A three-dimensional valve-on-chip microphysiological system implicates cell cycle progression, cholesterol metabolism and protein homeostasis in early calcific aortic valve disease progression.

Background: Calcific aortic valve disease (CAVD) is one of the most common forms of valvulopathy, with a 50 % elevated risk of a fatal cardiovascular event, and greater than 15,000 annual deaths in North America alone. The treatment standard is valve replacement as early diagnostic, mitigation, and drug strategies remain underdeveloped. The development of early diagnostic and therapeutic strategies requires the fabrication of effective in vitro valve mimetic models to elucidate early CAVD mechanisms.

Identifying and training deep learning neural networks on biomedical-related datasets.

This manuscript describes the development of a resources module that is part of a learning platform named 'NIGMS Sandbox for Cloud-based Learning' https://github.com/NIGMS/NIGMS-Sandbox. The overall genesis of the Sandbox is described in the editorial NIGMS Sandbox at the beginning of this Supplement.

Pre-Incisional and Multiple Intradermal Injection of N-Acetylcysteine Slightly Improves Incisional Wound Healing in an Animal Model.

The objective of this study was to investigate if delivering multiple doses of N-acetylcysteine (NAC) post-surgery in addition to pre-incisional administration significantly impacts the wound healing process in a rat model. Full-thickness skin incisions were carried out on the dorsum of 24 Sprague-Dawley rats in six locations. Fifteen minutes prior to the incision, half of the sites were treated with a control solution, with the wounds on the contralateral side treated with solutions containing 0.

Quantification of age-related changes in the structure and mechanical function of skin with multiscale imaging.

The mechanical properties of skin change during aging but the relationships between structure and mechanical function remain poorly understood. Previous work has shown that young skin exhibits a substantial decrease in tissue volume, a large macro-scale Poisson's ratio, and an increase in micro-scale collagen fiber alignment during mechanical stretch. In this study, label-free multiphoton microscopy was used to quantify how the microstructure and fiber kinematics of aged mouse skin affect its mechanical function.

Mechanical Models of Collagen Networks for Understanding Changes in the Failure Properties of Aging Skin.

Skin undergoes mechanical alterations due to changes in the composition and structure of the collagenous dermis with aging. Previous studies have conflicting findings, with both increased and decreased stiffness reported for aging skin. The underlying structure-function relationships that drive age-related changes are complex and difficult to study individually.

Neuro-regenerative behavior of adipose-derived stem cells in aligned collagen I hydrogels.

Peripheral nerve injuries persist as a major clinical issue facing the US population and can be caused by stretch, laceration, or crush injuries. Small nerve gaps are simple to treat, and the nerve stumps can be reattached with sutures. In longer nerve gaps, traditional treatment options consist of autografts, hollow nerve guidance conduits, and, more recently, manufactured fibrous scaffolds.

Label-Free Optical Metabolic Imaging in Cells and Tissues.

Over the last half century, the autofluorescence of the metabolic cofactors NADH (reduced nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) has been quantified in a variety of cell types and disease states. With the spread of nonlinear optical microscopy techniques in biomedical research, NADH and FAD imaging has offered an attractive solution to noninvasively monitor cell and tissue status and elucidate dynamic changes in cell or tissue metabolism. Various tools and methods to measure the temporal, spectral, and spatial properties of NADH and FAD autofluorescence have been developed.

Single shot quantitative polarized light imaging system for rapid planar biaxial testing of soft tissues.

Quantitative Polarized Light Imaging (QPLI) is an established technique used to compute the orientation of collagen fibers based on their birefringence. QPLI systems typically require rotating linear polarizers to obtain sufficient data to estimate orientation, which limits acquisition speeds and is not ideal for its application to mechanical testing. In this paper, we present a QPLI system designed with no moving parts; a single shot technique which is ideal to characterize collagen fiber orientation and kinematics during mechanical testing.

Improved segmentation of collagen second harmonic generation images with a deep learning convolutional neural network.

Collagen fibers play an important role in both the structure and function of various tissues in the human body. Visualization and quantitative measurements of collagen fibers are possible through imaging modalities such as second harmonic generation (SHG), but accurate segmentation of collagen fibers is difficult for datasets involving variable imaging depths due to the effects of scattering and absorption. Therefore, an objective approach to segmentation is needed for datasets with images of variable SHG intensity.

Multiscale Computational Model Predicts Mouse Skin Kinematics Under Tensile Loading.

Skin is a complex tissue whose biomechanical properties are generally understood in terms of an incompressible material whose microstructure undergoes affine deformations. A growing number of experiments, however, have demonstrated that skin has a high Poisson's ratio, substantially decreases in volume during uniaxial tensile loading, and demonstrates collagen fiber kinematics that are not affine with local deformation. In order to better understand the mechanical basis for these properties, we constructed multiscale mechanical models (MSM) of mouse skin based on microstructural multiphoton microscopy imaging of the dermal microstructure acquired during mechanical testing.

Single Dose of N-Acetylcysteine in Local Anesthesia Increases Expression of HIF1α, MAPK1, TGFβ1 and Growth Factors in Rat Wound Healing.

In this study, we aimed to investigate the influence of N-acetylcysteine (NAC) on the gene expression profile, neoangiogenesis, neutrophils and macrophages in a rat model of incisional wounds. Before creating wounds on the backs of 24 Sprague-Dawley rats, intradermal injections were made. Lidocaine-epinephrin solutions were supplemented with 0.

-Acetylcysteine Added to Local Anesthesia Reduces Scar Area and Width in Early Wound Healing-An Animal Model Study.

