Page 58 - IJB-9-2

International Journal of Bioprinting Bioprinting in wound dressing and healing

Figure 1. (A) Hemostasis, (B) inflammation, (C) proliferation, and (D) remodeling stages of wound healing.
1. Introduction The skin is the first barrier that protects the body and
must be repaired promptly when it is damaged to form a
The skin is an important line of defense for the body wound. Repairing damaged skin is an extremely complex
against external environmental stimuli and hazards. The and dynamic process divided into a hemostatic phase, an
skin has a complex tissue structure consisting of three main inflammatory response phase, a cell proliferation phase, and
parts: the epidermis, the dermis, and the subcutaneous a skin remodeling phase (Figure 1). The hemostatic phase
[5]
tissue . The epidermis is a dynamic, continuously self- usually occurs immediately after the appearance of the wound
[1]
renewing, multilayered epithelium composed mainly and is dominated by platelets, which undergo an aggregation
of keratinocytes. Keratinocytes produce keratin and are reaction. They form blood clots in the wound to fill the tissue
surrounded by rich lipids that play an important role in gaps, creating a temporary wound matrix. This phase activates
the skin’s protective function. The basement membrane inflammatory cells by stimulating the release of interleukin
connects the epidermis to the adjacent layer of the dermis. (IL)-6, IL-1, tumor necrosis factor beta (TNF-β), and other
The dermis consists mainly of fibroblasts and the fibers and factors while reducing blood loss. The inflammatory response
stroma they produce . Owing to the high elastin content phase and the hemostasis phase occur essentially at the same
[2]
in this layer, it provides mechanical support and elasticity time. Neutrophils and monocytes aggregate at the site of
to the skin. The dermis is connected to the subcutaneous trauma and remove bacteria, pathogens, necrotic tissue, and
tissue, and this part mainly plays the role of connection, cells by phagocytosis. At the same time, these cells can secrete
cushioning mechanical pressure, energy storage, and growth factors and cytokines that will lead the skin repair
thermal insulation . The complex tissue structure of the process to the next stage. The proliferative phase consists
[3]
skin makes it crucial in protecting the body from the mainly of migration, proliferation and differentiation of
external environment, regulating the body’s physiological fibroblasts, synthesis and deposition of extracellular matrix,
activities, and maintaining the health of the body .
[4]

Volume 9 Issue 2 (2023) 50 http://doi.org/10.18063/ijb.v9i2.653