Arterio-venous Anastomoses of the Sucquet-Hoyer Type: Complexity and Distribution in the Human Dermis

Our study aims at providing detailed information on numbers, form, and spatial distribution of arterio-venous anastomoses of the Sucquet-Hoyer type in the dermis of the nail bed, nail fold corner, thumb pad, arm, nose, glabella, lip, and ear. It further aims at providing a system, which relies on objective morphologic criteria for classifying Sucquet-Hoyer canals (SHCs). Using high-resolution episcopic microscopy (HREM), digital volume data of eight samples of each skin region were produced. Virtual three-dimensional (3D) models of the dermally located SHCs were created, and their 3D tortuosity (τ) values were determined. Dermal SHCs were identified in all 24 finger samples and in 1 lip sample. Beneath a field of 2 × 2 mm2, an average of four were located in the nail bed, three in the dermis of the thumb pad, and one in the dermis of the nail fold corner. Only a single dermal SHC was found in one lip sample. No SHCs were observed in the dermis of the other samples. The τ values of the SHCs ranged from 1.11 to 10. Building on these values, a classification system was designed, which distinguishes four SHC classes. The dermal distribution of the SHCs of different classes was similar in all specimens.

Three-Dimensional Skin CT Based on Intelligent Algorithm in the Analysis of Skin Lesion Sites Features in Children with Psoriasis

This research was to explore the application value of three-dimensional computed tomography (CT) based on artificial intelligent algorithm in analyzing the characteristics of skin lesions in children with psoriasis. In this study, 15 children with psoriasis were selected as the observation group, and 15 children with other skin diseases were selected as the control group. The CT images were optimized, and the feature selection was carried out based on artificial intelligent algorithm. Firstly, the results were compared with the results of simple skin three-dimensional CT to determine the effectiveness. Then, the two groups of three-dimensional skin CT image features of skin psoriasis-like hyperplasia, Munro microabscess, dermal papillary vascular dilation, and squamous epithelium based on intelligent algorithms were compared. After comparison, the detection rate of psoriasis-like hyperplasia, Munro microabscess, dermal papillary vascular dilation, and squamous epithelium in the observation group was higher than that in the control group, with significant difference and statistical significance (P < 0.05). In addition, the sensitivity of psoriasis-like hyperplasia, Munro microabscess, dermal papilla vascular dilatation, and squamous epithelium in children with psoriasis was 80.0%, 86.7%, 80.0%, and 93.3%, respectively. The specificity of psoriasis-like hyperplasia, Munro microabscess, dermal papilla vascular dilatation, and squamous epithelium in children with psoriasis was 86.7%, 93.3%, 60.0%, and 73.3%, respectively. The results showed that Munro microabscess and psoriasis-like hyperplasia had high sensitivity and specificity in all diagnostic items, which could be used as important features of skin lesion sites in the diagnosis of psoriasis in children. The research provides a basis for the clinical diagnosis of psoriasis in children, which is worthy of clinical promotion.

Linalool inhibits the angiogenic activity of endothelial cells by downregulating intracellular ATP levels and activating TRPM8

Angiogenesis crucially contributes to various diseases, such as cancer and diabetic retinopathy. Hence, anti-angiogenic therapy is considered as a powerful strategy against these diseases. Previous studies reported that the acyclic monoterpene linalool exhibits anticancer, anti-inflammatory and anti-oxidative activity. However, the effects of linalool on angiogenesis still remain elusive. Therefore, we investigated the action of (3R)-(-)-linalool, a main enantiomer of linalool, on the angiogenic activity of human dermal microvascular endothelial cells (HDMECs) by a panel of angiogenesis assays. Non-cytotoxic doses of linalool significantly inhibited HDMEC proliferation, migration, tube formation and spheroid sprouting. Linalool also suppressed the vascular sprouting from rat aortic rings. In addition, Matrigel plugs containing linalool exhibited a significantly reduced microvessel density 7 days after implantation into BALB/c mice. Mechanistic analyses revealed that linalool promotes the phosphorylation of extracellular signal-regulated kinase (ERK), downregulates the intracellular level of adenosine triphosphate (ATP) and activates the transient receptor potential cation channel subfamily M (melastatin) member (TRPM)8 in HDMECs. Inhibition of ERK signaling, supplementation of ATP and blockade of TRPM8 significantly counteracted linalool-suppressed HDMEC spheroid sprouting. Moreover, ATP supplementation completely reversed linalool-induced ERK phosphorylation. In addition, linalool-induced ERK phosphorylation inhibited the expression of bone morphogenetic protein (BMP)-2 and linalool-induced TRPM8 activation caused the inhibition of β1 integrin/focal adhesion kinase (FAK) signaling. These findings indicate an anti-angiogenic effect of linalool, which is mediated by downregulating intracellular ATP levels and activating TRPM8.

Colonization of dermal arterioles by Neisseria meningitidis provides a safe haven from neutrophils

The human pathogen Neisseria meningitidis can cause meningitis and fatal systemic disease. The bacteria colonize blood vessels and rapidly cause vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, we use a humanized mouse model to show that vascular colonization leads to the recruitment of neutrophils, which partially reduce bacterial burden and vascular damage. This partial effect is due to the ability of bacteria to colonize capillaries, venules and arterioles, as observed in human samples. In venules, potent neutrophil recruitment allows efficient bacterial phagocytosis. In contrast, in infected capillaries and arterioles, adhesion molecules such as E-Selectin are not expressed on the endothelium, and intravascular neutrophil recruitment is minimal. Our results indicate that the colonization of capillaries and arterioles by N. meningitidis creates an intravascular niche that precludes the action of neutrophils, resulting in immune escape and progression of the infection.

Characterization of dermal skin innervation in fibromyalgia syndrome

Introduction

We characterized dermal innervation in patients with fibromyalgia syndrome (FMS) as potential contribution to small fiber pathology.

Methods

Skin biopsies of the calf were collected (86 FMS patients, 35 healthy controls). Skin was immunoreacted with antibodies against protein gene product 9.5, calcitonine gene-related peptide, substance P, CD31, and neurofilament 200 for small fiber subtypes. We assessed two skin sections per patient; on each skin section, two dermal areas (150 x 700 μm each) were investigated for dermal nerve fiber length (DNFL).

Results

In FMS patients we found reduced DNFL of fibers with vessel contact compared to healthy controls (p<0.05). There were no differences for the other nerve fiber subtypes.

Discussion

We found less dermal nerve fibers in contact with blood vessels in FMS patients than in controls. The pathophysiological relevance of this finding is unclear, but we suggest the possibility of a relationship with impaired thermal tolerance commonly reported by FMS patients.

Enhanced extracellular vesicle production and ethanol-mediated vascularization bioactivity via a 3D-printed scaffold-perfusion bioreactor system

Extracellular vesicles (EVs) have garnered significant interest in the biotechnology field due to their intrinsic therapeutic properties as well as their ability to serve as vehicles for bioactive cargo. However, the lack of an established biomanufacturing platform and limited potency of EVs in vivo remain critical bottlenecks for clinical translation. In this study, we utilized a 3D-printed scaffold-perfusion bioreactor system to assess the response of dynamic culture on extracellular vesicle production from endothelial cells (ECs). We also investigated whether ethanol conditioning, which was previously shown to enhance vascularization bioactivity of EC-derived EVs produced in standard 2D culture conditions, could be employed successfully for the same purpose in a 3D production system. Our results indicate that dynamic culture in a perfusion bioreactor significantly enhances EV production from human ECs. Moreover, the use of ethanol conditioning in conjunction with dynamic culture induces pro-vascularization bioactivity of EC-derived EVs that is correlated with increased EV levels of pro-angiogenic lncRNAs HOTAIR and MALAT1. Thus, this study represents one of the first reports of rationally-designed EV potency enhancement that is conserved between static 2D and dynamic 3D EV production systems, increasing the potential for scalable biomanufacturing of therapeutic EC-derived EVs for a variety of applications. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) have substantial therapeutic potential in a variety of applications. However, translation of EV-based therapies may be hindered by biomanufacturing challenges. EV production to date has predominantly involved the use of tissue culture flasks. Here, we report, for the first time, the use of a tubular perfusion bioreactor system with an integrated 3D-printed biomaterial scaffold for EV production from human endothelial cells. This system increases EV yield by over 100-fold compared to conventional tissue culture systems. Further, we show that an ethanol-conditioning approach that our group previously developed in 2D culture for enhancing EV potency is compatible with this new system. Thus, potency enhancement of EVs for vascularization applications is possible even with significantly increased production rate.

