Automated digital image quantification of histological staining for the analysis of the trilineage differentiation potential of mesenchymal stem cells

The issue of heterogeneity of MSC-based advanced therapy medicinal products-a review

Mesenchymal stromal stem cells (MSCs) possess a remarkable potential for numerous clinical applications due to their unique properties including self-renewal, immunomodulation, paracrine actions and multilineage differentiation. However, the translation of MSC-based Advanced Therapy Medicinal Products (ATMPs) into the clinic has frequently met with inconsistent outcomes. One of the suspected reasons for this issue is the inherent and extensive variability that exists among such ATMPs, which makes the interpretation of their clinical efficacy difficult to assess, as well as to compare the results of various studies. This variability stems from numerous reasons including differences in tissue sources, donor attributes, variances in manufacturing protocols, as well as modes of administration. MSCs can be isolated from various tissues including bone marrow, umbilical cord, adipose tissue and others, each with its unique phenotypic and functional characteristics. While MSCs from different sources do share common features, they also exhibit distinct gene expression profiles and functional properites. Donor-specific factors such as age, sex, body mass index, and underlying health conditions can influence MSC phenotype, morphology, differentiation potential and function. Moreover, variations in preparation of MSC products introduces additional heterogeneity as a result of cell culture media composition, presence or absence of added growth factors, use of different serum supplements and culturing techniques. Once MSC products are formulated, storage protocols play a pivotal role in its efficacy. Factors that affect cell viability include cell concentration, delivery solution and importantly, post-thawing protocols where applicable. Ensuing, differences in administration protocols can critically affect the distribution and functionallity of administered cells. As MSC-based therapies continue to advance through numerous clinical trials, implication of strategies to reduce product heterogeneity is imperative. Central to addressing these challenges is the need for precise prediction of clinical responses, which require well-defined MSC populations and harmonized assessment of their specific functions. By addressing these issues by meaningful approaches, such as, e.g., MSC pooling, the field can overcome barriers to advance towards more consistent and effective MSC-based therapies.

LINE-1 RNA triggers matrix formation in bone cells via a PKR-mediated inflammatory response

Transposable elements (TEs) are mobile genetic modules of viral derivation that have been co-opted to become modulators of mammalian gene expression. TEs are a major source of endogenous dsRNAs, signaling molecules able to coordinate inflammatory responses in various physiological processes. Here, we provide evidence for a positive involvement of TEs in inflammation-driven bone repair and mineralization. In newly fractured mice bone, we observed an early transient upregulation of repeats occurring concurrently with the initiation of the inflammatory stage. In human bone biopsies, analysis revealed a significant correlation between repeats expression, mechanical stress and bone mineral density. We investigated a potential link between LINE-1 (L1) expression and bone mineralization by delivering a synthetic L1 RNA to osteoporotic patient-derived mesenchymal stem cells and observed a dsRNA-triggered protein kinase (PKR)-mediated stress response that led to strongly increased mineralization. This response was associated with a strong and transient inflammation, accompanied by a global translation attenuation induced by eIF2α phosphorylation. We demonstrated that L1 transfection reshaped the secretory profile of osteoblasts, triggering a paracrine activity that stimulated the mineralization of recipient cells.

In vitro determination of osteo-adipogenic lineage choice of bone marrow stromal/stem cells (BMSCs)

Bone marrow stromal/stem cells (BMSCs) are primitive and heterogeneous cells that can be differentiated into osteoblasts, adipocytes and other subsets. Their bone-fat lineage commitment is responsible for the homeostasis of bone marrow microenvironment. However, there are little effective methods and evidence to simultaneously visualise the lineage commitment of BMSCs. Here we provide a bivalent differentiation medium that can enable BMSCs differentiation into osteoblasts and adipocytes in vitro, and establish a method to simultaneously distinguish osteoblasts or adipocytes from the heterogeneous BMSCs based on Alizarin red S and Oil red O staining, which have been used for detection of specific mineralized nodules and lipid droplets, respectively. This assay provides a specifically simple but effective and low-cost method to evaluate the efficiency of osteo-adipogenic (OA) allocation of BMSCs.►Researchers can utilize the bivalent differentiation medium to evaluate the efficiency of osteogenic and adipogenic differentiation of BMSCs in vitro.

