Identification of cartilage injury using quantitative multiphoton microscopy.

Area of Science:

• Biomedical Engineering
• Orthopedics
• Cellular Biology

Background:

• Cartilage injury can lead to post-traumatic osteoarthritis (PTOA).
• Understanding immediate post-injury cellular changes is crucial.
• Current imaging methods for cartilage lack cellular resolution or are unsuitable for in vivo use.

Purpose of the Study:

• To apply multiphoton microscopy (MPM) with sodium fluorescein to evaluate chondrocyte death patterns post-injury.
• To assess the potential of MPM for in situ, cellular-resolution imaging of cartilage damage.
• To investigate early cellular changes following traumatic cartilage injury.

Main Methods:

• Equine osteochondral blocks were subjected to controlled compressive loading.
• Injured and control tissues were imaged unfixed using MPM and sodium fluorescein.
• MPM data was reconstructed and analyzed to quantify cell death patterns.

Main Results:

• Chondrocyte death was observed to cluster in circular or elliptical patterns.
• Dead chondrocytes were predominantly found near matrix cracks.
• Only 26.3% of chondrocytes near cracks remained viable.

Conclusions:

• MPM enables in situ evaluation of cellular-scale cartilage injury in live tissue.
• This technique can identify distinct chondrocyte death patterns post-trauma.
• MPM shows promise for early detection of subtle cartilage damage, aiding in PTOA diagnosis.