[Role of mechanosensitive protein Piezo1 in human age-dependent changes in the number of fibroblasts and blood vessels in human skin.]

The aim of this work was to examine the content of Piezo1 in fibroblasts and blood vessels of human dermis from the development until deep aging (from 20 weeks of pregnancy until 85 years old), and defining of a role of Piezo1 in age-dependent changes in the number of fibroblasts and blood vessels in the dermis. Piezo1, proliferating cells nuclear antigen (PCNA), endothelial cells marker CD31 were detected with indirect immunohistochemical technique. Results showed that a portion of fibroblasts with positive staining for Piezo1 in the dermis is decreased from 20 weeks of pregnancy to 40 years old. Percent of Piezo1 positive fibroblasts in dermis is increased sufficiently since 41 years old until 60-85 years old group. The content of Piezo1 in blood vessels in the human dermis is decreased sufficiently from 20 weeks of pregnancy until 40 years old. Age-related changes in the content of Piezo1 in fibroblasts and blood vessels is not associated with an age-related decrease in total number and percent of PCNA positive fibroblasts, the number of blood vessels in the dermis.

[Mechanosensitive protein of Hippo regulatory pathway - transcription coactivator with PZD-binding motif (TAZ) in human skin during aging.]

The aim of this work was to examine the content of transcription coactivator with PZD-binding motif (TAZ) in fibroblasts and blood vessels of human dermis from the development until deep aging (from 20 weeks of pregnancy until 85 years old), and defining of a role of TAZ in age-dependent changes in the number of fibroblasts and blood vessels in the dermis. TAZ, proliferating cells nuclear antigen (PCNA), endothelial cells marker CD31 were detected with indirect immunohistochemical technique. Results showed that portion of fibroblasts with positive staining for TAZ in the dermis is decreased from 20 weeks of pregnancy to 40 years old. Percent of TAZ positive fibroblasts in dermis is increased since 41 years old until 60-85 years old group. The content of TAZ in blood vessels in the human dermis is decreased sufficiently from 20 weeks of pregnancy until 40 years old followed by an increase from 41 years old. From 61 to 85 years of life, content of TAZ in dermal vessels was not differ from those in 41-60 age group. Age-related changes in the content of TAZ in fibroblasts and blood vessels is not associated with an age-related decrease in total number and percent of PCNA positive fibroblasts, the number of blood vessels in the dermis.

Diffuse dermal angiomatosis of the breast with adjacent fat necrosis: a case report and review of the literature

Diffuse dermal angiomatosis (DDA) is a type of reactive skin angioproliferation. Clinically, this rare disorder presents as red-violet purpuric papules and/or plaques (some with a greater tendency towards necrosis and ulceration), which can be localized in any body area, but is most often seen in the upper and lower extremities. Localization in the breast commonly presents with severe intractable breast pain and characteristic reticular violaceous erythematous plaques with central ulcerations. Histological examination is fundamental for the diagnosis and is characterized by varied patterns of lobular or diffuse hyperplasia of endothelial cells at the extravascular level. The condition is associated with various underlying conditions, many of which result in local tissue ischemia. In this report, we present a patient with DDA with an underlying mass lesion of the breast, which proved to be an adjacent fat necrosis. Various treatments have proven beneficial, including revascularization, oral corticosteroids, smoking cessation, and isotretinoin. In this case, our patient benefited from secondary excision of the affected area.

Cutaneous collagenous vasculopathy: development after coronary artery bypass surgery

Cutaneous collagenous vasculopathy (CCV) is a rare benign microangiopathy of the superficial dermal vessels. Clinically, it is characterized by widespread, asymptomatic development of cutaneous telangiectasia in the absence of systemic symptoms. Morphologically, it most resembles generalized essential telangiectasia and other telangiectatic syndromes such as telangiectasia macularis eruptiva perstans (TMEP), ataxia telangiectasia, and hereditary hemorrhagic telangiectasia. It is distinctive in its histology, showing characteristic dilated thick-walled blood vessels in the superficial dermis. The thickened walls of these superficial dermal blood vessels demonstrate reduplication of the basement membrane on PAS staining. We report a 63-year-old man with CCV with this condition for 20 years, starting in 1996. He was diagnosed in the past as having essential telangiectasia. The development of the telangectasias occurred after coronary artery bypass grafting, also performed in 1996. This case not only demonstrates the characteristic clinical and histologic findings, but also suggests a possible mechanism. Moreover, it illustrates that cases of generalized essential telangiectasia may in fact be CCV that are misclassified.

Contrast Ratio Quantification During Visualization of Microvasculature

INTRODUCTION

Visualization and monitoring of capillary loops in dermis and mucosa are of interest for a number of clinical applications, such as capillaroscopy, early cancer, or shock detection. For historical reasons, an unaided eye is still a primary aide to diagnostics in visual examinations for many medical specializations. However, the ability to make an early diagnosis using the unaided eye has remained poor. New optical modalities can significantly improve the accuracy of anomaly detection. To compare the image quality of various optical schemes, a systematic way to quantify it is required. The goal of this work is to develop an analytical approach for assessment of a contrast ratio as a single number quantitative metric image quality during optical imaging of capillary network.

METHODS

Based on skin layers geometry, we developed a two-layer optical tissue model. Then, we extended a two-layer Kubelka-Munk model to calculate the contrast ratio of a subsurface defect (absorption or scattering) imaging.

RESULTS

We have obtained an explicit expression for the contrast ratio in the two-layer model. Then, we investigated how the contrast ratio is affected by the tissue optical parameters and depth of the inhomogeneity. Based on this analysis we identified two important cases: (a) the top layer with negligible absorption, and (b) the 'optically thick' top layer. The contrast ratio deteriorates differently with the inhomogeneity depth in these two cases.

CONCLUSIONS

The contrast ratio can be used for quantification of image quality of subsurface inhomogeneities in the skin. The developed approach can be employed for estimation of interrogating depth of various tissue inhomogeneities and optimization of imaging techniques.

[CHANGES OF THE CONTENT OF DLL4 AND Jag-1 ANGIOGENESIS REGULATORS IN HUMAN DERMIS IN ONTOGENESIS]

The goal of this study was to examine the contents of D114 and Jag-1 angiogenesis regulators in human dermis at different age periods. D114 and Jag-1 were demonstrated by indirect immunohistochemistry in skin sections of fetuses of 20-40 gestational weeks and in persons aged from birth to 85 years. D114 was studied in 150 skin samples of 72 females and 78 males, while Jag-1 was examined in 120 samples of 58 females and 62 males. It is found that the immunoreactivity was mainly expressed by the endothelial cells. Vessels, which gave a positive reaction to D114 and Jag-1, were found throughout the entire thickness of the dermis, both in fetuses, and people of all age groups. Expression of D114 in the vessels of dermal microvasculature was shown to increase from 20 weeks of gestation to 20 years. With the further age increase, the intensity of the reaction of blood vessels for D114 was decreased. Expression of Jag-1 in dermal microvessels was enhanced from 20 weeks of gestation to 85 years. The results are discussed in connection with the role of D114 and Jag-1 in angiogenesis in human dermis during ontogeny.

