Molecular and cellular basis of regeneration and tissue repair: Skin stem and progenitor cells: Using regeneration as a tissue-engineering strategy
ABSTRACT Cell plasticity and mesenchymal-epithelial interactions are regarded as a hallmark of embryonic development and are not believed to occur extensively in the adult. Recently, adult mesenchymal stem cells were reported to differentiate in culture into a variety of mature cell types, including epithelial cells. Progress in stem and progenitor cell biology and recognition of the unique properties of such cells may enable intelligent bioengineering design of replacement skin which allows regeneration to occur in vivo. Ideally, a scaffold-free environment which stimulates skin stem cells in situ to initiate cell signals that result in regeneration rather than scar formation is required. Various skin progenitor cell types are considered along with the signalling cascades that they affect. We also discuss a mammalian model of scar-free regeneration. Many of these mechanisms, if fully understood, could be harnessed after injury to perfectly restore the skin.
- SourceAvailable from: Ana Maria Carvalho
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- "Skin, the largest human organ, works as a mechanical barrier against environment hazards and is, also, responsible for selfhealing , immune surveillance, sensor detection, thermoregulation , and fluid homeostasis  . Injuries, caused by extreme temperature, trauma, chronic ulcerations, pressure, or venous stasis, promote disruption of skin integrity allowing the deposition and colonisation of the injury tissue by a wide range of bacteria . "
ABSTRACT: The present work aims to assess the antibacterial potential of phenolic extracts, recovered from plants obtained on the North East of Portugal, and of their phenolic compounds (ellagic, caffeic, and gallic acids, quercetin, kaempferol, and rutin), against bacteria commonly found on skin infections. The disk diffusion and the susceptibility assays were used to identify the most active extracts and phenolic compounds. The effect of selected phenolic compounds on animal cells was assessed by determination of cellular metabolic activity. Gallic acid had a higher activity, against gram-positive (S. epidermidis and S. aureus) and gram-negative bacteria (K. pneumoniae) at lower concentrations, than the other compounds. The caffeic acid, also, showed good antibacterial activity against the 3 bacteria used. The gallic acid was effective against the 3 bacteria without causing harm to the animal cells. Gallic and caffeic acid showed a promising applicability as antibacterial agents for the treatment of infected wounds.04/2014; 2014(4):814590. DOI:10.1155/2014/814590
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- "Human melanocytes occur throughout the skin (mostly in the basal layer of the epidermis and sometimes in the dermis), in mucous membranes, hair follicles, hair matrix, as well as in other organ systems including the heart, the uvea of the eye, the inner ear, and the central nervous system. In mouse skin, melanocytes are only located in hair follicles and in hairless regions of the epidermis or dermis, such as the tail, ear and ventral paw [18,19]. Melanoblasts are the melanocyte precursor cells and arise during gastrulation of embryogenesis at the dorsal edge of the neural crest . "
ABSTRACT: Epidermal stem cells have become an object of intensive research. The epidermis constitutes one of the main sources of stem cells and is a tissue of choice for use in exploring their biology. Stratified squamous epithelium (epidermis) possesses the capacity for self-renewal and repair due to the presence of epidermal stem cells (ESC). They have been identified within basal layer of the interfollicular epidermis (IFE), in the “bulge” of the hair follicles of rodents, and also in the human follicular bulge. Melanocyte stem cells (MSC) from hair follicles (precisely from the bulge region, which also contains epidermal stem cells) provide an attractive model for the study of stem cells and their regulation at the niche. This review summarizes the rapidly developing field of epidermal stem cell research and their application in regenerative medicine, paying particular attention to melanocyte stem cells, their biology and some of the processes that occur during hair graying and regeneration of the pigmentary system, as well as discussing how aged-associated changes in the melanocyte stem cells compartment impact hair graying. This review also includes differentiation of human skin stem cells into functional epidermal melanocytes.Medical science monitor: international medical journal of experimental and clinical research 10/2012; 18(10):RA155-159. DOI:10.12659/MSM.883475 · 1.22 Impact Factor
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- "Therefore, the data obtained with human primary cells would be of utmost relevance for assessing possible health risks of MW exposure from mobile phones. Second, it now appears that most, if not all, adult tissues and organs, including blood, skin, and brain, contain stem cells (Metcalfe and Ferguson 2008). "
ABSTRACT: Background: It is widely accepted that DNA double-strand breaks (DSBs) and their misrepair in stem cells are critical events in the multistage origination of various leukemias and tumors, including gliomas. Objectives: We studied whether microwaves from mobile telephones of the Global System for Mobile Communication (GSM) and the Universal Global Telecommunications System (UMTS) induce DSBs or affect DSB repair in stem cells. Methods: We analyzed tumor suppressor TP53 binding protein 1 (53BP1) foci that are typically formed at the sites of DSB location (referred to as DNA repair foci) by laser confocal microscopy. Results: Microwaves from mobile phones inhibited formation of 53BP1 foci in human primary fibroblasts and mesenchymal stem cells. These data parallel our previous findings for human lymphocytes. Importantly, the same GSM carrier frequency (915 MHz) and UMTS frequency band (1947.4 MHz) were effective for all cell types. Exposure at 905 MHz did not inhibit 53BP1 foci in differentiated cells, either fibroblasts or lymphocytes, whereas some effects were seen in stem cells at 905 MHz. Contrary to fibroblasts, stem cells did not adapt to chronic exposure during 2 weeks. Conclusions: The strongest microwave effects were always observed in stem cells. This result may suggest both significant misbalance in DSB repair and severe stress response. Our findings that stem cells are most sensitive to microwave exposure and react to more frequencies than do differentiated cells may be important for cancer risk assessment and indicate that stem cells are the most relevant cellular model for validating safe mobile communication signals.Environmental Health Perspectives 10/2009; 118(3). DOI:10.1289/ehp.0900781 · 7.98 Impact Factor