Origin and properties of the blister formation factor in blister fluids from recessive dystrophic epidermolysis bullosa

Harnessing the role of microneedles as sensors: current status and future perspectives

In recent years, microneedles (MNs) have been transformed to serve a wide range of applications in the biomedical field. Their role as sensors in wearable devices has provided an alternative to blood-based monitoring of health and diagnostic methods. Hence, they have become a topic of research interest for several scientists working in the biomedical field. These MNs as sensors offer the continuous monitoring of biomarkers like glucose, nucleic acids, proteins, polysaccharides and electrolyte ions, which can therefore screen for and diagnose disease conditions in humans. The present review focuses on types of MN sensors and their applications. Various clinical trials and bottlenecks of MN R&D are also discussed.

Microneedle Sensors for Point-of-Care Diagnostics

Point-of-care (POC) has the capacity to support low-cost, accurate and real-time actionable diagnostic data. Microneedle sensors have received considerable attention as an emerging technique to evolve blood-based diagnostics owing to their direct and painless access to a rich source of biomarkers from interstitial fluid. This review systematically summarizes the recent innovations in microneedle sensors with a particular focus on their utility in POC diagnostics and personalized medicine. The integration of various sensing techniques, mostly electrochemical and optical sensing, has been established in diverse architectures of "lab-on-a-microneedle" platforms. Microneedle sensors with tailored geometries, mechanical flexibility, and biocompatibility are constructed with a variety of materials and fabrication methods. Microneedles categorized into four types: metals, inorganics, polymers, and hydrogels, have been elaborated with state-of-the-art bioengineering strategies for minimally invasive, continuous, and multiplexed sensing. Microneedle sensors have been employed to detect a wide range of biomarkers from electrolytes, metabolites, polysaccharides, nucleic acids, proteins to drugs. Insightful perspectives are outlined from biofluid, microneedles, biosensors, POC devices, and theragnostic instruments, which depict a bright future of the upcoming personalized and intelligent health management.

Assessment of the biochemical effects of percutaneous exposure of sulphur mustard in an in vitro human skin system

1. Sulphur mustard (HD) is a potent chemical warfare agent which causes incapacitating blisters on human skin. There is no specific pretreatment nor therapy against this agent and the mechanism of dermo-epidermal cleavage is unclear. The aim of this study was to use a human skin explant system to determine the consequences of percutaneous exposure to HD. 2. Increased activities of serine proteases associated with blistering disorders in humans were detected from human skin explants after exposure to HD. The most consistent response and the highest protease activities measured were found for trypsin. This class of enzyme is therefore implicated in the dermo-epidermal separation which is associated with blistering in humans following exposure to HD. 3. An inflammatory response was observed in the skin explants exposed to HD. At low doses of HD it was characterised by the presence of neutrophils in the papillary dermis, culminating in the infiltration of the epidermis by these inflammatory cells at higher concentrations of HD. A variety of other histopathological changes in the explants was found such as focal dermo-epidermal separation, nuclear pyknosis and perinuclear vacuolation. 4. The study indicates that full thickness human skin explants can be used to investigate various aspects of the possible pathogenesis of HD-induced skin damage, including the associated inflammatory response.

The generation of a human dermal equivalent to assess the potential contribution of human dermal fibroblasts to the sulphur mustard-induced vesication response

1. A human dermal equivalent (HDE) gel was constructed from rat tail tendon collagen (type 1) and human dermal fibroblasts (HFs). Histological studies revealed that the HFs within the HDE gel matrix assumed the shape of differentiated dermal fibroblasts and were metabolically viable as determined by the MTT assay. 2. The HDE system was developed to determine if viable, differentiated HFs have the potential to contribute to tissue damage by releasing the proteolytic enzyme elastase following exposure to sulphur mustard (HD). Elastase was measured, using the substrate suc-ala-ala-val-p-nitroanilide (SAAVNA), because of its association with various human pathological bullous skin diseases. An additional elastase substrate (suc-ala-ala-ala-p-nitroanilide; SAAANA) was also used. A miniaturised assay was employed to measure lactate dehydrogenase (LDH), a cytosolic enzyme released following damage to the cell membrane. 3. Elastase levels (measured with SAAVNA) increased to over 740% of those in control culture medium at 24 h after exposure of the HDE to HD (2 mM) and may therefore be part of the mechanism associated with dermo-epidermal separation and blistering in humans following exposure of skin to HD. LDH was released from the HDE after exposure to HD in a time dependent fashion, suggesting a steady leakage of cytosolic constituents after the initial exposure. 4. The results suggest that differentiated human dermal fibroblasts have the potential to contribute to the development of the vesication response by releasing proteases such as elastase extracellularly after HD exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of culturing temperature and proteinase inhibitors on the spontaneously occurring changes in the organ culture of psoriatic skin

