China
Africa
Explore chapters and articles related to this topic
Controlled Therapeutic Delivery in Wound Healing
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
Adam Jorgensen, Zishuai Chou, Sean Murphy
An important repository of skin stem cells appears to be located at the bulge of the hair follicle, which does not degenerate during the hair cycle. The hair follicle contains multipotent stem cells that are activated at the start of the hair cycle and mobilized upon injury to stimulate regeneration of the damaged epidermis. Bulge stem cells respond rapidly to epidermal wounding during the acute wound repair phase and acquire an epidermal phenotype but interestingly, they are eliminated from the epidermis over several weeks after injury. This suggests that bulge stem cells contribute to the wound repair but not to the homoeostasis of the epidermis [85]. In vitro, bulge stem cells maintain their stem cell characteristics after propagation and can contribute to hair follicles, epidermis, and sebaceous gland formation when combined with neonatal dermal cells in culture [86].
Bioprinting of human skin
Published in Ali Khademhosseini, Gulden Camci-Unal, 3D Bioprinting in Regenerative Engineering, 2018
Tania Baltazar, Carolina Catarino, Pankaj Karande
Scientists have been studying hair follicle development for more than three decades. Different approaches have been investigated for the regeneration of hair follicles in vivo and in vitro. One of the successful methods developed so far is known as the organ germ method. In this approach, epithelial and mesenchymal cells are injected in a hydrogel droplet and, following initial self-rearrangement, lead to the formation of the early organ germs (Toyoshima et al. 2012). After in vitro incubation, these structures are transferred to the subcutaneous region of mouse skin where they have shown to be able to reconstitute whisker fibers or human hair fibers depending on the origin of the cells (Nakao et al. 2007; Toyoshima et al. 2012). In a different approach, a skin model constituted by a dermal compartment containing dermal papilla cells as dissociated or self-assembled spheroids and an epidermal layer with primary keratinocytes was shown to generate hair follicles after a few weeks of engraftment on the back of a mouse model (Thangapazham et al. 2014).
Body Systems: The Basics
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Hair follicles, located in the dermis, are lined with epidermal cells. Living hair follicles grow hair, the keratinized filament that emerges at the surface of the skin. Hair is a strong, stable structure with layers of cells. Hair grows in cycles and, in humans, individual hair follicle growth cycles are independent of other hair follicles, so humans do not “shed” hair as most animals do. After a growing phase, human body hair passes through a two- to six-year resting phase before it is lost and replaced. For a more comprehensive discussion of human hair biology, see Ebling (1987).
Development, characterization and in vivo evaluation of the ointment containing hyaluronic acid for potential wound healing applications
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Thiago Gomes Figueira, Francisco Vieira dos Santos, Sérgio Akinobu Yoshioka
Regarding the presence of hair follicles in Figure 8(a), these are dynamic mini-organs that perform several important immune functions such as the production of chemokines that regulate the migration of dendritic cells in the skin, prevention of oxidative stress and degeneration process [30, 31]. Hair follicles have a hair cycle formed by a regeneration system that goes through three phases: growth (anagen), regression (catagen) and rest (telogen) under the influence of growth factors and other signalling molecules [32]. Besides, human follicle dermal papilla cells help regulate hair follicle growth and development [33]. Evidence shows that human follicle dermal papilla cells are associated with vascular remodelling and wound healing through the action of vascular epithelial growth factor (VEGF) and growth factors secreted by hair follicles, respectively [34–37]. Ansell et al. [38] reported that in vivo wound healing is associated with changes in epithelial, endothelial, and inflammatory cell types. Gene profiling results revealed a clear correlation between the transcription of genes beneficial for wound healing and those regulated during the anagen phase of the hair cycle in non-wound skin.