**1. Introduction**

Nanomedicine has had a significant impact on delivery system development for pharmaco‐ logical fields that include controlled‐release wound dressings and biocompatible nanocarriers for biomedical applications [1]. As the largest organ in the human body, skin gives the body protection, but in so doing sustains a variety of skin wounds that require immediate repair process [2]. Modern wound dressings have been under development for decades. Although there are a wide array of wound dressings, ointments, and medical devices for clinical use, the time‐consuming process of wound management is mainly restricted to wound repair rather than regeneration, which are two distinct definitions [3]. The key problem of skin regeneration is how to restore the native structure and function of the injured organ, including blood capillaries. Recently, biomaterial carriers in nanomedicine have shifted the focus from patient survival to quality of skin regeneration in terms of function, scar reduction, and improved aesthetics for reconstruction surgeries and burns [4]. In the formats of wound dressings and transdermal formulations, delivery systems have been applied to accelerate wound healing and to promote tissue regeneration, as well as to treat skin cancers using nanomedicine.

There are different circumstances in which people may need wound care and management. To meet the challenges of wound treatments for acute wounds and chronic wounds, such as large‐area skin loss, burns, ulcers (pressure, diabetic, neuropathic, or ischemic), trauma, and especially infected wounds, which are mostly caused by microbes [5], the accurate delivery of antimicrobial agents is attracting much attention from researchers [6–8]. In addition to antimicrobial wound dressing, delivery systems of bioactive proteins, such as peptides and growth factors (platelet‐derived growth factor, PDGF; endothelial growth factor, EGF; and fibroblast growth factor 2, FGF2 or bFGF), have demonstrated their promising effects in wound healing [9]. Cell therapy, including stem cell strategy, provides a novel therapeutic approach to wound healing [10]. Interestingly, mesenchymal stem cells (MSCs) and adipose‐derived stem cells (ASCs) have emerged as a new approach in skin tissue engineering to accelerate wound closure, which would be of enormous benefit particularly for those wounds experi‐ encing delayed healing in patients with diabetes and elderly [11, 12]. Gene delivery systems for wound healing have been also developed to transfer deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to wound sites [13, 14]. The regulations of delivery systems in wound healing can be complicated and vary greatly depending on the specific biomaterials and scaffolds, as well as the clinical use in particular [15]. In the commercialization of delivery wound healing systems, developmental and regulatory challenges are greater than in normal wound dressing and wound healing products. The biomaterials and scaffolds used in delivery systems take advantage of different structures, chemical parameters, and sources and so may require more rigorous development and regulation.

This chapter reviews biomaterials and scaffolds used in the design, characterization, and evaluation of delivery systems for wound healing, which include delivering antimicrobial drugs, combinations of proteins (growth factors and peptides), cells, and genes (**Figure 1**). Specific examples of application are summarized. Regenerations of skin tissues and recon‐ structions of blood capillaries in the wound care process are covered. In addition, the regula‐ tory considerations for delivery systems in the wound healing field are also explored.

**Figure 1.** Delivery systems in wound healing.

**1. Introduction**

74 Wound Healing - New insights into Ancient Challenges

Nanomedicine has had a significant impact on delivery system development for pharmaco‐ logical fields that include controlled‐release wound dressings and biocompatible nanocarriers for biomedical applications [1]. As the largest organ in the human body, skin gives the body protection, but in so doing sustains a variety of skin wounds that require immediate repair process [2]. Modern wound dressings have been under development for decades. Although there are a wide array of wound dressings, ointments, and medical devices for clinical use, the time‐consuming process of wound management is mainly restricted to wound repair rather than regeneration, which are two distinct definitions [3]. The key problem of skin regeneration is how to restore the native structure and function of the injured organ, including blood capillaries. Recently, biomaterial carriers in nanomedicine have shifted the focus from patient survival to quality of skin regeneration in terms of function, scar reduction, and improved aesthetics for reconstruction surgeries and burns [4]. In the formats of wound dressings and transdermal formulations, delivery systems have been applied to accelerate wound healing and to promote tissue regeneration, as well as to treat skin cancers using nanomedicine.

There are different circumstances in which people may need wound care and management. To meet the challenges of wound treatments for acute wounds and chronic wounds, such as large‐area skin loss, burns, ulcers (pressure, diabetic, neuropathic, or ischemic), trauma, and especially infected wounds, which are mostly caused by microbes [5], the accurate delivery of antimicrobial agents is attracting much attention from researchers [6–8]. In addition to antimicrobial wound dressing, delivery systems of bioactive proteins, such as peptides and growth factors (platelet‐derived growth factor, PDGF; endothelial growth factor, EGF; and fibroblast growth factor 2, FGF2 or bFGF), have demonstrated their promising effects in wound healing [9]. Cell therapy, including stem cell strategy, provides a novel therapeutic approach to wound healing [10]. Interestingly, mesenchymal stem cells (MSCs) and adipose‐derived stem cells (ASCs) have emerged as a new approach in skin tissue engineering to accelerate wound closure, which would be of enormous benefit particularly for those wounds experi‐ encing delayed healing in patients with diabetes and elderly [11, 12]. Gene delivery systems for wound healing have been also developed to transfer deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to wound sites [13, 14]. The regulations of delivery systems in wound healing can be complicated and vary greatly depending on the specific biomaterials and scaffolds, as well as the clinical use in particular [15]. In the commercialization of delivery wound healing systems, developmental and regulatory challenges are greater than in normal wound dressing and wound healing products. The biomaterials and scaffolds used in delivery systems take advantage of different structures, chemical parameters, and sources and so may

This chapter reviews biomaterials and scaffolds used in the design, characterization, and evaluation of delivery systems for wound healing, which include delivering antimicrobial drugs, combinations of proteins (growth factors and peptides), cells, and genes (**Figure 1**). Specific examples of application are summarized. Regenerations of skin tissues and recon‐

require more rigorous development and regulation.
