Enhanced neurogenic biomarker expression and reinnervation in human acute skin wounds treated by electrical stimulation

Electrical stimulation (ES) is known to promote cutaneous healing; however, its ability to regulate reinnervation remains unclear. First, we show that ES treatment of human acute cutaneous wounds (n = 40) increased reinnervation. Next, to define neurophysiologic mechanisms through which ES affects repair, microarray analysis of wound biopsy samples was performed on days 3, 7, 10, and 14 after wounding. This identified neural differentiation biomarkers TUBB3 (melanocyte development and neuronal marker) and its upstream molecule FIG4 (phosphatidylinositol (3,5)-bisphosphate 5-phosphatase) as significantly up-regulated after ES treatment. To demonstrate a functional ES-TUBB3 axis in cutaneous healing, we showed increased TUBB3 melanocytes and melanogenesis plus FIG4 and nerve growth factor expression, suggesting higher cellular differentiation. In support of this role of ES to regulate neural crest-derived cell fate and differentiation in vivo, knockdown of FIG4 in neuroblastoma cells resulted in vacuologenesis and cell degeneration, whereas ES treatment after FIG4-small interfering RNA transfection enhanced neural differentiation, survival, and integrity. Further characterization showed increased TUBB3 and protein gene product 9.5 Merkel cells during in vivo repair, after ES. We demonstrate that ES contributes to increased expression of neural differentiation biomarkers, reinnervation, and expansion of melanocyte and Merkel cell pool during repair. Targeted ES-assisted acceleration of healing has significant clinical implications

Retinoids in the treatment of photoageing:A histological study of topical retinoid efficacy in black skin.

Background Photoageing describes complex cutaneous changes that occur due to chronic exposure to solar ultraviolet radiation (UVR). The ‘gold standard’ for the treatment of photoaged white skin is all-trans retinoic acid (ATRA); however, cosmetic retinol (ROL) has also proven efficacious. Recent work has identified that black skin is susceptible to photoageing, characterised by disintegration of fibrillin-rich microfibrils (FRMs) at the dermal-epidermal junction (DEJ). However, the impact of topical retinoids for repair of black skin has not been well investigated.Objectives To determine the potential of retinoids to repair photoaged black skin.Methods An exploratory intervention study was performed using an in vivo, short-term patch-test protocol. Healthy but photoaged black volunteers (&gt;45 years) were recruited to the study and participant extensor forearms were occluded with either 0.025% ATRA (n = 6; 4-day application due to irritancy) or ROL (12-day treatment protocol for a cosmetic) at concentrations of 0.3% (n = 6) or 1% (n = 6). Punch biopsies from occluded but untreated control sites and retinoid-treated sites were processed for histological analyses of epidermal characteristics, melanin distribution and dermal remodelling.Results Treatment with ATRA and ROL induced significant acanthosis (all P &lt; 0.001) accompanied by a significant increase in keratinocyte proliferation (Ki67; all P &lt; 0.01), dispersal of epidermal melanin and restoration of the FRMs at the DEJ (all P &lt; 0.01), compared to untreated control.Conclusions This study confirms that topical ATRA has utility for the repair of photoaged black skin and that ROL induces comparable effects on epidermal and dermal remodelling, albeit over a longer timeframe. The effects of topical retinoids on black photoaged skin are similar to those reported for white photoaged skin and suggest conserved biology in relation to repair of UVR-induced damage. Further investigation of topical retinoid efficacy in daily use is warranted for black skin.<br/

Heterogeneity of fibrillin-rich microfibrils extracted from human skin of diverse ethnicity

The dermal elastic fibre network is the primary effector of skin elasticity, enabling it to extend and recoil many times over the lifetime of the individual. Fibrillin‐rich microfibrils (FRMs) constitute integral components of the elastic fibre network, with their distribution showing differential deposition in the papillary dermis across individuals of diverse skin ethnicity. Despite these differential findings in histological presentation, it is not known if skin ethnicity influences FRM ultrastructure. FRMs are evolutionarily highly conserved from jellyfish to man and, regardless of tissue type or species, isolated FRMs have a characteristic ‘beads‐on‐a‐string’ ultrastructural appearance, with an average inter‐bead distance (or periodicity) of 56 nm. Here, skin biopsies were obtained from the photoprotected buttock of healthy volunteers (18‐27 years; African: n = 5; European: n = 5), and FRMs were isolated from the superficial papillary dermis and deeper reticular dermis and imaged by atomic force microscopy. In the reticular dermis, there was no significant difference in FRM ultrastructure between European and African participants. In contrast, in the more superficial papillary dermis, inter‐bead periodicity was significantly larger for FRMs extracted from European participants than from African participants by 2.20 nm (p < .001). We next assessed whether these differences in FRM ultrastructure were present during early postnatal development by characterizing FRMs from full‐thickness neonatal foreskin. Analysis of FRM periodicity identified no significant difference between neonatal cohorts (p = .865). These data suggest that at birth, FRMs are developmentally invariant. However, in adults of diverse skin ethnicity, there is a deviation in ultrastructure for the papillary dermal FRMs that may be acquired during the passage of time from child to adulthood. Understanding the mechanism by which this difference in papillary dermal FRMs arises warrants further study

