Tissue Model Research Articles

Absolute mass spectrometry: A theoretical analytical technique for quantification

Mass spectrometry (MS) is an analytical chemistry technique that requires calibration with standards in order to quantify an analyte in a sample. In many cases the reference standards may be difficult to obtain or unavailable. In fact, when MS is applied to study reactions that yield multiple products, their quantification requires several standards and involves time-consuming and tedious calibration procedures. In other applications like Mass Spectrometry Imaging (MSI), quantification becomes even more tedious when on-tissue standards or mimetic tissue models are required. In this work, we introduce a new measurement technique that we called the Absolute Mass Spectrometry (AbMS), which allows the absolute quantification of an analyte without the need for calibration standards. This technique is based on the “Influence Method” developed in 2015 for nuclear measurements which, when applied to MS, produces this improvement for analyte quantification. Two possible applications of this technique are presented. One is the conceptual development of a mass spectrometer with electronic ionization that does not require calibration to determine the amount of analyte. The other one describes how to apply this technique in a mass spectrometer with other ionization sources like MALDI, DESI, and SIMS, which are used in MSI. AbMS technique uses the conceptual basis of Influence Method and two consecutive measurements to estimate the amount of analyte. Specifically, AbMS can be directly employed as an absolute method for quantification in MSI. Therefore, it constitutes an attractive complement for research applications in pharmaceutical and health sciences.

The influence of eyelashes on electric field distribution and absorbed power density in the cornea under millimeter-wave exposure.

As millimeter wave (MMW) technology, particularly in fifth-generation (5G) devices, gains prominence, there is a crucial need for comprehensive electromagnetic (EM) models of ocular tissues to understand and characterize EM exposure conditions accurately. This study employs numerical modeling to investigate the interaction between MMW and the cornea, aiming to characterize EM field distributions and absorption within an anatomically accurate eye model while considering the influence of eyelashes. Using the finite-difference time-domain (FDTD) method, we conduct simulations of EM radiation interactions from 20.0 to 100.0 GHz with a human eye model. Moreover, we analyze the temperature distribution increase within the eye model using a thermal sensor in XFdtd, employing a scheme based on the finite difference (FD) method. Our findings reveal a nonuniform distribution of the EM field, particularly intensified in corneal regions adjacent to eyelashes and eyelids. Despite similar EM field patterns, the presence or absence of eyelashes has minimal impact on temperature differences. However, the study highlights increased radiation absorption by the eyelid's epidermis at 100.0 GHz, reducing the rise in the cornea's temperature.

Aging and rejuvenation of engineered cardiovascular tissues: from research to clinical application

Aging is a key contributor to the pathogenesis of cardiovascular diseases (CVDs). However, current methods and models of CVD do not include the factor of aging due to the use of premature cardiomyocytes. There is an urgent need for an engineered cardiovascular tissue (ECT) model that includes aging as the greatest CVD risk factor to facilitate drug development for aged CVD patients. Cell therapy, which transplants pluripotent stem cell-derived cardiomyocytes in patients, was proved to be effective for cardiac repair, while the cell retention rate is limited. Alternatively, implantation of ECT could enable long-term retention of cells after translation and may result in rejuvenation in aged hearts. This review summarizes the key features of aging and the influencing factors in engineered cardiovascular tissues. The applications and challenges of engineered myocardium designed for clinical use are also discussed.

Controlling Cell Interactions with DNA Directed Assembly.

The creation of complex cellular environments is critical to mimicking tissue environments that will play a critical role in next-generation tissue engineering, stem cell programming, and therapeutic screening. To address this growing need, techniques capable of manipulating cell-cell and cell-material interactions are required that span single-cell to 3D tissue architectures. DNA programmed assembly and placement of cells present a powerful technique for the bottom-up synthesis of living microtissues for probing key questions in cell-cell and cell-material-driven behaviors through its refined control over placement and architecture. This review examines the current state of the art in the programming of cellular interactions with DNA and its applications spanning tissue model building, fundamental cellular biology, and cell manipulation for measurements across a host of applications.