Umbilical Cord Mesenchymal Stem Cells Combined With a Collagenfibrin Double-layered Membrane Accelerates Wound Healing

The aim of this study was to examine the effects of human umbilical cord mesenchymal stem cells (hUCMSCs) in combination with a collagen-fibrin double-layered membrane on wound healing in mice. A collagen-fibrin double-layered membrane was prepared, and the surface properties of the support material were investigated using a scanning electron microscope. Twenty-four mice were prepared for use as full-thickness skin wound models and randomly divided into 3 groups: group A, a control group in which the wounds were bound using a conventional method; group B, a group treated with hUCMSCs combined with a collagen membrane; and group C, a group treated with hUCMSCs combined with a collagen-fibrin double-layered membrane. The postoperative concrescence of the wounds was observed daily to evaluate the effects of the different treatments. Scanning electron microscope observation showed the collagen-fibrin scaffolds exhibited a highly porous and interconnected structure, and wound healing in the double-layered membrane group was better than in groups A or B. Treatment with hUCMSCs combined with a collagen-fibrin double-layered membrane accelerated wound healing.

Quick analysis of optical spectra to quantify epidermal melanin and papillary dermal blood content of skin

This paper presents a practical approach for assessing the melanin and blood content of the skin from total diffuse reflectance spectra, R(λ), where λ is wavelength. A quick spectral analysis using just three wavelengths (585 nm, 700 nm and 800 nm) is presented, based on the 1985 work of Kollias and Baquer who documented epidermal melanin of skin using the slope of optical density (OD) between 620 nm and 720 nm. The paper describes the non-rectilinear character of such a quick analysis, and shows that almost any choice of two wavelengths in the 600-900 range can achieve the characterization of melanin. The extrapolation of the melanin slope to 585 nm serves as a baseline for subtraction from the OD (585 nm) to yield a blood perfusion score. Monte Carlo simulations created spectral data for a skin model with epidermis, papillary dermis and reticular dermis to illustrate the analysis.

In vitro glycation of an endothelialized and innervated tissue-engineered skin to screen anti-AGE molecules

Glycation is one of the major processes responsible for skin aging through induction of the detrimental formation of advanced glycation end-products (AGEs). We developed an innovative tissue-engineered skin combining both a capillary-like and a nerve networks and designed a protocol to induce continuous AGEs formation by a treatment with glyoxal. We determined the optimal concentration of glyoxal to induce AGEs formation identified by carboxymethyl-lysin expression while keeping their toxic effects low. We showed that our tissue-engineered skin cultured for 44 days and treated with 200 μm glyoxal for 31 days displayed high carboxymethyl-lysine expression, which induced a progressively increased alteration of its capillary and nerve networks between 28 and 44 days. Moreover, it produced an epidermal differentiation defect evidenced by the lack of loricrin and filaggrin expression in the epidermis. These effects were almost completely prevented by addition of aminoguanidine 1.5 mm, an anti-glycation compound, and only slightly decreased by alagebrium 500 μm, an AGE-breaker molecule. This tissue-engineered skin model is the first one to combine a capillary and nerve network and to enable a continuous glycation over a long-term culture period. It is a unique tool to investigate the effects of glycation on skin and to screen new molecules that could prevent AGEs formation.

Transdermal deferoxamine prevents pressure-induced diabetic ulcers

There is a high mortality in patients with diabetes and severe pressure ulcers. For example, chronic pressure sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia inducible factor-1 alpha (HIF-1α). In diabetes, HIF-1α function is compromised by a high glucose-induced and reactive oxygen species-mediated modification of its coactivator p300, leading to impaired HIF-1α transactivation. We examined whether local enhancement of HIF-1α activity would improve diabetic wound healing and minimize the severity of diabetic ulcers. To improve HIF-1α activity we designed a transdermal drug delivery system (TDDS) containing the FDA-approved small molecule deferoxamine (DFO), an iron chelator that increases HIF-1α transactivation in diabetes by preventing iron-catalyzed reactive oxygen stress. Applying this TDDS to a pressure-induced ulcer model in diabetic mice, we found that transdermal delivery of DFO significantly improved wound healing. Unexpectedly, prophylactic application of this transdermal delivery system also prevented diabetic ulcer formation. DFO-treated wounds demonstrated increased collagen density, improved neovascularization, and reduction of free radical formation, leading to decreased cell death. These findings suggest that transdermal delivery of DFO provides a targeted means to both prevent ulcer formation and accelerate diabetic wound healing with the potential for rapid clinical translation.

An analysis of the binding characteristics of a panel of recently selected ICAM-1 binding Plasmodium falciparum patient isolates

The basis of severe malaria pathogenesis in part includes sequestration of Plasmodium falciparum-infected erythrocytes (IE) from the peripheral circulation. This phenomenon is mediated by the interaction between several endothelial receptors and one of the main parasite-derived variant antigens (PfEMP1) expressed on the surface of the infected erythrocyte membrane. One of the commonly used host receptors is ICAM-1, and it has been suggested that ICAM-1 has a role in cerebral malaria pathology, although the evidence to support this is not conclusive. The current study examined the cytoadherence patterns of lab-adapted patient isolates after selecting on ICAM-1. We investigated the binding phenotypes using variant ICAM-1 proteins including ICAM-1^Ref, ICAM-1^Kilifi, ICAM-1^S22/A, ICAM-1^L42/A and ICAM-1^L44/A using static assays. The study also examined ICAM-1 blocking by four anti-ICAM-1 monoclonal antibodies (mAb) under static conditions. We also characterised the binding phenotypes using Human Dermal Microvascular Endothelial Cells (HDMEC) under flow conditions. The results show that different isolates have variant-specific binding phenotypes under both static and flow conditions, extending our previous observations that this variation might be due to variable contact residues on ICAM-1 being used by different parasite PfEMP1 variants.

Cell type-specific recycling of tetrahydrobiopterin by dihydrofolate reductase explains differential effects of 7,8-dihydrobiopterin on endothelial nitric oxide synthase uncoupling

(6R)-5,6,7,8-Tetrahydro-L-biopterin (BH4) availability regulates nitric oxide and superoxide formation by endothelial nitric oxide synthase (eNOS). At low BH4 or low BH4 to 7,8-dihydrobiopterin (BH2) ratios the enzyme becomes uncoupled and generates superoxide at the expense of NO. We studied the effects of exogenously added BH2 on intracellular BH4/BH2 ratios and eNOS activity in different types of endothelial cells. Incubation of porcine aortic endothelial cells with BH2 increased BH4/BH2 ratios from 8.4 (controls) and 0.5 (BH4-depleted cells) up to ~20, demonstrating efficient reduction of BH2. Uncoupled eNOS activity observed in BH4-depleted cells was prevented by preincubation with BH2. Recycling of BH4 was much less efficient in human endothelial cells isolated from umbilical veins or derived from dermal microvessels (HMEC-1 cells), which exhibited eNOS uncoupling and low BH4/BH2 ratios under basal conditions and responded to exogenous BH2 with only moderate increases in BH4/BH2 ratios. The kinetics of dihydrofolate reductase-catalyzed BH4 recycling in endothelial cytosols showed that the apparent BH2 affinity of the enzyme was 50- to 300-fold higher in porcine than in human cell preparations. Thus, the differential regulation of eNOS uncoupling in different types of endothelial cells may be explained by striking differences in the apparent BH2 affinity of dihydrofolate reductase.

