A new in vivo model for the study of fetal wound healing

We have developed a new in vivo model for the study of fetal wound healing. Fetal ICR mice (total gestation, 21 days) received a full-thickness incisional wound in the hind limb at gestational day 14 (N = 100). The wound was made with a 28.5-gauge needle that was passed transplacentally into the amniotic cavity. The wounds were analyzed histologically on postoperative days 0, 1, 3, and 5 by hematoxylin-eosin and Mallory's trichrome stains. Once the wounding technique was mastered, the overall mortality rate for this model was 20% by postwounding day 5. Each fetus healed their wound without scar by postwounding day 3. In 3 animals, 5 microliters of human transforming growth factor beta 1 (25 micrograms per microliter) was injected into the wound site, resulting in scar and an inflammatory cell infiltrate, indicating that the 14-day-gestation fetal mouse can be manipulated if necessary. This model offers the advantages of an in vivo system that can be studied at an early gestational age. Furthermore, it is inexpensive, easy to manipulate, and can be studied with commercially available murine probes.