Assessing nanotoxicity of food-relevant particles: A comparative analysis of cellular responses in cell monolayers versus 3D gut epithelial cultures

Engineered nanoparticles (NPs) are extensively used in the food industry, yet safety concerns remain. The lack of validated methodologies is a bottleneck towards resolving this uncertainty. Hence, the current study aims to compare two cell models by examining the toxicological impacts of two food-relevant NPs (SiO2 and Ag) on intestinal epithelia using monolayer Caco-2 cells and full-thickness 3D tissue models of human small intestines (EpiIntestinal™). Comprehensive characterization and dosimetric analysis of the NPs were performed to determine effective doses and model realistic exposures. Neither genotoxicity nor cytotoxicity were detected in the 3D tissues after NP treatment, while the 2D cultures exhibited cytotoxic response from Ag NP treatment for 24 h at 1 μg/ml. Hyperspectral imaging and transmission electron microscopy confirmed uptake of both NPs by cells in both 2D and 3D culture models. Ag NPs caused an increase in autophagy, whereas SiO2 NPs induced increased cytoplasmic vacuolization. Based on realistic exposure levels studied, the 3D small intestinal tissue model was found to be more resilient to NP treatment compared to 2D cell monolayers. This comparative approach towards toxicological assessment of food relevant NPs could be used as a framework for future analysis of NP behavior and nanotoxicity in the gut.

Targeted nuclear degranulation of neutrophils promotes the progression of pneumonia in ulcerative colitis.

Both intestinal and pulmonary systems are parts of the mucosal immune system, comprising ∼80% of all immune cells. These immune cells migrate or are transported between various mucosal tissues to maintain tissue homeostasis. In this study, we isolated neutrophils from the peripheral blood of patients and utilized immunofluorescence, flow cytometry, and Western blotting to confirm the incidence of "nucleus-directed degranulation" in vitro. Subsequently, we conducted a precise analysis using arivis software. Furthermore, using the DSS mouse model of colitis and tissue clearing technologies, we validated the "targeted nuclear degranulation" of neutrophils and their migration to the lungs in an inflammatory intestinal environment. In this study, we found that among patients with ulcerative colitis, the migration of neutrophils with "targeted nuclear degranulation" from the intestinal mucosa to the lungs significantly exacerbates lung inflammation during pulmonary infections. Notably, patients with ulcerative colitis exhibited a higher abundance of neutrophils with targeted nuclear degranulation. Using DSS mice, we observed that neutrophils with targeted nuclear degranulation from the intestinal mucosa migrated to the lung and underwent activation during pulmonary infections. These neutrophils rapidly released a high amount of neutrophil extracellular traps to mediate the progression of lung inflammation. Alterations in the neutrophil cytoskeleton and its interaction with the nuclear membrane represent the primary mechanisms underlying targeted nuclear degranulation. This study revealed that neutrophils accelerate lung inflammation progression in colitis, offering new insights and potential treatment targets for lung infections for patients with colitis.

Tissue-Engineered Three-Dimensional Platforms for Disease Modeling and Therapeutic Development.

Three-dimensional (3D) tissue-engineered models are under investigation to recapitulate tissue architecture and functionality, thereby overcoming limitations of traditional two-dimensional cultures and preclinical animal models. This review highlights recent developments in 3D platforms designed to model diseases in vitro that affect numerous tissues and organs, including cardiovascular, gastrointestinal, bone marrow, neural, reproductive, and pulmonary systems. We discuss current technologies for engineered tissue models, highlighting the advantages, limitations, and important considerations for modeling tissues and diseases. Lastly, we discuss future advancements necessary to enhance the reliability of 3D models of tissue development and disease.

Suspended Tissue Open Microfluidic Patterning (STOMP).

Cell-laden hydrogel constructs suspended between pillars are powerful tools for modeling tissue structure and physiology, though current fabrication techniques often limit them to uniform compositions. In contrast, tissues are complex in nature with spatial arrangements of cell types and extracellular matrices. Thus, we present Suspended Tissue Open Microfluidic Patterning (STOMP), which utilizes a removable, open microfluidic patterning channel to pattern multiple spatial regions across a single suspended tissue. The STOMP platform contains capillary pinning features along the open channel that controls the fluid front, allowing multiple cell and extracellular matrix precursors to be pipetted into one tissue. We have used this technique to pattern suspended tissues with multiple regional components using a variety of native and synthetic extracellular matrices, including fibrin, collagen, and poly(ethylene glycol). Here, we demonstrate that STOMP models a region of fibrosis in a functional heart tissue and a bone-ligament junction in periodontal tissues. Additionally, the STOMP platform can be customized to allow patterning of suspended cores and more spatial configurations, enhancing its utility in complex tissue modeling. STOMP is a versatile technique for generating suspended tissue models with increased control over cell and hydrogel composition to model interfacial tissue regions in a suspended tissue.