Differential angiogenic properties of lithium chloride in vitro and in vivo

Wnt/β-catenin signaling induced by the Norrin/Frizzled-4 pathway has been shown to improve capillary repair following oxygen induced retinopathy (OIR) in the mouse, a model for retinopathy of prematurity. Here we investigated if treatment with the monovalent cation lithium that has been shown to augment Wnt/β-catenin signaling in vitro and in vivo has similar effects. In cultured human microvascular endothelial cells, LiCl as well as SB 216763, another small molecule that activates Wnt/β-catenin signaling, induced proliferation, survival and migration, which are all common parameters for angiogenic properties in vitro. Moreover, treatment with both agents caused an increase in the levels of β-catenin and their translocation to nuclei while quercetin, an inhibitor of Wnt/β-catenin signaling, completely blocked the effects of LiCl on proliferation. In mice with OIR, intraperitonal or intravitreal treatment with LiCl markedly increased the retinal levels of β-catenin, but did not improve capillary repair. In contrast, repair was significantly improved following intravitreal treatment with Norrin. The effects of LiCl on HDMEC in vitro have minor relevance for OIR in vivo, and the influence of the Norrin/Frizzled-4 pathway on capillary repair in OIR is not reproducible upon enhancing Wnt/β-catenin signaling by LiCl treatment strongly indicating the presence of additional and essential mechanisms.

Mast cells and angiogenesis in wound healing

OBJECTIVE

To investigate the role of mast cells and vascular endothelial growth factor (VEGF) as a mediator of angiogenesis to promote wound healing in surgical and pathological scars.

STUDY DESIGN

The study was carried out on 40 patients who presented with active scar lesions. They were subdivided into 4 groups. They included granulation tissue (10 cases), surgical scar (10 cases), hypertrophic scar (10 cases), and keloid scar (10 cases). Also 10 healthy volunteers of the same age and sex were selected as a control group. Skin biopsies were taken from the patients and the control group. Skin biopsies from clinically assessed studied groups were processed for routine histology and embedded in paraffin. Four sections were prepared from each paraffin block. The first section was stained with hematoxylin and eosin for histological evaluation. The second and third sections were processed for immunostaining of mast cells that contain chymase (MCCs) and mast cells that contain tryptase (MCTs). The fourth section was processed for immunostaining of VEGF.

RESULTS

MCCs exhibited mild expression in normal tissue, granulation tissue, and surgical, hypertrophic and keloid scars. MCTs exhibited mild expression in normal tissue, granulation tissue and keloid, whereas moderate expression was exhibited in hypertrophic and surgical scars. VEGF expression was absent in normal tissue, mild in keloid, surgical and hypertrophic scars, and moderate in keloids and granulation tissue.

CONCLUSION

Mast cell expression variation among different scar types signals the pathological evolution of the lesion, and hence may guide the need for therapeutic intervention.

Analysis of blood and lymph vascularization patterns in tissue-engineered human dermo-epidermal skin analogs of different pigmentation

PURPOSE

Bioengineered dermo-epidermal skin analogs containing melanocytes represent a promising approach to cover large skin defects including restoration of the patient's own skin color. So far, little is known about the development of blood and lymphatic vessels in pigmented skin analogs after transplantation. In this experimental study, we analyzed the advancement and differences of host blood and lymphatic vessel ingrowth into light- and dark-pigmented human tissue-engineered skin analogs in a rat model.

METHODS

Keratinocytes, melanocytes, and fibroblasts from light- and dark-pigmented skin biopsies were isolated, cultured, and expanded. For each donor, melanocytes and keratinocytes were seeded in ratios of 1:1, 1:5, and 1:10 onto fibroblast-containing collagen gels. The skin analogs were subsequently transplanted onto full-thickness wounds of immuno-incompetent rats and quantitatively analyzed for vascular and lymphatic vessel density after 8 and 15 weeks.

RESULTS

The skin analogs revealed a significant difference in vascularization patterns between light- and dark-pigmented constructs after 8 weeks, with a higher amount of blood vessels in light compared to dark skin. In contrast, no obvious difference could be detected within the light- and dark-pigmented group when varying melanocyte/keratinocyte ratios were used. However, after 15 weeks, the aforementioned difference in blood vessel density between light and dark constructs could no longer be detected. Regarding lymphatic vessels, light and dark analogs showed similar vessel density after 8 and 15 weeks, while there were generally less lymphatic than blood vessels.

CONCLUSION

These data suggest that, at least during early skin maturation, keratinocytes, melanocytes, and fibroblasts from different skin color types used to construct pigmented dermo-epidermal skin analogs have distinct influences on the host tissue after transplantation. We speculate that different VEGF expression patterns might be involved in this disparate revascularization pattern observed.

Traumatic neuroma of the penis

Traumatic neuromas are tumors produced by a reactive process to regenerate injured nerves that result in a disordered proliferation of nerve bundles. These tumors are usually related to previous surgery or trauma. We describe a case of traumatic neuroma on the penis of a 24-year-old man; the tumor was initially suspected to be a condyloma. A shave biopsy was both diagnostic and curative.

[Blood vessels in human dermis during aging]

A factor that potentially influences on skin aging is blood supply which determines global conditions for an organ or a tissue functioning, including skin. Scientific data on conditions of blood supply in the skin during aging are insufficient and contradictory. Therefore, this work was aimed to the study of age-related changes in the number of blood vessels in the human dermis. Blood vessels were visualized with immunohistochemical technique to two endothelial markers, as von Willebrand factor and antigen CD31. The results showed that von Willebrand factor and antigen CD31 are present in endothelial cells of blood vessels of dermis in all examined age periods, from 20 weeks of pregnancy to 85 yeas. Intensity of immunohistochemical staining to von Willebrand factor is enhanced during age. Intensity of staining to CD31 is not changed with age. The number of blood vessels positively stained either to von Willebrand factor or to CD31 in dermis was decreased gradually with age. A total number of fibroblasts in dermis decreased with age. The number of PCNA+ fibroblasts in dermis showing their proliferative activity was decreased with the progression of age. The decrease in the number of blood vessels is statistically associated with that in the general number of fibroblasts and proliferating fibroblasts. Hence, a factor that leads to aged decrease in the number of dermal fibroblasts is diminished blood supply, and actions targeted to enhancement of blood supply are to be in the basis of clinical approaches to prophylaxis and treatment aging changes of the skin.

Increased human dermal microvascular endothelial cell survival induced by cysteamine

BACKGROUND

Cystinosis is an autosomal recessive disease caused by intralysosomal cystine accumulation, treated with cysteamine. Recently, new adverse effects of cysteamine were reported. Skin biopsies showed microvascular proliferation (angioendotheliomatosis). To examine the mechanism of angioendotheliomatosis associated with cysteamine toxicity, we examined the effect of cysteamine on human dermal microvascular endothelial cells (HDMVEC).

METHODS

After cysteamine exposure (range 0-3.0 mM) during 24 h, cell viability was measured using water soluble tetrazolium salt-1 (WST-1) in both control HDMVEC and fibroblasts. Cell proliferation and apoptosis rate were measured in HDMVEC by bromodeoxyuridine (BrdU) incorporation and caspase 3 and caspase 7 activity, respectively. Intracellular glutathione (GSH) was measured in HDMVEC after cysteamine exposure of 0, 0.1 or 1.0 mM. Medium and cysteamine were refreshed every 6 h to mimic the in vivo situation. Next, cell viability in HDMVEC was measured after 24 h of GSH exposure (range 0-10.0 mM).

RESULTS

HDMVEC viability and proliferation increased after cysteamine exposure 0.03-3.0 mM (p < 0.01) and 0.03-1.0 mM (p = 0.01) respectively; cell viability in fibroblasts was not affected by incubation with cysteamine. Apoptosis remained unaffected by incubation with 0-1.0 mM cysteamine, 3.0 mM caused increased apoptosis. Intracellular GSH was significantly increased after incubation with cysteamine 0.1 mM (p = 0.02) and 1.0 mM (p < 0.01). HDMVEC viability increased after exposure to GSH 1.0-5.0 mM (p < 0.01).