Skin explants from involved psoriatic lesions showed dissociation of keratinocytes, dermal-epidermal separation and degenerative changes such as cytoplasmic swelling of subcorneal prickled cells within 24 h after culture initiation at 37 degrees C in the absence of fetal bovine serum (FBS). These histological changes developed time dependently, while normal skin explants did not exhibit such phenomena. Some of the uninvolved psoriatic skin explants showed only degenerative change 48 to 72 h after culture initiation at 37 degrees C. To determine the nature of these spontaneously occurring changes in psoriatic skin explants and then to approach the pathogenesis of psoriasis, the effects of FBS, various proteinase inhibitors (PIs) and culturing temperature (37, 31, 24 degrees C) were examined in skin organ culture of normal and involved psoriatic skin. At 37 degrees C, only serine PIs (5 or 10 mg/ml of soybean trypsin inhibitor (SBTI), 1000 KIU/ml of aprotinin, or 2 mg/ml of camostat mesilate in the medium) or FBS (20% in the medium) could suppress the occurrence of dissociation of keratinocytes and dermal-epidermal separation but not the degenerative change in involved psoriatic skin explants, while other types of PIs did not exhibit any such inhibition. When the culturing temperature was reduced from 37 degrees C to 31 or 24 degrees C, the formation of dissociation of keratinocytes and dermal-epidermal separation was almost non-existent and only moderate degenerative change was observed. The addition of FBS or serine PIs to the culture at 31 degrees C revealed the formation of very weak degenerative change.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagenase expression in skin fibroblasts from families with recessive dystrophic epidermolysis bullosa

The collagenase production of cultured skin fibroblasts from Scandinavian families with dominant (D-EBD) and recessive (R-EBD) epidermolysis bullosa dystrophica has been investigated. Heterogeneity as a result of body location origin has been ruled out as fibroblasts obtained from predilection sites produce the same amount of immunoreactive collagenase as those obtained from non-predilection sites of the same subjects. Large variations in in vitro collagenase production were found between individuals and families. Within the R-EBD group, four out of eighteen patients showed an in vitro elevated level of immunoreactive collagenase compared to their healthy relatives, other EB types, and the control group. This shows that an in vitro elevated collagenase production is not a marker for the entire disease group and that the disease denoted as R-EBD probably is etiologically and pathogenetically heterogeneous.

Protease inhibitor therapy for recessive dystrophic epidermolysis bullosa. In vitro effect and clinical trial with camostat mesylate

Recently we reported that a kind of serine protease, SH protease, and collagenase might be involved in blister formation and, furthermore, that the cooperative action of these three proteases was essential for blister formation in recessive dystrophic epidermolysis bullosa. In this study we examined the inhibitory effect of clinically usable serine protease inhibitors for blister formation in organ culture and in clinical trials of recessive dystrophic epidermolysis bullosa patients. Camostat mesylate, a synthetic serine protease inhibitor that is available for the treatment of chronic pancreatitis, demonstrated a striking effect of inhibiting blistering in organ culture of normal human skin with recessive dystrophic epidermolysis bullosa blister fluids. Subsequently we administered camostat mesylate by topical application to four patients with recessive dystrophic epidermolysis bullosa to assess its ability to reduce blistering. Therapeutic response was favorable; a significant effect in decreasing the number of blisters was observed in three of four patients. These findings actually supported the hypothesis that a kind of serine protease had a close relationship with blistering in recessive dystrophic epidermolysis bullosa and that therapy with a clinically usable protease inhibitor was useful for the treatment of this disease.