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Published in Henry J. Woodford, Essential Geriatrics, 2022
Surgical intervention is usually only recommended for grade 3 or 4 ulcers in patients suitable to undergo an operation. Debridement is believed to improve wound healing by removing the necrotic tissue that has harmful effects on the wound. It has the added benefits of potentially unmasking underlying abscesses and allowing samples to be taken for culture, for example bone to diagnose osteomyelitis. Skin repair techniques include direct closure, skin grafts and the use of skin flaps.87 They are associated with high recurrence and adverse event rates in older, immobile people. Appropriate patient selection is important.
Hyaluronan-Based Hydrogels as Functional Vectors for Standardised Therapeutics in Tissue Engineering and Regenerative Medicine
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Alexandre Porcello, Alexis Laurent, Nathalie Hirt-Burri, Philippe Abdel-Sayed, Anthony de Buys Roessingh, Wassim Raffoul, Olivier Jordan, Eric Allémann, Lee Ann Applegate
In the context of skin lesions, hyaluronan accumulates at the repair site over three days to initiate tissue responses, maintains cell integrity, and finalises skin repair before being eliminated by HYAL enzymes after ten days (Mesa et al. 2002; Kavasi et al. 2017). Around 20%–30% of the hyaluronan turnover takes place locally in the skin, while the rest is eliminated by the lymphatic system. Interactions with specific receptors (i.e. CD44 and RHAMM) induce mitotic, migratory, and angiogenic responses (Dicker et al. 2014). Various specific hyaluronan polymer sizes establish and mediate the dialogue between damaged ECM and resident cells (e.g. fibroblasts, phagocytes), modulating both inflammatory and immune responses during tissue repair (Šafránková et al. 2010). Pivotal and specific roles of hyaluronan-mediated repair processes may be observed in developing foetuses, wherein high hyaluronan contents in the amniotic fluid prevent fibrosis and scarring (Nyman et al. 2013; Aya and Stern 2014). Specifically, longer persistence of hyaluronan may reduce collagen deposition and prevent scarring, leading to scar-free tissue repair in the foetus (Weindl et al. 2004). Such activities are drastically hindered in elderly organisms, functionally delaying or impairing the tissue repair process (Price et al. 2005).
Photodamaged and aged skin
Published in Giuseppe Micali, Francesco Lacarrubba, Dermatoscopy in Clinical Practice, 2018
Anne-Sophie Brillouet, Michael D. Southall
Skin moisturization is significantly decreased when the skin is damaged, and skin repair can be dependent on retarding the loss of moisture from the skin. The unique structure of the stratum corneum of the skin contributes to its function as a barrier to water loss and the external harsh environment. Injury to this barrier by the environment, UV exposure, common irritants, and age, with the resulting loss of water from the skin, is an important cause of the development of dry skin.
Bilayer nanofibrous wound dressing prepared by electrospinning containing gallic acid and quercetin with improved biocompatibility, antibacterial, and antioxidant effects
Published in Pharmaceutical Development and Technology, 2023
Yuanju Lv, Wenli Wu, Zemei Liu, Guangyan Zheng, Lihong Wang, Xin Che
Healing of the damaged skin is a slow and complicated process, which generally experienced four stages, namely hemostasis, inflammation, cell proliferation, and tissue remodeling (Zhang et al. 2017; Yang et al. 2022). Mild injury can regenerate spontaneously by skin repair. But when the injury is serious, bacterial infection increases inflammation and the wound cannot be healed by skin repair (Selvaraj and Fathima 2017; Ajmal et al. 2019). A traditional wound dressing has been widely used in clinical practice, such as gauze and bandages, can protect the wound from external factors. However, they cannot inhibit the bacteria in the wound site, and it is easy to form tissue adhesion and make the wound dehydrated when they are used (Qu et al. 2018; Li et al. 2019; Memic et al. 2019; Demir et al. 2022).Therefore, developing a new wound dressing with good biocompatibility and antibacterial and antioxidant activities is highly desirable.
Pharmaceutical, biomedical and ophthalmic applications of biodegradable polymers (BDPs): literature and patent review
Published in Pharmaceutical Development and Technology, 2022
Barzan Osi, Mouhamad Khoder, Ali A. Al-Kinani, Raid G. Alany
Collagen is a protein made from amino acids, specifically glycine, proline, hydroxyproline, and arginine and it is a major structural component of many human tissues, including skin, tendon, cornea and basement membranes (Dmour and Taha 2018). It is one of the most abundant proteins in mammals, constituting around 30% of total body proteins (Sibilla et al. 2015). Owing to its biocompatibility, enzymatic degradability, and high tensile strength, collagen has been widely investigated for various biomedical applications (Gu et al. 2019). Collagen-based materials have been successfully used for skin repair. TheraSkin™, Apligraf™ and Dermagraft™ are FDA-approved products for the treatment of venous leg ulcers and diabetic foot. (Lee et al. 2016; Dmour and Taha 2018). Furthermore, collagen has also been widely used as hemostatic agent due to its high thrombogenic properties (Lee et al. 2019). Several collagen-based hemostats are currently in use for a variety of surgical indications; these include FloSeal™ (Baxter Healthcare, the USA), SurgiFlo™ (Ethicon Inc., the USA) and CollaStat™ (Dalim Tissen Co. Ltd., Korea) (Lee et al. 2019). The fact that collagen is non-toxic, can be easily cross-linked and chemically modified promoted the use of this polymer for drug delivery applications. Chlorhexidine chip made of bovine gelatine has shown beneficial effects in the management of Chronic Periodontitis (John et al. 2015). GARAMYCIN™ (Innocoll Pharmaceuticals Ltd) is a collagen-based gentamicin-delivery implant that permits the localised and sustained delivery of gentamycin with limited systemic exposure (Mishra et al. 2014).
Are hair follicle stem cells promising candidates for wound healing?
Published in Expert Opinion on Biological Therapy, 2019
Bingmin Li, Wenzhi Hu, Kui Ma, Cuiping Zhang, Xiaobing Fu
HFSCs have long been speculated as an important reservoir for the regeneration of epidermal tissue after injuries, as the phenomenon by which hair follicle-containing punch grafts manifest better potential for treating chronic cutaneous wounds has been observed clinically [58–61]. In human-based studies, several randomized controlled trials have proved that hair follicle-containing scalp punch grafts feature a better curative effect than those harvested from non-hairy areas in chronic venous leg ulcer [58,61–63]. As a matter of fact, human research data is limited due to ethical reasons; a large share of relevant studies are performed using animal models. Albeit with differences in hair follicle structure and healing process between human and rodents, certain well-designed and high-quality rodent trails can still help and provide references for future HFSCs application in wound healing. In animal models, malfunction of HFSCs in mice was associated with an impaired initial healing response towards full-thickness skin wounds [64]. Besides, cell therapy with CD34+ bulge hair follicle SCs accelerated skin wound healing in rats [65]. Hair follicle cycle also carries an impact on skin repair. Wounds in anagen skin heal significantly faster than those in telogen areas. Alterations in the gene profile have also been observed, as the transcription of genes beneficial for wound healing are upregulated during the anagen phase in unwounded skin [5,66]. Studies indicated that HFSCs facilitate wound closure by promoting re-epithelization and improving angiogenesis. The mechanisms are briefly reviewed as follow.