Evolution of ischemic tissue injury in a random pattern flap: a new mouse model using intravital microscopy

Area of Science:

• Regenerative Medicine
• Vascular Biology
• Surgical Research

Background:

• Random pattern flap dissection can lead to microcirculatory dysfunction and ischemia, compromising wound healing.
• Impaired tissue viability is a significant concern in flap surgery.
• Current methods lack continuous monitoring of microcirculatory changes and tissue injury.

Purpose of the Study:

• To develop an in vivo model for continuous monitoring of microcirculatory dysfunction, ischemia, and tissue injury in random pattern flaps.
• To analyze the interplay between microcirculation, apoptosis, and necrosis in flap failure.
• To provide a tool for evaluating novel protective strategies in flap surgery.

Main Methods:

• A random pattern skin flap was created in mice and placed within a dorsal skinfold chamber.
• Intravital fluorescence microscopy was used to analyze arteriolar blood flow, functional capillary density, and apoptotic cell death.
• Measurements were taken at multiple time points post-surgery to assess flap viability and necrosis.

Main Results:

• A significant decrease in arteriolar blood flow and functional capillary density was observed in the flap distal part by day 1.
• Impaired microcirculation correlated with increased apoptotic cell death.
• Microcirculatory dysfunction persisted, leading to substantial flap necrosis (49%) by day 7.

Conclusions:

• The developed in vivo model allows for simultaneous evaluation of microvascular hypoperfusion, apoptosis, and tissue necrosis in random pattern flaps.
• This model has potential for analyzing flap failure mechanisms using gene-targeted mice.
• It serves as a valuable tool for studying protective strategies like angiogenesis induction.