An engineered model of metastatic colonization of human bone marrow reveals breast cancer cell remodeling of the hematopoietic niche

Incomplete understanding of metastatic disease mechanisms continues to hinder effective treatment of cancer. Despite remarkable advancements toward the identification of druggable targets, treatment options for patients in remission following primary tumor resection remain limited. Bioengineered human tissue models of metastatic sites capable of recreating the physiologically relevant milieu of metastatic colonization may strengthen our grasp of cancer progression and contribute to the development of effective therapeutic strategies. We report the use of an engineered tissue model of human bone marrow (eBM) to identify microenvironmental cues regulating cancer cell proliferation and to investigate how triple-negative breast cancer (TNBC) cell lines influence hematopoiesis. Notably, individual stromal components of the bone marrow niche (osteoblasts, endothelial cells, and mesenchymal stem/stromal cells) were each critical for regulating tumor cell quiescence and proliferation in the three-dimensional eBM niche. We found that hematopoietic stem and progenitor cells (HSPCs) impacted TNBC cell growth and responded to cancer cell presence with a shift of HSPCs (CD34+CD38-) to downstream myeloid lineages (CD11b+CD14+). To account for tumor heterogeneity and show proof-of-concept ability for patient-specific studies, we demonstrate that patient-derived tumor organoids survive and proliferate in the eBM, resulting in distinct shifts in myelopoiesis that are similar to those observed for aggressively metastatic cell lines. We envision that this human tissue model will facilitate studies of niche-specific metastatic progression and individualized responses to treatment.

Evaluation and the mechanism of ShengXian and JinShuiLiuJun decoction in the treatment of silicotic fibrosis: An integrated network pharmacology, life omics, and experimental validation study

BackgroundSilicosis is a systemic disease characterized by extensive fibrosis due to prolonged exposure to silica dust, with rising incidence rates significantly impacting global public health. ShengXian and JinShuiLiuJun Decoction (SXD) is a Chinese medicinal preparation containing a variety of medicinal plants. It has shown notable clinical efficacy in treating silicotic fibrosis in China. However, the precise mechanisms underlying its therapeutic effects remain unclear. This study integrates network pharmacology, multi-omics analysis, and experimental validation to investigate the potential mechanisms by which SXD treats silicotic fibrosis. ObjectiveThe study aims to investigate the therapeutic efficacy of SXD in treating silicotic fibrosis and to elucidate its underlying molecular mechanisms. MethodsHPLC-Q-TOF-MS was used to identify the active components of SXD, and combined with network pharmacology, metabolomics, and transcriptomics, the mechanism of SXD in treating silicotic fibrosis was explored from multiple perspectives. The therapeutic effect of SXD was assessed through HE staining, Masson staining, Micro CT imaging, pulmonary function tests, and hydroxyproline content in lung tissue. Finally, network pharmacology and multi-omics findings were validated using molecular docking. CETSA, immunofluorescence, SPR, and Western blotting were used to analyze key factors in the NF-κB pathway at the animal, cellular, and molecular levels. ResultsSXD treatment improved lung function in silicosis rats, reduced inflammatory cell infiltration, collagen deposition, fibrosis and other pathological changes, and inhibited the protein expression of TNF-α, IL-17A, and IL-1β, and NF-κB in lung tissue. HPLC-Q-TOF-MS combined with network pharmacology identified key compounds such as Liquiritigenin, 3-Methoxynobiletin, Isomangiferin, Hesperidin, shogaol, and Ligustroflavone, which likely exert therapeutic effects through the TNF, IL-17, NF-κB, and TGF-β signaling pathways. Transcriptomics and metabolomics results revealed that SXD up-regulated the expression of NF-κB pathway-related genes (NFKBIA, NFKBIZ) and key regulators of the retinol metabolism pathway, while down-regulating pro-inflammatory genes (IL1B, IL17A, IL6). Experimental findings confirmed that SXD suppressed the expression of NF-κB pathway-related proteins and upstream activators TNF-α, IL-17A, and IL-1β, as well as their receptors, in both lung tissue and cellular models. Additionally, SXD-containing serum had a direct, non-toxic effect on MRC-5 cells, effectively inhibiting collagen expression and TGF-β secretion. SXD also had a positive effect on collagen production and extracellular matrix (ECM) aggregation in fibroblasts. Molecular dynamics studies showed that SXD directly binds to NF-κB and IκB. ConclusionSXD exerts therapeutic effects on silicotic fibrosis by inhibiting NF-κB signaling transduction mediated by TNF-α, IL-17A, and IL-1β, and suppressing fibroblast activation.