Murine iPSC-Loaded Scaffold Grafts Improve Bone Regeneration in Critical-Size Bone Defects

In certain situations, bones do not heal completely after fracturing. One of these situations is a critical-size bone defect where the bone cannot heal spontaneously. In such a case, complex fracture treatment over a long period of time is required, which carries a relevant risk of complications. The common methods used, such as autologous and allogeneic grafts, do not always lead to successful treatment results. Current approaches to increasing bone formation to bridge the gap include the application of stem cells on the fracture side. While most studies investigated the use of mesenchymal stromal cells, less evidence exists about induced pluripotent stem cells (iPSC). In this study, we investigated the potential of mouse iPSC-loaded scaffolds and decellularized scaffolds containing extracellular matrix from iPSCs for treating critical-size bone defects in a mouse model. In vitro differentiation followed by Alizarin Red staining and quantitative reverse transcription polymerase chain reaction confirmed the osteogenic differentiation potential of the iPSCs lines. Subsequently, an in vivo trial using a mouse model (n = 12) for critical-size bone defect was conducted, in which a PLGA/aCaP osteoconductive scaffold was transplanted into the bone defect for 9 weeks. Three groups (each n = 4) were defined as (1) osteoconductive scaffold only (control), (2) iPSC-derived extracellular matrix seeded on a scaffold and (3) iPSC seeded on a scaffold. Micro-CT and histological analysis show that iPSCs grafted onto an osteoconductive scaffold followed by induction of osteogenic differentiation resulted in significantly higher bone volume 9 weeks after implantation than an osteoconductive scaffold alone. Transplantation of iPSC-seeded PLGA/aCaP scaffolds may improve bone regeneration in critical-size bone defects in mice.

Fluid flow-induced modulation of viability and osteodifferentiation of periodontal ligament stem cell spheroids-on-chip

Developing physiologically relevant in vitro models for studying periodontitis is crucial for understanding its pathogenesis and developing effective therapeutic strategies. In this study, we aimed to integrate the spheroid culture of periodontal ligament stem cells (PDLSCs) within a spheroid-on-chip microfluidic perfusion platform and to investigate the influence of interstitial fluid flow on morphogenesis, cellular viability, and osteogenic differentiation of PDLSC spheroids. PDLSC spheroids were seeded onto the spheroid-on-chip microfluidic device and cultured under static and flow conditions. Computational analysis demonstrated the translation of fluid flow rates of 1.2 μl min-1 (low-flow) and 7.2 μl min-1 (high-flow) to maximum fluid shear stress of 59 μPa and 360 μPa for low and high-flow conditions, respectively. The spheroid-on-chip microfluidic perfusion platform allowed for modulation of flow conditions leading to larger PDLSC spheroids with improved cellular viability under flow compared to static conditions. Modulation of fluid flow enhanced the osteodifferentiation potential of PDLSC spheroids, demonstrated by significantly enhanced alizarin red staining and alkaline phosphatase expression. Additionally, flow conditions, especially high-flow conditions, exhibited extensive calcium staining across both peripheral and central regions of the spheroids, in contrast to the predominantly peripheral staining observed under static conditions. These findings highlight the importance of fluid flow in shaping the morphological and functional properties of PDLSC spheroids. This work paves the way for future investigations exploring the interactions between PDLSC spheroids, microbial pathogens, and biomaterials within a controlled fluidic environment, offering insights for the development of innovative periodontal therapies, tissue engineering strategies, and regenerative approaches.