The aim of the study was to evaluate if a pre-incisional -acetylcysteine (NAC) treatment altered the process of wound healing in a rat model. The dorsal skin of 24 Sprague-Dawley rats was incised in six locations. Before the incisions were made, skin was injected either with lidocaine and epinephrine (one side) or with these agents supplemented with 0.

Label-Free Multiphoton Microscopy for the Detection and Monitoring of Calcific Aortic Valve Disease.

Calcific aortic valve disease (CAVD) is the most common valvular heart disease. CAVD results in a considerable socio-economic burden, especially considering the aging population in Europe and North America. The only treatment standard is surgical valve replacement as early diagnostic, mitigation, and drug strategies remain underdeveloped.

Tissue Imaging and Quantification Relying on Endogenous Contrast.

Cell-matrix interactions play an important role in regulating a variety of essential processes in multicellular organisms, and are closely associated with numerous diseases. Modified interactions have major effects upon key features of both cells and extracellular matrix (ECM), and a thorough understanding of changes in these features can lead to critically important insights of diseases as well as the identification of effective therapeutic targets. Here, we summarize recent advances in quantitative, optical imaging of cellular metabolism and ECM spatial organization using endogenous sources of contrast.

Efficacy of Combined Electroporation-Mediated Gene Transfer of VEGF, HGF, and IL-10 on Skin Flap Survival, Monitored by Label-Free Optical Imaging: A Feasibility Study.

Preventing surgical flaps necrosis remains challenging. Laser Doppler imaging and ultrasound can monitor blood flow in flap regions, but they do not directly measure the cellular response to ischemia. The study aimed to investigate the efficacy of synergistic electroporation-mediated gene transfer of interleukin 10 (IL-10) with either hepatocyte growth factor (HGF) or vascular endothelial growth factor (VEGF) on the survival of a modified McFarlane flap, and to evaluate the effect of the treatment on cell metabolism, using label-free fluorescence lifetime imaging.

Three-Dimensional Quantification of Collagen Microstructure During Tensile Mechanical Loading of Skin.

Skin is a heterogeneous tissue that can undergo substantial structural and functional changes with age, disease, or following injury. Understanding how these changes impact the mechanical properties of skin requires three-dimensional (3D) quantification of the tissue microstructure and its kinematics. The goal of this study was to quantify these structure-function relationships second harmonic generation (SHG) microscopy of mouse skin under tensile mechanical loading.

Automated Extraction of Skin Wound Healing Biomarkers From In Vivo Label-Free Multiphoton Microscopy Using Convolutional Neural Networks.

Background And Objectives: Histological analysis is a gold standard technique for studying impaired skin wound healing. Label-free multiphoton microscopy (MPM) can provide natural image contrast similar to histological sections and quantitative metabolic information using NADH and FAD autofluorescence. However, MPM analysis requires time-intensive manual segmentation of specific wound tissue regions limiting the practicality and usage of the technology for monitoring wounds.

Label-free optical biomarkers detect early calcific aortic valve disease in a wild-type mouse model.

Background: Calcific aortic valve disease (CAVD) pathophysiology is a complex, multistage process, usually diagnosed at advanced stages after significant anatomical and hemodynamic changes in the valve. Early detection of disease progression is thus pivotal in the development of prevention and mitigation strategies. In this study, we developed a diet-based, non-genetically modified mouse model for early CAVD progression, and explored the utility of two-photon excited fluorescence (TPEF) microscopy for early detection of CAVD progression.

Glutamine Metabolism Controls Stem Cell Fate Reversibility and Long-Term Maintenance in the Hair Follicle.

Stem cells reside in specialized niches that are critical for their function. Upon activation, hair follicle stem cells (HFSCs) exit their niche to generate the outer root sheath (ORS), but a subset of ORS progeny returns to the niche to resume an SC state. Mechanisms of this fate reversibility are unclear.

Label-free metabolic biomarkers for assessing valve interstitial cell calcific progression.

Calcific aortic valve disease (CAVD) is the most common form of valve disease where the only available treatment strategy is surgical valve replacement. Technologies for the early detection of CAVD would benefit the development of prevention, mitigation and alternate therapeutic strategies. Two-photon excited fluorescence (TPEF) microscopy is a label-free, non-destructive imaging technique that has been shown to correlate with multiple markers for cellular differentiation and phenotypic changes in cancer and wound healing.

Skin Structure-Function Relationships and the Wound Healing Response to Intrinsic Aging.

Chronic wounds, such as diabetic foot ulcers, venous stasis ulcers, and pressure ulcers affect millions of Americans each year, and disproportionately afflict our increasingly older population. Older individuals are predisposed to wound infection, repeated trauma, and the development of chronic wounds. However, a complete understanding of how the attributes of aging skin affect the wound healing process has remained elusive.

Quantifying Age-Related Changes in Skin Wound Metabolism Using Multiphoton Microscopy.

The elderly are at high risk for developing chronic skin wounds, but the effects of intrinsic aging on skin healing are difficult to isolate due to common comorbidities like diabetes. Our objective is to use multiphoton microscopy (MPM) to find endogenous, noninvasive biomarkers to differentiate changes in skin wound healing metabolism between young and aged mice . We utilized MPM to monitor skin metabolism at the edge of full-thickness, excisional wounds in 24- and 4-month-old mice of both sexes for 10 days.

Characterizing differences in the collagen fiber organization of skin wounds using quantitative polarized light imaging.

Collagen fiber organization requires characterization in many biomedical applications, but it is difficult to objectively quantify in standard histology tissue sections. Quantitative polarized light imaging is a low-cost technique that allows for rapid measurement of collagen fiber orientation and thickness. In this study, we utilize a quantitative polarized light imaging system to characterize fiber orientation and thickness from wound sections.