New Scar Treatment Methods

New Scar Treatment Developments: Regeneration, Contraction & Scar Tissue

Three processes contribute to the healing outcome of a trauma, wound or injury caused by trauma, an accident or from undergoing plastic or reconstructive surgery: contraction, scar formation and regeneration. Of the three processes, contraction (rather than scar formation) is the clearly dominant process for spontaneous wound closure in adults.

In contrast skin wounds on early mammalian embryos heal perfectly with no signs of scarring and complete restitution of the normal skin architecture.

Regeneration.

Limb regeneration in certain amphibians is a spectacular feat by which an amputated limb grows back to its original form and recovers its normal function. It is the prototypical paradigm of regeneration . Very few adult amphibians, and none of the adult mammals, can replicate this feat. Instead, the vast majority of mammals, including adult humans, respond to severe injury by a spontaneous repair process.

Repair closes the wound by contraction and synthesis of scar tissue without recovery of the uninjured tissues . In contrast, regeneration closes the wound by synthesis of the missing organ (skin is an organ) at the original site, yielding a regenerate. Regeneration restores the normal structure and function of the organ; repair does not.

Wounds in early mammalian embryos heal without scar formation.

In clear contrast to the adult, the mammalian foetus heals its wounds spontaneously by regeneration with negligible contraction, no scar formation, diminished inflammatory response and increased levels of hyaluronic acid (hyaluronan, HA) synthesis , provided that the injury has been inflicted at a sufficiently early stage of gestation, typically before the third trimester.

A developmental transition, occurring during late mammalian gestation, leads from healing primarily by regeneration to healing by repair. During this transition closure of the injured site by regeneration is largely replaced by closure based on contraction and scar formation.

It is also a fact that scarring is often worse in children and teenagers, due to their enhanced inflammatory response, whilst the quality of scarring in people over 65 years is often improved as a result of an altered inflammatory and immune response at the wound site.

To gain insights into the mechanisms underlying scar-free wound healing, researchers lead by Dr Mark Ferguson, D.D.S., Ph.D., professor in the faculty of life sciences at the University of Manchester, England have analyzed the differences in cellular and molecular responses to wounding in embryonic and adult wound healing models.

Scar formation

To restore the barrier function of the skin as quickly as possible, closure of skin wounds and repair of missing skin tissue occur rapidly in adult skin by a mechanism that leads to scarring.

The transition from scar free embryonic wound healing to scar-forming adult wound healing is a gradual one and is characterized by the abnormal organization of the neo-dermis, predominantly the abnormal deposition of small parallel bundles of extracellular matrix between the margins of the wound (consisting largely of collagen types I and III and fibronectin) to form the scar as opposed to the deposition of large bundles of extracellular matrix in a normal basketweave orientation in the normal skin and in the neo-dermis of an embryonic wound. Scarring is therefore a morphogenetic problem, i.e. a failure of the regeneration of the normal skin structure as opposed to a biochemical problem, e.g. abnormal composition of the scar tissue.

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