A Tensioned Human Skin Explant Model Used for Preliminary Assessment of Chemexfoliant-Stimulated Bioeffects.

A tensioned ex vivo full-thickness human skin explant platform was used to assess the bioeffects arising from application of several commercial chemexfoliation agents. Although such treatments are well-established, and improved understanding of the underlying mechanistic processes continues to emerge, research into the optimum treatments for specific skin types/conditions is still needed for enhanced efficacy while minimizing recovery time. The 3 commercial chemexfoliation agents employed all contained trichloroacetic acid at well-defined concentrations (6, 10, and 20%) and were applied to the explants' stratum corneum. Subsequently, measurements of dermal remodeling factors (COL1A1, ELN, HAS2, HAS3, and procollagen type I) and inflammatory marker (IL-1b) were undertaken using qPCR and immunofluorescent analyses. Statistical analysis of these data facilitated the establishment of benchmarking biological responses to these trichloroacetic acid-containing agents against untreated controls. The performance of an innovative trichloroacetic acid-free chemexfoliation agent was then measured and, upon comparison with the previous benchmarking data, indicated that dermal remodeling factors could be upregulated in fashion comparable with that of the trichloroacetic acid-containing agents but with significant suppression of inflammatory response. Our measurements thus underscore the promise of the tensioned explant over prolonged study periods and also that potentially valuable insights to guide preclinical strategies may be forthcoming from the protocol developed.

Like Father like Daughter: Surgical Redo Thoracoabdominal Aneurysm Repairs in a Family With Loeys-Dietz Syndrome.

Loeys Dietz Syndrome (LDS) is an autosomal dominant connective tissue disorder resulting from a mutation in the transforming growth factor beta receptor (TGFBR) family of genes. It is commonly associated with the development of aortic aneurysms and dissections. We report the successful open surgical management of thoracoabdominal aneurysms in a father and daughter with Loeys-Dietz Syndrome after failed endovascular repair. The daughter required stent graft explantation, while the stent graft remained in the father. These cases highlight the importance of early genetic testing of both patients and first-degree family members in those with a strong history of aortic disease, even when there is a lack of typical connective tissue disorder associated physical exam findings and open surgical index operations.

Retinal Explant Culture from Mouse, Human, and Nonhuman Primates and Its Applications in Vision Research.

The retinal explant culture system is a valuable tool for studying the pharmacological, toxicological, and developmental aspects of the retina. It is also used for translational studies such as gene therapy. While no photoreceptor-like cell lines are available for in vitro studies of photoreceptor cell biology, the retinal explant culture maintains the laminated retinal structure ex vivo for as long as a month. Human and nonhuman primate (NHP) postmortem retinal explants cut into small pieces offer the possibility of testing multiple conditions for safety and adeno-associated viral (AAV) vector optimization. In addition, the cone-enriched foveal area can be studied using the retinal explants. Here, we present a detailed working protocol for retinal explant isolation and culture from mouse, human, and NHP for testing drug efficacy and AAV transduction. Future applications of this protocol include combining live imaging and multiwell retinal explant culture for high-throughput drug screening systems in rodent and human retinal explants to identify new drugs against retinal degeneration.

Cytokine production in an ex vivo model of SARS-CoV-2 lung infection.

Introduction: The mechanisms of the SARS-CoV-2-triggered complex alterations in immune cell activation and production of cytokines in lung tissue remain poorly understood, in part because of the limited use of adequate tissue models that simulate the structure and cell composition of the lung in vivo. We developed a novel ex vivo model of SARS-CoV-2 infection of lung explants, that maintains the intact tissue composition and the viral load for up to 7-10 days. Using this model, we studied cytokine production during SARS-CoV-2 infection. Materials and methods: Lung tissue was monitored for viability and cell composition using flow cytometry and histological analysis. SARS-CoV-2 infection was verified immunohistochemically, viral loads in tissue and culture medium were monitored by qPCR. A panel of 41 cytokines was measured in culture medium using xMAP technology. Results: The explant lung tissue was viable and maintained viral infection that influenced the cytokine production. Elevated concentrations of G-CSF, GM-CSF, GRO-a, IFN-g, IL-6, IL-8, IP-10, MCP-3, MIP-1a, PDGF-AA, and VEGF, and decreased IL-1RA concentration were observed in infected tissue compared to non-infected tissue. Discussion: Our results generally reflect the data obtained in COVID-19 patients. GRO-a, IFN-g, IL-6, IL-8, MCP-1, MCP-3, and RANTES correlated with the viral load, forming a distinct pro-inflammatory cluster. Thus, our lung ex vivo model faithfully reproduces some aspects of cytokine alterations in COVID-19 patients at an early disease stage, making the investigation of SARS-CoV-2 infection mechanisms more accessible and providing a potential platform for antiviral drug testing.

