Wound healing, overview

Wound healing, a complex process

Wound healing is a complex and dynamic process of restoring skin cellular structures and tissue layers that involves multiple components: differentiated cells , stem cells , hair follicles, extracellular matrix (ECM) proteins, cytokines networks, microRNAs , blood vessels, nerves  and mechanical forces.

Wound healing process consists of 4 interrelated and overlapping phases:

  • haemostasis,
  • inflammation,
  • granulation/proliferation
  • and maturation/remodelling,

resulting in the replacement of missing skin with fibroblast-mediated scar tissue, not exactly identical to uninjured  skin. The skin of the scar has abnormal collagen architecture, compared to the surrounding skin and generally shows no skin appendages. Its slightly lighter colour renders scar more noticeable, which can cause profound psychological implications.

Physiopathology and pharmacology of wound care

Furthermore, numerous physiological or pathological factors including age, infection, diabetes/vascular disease, neuropathy, malnutrition, cancer, and chemo- and radiotherapies, can negatively affect skin regeneration. In addition, wound healing process can sometimes discontinue or become deregulated and lead to either delayed skin repair resulting in chronic wounds , or excessive healing, such as hypertrophic and keloid scarring. Although numerous treatments like silicone gel sheeting, pressure therapy, corticosteroids, cryotherapy, 5-fluorouracil, laser therapy, and radiotherapy are available, none are optimal and efficient options are missing.

Facilitating skin healing, minimizing the aesthetic impact on the patient and restoring optimal tissue function remain therefore a central concern of clinical and cosmetic dermatology in wound management. As a good understanding of the cellular and molecular mechanisms participating in skin regeneration is fundamental to test and develop clinical, cosmetological and pharmacological solutions in normal and impaired wound healing, current knowledge on wound healing process, with highlight of some effectors involved in the repair of damaged tissue, is presented below.

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granulation wound healing

The third phase of wound healing, consisting in the replacement of the provisional  fibrin matrix with granulation tissue once the wound has been debrided, includes several sub-phases: re-epithelialization, fibroplasia, collagen deposition and angiogenesis.

The inflammatory phase is characterized by the sequential infiltration of polymorphonuclear neutrophils (PMNs), monocytes/macrophages and lymphocytes. IL-8 facilitates PMNs migration from surrounding blood vessels.

Wound healing is a complex and dynamic process of restoring skin cellular structures and tissue layers that involves multiple components: differentiated cells , stem cells , hair follicles, extracellular matrix (ECM) proteins, cytokines networks, microRNAs , blood vessels, nerves and mechanical forces.

Our studies highlight the potential of foreskin tissue for autograft applications in boys. A suitable alternative donor site for autologous cell transplantation in female paediatric burn patients remains an open question in our department. We tested the hypothesis that in vitro studies and RHE reconstructive capacities of cells from different body sites can be helpful to select an optimal site for keratinocyte isolation before considering graft protocols for girls.

In the contexte of skin graft, cell suspensions transplanted directly to the wound is an attractive process, removing the need for attachment to a membrane before transfer and avoiding one potential source of inefficiency. Choosing an optimal donor site containing cells with high proliferative capacity is essential for graft success in burns.

We report a successful method for grafting paediatric males presenting large severe burns through direct spreading of autologous foreskin keratinocytes. This alternative method is easy to implement, improves the quality of skin and minimizes associated donor site morbidity. in vitro studies have highlighted the potential of foreskin tissue for graft applications and could help in tissue selection with the prospect of grafting burns for girls.

Keratinocytes from foreskin have a high capacity for division. A potential source of cells to provide coverage in paediatric burns.

To assess whether the keratinocyte progeny of human embryonic stem cells (hESCs) could be used to form a temporary skin substitute for use in patients awaiting autologous grafts, we investigated the cells’ capability of constructing a pluristratified epidermis.

burns

The keratinocytes resulting from foreskin have a high capacity of division. These cells can divide a long time before differentiation. The observations enable us to propose with our patients the keratinocytes from foreskin for wound healing especially for burns in children.

lipidocolloid dressing

The effect of Urgotul on normal human dermal fibroblast proliferation was studied in vitro and compared with that of two other dressing: Mepitel and Tulle Gras.

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