Abnormal Chondrocyte Apoptosis in the Cartilage Growth Plate is Influenced by Genetic Background and Deletion of CHOP in a Targeted Mouse Model of Pseudoachondroplasia

<div><p>Pseudoachondroplasia (PSACH) is an autosomal dominant skeletal dysplasia caused by mutations in cartilage oligomeric matrix protein (COMP) and characterised by short limbed dwarfism and early onset osteoarthritis. Mouse models of PSACH show variable retention of mutant COMP in the ER of chondrocytes, however, in each case a different stress pathway is activated and the underlying disease mechanisms remain largely unknown. T585M COMP mutant mice are a model of moderate PSACH and demonstrate a mild ER stress response. Although mutant COMP is not retained in significant quantities within the ER of chondrocytes, both BiP and the pro-apoptotic ER stress-related transcription factor CHOP are mildly elevated, whilst bcl-2 levels are decreased, resulting in increased and spatially dysregulated chondrocyte apoptosis. To determine whether the abnormal chondrocyte apoptosis observed in the growth plate of mutant mice is CHOP-mediated, we bred T585M COMP mutant mice with CHOP-null mice to homozygosity, and analysed the resulting phenotype. Although abnormal apoptosis was alleviated in the resting zone following CHOP deletion, the mutant growth plates were generally more disorganised. Furthermore, the bone lengths of COMP mutant CHOP null mice were significantly shorter at 9 weeks of age when compared to the COMP mutant mice, including a significant difference in the skull length. Overall, these data demonstrate that CHOP-mediated apoptosis is an early event in the pathobiology of PSACH and suggest that the lack of CHOP, in conjunction with a COMP mutation, may lead to aggravation of the skeletal phenotype via a potentially synergistic effect on endochondral ossification.</p></div

Mass spectrometry (LC-MS/MS) of T585M mutant and CHOP wild type [CHOP^+/+/COMP^m/m] or knock-out [CHOP^−/−/COMP^m/m] cartilage at 3 weeks of age.

<p>The average number of spectra are shown for each genotypes (n = 4).</p

Head and bone measurements in COMP mutant and CHOP null mice.

<p><b>A</b>) Head measurements in T585M COMP mutant and either CHOP wild type [CHOP^+/+COMP^m/m] or CHOP null [CHOP^−/−COMP^m/m] showing shorter skulls in [CHOP^−/−COMP^m/m] at 9 weeks of age (n = 10; One Way ANOVA). <b>B</b>) Long bone measurements in [CHOP^−/−COMP^m/m] mice showing a further exacerbated short limbed dwarfism following CHOP deletion (n = 10; One Way ANOVA). Error bars represent standard error of the mean (SEM) Key: Key: CHOP^+/+COMP^m/m = CHOP wild type and T585M COMP mutation (homozygous); CHOP^−/−COMP^m/m = CHOP null and T585M COMP mutation (homozygous); ICD = inner canthal distance. Error bars represent standard error of the mean (SEM); * P<0.05, ** P<0.01, *** P<0.001.</p

Histochemical analysis of growth plate cartilage.

<p><b>A</b>) Haematoxylin and eosin staining of wild type and CHOP null growth plates at 3 weeks of age showing normal columnar organisation of chondrocytes in the growth plates of both genotypes and delineating the resting (RZ), proliferating (PZ) and hypertrophic (HZ) zones of the growth plate. <b>B</b>) Immunohistochemistry for COMP showing the normal distribution of COMP in wild type and CHOP null growth plate at 3 weeks of age. The negative control was generated using the secondary antibody only. Key: RZ = resting zone; PZ = proliferative zone; HZ = hypertrophic zone; CHOP^+/+ = wild type, CHOP^−/− = knock-out. Scale bar for all images is 100 µm.</p