Staphylococcus felis C4 exhibits in vitro antimicrobial activity against methicillin-resistant Staphylococcus pseudintermedius in a novel canine skin explant model.

BACKGROUND: Canine superficial pyoderma is a common bacterial skin infection of dogs, generally caused by Staphylococcus pseudintermedius. The C4 strain of Staphylococcus felis was recently discovered to have strong antimicrobial activity against S. pseudintermedius in mice. OBJECTIVES: We aimed to evaluate in vitro if this antimicrobial activity was maintained using a novel canine skin explant model. MATERIALS AND METHODS: Punch biopsies (8 mm) of skin from recently euthanised dogs were collected and placed into six-well plates on top of an agarose pedestal. RESULTS: Histological examination of the skin explants showed an intact dermal-epidermal organisation and a stratum corneum that was successfully colonised by S. pseudintermedius after topical application. The number of colony forming units of S. pseudintermedius showed a 2 log increase after 24 h colonisation, indicating that the explant supported bacterial growth. By contrast, co-treatment with S. felis C4 live bacteria and its sterile protein product significantly reduced the growth of a methicillin-susceptible (ST540, p = 0.0357) and a methicillin-resistant (MR) strain (ST71, p = 0.0143) of S. pseudintermedius. No detectable bacteria were recovered from or visualised on skin 24 h posttreatment with the S. felis C4 sterile protein product. CONCLUSIONS AND CLINICAL RELEVANCE: Using a novel canine explant model, we demonstrate that the S. felis C4 strain inhibits the growth of S. pseudintermedius and that it is a promising candidate for a new probiotic therapy to treat cutaneous infections caused by S. pseudintermedius, including MR strains.

Replication Characteristics of African Swine Fever Virus (ASFV) Genotype I E70 and ASFV Genotype II Belgium 2018/1 in Perivenous Macrophages Using Established Vein Explant Model.

African Swine Fever Virus (ASFV), resulting in strain-dependent vascular pathology, leading to hemorrhagic fever, is an important pathogen in swine. The pathogenesis of ASFV is determined by the array and spatial distribution of susceptible cells within the host. In this study, the replication characteristics of ASFV genotype I E70 (G1-E70) and ASFV genotype II Belgium 2018/1 (G2-B18) in the environment of small veins were investigated in an established vein explant model. Immunofluorescence staining analysis revealed that perivenous macrophages (CD163+ cells) were widely distributed in the explant, with most of them (approximately 2-10 cells/0.03 mm2) being present close to the vein (within a radius of 0-348 µm). Upon inoculation with G1-E70 and G2-B18, we observed an increase in the quantity of cells testing positive for viral antigens over time. G1-E70 replicated more efficiently than G2-B18 in the vein explants (7.6-fold for the ear explant at 72 hpi). The majority of ASFV+ cells were CD163+, indicating that macrophages are the primary target cells. Additional identification of cells infected with ASFV revealed the presence of vimentin+, CD14+, and VWF+ cells, demonstrating the cellular diversity and complexity associated with ASFV infection. By the use of this new vein explant model, the susceptibility of vascular and perivascular cells to an ASFV infection was identified. With this model, it will be possible now to conduct more functional analyses to get better insights into the pathogenesis of ASFV-induced hemorrhages.

Evaluating the suitability of placental bovine explants for ex vivo modelling of host-pathogen interactions in Neospora caninum infections.