Molecular characterization of a novel putative pathogen, Streptococcus nakanoensis sp. nov., isolated from sputum culture.

The genus Streptococcus encompasses a wide range of bacteria with more than 60 species. Recently, there has been a notable increase in reports of novel species of α-Streptococcus based on genomic analysis data. However, limited information exists regarding the pathogenicity of these species. In this study, a quinolone-resistant α-hemolytic Streptococcus strain, MTG105, was isolated from a patient with pneumonia. Genetic analysis revealed that this species was a novel species closely related to S. pseudopneumoniae. In an infection assay using organotypic lung tissue models, MTG105 induced epithelial damage comparable to that caused by S. pneumoniae and S. pseudopneumoniae, strongly suggesting its potential as a pathogenic α-Streptococcus. The natural transformation abilities of Streptococcus species facilitate gene exchange within the same genus, leading to the emergence of species with increasingly diverse genome structures. Therefore, the identification of this species underscores the importance of monitoring the emergence of novel species exhibiting virulence and/or multidrug resistance.

Effects of cognitive training under hypoxia on cognitive proficiency and neuroplasticity in remitted patients with mood disorders and healthy individuals: ALTIBRAIN study protocol for a randomized controlled trial

BackgroundCognitive impairment is prevalent across neuropsychiatric disorders but there is a lack of treatment strategies with robust, enduring effects. Emerging evidence indicates that altitude-like hypoxia cognition training may induce long-lasting neuroplasticity and improve cognition. We will investigate whether repeated cognition training under normobaric hypoxia can improve cognitive functions in healthy individuals and patients with affective disorders and the neurobiological underpinnings of such effects.MethodsIn sub-study 1, 120 healthy participants are randomized to one of four treatment arms in a double-blind manner, allowing for examination of separate and combined effects of three-week repeated moderate hypoxia and cognitive training, respectively. In sub-study 2, 60 remitted patients with major depressive disorder or bipolar disorder are randomized to hypoxia with cognition training or treatment as usual. Assessments of cognition, psychosocial functioning, and quality of life are performed at baseline, end-of-treatment, and at 1-month follow-up. Functional magnetic resonance imaging (fMRI) scans are conducted at baseline and 1-month follow-up, and [11C]UCB-J positron emission tomography (PET) scans are performed at end-of-treatment to quantify the synaptic vesicle glycoprotein 2A (SV2A). The primary outcome is a cognitive composite score of attention, verbal memory, and executive functions. Statistical power of ≥ 80% is reached to detect a clinically relevant between-group difference with minimum n = 26 per treatment arm. Behavioral data are analyzed with an intention-to-treat approach using mixed models. fMRI data is analyzed with the FMRIB Software Library, while PET data is quantified using the simplified reference tissue model (SRTM) with centrum semiovale as reference region.DiscussionThe results will provide novel insights into whether repeated hypoxia cognition training increases cognition and brain plasticity, which can aid future treatment development strategies.Trial registrationClinicalTrials.gov, NCT06121206. Registered on 31 October 2023.

