Results of artificial inflammation in scarless foetal wound healing: an experimental study in foetal lambs

Recent experimental and clinical evidence suggests that the foetus responds to injury in a fashion fundamentally different from the adult. Foetal wound healing occurs without scar formation. The mechanisms causing this difference are still not well defined but absence of inflammation may play a significant role. The aim of this study was to investigate the effects of artificially induced inflammation on scarless foetal wound healing. Twelve time-dated pregnant ewes underwent hysterotomies at 70 and 90 days' gestation. A potent chemoattractant agent (N-formyl-methionyl-leucyl-phenylalanine) was injected into the upper lip of the foetus in the first operation. In the second operation, a full-thickness incisional wound on the right side and a 3-mm excisional wound on the left side of the upper lip were created and closed primarily. A control wound was created on the lower lip. Macroscopic and histologic examinations of the wounds after birth revealed visible scar lines on the upper-lip wounds but no scar line on the lower lip, and an increase in fibrous tissue and collagen content in the upper-lip wounds. We have shown that injecting a chemotactic agent can stimulate inflammation in a period of gestation when tissue injury can not. Although lack of inflammation due to tissue injury in the early period of foetal life may be an important cause of scarless healing, further experimental studies should be carried out to investigate the pathways that are not activated by tissue injury, the immune status of the foetus and the growth factors involved in the inflammatory response.