Bovine abortions, often caused by infectious agents like Neospora caninum, inflict substantial economic losses. Studying host-pathogen interactions in pregnant cows is challenging, and existing cell cultures lack the intricate complexity of real tissues. To bridge the gap between in vitro and in vivo models, we explored the use of cryopreserved bovine placental explants. Building upon our successful development of protocols for obtaining, culturing, and cryopreserving sheep placental explants, we applied these methods to bovine tissues. Here, we compared fresh and cryopreserved bovine explants, evaluating their integrity and functionality over culture time. Additionally, we investigated their susceptibility to N. caninum infection. Our findings revealed that bovine explants deteriorate faster in culture compared to sheep explants, exhibiting diminished viability and function. Cryopreservation further exacerbated this deterioration. While fresh explants were successfully infected with N. caninum, parasite replication was limited. Notably, cryopreservation reduced infection efficiency. This pioneering work paves the way for developing ex vivo models to study reproductive pathogens in cattle. However, further optimization of the model is essential. These improved models will have the potential to significantly reduce the reliance on animals in research.

Explant analysis of a chromium nitride coated metal-on-metal total wrist replacement: A case study.

Explant analysis can provide important understanding of how artificial joints perform in the human body. The articulating surfaces of the metacarpal head and the radius cup from a chromium nitride coated metal-on-metal Motec wrist implant were analysed. Due to bone resorption and aseptic loosening, the implant was removed after 6 years in the patient, and metallosis was observed during removal. Visually, some areas of the articulating surfaces appeared polished, others were dulled. A chemical composition analysis of the metacarpal head showed that the polished surfaces were chromium rich, implying this surface was the original chromium nitride coating, whereas the dulled surfaces were cobalt rich, indicating the underlying cobalt chromium substrate. In addition, the underlying cobalt chromium substrate was an order of magnitude rougher than the polished surface, indicating the scale of damage to it. It is speculated that the loss of the coating, and the subsequent damage to the underlying substrate due to a third-body wear process, led to osteolysis and the metallosis seen at revision surgery.

How did the floating Ulva prolifera develop into the world's largest green tide?

It has been 16 years since the world's largest Ulva bloom appeared in the Yellow Sea. However, it remains unclear how the floating Ulva prolifera developed into the immense green tide within two months especially considering that source control measures have been conducted since 2019. In this study, we investigated the growth mechanism of the floating population by examining the production and regeneration of U. prolifera explants and constructing a growth model. The results showed that U. prolifera explants exhibited rapid regeneration mainly through branches at 15, 20 and 25 °C. Algivore feeding and sporulation (at 20-25 °C) contributed to mass production of explants. The growth of floating population could be attributed to the coupling of mass production and rapid regeneration of explants through multiple cycles, which accounted for the outbreak of floating green tide. This finding presented a novel population growth model to elucidate macroalgal bloom occurrences.

Analysis of Circadian Clock Gene Expression in Human Skin Explants.

Many aspects of skin biochemistry and physiology are known to vary over the course of the 24-hour day. Traditional approaches to study circadian rhythms in the skin have employed rodents or human subjects, which limit the experimental variables that can be studied. Although explants derived from discarded surgical skin are a commonly used model in the skin biology field, circadian rhythms have yet to be examined ex vivo. In this study, using human panniculectomy skin, we used RT-qPCR to monitor the epidermal expression of 4 core circadian clock genes over the course of 1 day ex vivo. Although significant interindividual variability in overall gene expression profiles was observed, robust circadian oscillations were observed in many of the genes and individual explants. Comparison of our gene expression data with microarray data from 2 previous human-subject studies involving primarily young adult White males revealed both similarities and differences, including greater distribution in the time of day of peak expression in the skin explants. This increased variability appears to be due in part to the increased age and altered sex distribution of the donated skin. Nonetheless, our results indicate that skin explants offer an additional experimental system for studying circadian skin biology.

Culture system for longitudinal monitoring of bone dynamics ex vivo.

To quantify and visualize both bone formation and resorption within osteochondral explants cultured ex vivo is challenging with the current analysis techniques. An approach that enables monitoring of bone remodeling dynamics is longitudinal microcomputed tomography (µCT), a non-destructive technique that relies on repeated µCT scanning and subsequent registration of consecutive scans. In this study, a two-compartment culture system suitable for osteochondral explants that allowed for µCT scanning during ex vivo culture was established. Explants were scanned repeatedly in a fixed orientation, which allowed assessment of bone remodeling due to adequate image registration. Using this method, bone formation was found to be restricted to the outer surfaces when cultured statically. To demonstrate that the culture system could capture differences in bone remodeling, explants were cultured statically and under dynamic compression as loading promotes osteogenesis. No quantitative differences between static and dynamic culture were revealed. Still, only in dynamic conditions, bone formation was visualized on trabecular surfaces located within the inner cores, suggesting enhanced bone formation towards the center of the explants upon mechanical loading. Taken together, the ex vivo culture system in combination with longitudinal µCT scanning and subsequent registration of images demonstrated potential for evaluating bone remodeling within explants.