Comparing continuum and direct fiber models of soft tissues: An ocular biomechanics example reveals that continuum models may artificially disrupt the strains at both the tissue and fiber levels

Collagen fibers are the main load-bearing component of soft tissues but difficult to incorporate into models. Whilst simplified homogenization models suffice for some applications, a thorough mechanistic understanding requires accurate prediction of fiber behavior, including both detailed fiber-level strains and long-distance transmission. Our goal was to compare the performance of a continuum model of the optic nerve head (ONH) built using conventional techniques with a fiber model we recently introduced which explicitly incorporates the complex 3D organization and interaction of collagen fiber bundles [1]. To ensure a fair comparison, we constructed the continuum model with identical geometrical, structural, and boundary specifications as for the fiber model. We found that: 1) although both models accurately matched the intraocular pressure (IOP)-induced globally averaged displacement responses observed in experiments, they diverged significantly in their ability to replicate specific 3D tissue-level strain patterns. Notably, the fiber model faithfully replicated the experimentally observed depth-dependent variability of radial strain, the ring-like pattern of meridional strain, and the radial pattern of circumferential strain, whereas the continuum model failed to do so; 2) the continuum model disrupted the strain transmission along each fiber, a feature captured well by the fiber model. These results demonstrate limitations of the conventional continuum models that rely on homogenization and affine deformation assumptions, which render them incapable of capturing some complex tissue-level and fiber-level deformations. Our results show that the strengths of explicit fiber modeling help capture intricate ONH biomechanics. They potentially also help modeling other fibrous tissues. Statement of SignificanceUnderstanding the mechanics of fibrous tissues is crucial for advancing knowledge of various diseases. This study uses the ONH as a test case to compare conventional continuum models with fiber models that explicitly account for the complex fiber structure. We found that the fiber model captured better the biomechanical behaviors at both the tissue level and the fiber level. The insights gained from this study demonstrate the significant potential of fiber models to advance our understanding of not only glaucoma pathophysiology but also other conditions involving fibrous soft tissues. This can contribute to the development of therapeutic strategies across a wide range of applications.

Modeling electrical impedance in brain tissue with diffusion tensor imaging for functional neurosurgery applications

Objective.Decades ago, neurosurgeons used electrical impedance measurements in the brain for coarse intraoperative tissue differentiation. Over time, these techniques were largely replaced by more refined imaging and electrophysiological localization. Today, advanced methods of diffusion tensor imaging (DTI) and finite element method (FEM) modeling may permit non-invasive, high-resolution intracerebral impedance prediction. However, expectations for tissue-impedance relationships and experimentally verified parameters for impedance modeling in human brains are lacking. This study seeks to address this need.Approach.We used FEM to simulate high-resolution single- and dual-electrode impedance measurements along linear electrode trajectories through (1) canonical gray and white matter tissue models, and (2) selected anatomic structures within whole-brain patient DTI-based models. We then compared intraoperative impedance measurements taken at known locations along deep brain stimulation (DBS) surgical trajectories with model predictions to evaluate model accuracy and refine model parameters.Main results.In DTI-FEM models, single- and dual-electrode configurations performed similarly. While only dual-electrode configurations were sensitive to white matter fiber orientation, other influences on impedance, such as white matter density, enabled single-electrode impedance measurements to display significant spatial variation even within purely white matter structures. We compared 308 intraoperative single-electrode impedance measurements in five DBS patients to DTI-FEM predictions at one-to-one corresponding locations. After calibration of model coefficients to these data, predicted impedances reliably estimated intraoperative measurements in all patients (R=0.784±0.116,n=5). Through this study, we derived an updated value for the slope coefficient of the DTI conductance model published by Tuchet al,k=0.0649 S⋅smm-3 (originalk=0.844), for use specifically in humans at physiological frequencies.Significance.This is the first study to compare impedance estimates from imaging-based models of human brain tissue to experimental measurements at the same locationsin vivo. Accurate, non-invasive, imaging-based impedance prediction has numerous applications in functional neurosurgery, including tissue mapping, intraoperative electrode localization, and DBS.

Technical note: Computational study on thermal management schemes for tumor-treating fields therapy.

