Using mesenchymal stem cells to improve wound healing in acute and chronic phases

Today, mesenchymal stem cells (MSCs) have been identified as a powerful tool for wound healing. The differentiation potential of MSCs together with easy accessibility, low immunogenicity and integral and important role in wound healing physiology make these cells an attractive candidate for therapeutic purposes. Mesenchymal stem cells are effective at all stages of wound healing. These cells migrate to the site of skin damage and mainly inhibit the immune and inflammatory responses through paracrine signalling. At the stage of proliferation, MSCs not only differentiate into the desired cells but also stimulate the proliferation and differentiation of resident progenitor cells, including fibroblasts, endothelial cells and epidermal cells, and thus induce angiogenesis, epithelialization and granule tissue formation and accelerate wound healing. In the regeneration and maturation phase which occurs following wound closure, the use of MSCs increases wound tensile strength, reduces scar formation, weakens wound contraction, and increases collagen expression. These cells alter their function based on the biomolecular and biochemical factors that characterize the microenvironment of the lesion site, such as hypoxia, and create a wound-healing rather than fibrotic microenvironment.Modern bioengineering techniques have led to significant progresses in stromal cell delivery methods for wound healing. MSCs are transplanted either by intravenous delivery or local injection into the dermis. They can be delivered in phosphate buffered saline or in combination with matrigel, fibrin polymer or hydrogels. In addition, the conditioned medium of MSCs is also effective alone and circumvents the challenges associated with MSCs transplantation.