Construction of Optimal Regeneration System for Chrysanthemum '11-C-2' Stem Segment with Buds.

Chrysanthemum morifolium '11-C-2' is a variety of chrysanthemums with high ornamental and tea value, experiencing significant market demand. However, as cultivation areas expand, issues such as viral infection, germplasm degradation, low proliferation coefficient, and slow proliferation rate arise, necessitating the establishment of an efficient in vitro regeneration system. This study, based on the principles of orthogonal experimental design, explored the regeneration system of Chrysanthemum cultivar '11-C-2' using sterile seedlings. The research focused on three key stages: adventitious bud differentiation, rooting culture, and acclimatization-transplantation, employing shoot-bearing stem segments and leaves as explants. The findings indicate that the optimal explant for the Chrysanthemum '11-C-2' sterile seedlings is the shoot-bearing stem segment. The best medium for adventitious bud differentiation was determined to be MS supplemented with 1.5 mg/L 6-BA and 0.5 mg/L NAA. Bud differentiation began on day 17 with a 100% differentiation rate, completing around day 48. The maximum differentiation coefficient reached 87, with an average of 26.67. The adventitious buds were then cultured for rooting in the optimal medium of 1/2 MS supplemented with 0.1 mg/L NAA. Rooting was initiated on day 4 and was completed by day 14, achieving a rooting rate of 97.62%. After a 5-day acclimatization under natural light, the rooted seedlings were transplanted into a growth substrate with a peat-to-vermiculite ratio of 1:2. The plants exhibited optimal growth, with a transplantation survival rate of 100%. The findings provide data support for the efficient large-scale propagation of '11-C-2' and lay the foundation for germplasm preservation and genetic transformation research of tea chrysanthemums.

Evaluation of Rho kinase inhibitor effects on neuroprotection and neuroinflammation in an ex-vivo retinal explant model.

BACKGROUND: Glaucoma is a leading cause of blindness, affecting retinal ganglion cells (RGCs) and their axons. By 2040, it is likely to affect 110 million people. Neuroinflammation, specifically through the release of proinflammatory cytokines by M1 microglial cells, plays a crucial role in glaucoma progression. Indeed, in post-mortem human studies, pre-clinical models, and ex-vivo models, RGC degeneration has been consistently shown to be linked to inflammation in response to cell death and tissue damage. Recently, Rho kinase inhibitors (ROCKis) have emerged as potential therapies for neuroinflammatory and neurodegenerative diseases. This study aimed to investigate the potential effects of three ROCKis (Y-27632, Y-33075, and H-1152) on retinal ganglion cell (RGC) loss and retinal neuroinflammation using an ex-vivo retinal explant model. METHODS: Rat retinal explants underwent optic nerve axotomy and were treated with Y-27632, Y-33075, or H-1152. The neuroprotective effects on RGCs were evaluated using immunofluorescence and Brn3a-specific markers. Reactive glia and microglial activation were studied by GFAP, CD68, and Iba1 staining. Flow cytometry was used to quantify day ex-vivo 4 (DEV 4) microglial proliferation and M1 activation by measuring the number of CD11b+, CD68+, and CD11b+/CD68+ cells after treatment with control solvent or Y-33075. The modulation of gene expression was measured by RNA-seq analysis on control and Y-33075-treated explants and glial and pro-inflammatory cytokine gene expression was validated by RT-qPCR. RESULTS: Y-27632 and H-1152 did not significantly protect RGCs. By contrast, at DEV 4, 50 µM Y-33075 significantly increased RGC survival. Immunohistology showed a reduced number of Iba1+/CD68+ cells and limited astrogliosis with Y-33075 treatment. Flow cytometry confirmed lower CD11b+, CD68+, and CD11b+/CD68+ cell numbers in the Y-33075 group. RNA-seq showed Y-33075 inhibited the expression of M1 microglial markers (Tnfα, Il-1ß, Nos2) and glial markers (Gfap, Itgam, Cd68) and to reduce apoptosis, ferroptosis, inflammasome formation, complement activation, TLR pathway activation, and P2rx7 and Gpr84 gene expression. Conversely, Y-33075 upregulated RGC-specific markers, neurofilament formation, and neurotransmitter regulator expression, consistent with its neuroprotective effects. CONCLUSION: Y-33075 demonstrates marked neuroprotective and anti-inflammatory effects, surpassing the other tested ROCKis (Y-27632 and H-1152) in preventing RGC death and reducing microglial inflammatory responses. These findings highlight its potential as a therapeutic option for glaucoma.