The study focuses on thermal management in tumor-treating fields (TTFields) therapy, crucial for patient compliance and therapeutic effectiveness. TTFields therapy, an established treatment for glioblastoma, involves applying alternating electric fields to the brain. However, managing the thermal effects generated by electrodes is a major challenge, impacting patient comfort and treatment efficiency. This research aims to explore methods for controlling temperature increases during TTFields therapy without reducing its duty cycle. The study emphasizes optimizing electrode configurations and array arrangements to mitigate temperature rise, thereby maintaining therapy effectiveness and patient compliance. Using a simplified multi-layer tissue model and finite element analysis, various electrode configurations and array shapes were tested in COMSOL Multiphysics v6.0. Adjustments included changing the electrode gel layer radius from 8 to 12mm, electrode spacing, and transitioning to a more uniform array arrangement, such as a square array or a circular array. The study revealed a strong correlation between high temperatures and edge current density distributions on electrodes. It was found that increasing the electrode gel layer's diameter, enlarging electrode spacing, and adopting a uniform array arrangement markedly mitigated temperature rises. By increasing the gel layer radius from the original 10 to 12mm, a reduction in the peak temperature increases of approximately 0.3°C was observed. Changing the layout from rectangular to circular with the same area further reduced the peak temperature rise by 0.5°C. Additionally, enlarging the spacing between electrodes also contributed to temperature control. By integrating these strategies, we designed a new circular electrode array with an electrode spacing of 45mm and a gel radius of 12mm, successfully reducing the peak temperature from 42.1°C to 40.8°C, effectively achieving temperature control. The research demonstrates that improving electrode and array configurations can effectively manage temperature in TTFields therapy without compromising treatment duration. This strategy is crucial as TTFields therapy relies on prolonged field exposure for effectiveness. The findings offer valuable insights into thermal management in electrode array design and could lead to enhanced patient compliance and treatment efficacy in TTFields therapy.

An optical system for cellular mechanostimulation in 3D hydrogels

We introduce a method utilizing single laser-generated cavitation bubbles to stimulate cellular mechanotransduction in dermal fibroblasts embedded within 3D hydrogels. We demonstrate that fibroblasts embedded in either amorphous or fibrillar hydrogels engage in Ca2+ signaling following exposure to an impulsive mechanical stimulus provided by a single 250 µm diameter laser-generated cavitation bubble. We find that the spatial extent of the cellular signaling is larger for cells embedded within a fibrous collagen hydrogel as compared to those embedded within an amorphous polyvinyl alcohol polymer (SLO-PVA) hydrogel. Additionally, for fibroblasts embedded in collagen, we find an increased range of cellular mechanosensitivity for cells that are polarized relative to the radial axis as compared to the circumferential axis. By contrast, fibroblasts embedded within SLO-PVA did not display orientation-dependent mechanosensitivity. Fibroblasts embedded in hydrogels and cultured in calcium-free media did not show cavitation-induced mechanotransduction; implicating calcium signaling based on transmembrane Ca2+ transport. This study demonstrates the utility of single laser-generated cavitation bubbles to provide local non-invasive impulsive mechanical stimuli within 3D hydrogel tissue models with concurrent imaging using optical microscopy. Statement of significanceCurrently, there are limited methods for the non-invasive real-time assessment of cellular sensitivity to mechanical stimuli within 3D tissue scaffolds. We describe an original approach that utilizes a pulsed laser microbeam within a standard laser scanning microscope system to generate single cavitation bubbles to provide impulsive mechanostimulation to cells within 3D fibrillar and amorphous hydrogels. Using this technique, we measure the cellular mechanosensitivity of primary human dermal fibroblasts embedded in amorphous and fibrillar hydrogels, thereby providing a useful method to examine cellular mechanotransduction in 3D biomaterials. Moreover, the implementation of our method within a standard optical microscope makes it suitable for broad adoption by cellular mechanotransduction researchers and opens the possibility of high-throughput evaluation of biomaterials with respect to cellular mechanosignaling.

304 (PB292): Effects of Nectin-4 targeted Bicycle Toxin Conjugate, zelenectide pevedotin (BT8009), and enfortumab vedotin on a human corneal tissue model

304 (PB292): Effects of Nectin-4 targeted Bicycle Toxin Conjugate, zelenectide pevedotin (BT8009), and enfortumab vedotin on a human corneal tissue model

Sorting differentiated mammalian cells using deterministic lateral displacement microfluidic devices.

