β1 integrin regulates multiple epithelial cell functions by connecting cells with the extracellular matrix (ECM). While β1 integrin-mediated signaling in murine epithelial stem cells is well-studied, its role in human adult epithelial progenitor cells (ePCs) in situ remains to be defined. Using microdissected, organ-cultured human scalp hair follicles (HFs) as a clinically relevant model for studying human ePCs within their natural topobiological habitat, β1 integrin-mediated signaling in ePC biology was explored by β1 integrin siRNA silencing, specific β1 integrin-binding antibodies and pharmacological inhibition of integrin-linked kinase (ILK), a key component of the integrin-induced signaling cascade. β1 integrin knock down reduced keratin 15 (K15) expression as well as the proliferation of outer root sheath keratinocytes (ORSKs). Embedding of HF epithelium into an ECM rich in β1 integrin ligands that mimic the HF mesenchyme significantly enhanced proliferation and migration of ORSKs, while K15 and CD200 gene and protein expression were inhibited. Employing ECM-embedded β1 integrin-activating or -inhibiting antibodies allowed to identify functionally distinct human ePC subpopulations in different compartments of the HF epithelium. The β1 integrin-inhibitory antibody reduced β1 integrin expression in situ and selectively enhanced proliferation of bulge ePCs, while the β1 integrin-stimulating antibody decreased hair matrix keratinocyte apoptosis and enhanced transferrin receptor (CD71) immunoreactivity, a marker of transit amplifying cells, but did not affect bulge ePC proliferation. That the putative ILK inhibitor QLT0267 significantly reduced ORSK migration and proliferation and induced massive ORSK apoptosis suggests a key role for ILK in mediating the ß1 integrin effects. Taken together, these findings demonstrate that ePCs in human HFs require β1 integrin-mediated signaling for survival, adhesion, and migration, and that different human HF ePC subpopulations differ in their response to β1 integrin signaling. These insights may be exploited for cell-based regenerative medicine strategies that employ human HF-derived ePCs.
The aim of this study was to investigate the myotoxic effects of bupivacaine, ropivacaine, and levobupivacaine which were applied intramuscularly to rat skeletal muscle. Forty Wistar-Albino rats were divided into four groups. In the study, .5% bupivacaine (Group B), .5% ropivacaine (Group R), .5% levobupivacaine (Group L), or .9% normal saline (Group SF) was applied intramuscularly to the right gastrocnemius muscle of rats. The rats in each group were sacrificed on the second day after injection. Sections of muscle samples were stained with hematoxylin-eosin for light microscopic investigation and prepared for the evaluation of ultrastructural changes in the subcellular level with transmission electron microscopy. All three local anesthetic agents caused qualitatively similar skeletal muscle damage. The most observed muscle damage was in Group B, muscle damage of Group R was less than that of Group B, and the least damage was seen in Group L quantitatively. Electron microscopic examination of each group that caused cellular damage was qualitatively similar. The most subcellular damage was observed in the group receiving bupivacaine, less was seen in the ropivacaine group, and the least was observed in the levobupivacaine group. The results indicated that bupivacaine caused more myotoxic damage than the other two agents in the skeletal muscle of rats and that levobupivacaine caused less myotoxic damage than both bupivacaine and ropivacaine at the cell and tissue levels.
The combination of an aging population and an increasing prevalence of diseases associated with impaired-wound healing, including obesity, peripheral vascular disease and diabetes, is likely to result in a dramatic increase in the incidence and prevalence of chronic skin wounds. Indeed, systemic reviews are now not only trying to establish both the prevalence and the often under-estimated socio-economic costs of chronic skin wounds, but most importantly are addressing the impact that chronic wounds have on quality of life. Given the clear need for novel approaches to the management of chronic skin ulceration, ideally developed and tested in the human system in a manner that can be rapidly translated into clinical practice, we examined the effects of multipotent primary human nestin
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progenitor cells on human wound healing in an ex vivo model. Human sweat gland-derived nestin
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cells demonstrated the capacity to significantly promote two key wound healing parameters, i.e., both reepithelialisation and angiogenesis in experimentally wounded, organ-cultured human skin. The current data further support the use of full-thickness human skin wound-healing models ex vivo to pre-clinically test wound healing-promoting candidate agents. Whilst larger studies are required to substantiate a firm “proof-of-concept,” our preliminary studies encourage further efforts to systemically determine the potential of cell-based regenerative medicine strategies in general, and the use of skin appendage-associated human nestin
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cells in particular, as novel treatment strategies for chronic skin ulceration.
Electronic supplementary material
The online version of this article (10.1007/s00403-019-01889-x) contains supplementary material, which is available to authorized users.
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