Skin, the largest organ of the body, has multiple important functions, such as acts as a barrier to foreign pathogens, regulates body temperature, supplies sensation, and prevents dehydration of the body. The skin wound might be of different nature and varies from surgical to accidental lacerations, burns, pressure ulcers, diabetic ulcers, and venous ulcers. Disruption of the cellular and molecular signals in conditions such as diabetes, infection, or radiation exposure may result in an inefficient healing.
The wound healing process starts with coagulation and fibrin clot formation called hemostasis. Local inflammatory agents, such as activated complement and histamine, cause redness and swelling. Inflammatory cells promote the recruitment and proliferation of fibroblasts, vascular endothelial cells, and keratinocytes during the proliferative phase. Neovascularization also occurs in concert with the help of invaded capillaries, recruited vascular endothelial cells, and endothelial progenitor cells to support the newly formed tissue and to transport circulatory cells to the wound
Acute cutaneous wounds resulted from a trauma, which undergo a repair process and lead to a benign scar when
the repair process is orderly and timely. Patients with chronic wounds have underlying conditions, such as high blood sugar level and obesity, that impair wound healing. Pressure ulcers and venous ulcers are also some of the most common forms of chronic wounds. Chronic wounds are frequently linked to old age and correlates with a poor reservoir of fully functional stem cells
To achieve a complete healing of the wound, an appropriate wound care is critical, and standard treatment modalities are used to improve the wound bed. Therapy for chronic wounds mainly focuses on the identification and correction of the precipitating and perpetuating factors. This approach includes the use of antibiotics for accompanying cellulitis,
revascularization of ischemic limbs, and compression devices for venous ulcers and rigorous off-loading for decubitus
Epidermal stem cells in the basal layer, as an endogenous source of stem cells, can regenerate skin, but these cells are not sufficient to provide perfect repair after deep and extensive skin damage. Thus, exogenous supply of stem cells in traumatic conditions may be one of the novel therapeutic strategies to achieve perfect skin repair. Human stem cells may offer considerable opportunities providing both undifferentiated and differentiated cells for gene therapy, drug discovery, and regenerative medicine.
A substantial number of stem cell therapies for cutaneous wounds are currently under development as a result of encouraging preliminary findings in both preclinical and clinical studies.
Mesenchymal stromal cells, also known as mesenchymal stem cells (MSCs), are adult stem cells capable of self-renewal and multipotential differentiation. can be obtained from the bone marrow and other tissues such as adipose tissue, nerve tissue, umbilical cord blood, and dermis with phenotypic heterogeneitySeveral studies have demonstrated that transplanted MSCs can differentiate into epidermal keratinocytes, endothelial cells, and pericytes directly participating in the structural repair of a wound. MSC transplantation led to accelerated cutaneous wound closure in both normal and diabetic mice, where MSCs express keratinocyte-specific markers suggesting their role to promote wound healing by differentiation.
Several cell types, such as embryonic stem cells, iPSCs, mesenchymal stem cells, resident tissue stem cells, epithelial stem cells, adipose-derived stem cells, and hematopoietic stem cells, are currently under intense investigation. The mechanisms by which these stem cells contribute to the healing process have yet to be elucidated.
Authors: Suman Kanji, Hiranmoy Das. Advances of Stem Cell Therapeutics in Cutaneous Wound Healing and Regeneration. Mediators Inflamm. 2017; 2017: 5217967. Published online 2017 Oct 29