CONCLUSION

Cysteamine concentrations, similar to those described in plasma of cystinosis patients, stimulate HDMVEC viability and proliferation and increase intracellular GSH content. We postulate that this mechanism might underlie angioendotheliomatosis induced by cysteamine.

Substantiation of medical and technical requirements for noninvasive spectrophotometric diagnostic devices

A scientific approach to the formulation of medical and technical requirements (MTRs) for noninvasive spectrophotometric diagnostic devices using optical technologies such as laser Doppler flowmetry and absorption spectroscopy is proposed. The theoretical modeling framework, metrological certification, and testing of these devices are still in the early stages of development. The theoretical estimation of the received signal levels for wavelengths between 514 and 940 nm is highly dependent on the blood volume level in the subject tissue. The proposed approach allows, in particular, the calculation of technical and metrological performance constraints of the instruments, such as the ranges of the sensitivity and power-related signal-to-noise ratios for different spectral channels and different biomedical (biochemical and physiological) parameters. Substantiation of specialized MTRs for the noninvasive spectrophotometric diagnostic devices can enable them to develop to the level of standardized measurement techniques.

[Effects of low temperature exposure on dermal microvascular endothelial cells function]

OBJECTIVE

To explore the damage effects and expression of vascular endothelial growth factor (VEGF) exposed with different low-temperatures on rat dermal microvascular endothelial cells (DMVECs).

METHODS

Primary DMVECs were obtained by discontinuous Percoll gradient centrifugation. The DMVECs were identified by phase contrast microscope and immunofluorescence studies for CD31 antigen. Applied 28 degrees C, 12 degrees C and 0 degrees C to interfere with rat DMVECs as cold-exposure model. The changes of cells morphology were observed under invert microscope. The membrane integrity was determined by lactate dehydrogenase (LDH) activity. RT-PCR was used to examine the expression of vascular endothelial growth factor mRNA in cells.

RESULTS

The monolayer of cultured PMVECs displayed the shape of pavingstone. CD31 antigen and binding BSI results by fluorescence microscope identified the cultured cells were DMVECs. After 24 h cold exposure, the cell morphology of 0 degrees C group was shrunken, the other groups were "Fibroblast-like". The LDH activity (U/L) in the medium of 28 degrees C, 12 degrees C and 0 degrees C groups was 54.17 +/- 3.02, 64.66 +/- 3.03, 82.13 +/- 10.91 respectively, which was significantly higher than that of 37 degrees C group (12.23 +/- 3.0, P < 0.01). The VEGF mRNA expression level was up-regulated in 28 degrees C group and 12 degrees C group versus control group (P < 0.05), but unchanged in 0 degrees C group.

CONCLUSION

The rat DMVECs injury severity are deteriorated with temperature decreasing, and VEGF might be involved in the regulation of membrane permeability in this period.

Intravital immunofluorescence for visualizing the microcirculatory and immune microenvironments in the mouse ear dermis

Visualizing the dynamic behaviors of immune cells in living tissue has dramatically increased our understanding of how cells interact with their surroundings, contributing important insights into mechanisms of leukocyte trafficking, tumor cell invasion, and T cell education by dendritic cells, among others. Despite substantial advances with various intravital imaging techniques including two-photon microscopy and the generation of multitudes of reporter mice, there is a growing need to assess cell interactions in the context of specific extracellular matrix composition and microvascular functions, and as well, simpler and more widely accessible methods are needed to image cell behaviors in the context of living tissue physiology. Here we present an antibody-based method for intravital imaging of cell interactions with the blood, lymphatic, and the extracellular matrix compartments of the living dermis while simultaneously assessing capillary permeability and lymphatic drainage function. Using the exposed dorsal ear of the anesthetized mouse and a fluorescence stereomicroscope, such events can be imaged in the context of specific extracellular matrix proteins, or matrix-bound chemokine stores. We developed and optimized the method to minimize tissue damage to the ear, rapidly immunostain for multiple extracellular or cell surface receptors of interest, minimize immunotoxicity with pre-blocking Fcγ receptors and phototoxicity with extracellular antioxidants, and highlight the major dermal tissue structures with basement membrane markers. We demonstrate differential migration behaviors of bone marrow-derived dendritic cells, blood-circulating leukocytes, and dermal dendritic cells, with the latter entering sparse CCL21-positive areas of pre-collecting lymphatic vessels. This new method allows simultaneous imaging of cells and tissue structures, microvascular function, and extracellular microenvironment in multiple skin locations for 12 hours or more, with the flexibility of immunolabeling in addition to genetic-based fluorescent reporters.

Adhesion of Neisseria meningitidis to dermal vessels leads to local vascular damage and purpura in a humanized mouse model

Septic shock caused by Neisseria meningitidis is typically rapidly evolving and often fatal despite antibiotic therapy. Further understanding of the mechanisms underlying the disease is necessary to reduce fatality rates. Postmortem samples from the characteristic purpuric rashes of the infection show bacterial aggregates in close association with microvessel endothelium but the species specificity of N. meningitidis has previously hindered the development of an in vivo model to study the role of adhesion on disease progression. Here we introduced human dermal microvessels into SCID/Beige mice by xenografting human skin. Bacteria injected intravenously exclusively associated with the human vessel endothelium in the skin graft. Infection was accompanied by a potent inflammatory response with the secretion of human inflammatory cytokines and recruitment of inflammatory cells. Importantly, infection also led to local vascular damage with hemostasis, thrombosis, vascular leakage and finally purpura in the grafted skin, replicating the clinical presentation for the first time in an animal model. The adhesive properties of the type IV pili of N. meningitidis were found to be the main mediator of association with the dermal microvessels in vivo. Bacterial mutants with altered type IV pili function also did not trigger inflammation or lead to vascular damage. This work demonstrates that local type IV pili mediated adhesion of N. meningitidis to the vascular wall, as opposed to circulating bacteria, determines vascular dysfunction in meningococcemia.

Certain bacterial pathogens access the bloodstream during infection and this is associated with extremely severe conditions such as septic shock. A central feature of these infections is the rapid alteration of blood vessel function with deregulated inflammation, coagulation and loss of vessel integrity. Studying the mechanisms of infection of Neisseria meningitis in vivo for the first time, we show that the ability of this bacterium to adhere to and proliferate in the blood vessel, a process we refer to as vascular colonization, is a prerequisite to the alteration of vascular function. Previously, circulating bacteria were thought to be responsible. We identified the bacterial factors involved in this process by showing that it is largely dependent on type IV pili, long filamentous appendages that allow bacteria to stick to the vessel walls. To study infection by N. meningitidis, a highly human specific pathogen, we introduced human vessels into mice by grafting human skin onto immunodeficient mice. This work thus also introduces a new animal model of infection that reproduces the cardinal features of meningococcal infections. Such a model will be useful to the scientific community to explore the mechanisms of disease, and test new treatment or preventive strategies.

The process of ageing reflected by histological changes in the skin

Structural and functional alterations, as well as changes occurring in the aspect of the skin during the ageing process, are due to some complex mechanisms, determined by intrinsic and extrinsic factors, which act synergistically. This study aims to analyze the histological changes of collagen and elastic fibers and of skin vasculature that occur in time, during the process of ageing. Fragments of skin have been collected from subjects of both sexes and of different ages, totaling 121 samples from different body regions. The following stains were used: Modified Goldner's Masson trichrome, Ferric Orcein-Hematoxylin and the combined stains Orcein-Goldner's trichrome. As the process of ageing advances, collagen fibers become thinner and change their aspect; at advanced age, the lysis of collagen fibers and their thickening in the deep dermis is present, as they become more fibrous. Elastic fibers show the tendency of fragmentation at more advanced age, gradually change their tinctorial affinity and reduce in amount; in the deep dermis, they tend to thicken progressively, in the presence of discrete elastolysis processes that evolve steadily and irreversibly. Thus, processes of elastic fibers degeneration and lysis run faster by comparison with those of collagen fibers degeneration. With ageing, a progressive reduction of dermis vasculature is present, due to a reduction in the number and size of vascular vessels, which is in its turn associated with the progressive alterations of vascular walls components, changes that advance until the function of the vessel ceases.