Separation of differentiated and undifferentiated cells without labeling is required for cell analyses and clinical application of cultured differentiated cells in vitro. To proceed with the passive separation of differentiated cells inside a clean bench, we developed a system of deterministic lateral displacement (DLD) microfluidic devices and applied this system to sort differentiated cells in vitro. The fluid flow is driven by compressed air to the buffer. Priming and sorting can be completed by air pressure control. We use this system to separate C2C12 mononuclear myocytes from multinuclear myotubes. Additionally, using a DLD microfluidic channel of Dc = 20μm, multinuclear myotubes can be effectively sorted as larger particles. We prepared differentiated adipocytes from mouse embryonic fibroblast (MEF) cells and sorted those containing lipid droplets. The diameters of these sorted adipocytes considered larger particles, exceeded 20μm, similar to the Dc of the DLD microfluidic channel. Differentiated cell sorting by cell size will contribute to single-cell analyses and in vitro tissue model preparation for drug discovery.

New Formulations of Acyclothymidine Dinucleosides Reduce Damaging Effects of Ultraviolet Radiation in an Ex Vivo Skin Model.

The greatest risk factor for skin cancer is exposure to ultraviolet (UV) rays of the sun. Among the three types of solar radiation (UVA, UVB, UVC), UVB rays are most commonly associated with skin cancer. UVB exposure promotes the formation of cyclobutane pyrimidine dimers (CPDs) in the DNA of cells in the epidermal skin layers, which can lead to mutations as DNA repair machinery attempts to repair the damage. These mutations can lead directly to skin carcinogenesis. Previous studies in animal and in human ex vivo skin models have shown that topical application of acyclothymidine dinucleosides protects DNA from UV-induced damage by preventing the formation of CPDs and helps initiate repair through the activation of DNA repair enzymes. Here we review the biological evidence leading to the development and formulation of ProteXidineTM (Topix Pharmaceuticals, Inc., Amityville, NY), as a UV protective agent for topical human application. We also provide clinical data pertaining to four ProteXidineTM formulations (test materials 1-4) tested for their abilities to reduce CPDs in an ex vivo human skin tissue model. J Drugs Dermatol. 2024;23(11):953-956. doi:10.36849/JDD.8420.

Vitamin D’s Capacity to Increase Amphetamine-Induced Dopamine Release in Healthy Humans: A Clinical Translational [11C]-PHNO Positron Emission Tomography Study

BackgroundDopaminergic tone and phasic release have transdiagnostic relevance. Preclinical research suggests that the active form of vitamin D, calcitriol, increases subcortical tyrosine hydroxylase, D2/3 receptors, and amphetamine-stimulated dopamine release in rodents. Comparable studies have not been conducted in humans. MethodsHealthy, vitamin-D-sufficient adults (N=18; 32.8 ±6.6 years; 33% female) participated in a randomized, double-blind, placebo-controlled within-subjects study involving four total scans over two visits consisting of same-day pre-amphetamine and post-amphetamine (0.3 mg/kg) 11C-PHNO positron emission tomography (PET) scanning to examine D2/3 receptor availability (BPND) following active calcitriol (1.5 μg night before experimental day and 1.5 μg morning of experimental day) or placebo at least six days apart. Parametric images of 11C-PHNO PET BPND were computed using a simplified reference tissue model with the cerebellum as reference. Blood samples were acquired to measure serum calcitriol, amphetamine, and calcium levels. Regions of interest examined were the dorsal caudate, dorsal putamen, ventral striatum, globus pallidus, and substantia nigra. ResultsFor pre-amphetamine scans, there was a medication-by-region-of-interest interaction (F4,153=2.59, p=0.039) and a main effect of medication (F1,153=4.88, p=0.029) on BPND, with higher BPND values on calcitriol in the ventral striatum (t=2.89, p=0.004) and dorsal putamen (t=2.15, p=0.033). There was a main effect of medication on post-amphetamine change in BPND (F4,153=5.93, p=0.016), with greater decreases on calcitriol in the ventral striatum (t=3.00, p=0.003), substantia nigra (t=2.49, p=0.014), and dorsal caudate (t=2.29, p=0.023). ConclusionsResults provide translational support for vitamin D to target dopaminergic tone, with implications for clinical disorders involving dysregulated dopamine function. Clinical Trial RegistrationVitamin D as a Therapeutic Adjunct in the Stimulant Treatment of ADHD; https://clinicaltrials.gov/study/NCT03103750; ClinicalTrials.gov ID: NCT03103750