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Conducting Polymer-Based Nanomaterials for Tissue Engineering
Published in Ram K. Gupta, Conducting Polymers, 2022
Murugan Prasathkumar, Chenthamara Dhrisya, Salim Anisha, Robert Becky, Subramaniam Sadhasivam
The process of wound healing is complex and involves various stages such as hemostasis, inflammation, proliferation, and remodeling. The application of wound dressing facilitates maintaining moist conditions, promotes speedy re-epithelization and recovery. Advanced material formulation viz., films, foams, hydrogels, hydrocolloids, and hydrofibers were used to promote wound healing. Natural polymers, such as chitosan, fibrin, elastin, gelatin, and synthetic polymers (PCL and PLA), were generally used to fulfill the material fabrication. In current years, CPs are widely used as wound dressing materials and enable faster recovery due to their electrochemical properties [13]. The integration of CPs into wound dressing enables improved antibacterial activity and aids the controlled release of drugs.
Tissue Engineering of Articular Cartilage
Published in Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi, Articular Cartilage, 2017
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi
The inclusion of stimulatory growth factors is one of the most common means to accelerate tissue growth in engineered constructs. Many growth factors have been shown to be effective at stimulating cellular proliferation and matrix synthesis in articular cartilage, both in vitro and in vivo. Since growth factors normally play a role in healing and development, their therapeutic use is intended to replicate this function to promote rapid regeneration of a tissue. Varying amounts of growth factors are constantly present throughout the body, so higher concentrations are typically used in experiments to elicit more dramatic effects. For example, culture medium with 20% fetal bovine serum added was shown to have similar effects on proliferation and protein synthesis as a medium that included the three growth factors (TGF-β1, basic fibroblast growth factor [bFGF], and insulin-like growth factor 1 [IGF-1]) (Chaipinyo et al. 2002). Comparatively, lower concentrations of serum in the medium produced poorer results. The problem with serum, however, is that its composition and the concentrations of its components are generally unknown and can vary widely from source to source and batch to batch (Figure 4.20) (Bilgen et al. 2007).
Wound Dressings and Cosmetic Materials from Bacterial Nanocellulose
Published in Miguel Gama, Paul Gatenholm, Dieter Klemm, Bacterial NanoCellulose, 2016
Stanislaw Bielecki, Halina Kalinowska, Alina Krystynowicz, Katarzyna Kubiak, Marek Kołodziejczyk, Manu de Groeve
A wound is defined as breakage in the continuity of skin (Enoch and Price 2004). It can affect the epithelial layer of skin or also the underlying dermis, subcutaneous fat, and even the muscle, nerves, and bone. Wounds are classified according to etiology (caused by burns, cuts, friction or shear force, pressure, disease, etc.), anatomical location, or duration of healing (acute and chronic wounds). Wound healing is a complex process involving various types of cells (connective tissue and immune system components) and controlled by a variety of signal molecules, such as growth factors, proteinases and their inhibitors, cytokines, and other inflammatory response mediators. Acute wound healing is a systematic cascade of overlapping but carefully regulated processes that requires the coordinated completion of a variety of cellular activities. These processes, which are triggered by tissue injury, involve four phases: hemostasis, inflammation, proliferation (repair), and remodeling. The healing of acute wounds usually takes a few weeks or months, while chronic wounds fail to heal within this period because of the permanent inflammatory state caused by high activity of destructive proteolytic enzymes such as metalloproteinases and elastase, and excessive amount of exudates. The latter can cause maceration of healthy tissue surrounding the wound and increase its surface area. Examples of chronic wounds are decubitus wounds (pressure sores); venous, arterial, and diabetic foot ulcers; and wounds caused by autoimmune diseases.