A novel role for inducible Fut2 in angiogenesis

RATIONALE

Angiogenesis plays an important role in wound healing and tumor growth. Fucosyltransferases synthesize fucosylated glycans and may play a major role in vascular biology.

OBJECTIVE

To examine the role of an alpha(1,2) fucosyltransferase (Fut2) in angiogenesis.

METHODS AND RESULTS

We found that Fut2 mRNA and protein expression is inducible in human dermal microvascular endothelial cells (HMVECs). After finding that Fut2 is inducible in HMVECs, we examined if Fut2 contributes to angiogenesis. We found that Fut2 null endothelial cell (EC) migration and tube formation were significantly less compared to wild type (wt) ECs. Angiogenesis was impaired in Fut2 null compared to wt mice in the mouse Matrigel plug and the sponge granuloma angiogenesis assays. To assess the characteristics of Fut2 null ECs in vivo, we performed Matrigel plug angiogenesis assays in wt mice using Fut2 null and wt mouse ECs. We found a significant decrease in Fut2 null EC incorporation in neoangiogenesis compared to wt ECs. ERK1/2 activation, fibroblast growth factor receptor2, and vascular endothelial growth factor expression were less in Fut2 null ECs, suggesting a possible mechanism of impaired angiogenesis when Fut2 is lacking.

CONCLUSIONS

These data suggest a novel role for Fut2 as a regulator of angiogenesis.

Different modulation of dipeptidyl peptidase-4 activity between microvascular and macrovascular human endothelial cells

Dipeptidyl peptidase 4 (DPP-4) is an enzyme that is produced by endothelial cells in different districts and circulates in plasma. Patients with type 2 diabetes show a reduction in active Glucagon-Like Peptide-1 (GLP-1) that could be due to impairment of secretion or its degradation or both. GLP-1 is rapidly inactivated in vivo, mainly by the DPP-4. Some authors suggest that Metformin has no direct inhibitory effect on DPP-4 activity and that Metformin and the other biguanides enhance GLP-1 secretion; others suggest a possible role of Metformin in the inhibition of the DPP-4 activity. In order to better elucidate the role of insulin sensitizers on the modulation of GLP-1 circulating levels, DPP-4 activity and mRNA expression were measured in cultured human aortic endothelial cells (HAEC) and human microvascular dermal endothelial cells (HMVEC) exposed to high glucose, Metformin and Rosiglitazone. Present data show that hyperglycemia is capable of increasing in a significant manner the DPP-4 activity only in microvascular endothelial cells. Rosiglitazone is able to modulate in a negative manner the expression of DPP-4 but not its activity in macrovascular endothelial cells, while at 24 h of exposure it is able to increase significantly DPP-4 activity but not its expression in microvascular endothelial cells. Metformin at 48 h only in microvascular endothelial cells is able to reduce in a significant manner (p = 0.01) the activity of DPP-4 but not its expression. The modulation of DPP-4 is site specific.

[Experimental study on the effect of vascular endothelial growth factor 165 gene on vascularization of dermal substitute]

OBJECTIVE

To investigate the effect of vascular endothelial growth factor 165 (VEGF 165) gene on vascularization of dermal substitute in vivo.

METHODS

Human umbilical vein endothelial cells (HUVECs) were cultured in M199 medium containing FBS in the volume fraction of 10% (briefly called complete medium). (1) HUVECs were divided into non-transfection group (without transfection), empty vector group [transfected with pIRES2-enhanced green fluorescent protein (EGFP) plasmid], and VEGF plasmid group (transfected with pIRES2-EGFP-VEGF plasmid) according to the random number table, with 6 wells in each group. At post transfection hour (PTH) 24, the expression of green fluorescent protein (GFP) in each group was observed under inverted phase contrast fluorescence microscope, and the expression rate of GFP was detected with flow cytometer. Cells in non-transfection group were tested with the same methods as listed above. The cells in stable transfection in empty vector group and VEGF plasmid group were sifted by neomycin. The mRNA and protein expression levels of VEGF 165 in cells and the protein amount of VEGF 165 in the supernatant of cell culture medium in 3 groups were respectively determined by real-time fluorescent quantitation PCR, Western blotting, and enzyme-linked immunosorbent assay. (2) Forty-eight male nude mice were divided into 4 groups according to the random number table, with 12 mice in each group. Mice in saline group were subcutaneously implanted with dermal substitutes which had been cultured in saline for 2 days on both sides of back (the same site below); mice in medium group were subcutaneously implanted with dermal substitutes which had been cultured in complete medium for 2 days; mice in non-transfected cells group were subcutaneously implanted with dermal substitutes that had been cultured in complete medium with non-transfected HUVECs for 2 days; mice in transfected cells group were subcutaneously implanted with dermal substitutes that had been cultured in complete medium with HUVECs stably transfected with VEGF plasmid for 2 days. The dermal substitutes in every group were taken out on post operation day (POD) 3, 7, 14, and 21. Distributions of microvessels and HUVECs in dermal substitutes were observed by immunohistochemical staining, and the microvessel number was counted on POD 14; the expression level of VEGF 165 protein in dermal substitutes was determined by Western blotting. The experiments were all done in triplicate. Data were processed with one-way analysis of variance and LSD method.

RESULTS

(1) Obvious green fluorescence was only observed in the two groups with transfected cells at PTH 24. Expression rates of GFP in the cells of non-transfection group, empty vector group, and VEGF plasmid group were respectively 0, (85.2 ± 3.2) %, and (93.1 ± 2.4) %. In the non-transfection group, empty vector group, and VEGF plasmid group, the relative expression amounts of VEGF 165 mRNA were respectively 1, 1.05 ± 0.09, and 3.02 ± 0.13 (F = 5.28, P < 0.05); the relative expression amounts of VEGF 165 protein were respectively 0.78 ± 0.16, 0.76 ± 0.13, and 1.92 ± 0.18 (F = 7.62, P < 0.05); the protein quantity of VEGF 165 in cell supernatant was respectively (62.4 ± 2.7), (73.1 ± 3.8), (117.5 ± 3.1) pg/mL (F = 15.08, P < 0.05). The mRNA and protein levels of VEGF 165 and VEGF 165 protein amount in supernatant were significantly higher in VEGF plasmid group than in the other two groups, with P values all below 0.05. (2) The number of HUVECs in dermal substitutes of transfected cells group was significantly higher than that of the other three groups on POD 14. The numbers of microvessels of dermal substitutes on POD 14 in saline group, medium group, non-transfected cells group, transfected cells group were respectively 4.2 ± 1.1, 5.2 ± 1.1, 6.6 ± 0.9, 13.8 ± 0.8 per 200 times visual field (F = 17.96, P < 0.01). The microvessel number in transfected cells group was significantly higher than that of the other three groups, with P values all below 0.05. The relative expression ratio of VEGF 165 protein of dermal substitutes in transfected cells group was significantly higher than that in saline group as of POD 7. On POD 14 and 21, the relative expression ratios of VEGF 165 proteins in non-transfected cells group (1.652 ± 0.086, 2.152 ± 0.062) and transfected cells group (2.403 ± 0.091, 2.879 ± 0.047) were significantly higher than those of saline group (1.299 ± 0.027, 1.362 ± 0.103), with P values all below 0.05. And the index level of transfected cells group was significantly higher than that in non-transfected cells group (with P values below 0.05). The VEGF 165 protein content in dermal substitutes increased with time extension in all groups.

CONCLUSIONS

Transfection of VEGF 165 gene in HUVEC could effectively facilitate vascularization of dermal substitutes in vivo by high expression of VEGF 165 protein.