Photobiomodulation Using 830 nm Lighting-Emitting Diode Inhibits Melanogenesis via FOXO3a in Human Melanocyte.

Photobiomodulation (PBM) using 830 nm light-emitting diode (LED) benefits tissue regeneration, wound healing and neural stimulation. However, there is not much exploration of its effect on melanocytes and ex vivo skin model. This study aims to investigate the mechanism behind the anti-melanogenic activity of 830 nm LED and provides evidence for its activity in human ex vivo skin model. Our results showed that 830 nm LED at fluences ranging from 5 to 20 J/cm2 inhibited melanosome maturation and reduced melanin content, tyrosinase activity and melanogenesis-related proteins. 830 nm LED inhibited the phosphorylation of AKT and its downstream FOXO3a, leading to nuclear translocation of FOXO3a. Furthermore, FOXO3a knockdown and AKT activator like SC79 could reverse the melanogenesis inhibition phenotype induced by 830 nm LED. In human ex vivo skin model, Fontana-Masson staining revealed a decrease in epidermal basal pigmentation after 830 nm LED irradiation. Taken together, 830 nm LED demonstrated the anti-melanogenic activity via FOXO3a.

In vitro assessment of nanomedicines' propensity to cause palmar-plantar erythrodysesthesia: A Doxil vs. doxorubicin case study.

Palmar-plantar erythrodysesthesia (PPE), also known as hand and foot syndrome, is a condition characterized by inflammation-mediated damage to the skin on the palms and soles of the hands and feet. PPE limits the successful therapeutic applications of anticancer drugs. However, identifying this toxicity during preclinical studies is challenging due to the lack of accurate in vitro and in vivo animal-based models. Therefore, there is a need for reliable models that would allow the detection of this toxicity early during the drug development process. Herein, we describe the use of an in vitro skin explant assay to assess traditional DXR, Doxil reference listed drug (RLD) and two generic PEGylated liposomal DXR formulations for their abilities to cause inflammation and skin damage. We demonstrate that the results obtained with the in vitro skin explant assay model for traditional DXR and Doxil correlate with the clinical data.

Comprehensive analysis of substernal lead removal: experience from EV ICD Pilot, Pivotal, and Continued Access Studies.

AIMS: The extravascular implantable cardioverter-defibrillator (EV ICD) has been shown to be safe and effective for patients at risk of sudden cardiac death, but little is known about EV ICD lead removal in humans. This analysis aimed to characterize the EV ICD lead removal experience thus far. METHODS AND RESULTS: This was a retrospective analysis of lead removals from the EV ICD Pilot, Pivotal, and Continued Access Studies. Patients with a successful EV ICD implant who underwent lead removal were included. The main objective was lead removal success. Ancillary objectives included characterizing technique used, procedure complications, and reimplantation status. An EV ICD system was successfully implanted in 347 patients across the 3 studies (25.9% female; 53.4 ± 13.3 years; left ventricular ejection fraction: 39.7 ± 15.9). Of these patients, 29 (8.4%) underwent lead removal with a mean lead dwell time of 12.6 ± 14.3 months (0.2-58.4). The main reason for lead removal was lead dislodgement (n = 9, 31.0%). Lead removal was successful in 27/29 (93.1%) cases [100% (19/19) success rate <1 year and 80% (8/10) success rate >1 year post-implant]. Simple traction was used in 22/26 (84.6%) and extraction tools in 4/26 (15.4%) successful cases where technique was known. No complications were reported for any of the removal procedures. All 11 EV ICD reimplant attempts were successful. CONCLUSION: Complete removal of the EV ICD lead was successful in 93.1% of cases, and simple traction was sufficient in most instances. Based on these results, lead removal from the substernal space was safe and achievable up to 3 years post-implant.

