Tissue reaction to an implantable identification device in mice

Area of Science:

• Biomedical Engineering
• Laboratory Animal Science
• Toxicology

Background:

• Reliable animal identification is crucial for long-term toxicity and carcinogenicity studies.
• Traditional identification methods can be unreliable, necessitating advanced techniques.
• Electronic identification offers a dependable alternative for animal tracking.

Purpose of the Study:

• To assess the stability and tissue response of glass-sealed microchips implanted subcutaneously in mice over a two-year period.
• To evaluate the suitability of microchips as a reliable identification method for long-term animal studies.

Main Methods:

• A two-year subcutaneous implantation study was conducted on 140 B6C3F1 mice (70 of each sex).
• Microchips were detected electronically and palpated periodically.
• Histopathological evaluations were performed at 3, 15, and 24 months post-implantation.

Main Results:

• Out of 140 implanted devices, only 7 (5%) were lost or failed during the 24-month study.
• Implants remained palpable and fixed, with no significant inflammation or swelling observed.
• Histological analysis revealed thin connective tissue encapsulation with minimal inflammation and no neoplastic changes around the implants.

Conclusions:

• Glass-sealed microchips are stable and well-tolerated in mice for up to 24 months.
• These microchips represent a reliable and safe method for long-term animal identification in research settings.
• The study supports the use of microchips to overcome limitations of traditional animal identification methods.