Dopamine regulates mobilization of mesenchymal stem cells during wound angiogenesis

Angiogenesis is an important step in the complex biological and molecular events leading to successful healing of dermal wounds. Among the different cellular effectors of wound angiogenesis, the role of mesenchymal stem cells (MSCs) is of current interest due to their transdifferentiation and proangiogenic potentials. Skin is richly innervated by sympathetic nerves which secrete dopamine (DA) and we have recently shown that concentration of DA present in synaptic cleft can significantly inhibit wound tissue neovascularization. As recent reports indicate that MSCs by mobilizing into wound bed play an important role in promoting wound angiogenesis, we therefore investigated the effect of DA on the migration of MSCs in wound tissues. DA acted through its D(2) receptors present in the MSCs to inhibit their mobilization to the wound beds by suppressing Akt phosphorylation and actin polymerization. In contrast, this inhibitory effect of DA was reversed after treatment with specific DA D(2) receptor antagonist. Increased mobilization of MSCs was demonstrated in the wound site following blockade of DA D(2) receptor mediated actions, and this in turn was associated with significantly more angiogenesis in wound tissues. This study is of translational value and indicates use of DA D(2) receptor antagonists to stimulate mobilization of these stem cells for faster regeneration of damaged tissues.

LPS and TNF-α induce expression of sphingosine-1-phosphate receptor-2 in human microvascular endothelial cells

Sphingosine-1-phosphate (S1P) is a bioactive sophospholipid with various S1P receptor (S1PR) expression profiles in cells of different origin. S1PR1, R3 and - to a lesser extent - R2 were the main receptors expressed in most of endothelial cells (ECs). The balances in the expression and activation of S1PR1, R2 and R3 help to maintain the physiological functions of ECs. Reverse transcription-PCR and Western blotting were used to detect the mRNA transcript level and protein expression of S1PR. Endothelial barrier function was measured by transflux of tracer protein through endothelial monolayer. Human dermal microvascular ECs predominantly expressed S1PR1 and S1PR3. Lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α) significantly upregulated S1PR2 mRNA and protein levels. The application of S1PR2 antagonist JTE-013 decreased the endothelial monolayer hyper-permeability response induced by LPS and TNF-α. Inflammatory mediators LPS and TNF-α induce S1PR2 expression in endothelium, suggesting that S1PR2 up-regulation may be involved in LPS and TNF-α elicited endothelial barrier dysfunction.

A new in vitro wound model based on the co-culture of human dermal microvascular endothelial cells and human dermal fibroblasts

BACKGROUND INFORMATION

Different in vitro models, based on co-culturing techniques, can be used to investigate the behaviour of cell types, which are relevant for human wound and soft-tissue healing. Currently, no model exists to describe the behaviour of fibroblasts and microvascular endothelial cells under wound-specific conditions. In order to develop a suitable in vitro model, we characterized co-cultures comprising NHDFs (normal human dermal fibroblasts) and HDMECs (human dermal microvascular endothelial cells). The CCSWMA (co-culture scratch wound migration assay) developed was supported by direct visualization techniques in order to investigate a broad spectrum of cellular parameters, such as migration and proliferation activity, the differentiation of NHDFs into MFs (myofibroblasts) and the expression of endothelin-1 and ED-A-fibronectin (extra domain A fibronectin). The cellular response to hypoxia treatment, as one of the crucial conditions in wound healing, was monitored.

RESULTS

The comparison of the HDMEC-NHDF co-culture with the respective mono-cultures revealed that HDMECs showed a lower proliferation activity when co-cultured, but their number was stable throughout a period of 48 h. NHDFs in co-culture were slightly slower at proliferating than in the mono-culture. The MF population was stable for 48 h in the co-culture, as well as in NHDF mono-culture. Co-cultures and HDMEC mono-cultures were characterized by a slower migration rate than NHDF mono-cultures. Hypoxia decreased both cell proliferation and migration in the mono-cultures, as well as in the co-cultures, indicating the general suitability of the assay. Exclusively, in co-cultures well-defined cell clusters comprising HDMECs and MFs formed at the edges of the in vitro wounds.

CONCLUSIONS

On the basis of these results, the CCSWMA developed using co-cultures, including HDMECs, NHDFs and MFs, proved to be an effective tool to directly visualize cellular interaction. Therefore, it will serve in the future to evaluate the influence of wound-healing-related factors in vitro, as shown for hypoxia in the present study.

Spatial frequency domain spectroscopy of two layer media

Monitoring of tissue blood volume and oxygen saturation using biomedical optics techniques has the potential to inform the assessment of tissue health, healing, and dysfunction. These quantities are typically estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in superficial tissue such as the skin can be confounded by the strong absorption of melanin in the epidermis. Furthermore, epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. This study describes a technique for decoupling the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. An artificial neural network was used to map input optical properties to spatial frequency domain diffuse reflectance of two layer media. Then, iterative fitting was used to determine the optical properties from simulated spatial frequency domain diffuse reflectance. Additionally, an artificial neural network was trained to directly map spatial frequency domain reflectance to sets of optical properties of a two layer medium, thus bypassing the need for iteration. In both cases, the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis were determined independently. The accuracy and efficiency of the iterative fitting approach was compared with the direct neural network inversion.

Dopamine regulates angiogenesis in normal dermal wound tissues

Cutaneous wound healing is a normal physiological process and comprises different phases. Among these phases, angiogenesis or new blood vessel formation in wound tissue plays an important role. Skin is richly supplied by sympathetic nerves and evidences indicate the significant role of the sympathetic nervous system in cutaneous wound healing. Dopamine (DA) is an important catecholamine neurotransmitter released by the sympathetic nerve endings and recent studies have demonstrated the potent anti-angiogenic action of DA, which is mediated through its D₂ DA receptors. We therefore postulate that this endogenous catecholamine neurotransmitter may have a role in the neovascularization of dermal wound tissues and subsequently in the process of wound healing. In the present study, the therapeutic efficacy of D₂ DA receptor antagonist has been investigated for faster wound healing in a murine model of full thickness dermal wound. Our results indicate that treatment with specific D₂ DA receptor antagonist significantly expedites the process of full thickness normal dermal wound healing in mice by inducing angiogenesis in wound tissues. The underlined mechanisms have been attributed to the up-regulation of homeobox transcription factor HoxD3 and its target α5β1 integrin, which play a pivotal role in wound angiogenesis. Since D₂ DA receptor antagonists are already in clinical use for other disorders, these results have significant translational value from the bench to the bedside for efficient wound management along with other conventional treatment modalities.

Sirtinol treatment reduces inflammation in human dermal microvascular endothelial cells

Histone deacetylases (HDAC) are key enzymes in the epigenetic control of gene expression. Recently, inhibitors of class I and class II HDAC have been successfully employed for the treatment of different inflammatory diseases such as rheumatoid arthritis, colitis, airway inflammation and asthma. So far, little is known so far about a similar therapeutic effect of inhibitors specifically directed against sirtuins, the class III HDAC. In this study, we investigated the expression and localization of endogenous sirtuins in primary human dermal microvascular endothelial cells (HDMEC), a cell type playing a key role in the development and maintenance of skin inflammation. We then examined the biological activity of sirtinol, a specific sirtuin inhibitor, in HDMEC response to pro-inflammatory cytokines. We found that, even though sirtinol treatment alone affected only long-term cell proliferation, it diminishes HDMEC inflammatory responses to tumor necrosis factor (TNF)α and interleukin (IL)-1β. In fact, sirtinol significantly reduced membrane expression of adhesion molecules in TNFã- or IL-1β-stimulated cells, as well as the amount of CXCL10 and CCL2 released by HDMEC following TNFα treatment. Notably, sirtinol drastically decreased monocyte adhesion on activated HDMEC. Using selective inhibitors for Sirt1 and Sirt2, we showed a predominant involvement of Sirt1 inhibition in the modulation of adhesion molecule expression and monocyte adhesion on activated HDMEC. Finally, we demonstrated the in vivo expression of Sirt1 in the dermal vessels of normal and psoriatic skin. Altogether, these findings indicated that sirtuins may represent a promising therapeutic target for the treatment of inflammatory skin diseases characterized by a prominent microvessel involvement.

