A lack of
oxygen is classically described as a major cause of impaired wound healing in diabetic patients. Even if the role of
oxygen in the wound healing process is well recognized, measurement of
oxygen levels in a
wound remains challenging. The purpose of the present study was to assess the value of electron paramagnetic resonance (EPR) oximetry to monitor pO2 in
wounds during the healing process in diabetic mouse models. Kinetics of
wound closure were carried out in
streptozotocin (STZ)-treated and db/db mice. The pO2 was followed repeatedly during the healing process by 1 GHz EPR spectroscopy with
lithium phthalocyanine (LiPc) crystals used as
oxygen sensor in two different
wound models: a full-thickness excisional skin
wound and a pedicled skin flap.
Wound closure kinetics were dramatically slower in 12-week-old db/db compared to control (db/+) mice, whereas kinetics were not statistically different in STZ-treated compared to control mice. At the center of excisional
wounds, measurements were highly influenced by atmospheric
oxygen early in the healing process. In
pedicled flaps,
hypoxia was observed early after wounding. While reoxygenation occurred over time in db/+ mice,
hypoxia was prolonged in the diabetic db/db model. This observation was consistent with impaired healing and microangiopathies observed using intravital microscopy. In conclusion, EPR oximetry using LiPc crystals as the
oxygen sensor is an appropriate technique to follow
wound oxygenation in acute and chronic
wounds, in normal and diabetic animals. Nevertheless, the technique is limited for measurements in pedicled skin flaps and cannot be applied to excisional
wounds in which diffusion of atmospheric
oxygen significantly affects the measurements.