Quaternary ammonium salt-modified isabgol scaffold as an antibacterial dressing to improve wound healing
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Vasudha T. K., Anand Kumar Patel, Vignesh Muthuvijayan
Wound healing is an orderly progression of biological and molecular events that occurs in roughly four stages, viz., hemostasis, inflammation, proliferation, and remodeling stages. In the hemostasis phase, platelets arrive at the wound site and clot formation occurs to cover the wound and ward-off bacteria. In the inflammation stage, wound debridement action is performed by macrophages and neutrophils that are recruited to the wound site. These inflammatory cells remove cell debris and bacteria at the wound site. The proliferation stage is characterized by the formation of extracellular matrix proteins, angiogenesis, wound contraction, and keratinocyte migration. In the remodeling phase, collagen fibers deposited in the proliferative phase are aligned in an orderly fashion to increase the tensile strength of the newly formed tissue [1]. Infection is one of the leading causes of impaired wound healing. Infection results in prolonged inflammation where inflammatory cells accumulate at the wound site and release inflammatory cytokines. This triggers the secretion of matrix metalloproteases (MMPs) that destroy the wound healing process. Additionally, production of factors like vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) is also affected. Under these conditions, the transition from the inflammatory to proliferative stage does not occur, preventing the formation of new healthy tissue. It is, therefore, crucial to prevent infection at the wound site [1–3].
Self-assisted wound healing using piezoelectric and triboelectric nanogenerators
Published in Science and Technology of Advanced Materials, 2022
Fu-Cheng Kao, Hsin-Hsuan Ho, Ping-Yeh Chiu, Ming-Kai Hsieh, Jen‐Chung Liao, Po-Liang Lai, Yu-Fen Huang, Min-Yan Dong, Tsung-Ting Tsai, Zong-Hong Lin
In the case of poor wound healing, wound infection is the major concern. In this context, Du et al. [101] proposed a drug-loaded TENG patch with a surface-engineered electrode possessing Mg–Al layered double hydroxides (LDH) in 2021. The drug-loaded TENG was designed as an arch-shaped patch composed of PTFE (electronegative) and Mg–Al LDH@Al film (electropositive) as the electrode and minocycline container (Figure 8(c)). An alternating current was induced via contact and separation between the two fabric materials by an external force. Electrical stimulation was found to help wound healing and promote the Mg-Al LDH@Al to release loaded minocycline when the electrode came into contact with the serum fluid. In an in vitro study, almost 100% wipeout of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was found 24 h after application of this surface-engineered TENG patch. Elevated fibroblast proliferation and migration was also observed. In the in vivo component of that study, full-thickness skin wounds infected with S. aureus were created on the backs of mice. An AC voltage of 0.5–4.5 V and a current of 5–40 nA were collected from the mouse motions via the surface-engineered TENG device. The antibacterial efficacy (96.7% inhibition) and rapid wound healing process both yielded exceptional results compared to the untreated control group (Figure 8(d)). This further realization of medication-containing surface-engineered TENG devices has established a new application route in the field of biomedicine.
Negative pressure wound therapy: device design, indications, and the evidence supporting its use
Published in Expert Review of Medical Devices, 2021
Stephen J. Poteet, Steven A. Schulz, Stephen P. Povoski, Albert H. Chao
Normal wound healing progresses through the stages of hemostasis, inflammation, proliferation, and tissue remodeling. Since the introduction of NPWT in the 1990s, many studies have investigated the mechanisms through which negative pressure augments normal wound healing. In 1997, Argenta and Morykwas published a series of animal studies demonstrating the positive healing effects of sub atmospheric (125 mmHg below ambient) pressure in a pig model. The results of their study demonstrated a four-fold increase in blood flow within the wound bed and surrounding tissues, and a significant increase in granulation tissue formation with both continuous and intermittent negative pressure application. Additionally, a statistically significant decrease in tissue bacterial counts was observed, suggesting that vacuum-assisted closure devices improved wound bioburden [5,23]. In another study, microvascular blood flow was found to increase substantially in a porcine sternotomy wound model utilizing NPWT[24]. Although microvascular blood flow to wound tissues has been shown to increase as a result of negative pressure, some studies have shown a decrease in adjacent tissue perfusion related to the positive pressure of the foam sponge dressing [25,26].