An Enzyme-Free Method for Isolation and Expansion of Muscle Stem Cells for Cultivated Meat Applications.

Cultivated meat, an alternative to conventional meat, holds great promise in alleviating environmental and ethical concerns. Skeletal muscle stem cell isolation is a critical phase in cultivated meat production, and efficiency is a major determinant in the final differentiated muscle cell yield. The conventional enzymatic dissociation method for cell isolation presents drawbacks, including added costs and the destruction of vital extracellular matrix components. We developed an alternative cell isolation technique, explant cell isolation, to isolate muscle stem cells from muscle tissue. The present protocol yields myogenic cell populations, mainly composed of skeletal muscle stem cells without the use of enzymes, and through a simplified process. Overall, the explant method allows for propagation of cells in their natural environment, preserving intricate cell-cell and cell-matrix interactions, resulting in both economic efficiency and consistent generation of high-quality cells.

Isolation and Characterization of Human Dental Pulp Stem Cells Derived from Dental Pulp of Permanent Teeth.

Dental pulp stem cells (DPSCs) are a promising alternative to the source of mesenchymal stem cells (MSCs), as they are readily available in minimally invasive procedures compared to more invasive methods associated with harvesting other MSCs sources. Despite the encouraging pre-clinical outcomes in animal disease models, culture-expanding procedures are needed to obtain a sufficient number of MSCs required for delivery to the damaged site. However, this contributes to increasing regulatory difficulties in translating stem cells and tissue engineering therapy to clinical use. Moreover, discussions continue as to which isolation method is to be preferred when obtaining DPSCs from extracted molars. This protocol describes a simple explant isolation technique of human dental pulp stem cells from the dental pulp of permanent teeth based upon the plastic adherence of MSCs and subsequent outgrowth of cells out of tissue fragments with high efficacy.

Development of a 3-dimensional organotypic model with characteristics of peripheral sensory nerves.

We developed a rat dorsal root ganglion (DRG)-derived sensory nerve organotypic model by culturing DRG explants on an organoid culture device. With this method, a large number of organotypic cultures can be produced simultaneously with high reproducibility simply by seeding DRG explants derived from rat embryos. Unlike previous DRG explant models, this organotypic model consists of a ganglion and an axon bundle with myelinated A fibers, unmyelinated C fibers, and stereo-myelin-forming nodes of Ranvier. The model also exhibits Ca2+ signaling in cell bodies in response to application of chemical stimuli to nerve terminals. Further, axonal transection increases the activating transcription factor 3 mRNA level in ganglia. Axons and myelin are shown to regenerate 14 days following transection. Our sensory organotypic model enables analysis of neuronal excitability in response to pain stimuli and tracking of morphological changes in the axon bundle over weeks.

Recovery kinetics of dual AAV-mediated human otoferlin expression.

Deafness-causing deficiencies in otoferlin (OTOF) have been addressed preclinically using dual adeno-associated virus (AAV)-based approaches. However, timing of transduction, recombination of mRNA, and protein expression with dual hybrid AAV methods methods have not previously been characterized. Here, we have established an ex vivo assay to determine the kinetics of dual-AAV mediated expression of OTOF in hair cells of the mouse utricle. We utilized two different recombinant vectors that comprise DB-OTO, one containing the 5' portion of OTOF under the control of the hair cell-specific Myo15 promoter, and the other the 3' portion of OTOF. We explored specificity of the Myo15 promoter in hair cells of the mouse utricle, established dose response characteristics of DB-OTO ex vivo in an OTOF-deficient mouse model, and demonstrated tolerability of AAV1 in utricular hair cells. Furthermore, we established deviations from a one-to-one ratio of 5' to 3' vectors with little impact on recombined OTOF. Finally, we established a plateau in quantity of recombined OTOF mRNA and protein expression by 14 to 21 days ex vivo with comparable recovery timing to that in vivo model. These findings demonstrate the utility of an ex vivo model system for exploring expression kinetics and establish in vivo and ex vivo recovery timing of dual AAV-mediated OTOF expression.