaneous, intratracheal, or intracerebral injection — to achieve depletion in specific tissues. Always refer to relevant literature or consult the Yeasen technical support team before beginning your experiment.
2. Dosing and Administration Schedule
|
Type |
Protocol |
|
Short-Term Depletion |
Single injection of 200 µL clodronate liposomes per 20–25 g mouse. Assess macrophage depletion or perform downstream assays at desired timepoints. |
|
Long-Term Depletion |
Initial dose: 200 µL per 20–25 g mouse, followed by 200 µL every 2–3 days to maintain macrophage depletion for one week or longer. |
3. Reference Protocols for Different Organs
|
Organ / Target Macrophages |
Recommended Dose (20–25 g mouse) |
Notes |
|
Spleen (Red Pulp Macrophages) |
200 µL per injection (IV or IP) |
For long-term depletion, repeat every 2–3 days. |
|
Liver (Kupffer Cells) |
200 µL per injection (IV or IP) |
Repeat dosing maintains depletion. |
|
Lung (Alveolar Macrophages) |
IV (150–200 µL) + Intranasal or Intratracheal (50 µL) |
Combined routes achieve best effect. |
|
Lymph Nodes |
100–200 µL per injection |
Adjust according to literature. |
|
Brain (Microglia) |
Intracerebroventricular injection: 10 µL (mouse), 50 µL (rat) |
Targets central nervous system macrophages. |
|
Blood (Monocytes) |
150–200 µL (IV injection) |
Maximal depletion within 24 h; duration varies by strain. |
[Note]: The above dosages are general recommendations. Please consult published literature and Yeasen’s technical experts before conducting your experiments.
Conclusion
Clodronate liposomes provide a powerful and versatile approach to selectively deplete macrophages across various tissues. By tailoring your injection route, timing, and dosing schedule, you can achieve reproducible and tissue-specific macrophage clearance — enabling deeper insights into their physiological and pathological functions.
Stay tuned for the next lesson in our “Macrophage Clearance Classroom” series, where we’ll explore organ-specific depletion strategies and verification methods to help you refine your experimental design.
Related Product
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Name |
Cat. No. |
Size |
|
40337ES08/10 |
5 mL/10 mL |
|
|
40338ES08/10 |
5 mL/10 mL |