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Updated: Aug 19, 2025
Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
Macrophage polarity and wound age determination
Yumi Kuninaka1, Yuko Ishida2, Akiko Ishigami1
1Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
Abstract:
We investigated the dynamics of the gene expression of M1 and M2 macrophage markers during skin wound healing in mice. Expression of M1-macrophage markers, such as Il12a, Tnf, Il6, Il1b, and Nos2 was upregulated after wounding and peaked at 1 or 3 days after injury, and that of M2-macrophage markers such as Mrc1, Cd163, Ccl17, Arg, and Tgfb1, peaked at 6 days after injury. Consistent with these findings, using triple-color immunofluorescence analysis revealed that F4/80+CD80+ M1 macrophages were more abundant than F4/80+CD206+ M2 macrophages on day 3 in mouse wound specimens, and that M2 macrophages were prominently detected in day 6 wounds. For application in forensic practice, we examined macrophage polarization using human wound specimens. The average ratios of CD68+iNOS+ M1 macrophages to CD68+CD163+ M2 macrophages (M1/M2 ratios) were greater than 2.5 for the wounds aged 2-5 days. Out of 11 wounds aged 1-5 days, five samples had the M1/M2 ratios of > 3.0. These observations propose that the M1/M2 ratios of 3.0 would indicate a wound age of 1-5 days as the forensic opinion. This study showed that M1 and M2 macrophages in human skin wound might be a promising marker for wound age determination.
Insights
This study reveals that macrophage polarization dynamics, specifically the M1/M2 ratio, can predict skin wound age. This finding offers a novel forensic tool for determining wound age in human skin.
Area of Science:
- Immunology
- Forensic Science
- Wound Healing Research
Background:
- Macrophage polarization into M1 (pro-inflammatory) and M2 (pro-resolving) subtypes plays a critical role in wound healing.
- Understanding the temporal dynamics of these macrophage populations is crucial for accurate wound age estimation.
Purpose of the Study:
- To investigate the gene expression patterns of M1 and M2 macrophage markers during murine skin wound healing.
- To evaluate the utility of macrophage polarization ratios as a forensic marker for determining the age of human skin wounds.
Main Methods:
- Gene expression analysis of M1 and M2 markers in mouse wound models.
- Triple-color immunofluorescence staining to quantify M1 and M2 macrophage populations in mouse and human wound tissues.
- Calculation of M1/M2 macrophage ratios in human wounds of varying ages.
Main Results:
- M1 macrophage markers peaked at 1-3 days post-injury, while M2 markers peaked at 6 days in mice.
- Immunofluorescence confirmed M1 dominance early in healing (day 3) and M2 dominance later (day 6) in mice.
- In human wounds aged 2-5 days, M1/M2 ratios exceeded 2.5, with ratios >3.0 observed in wounds aged 1-5 days.
Conclusions:
- Macrophage polarization exhibits distinct temporal dynamics during skin wound healing.
- The M1/M2 macrophage ratio in human skin wounds shows potential as a reliable indicator for forensic wound age determination, particularly for wounds aged 1-5 days.