Extended focus high-speed swept source OCT with self-reconstructive illumination

We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300 nm with up to 440 kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin. Decoupling the illumination from the gaussian detection increases the global sensitivity and enables dark field imaging. Dark field imaging is useful to avoid strong reflexes from the sample surface that adversely affect the sensitivity due to the limited dynamic range of high speed 8 bit acquisition cards. In addition the possibility of contrasting capillaries with high sensitivity is shown, using inter-B-scan speckle variance analysis. We demonstrate intrinsic advantages of the extended focus configuration, in particular the reduction of the phase decorrelation effect below vessels leading to improved axial vessel definition.

Retrieving skin properties from in vivo spectral reflectance measurements

A previously developed inverse method was applied to in vivo normal-hemispherical spectral reflectance measurements taken on the inner and outer forearm as well as the forehead of healthy white Caucasian and black African subjects. The inverse method was used to determine the thickness and melanin concentration in the epidermis, dermal blood volume fraction and oxygen saturation, and skin's spectral scattering coefficient. It was established that changes in melanin concentration due to racial difference and tanning, and differences in epidermal thickness and blood volume with anatomical location were detectable. The retrieved values were also consistent with independent measurements reported in the literature. The same method could be used for optical diagnosis of pathologies affecting the structure and pigmentation of human skin.

Retrieving skin properties from in vivo spectral reflectance measurements

A previously developed inverse method was applied to in vivo normal-hemispherical spectral reflectance measurements taken on the inner and outer forearm as well as the forehead of healthy white Caucasian and black African subjects. The inverse method was used to determine the thickness and melanin concentration in the epidermis, dermal blood volume fraction and oxygen saturation, and skin's spectral scattering coefficient. It was established that changes in melanin concentration due to racial difference and tanning, and differences in epidermal thickness and blood volume with anatomical location were detectable. The retrieved values were also consistent with independent measurements reported in the literature. The same method could be used for optical diagnosis of pathologies affecting the structure and pigmentation of human skin.

The glycocalyx of human, bovine and murine microvascular endothelial cells cultured in vitro

This study investigated the morphology and thickness of the glycocalyx linings of microvascular endothelial cells (MVEC). Three distinct cell types were used: the human dermal cells (HDMVEC), the murine cardiac cells (MCMVEC) and the bovine luteal cells (BLMVEC). Cells were cultivated for 48 h. Glycocalyx was stained with ruthenium red and examined under a transmission electron microscope. The glycocalyx of HDMVEC was thin and constant (10-22 nm). No glycocalyx was detected within intracellular vesicles. Two cell populations of MCMVEC were recorded. The minor MCMVEC population was well differentiated and covered with heterogenous glycocalyx (2-200 nm). Conglomerates formed above the baseline along the cell extensions. The major MCMVEC population was undifferentiated and coated by a smooth and thin (12-25 nm) layer of glycocalyx. Intracellular vesicles were also coated with glycocalyx. In the BLMVEC population, 10% had 3-170 nm of discontinuous glycocalyx. Rough conglomerates were observed along cell sprouts. Their intracellular vesicles were coated with glycocalyx. The study found vast differences in the morphology and thickness of endothelial glycocalyx among different MVEC under in vitro cultivation. The only record of active endocytosis was in BLMVEC and MCMVEC. No evidence of active endocytosis was found in HDMVEC.

Observation of capillary flow in human skin during tissue compression using CCD video-microscopy

Recent technological advances of the CCD video-camera have made microscopes more compact and greatly improved their sensitivity. We newly designed a compact capillaroscopy which was composed with a CCD video-probe equipped a contact-type objective lens and illuminator. In the present study, we evaluated usefulness of the instrument for a bed-side human capillaroscopy to observe the capillary flow in various dermal regions. The influences of tissue compression on the dermal capillary blood flow were also investigated to confirm the utility for clinical applications. Our capillaroscopy visualized the nutritional capillary blood flow in almost all parts of skin surface. Our observations showed that a level of vertical stress similar to arterial pressure was required to stop the capillary flow. From these demonstrations the present CCD video-probe based capillaroscopy would be useful for clinical applications as a bed-side human capillaroscopy.

Tissue viability (TiVi) imaging: temporal effects of local occlusion studies in the volar forearm

Tissue Viability (TiVi) imaging is a promising new technology for the assessment of microcirculation in the upper human dermis. Although the technique is easily implemented and develops large amounts of observational data, its role in the clinical workplace awaits the development of standardised protocols required for routine clinical practice. The present study investigates the use of TiVi technology in a human, in vivo, localized, skin blood flow occlusion protocol. In this feasibility study, the response of the cutaneous microcirculation after provocation on the volar surface of the forearm was evaluated using a high temporal-low spatial resolution TiVi camera. 19 healthy subjects - 10 female and 9 male - were studied after a localized pressure was applied for 5 different time periods ranging from 5 to 25 seconds. Areas corresponding to 100 x 100 pixels (2.89 cm(2)) were monitored for 60 seconds prior to, during and after each occlusion period. Our results demonstrated the removal of blood from the local area and a hyperaemic response supporting the suitability of TiVi imaging for the generation of detailed provocation response data of relevance for the physiological function of the skin microcirculation in health and disease.

Optical assessment of cutaneous blood volume depends on the vessel size distribution: a computer simulation study

A Monte Carlo simulation was adapted to specify a skin model with pigmented epidermis, dermis with low baseline blood content, and vessels of a vascular lesion with an average added blood volume fraction of 5%. In the study, the lesion vessel diameters were increased and the number of lesion vessels decreased, such that the total lesion blood content was constant. The results show that reflectance (R) increases as vessel size increases, even though the blood content is constant. Light cannot penetrate effectively into larger blood vessels, so the interior of the vessel becomes less visible to the light - a result known in the literature. This study did repeated random placement of vessels to learn the variation in R due to variable vessel placement. The coefficient of variation was about 10% due to random placement. R varies with size, even with small vessels, and does not simply apply to large vessels.

Total particulate matter and wound healing: an in vivo study with histological insights

OBJECTIVES

Wound healing in the skin is a multifarious orchestration of cellular processes and cigarette smoking may be a cause for delayed wound healing. The aim of this study was to investigate the plausible association between exposures of cigarette total particulate matter (TPM) and wound healing.

METHODS

An in vivo wound healing model of mice was established for determination of assorted events of wound healing, dermal matrix regeneration, re-epithelialization, and neovascularization. A total of 72 adult mice, separated in eight groups, were exposed to TPM for 12 days.

RESULTS

A highly considerable diminution in wound closure (P < 0.001) was pragmatic among all TPM-treated mice from day 6 to day 8 post-wounding. Histological investigations unveiled a noteworthy impede in the outcome of re-epithelialization, dermal matrix regeneration and maturation of collagen bundles among all TPM-exposed wounds. Delayed commencement of neovascularization was pragmatic among all TPM-treated mice, on day 12 post wounding. Abbot curve, angular spectrum, and other different parameters of 3D surface behavior of wounds revealed a very highly significant reduction (P < 0.001) in angiogenesis on days 6 and 8 post-wounding, which points that application of TPM instigates extensive delay in trigging the progression of angiogenesis, resulting in delayed onset of wound healing.

CONCLUSION

Our annotations validate the damaging effects of TPM on wound healing and excessive use of TPM may lead to the production of chronic wounds and oral ulcers.