Xanthium strumarium seed extract boosts osteogenesis in human dental pulp stem cell model

BACKGROUND

In traditional medicine, Xanthium strumarium is used as an anti-inflammatory and anti-arthritic plant-based medicine. Human Dental Pulp Stem Cells (hDPSCs) are an ideal in vitro model for drug and bioactive compound screening. This study assessed the potential of X. strumarium aqueous extract on hDPSCs differentiation towards the osteogenic lineage.

MATERIALS AND METHODS

HDPSCs were isolated and cultured by explant method and characterized by surface marker expression, Colony Forming units fibroblasts (CFU-F), Population Doubling time (PDT), and tri-lineage differentiation. X. strumarium aqueous seed extract (XSE) was prepared and its cytotoxic effect on hDPSCs was examined by MTT assay. The effect of XSE on hDPSC differentiation into osteocytes was investigated by biochemical staining and gene expression.

RESULTS

The hDPSCs were positive for CD73, CD90, and CD105 and negative for CD34, CD45, and HLA-DR surface markers. The cells had a colony-forming ability with a PDT of 44.91 h. The hDPSCs differentiated into osteocytes, chondrocytes, and adipocytes. The XSE concentration of 15 μg/ml had a significant increase in hDPSC viability. Alizarin Red S staining revealed that XSE treatment enhanced calcium accumulation and matrix mineralization in hDPSCs. XSE treatment also increased osteonectin and IL-6 transcript expression in osteogenesis-induced hDPSCs.

CONCLUSION

X. strumarium aqueous extract is a suitable candidate for bone repair because it promotes osteogenic differentiation in hDPSCs. Therefore this could be explored further in the treatment of bone disorders.

Development of an image processing software for quantification of histological calcification staining images

Quantification of the histological staining images gives important insights in biomedical research. In wet lab, it is common to have some stains off the target to become unwanted noisy stains during the generation of histological staining images. The current tools designed for quantification of histological staining images do not consider such situations; instead, the stained region is identified based on assumptions that the background is pure and clean. The goal of this study is to develop a light software named Staining Quantification (SQ) tool which could handle the image quantification job with features for removing a large amount of unwanted stains blended or overlaid with Region of Interest (ROI) in complex scenarios. The core algorithm was based on the method of higher order statistics transformation, and local density filtering. Compared with two state-of-art thresholding methods (i.e. Otsu's method and Triclass thresholding method), the SQ tool outperformed in situations such as (1) images with weak positive signals and experimental caused dirty stains; (2) images with experimental counterstaining by multiple colors; (3) complicated histological structure of target tissues. The algorithm was developed in R4.0.2 with over a thousand in-house histological images containing Alizarin Red (AR) and Von Kossa (VK) staining, and was validated using external images. For the measurements of area and intensity in total and stained region, the average mean of difference in percentage between SQ and ImageJ were all less than 0.05. Using this as a criterion of successful image recognition, the success rate for all measurements in AR, VK and external validation batch were above 0.8. The test of Pearson's coefficient, difference between SQ and ImageJ, and difference of proportions between SQ and ImageJ were all significant at level of 0.05. Our results indicated that the SQ tool is well established for automatic histological staining image quantification.

SAXS imaging reveals optimized osseointegration properties of bioengineered oriented 3D-PLGA/aCaP scaffolds in a critical size bone defect model

Healing large bone defects remains challenging in orthopedic surgery and is often associated with poor outcomes and complications. A major issue with bioengineered constructs is achieving a continuous interface between host bone and graft to enhance biological processes and mechanical stability. In this study, we have developed a new bioengineering strategy to produce oriented biocompatible 3D PLGA/aCaP nanocomposites with enhanced osseointegration. Decellularized scaffolds -containing only extracellular matrix- or scaffolds seeded with adipose-derived mesenchymal stromal cells were tested in a mouse model for critical size bone defects. In parallel to micro-CT analysis, SAXS tensor tomography and 2D scanning SAXS were employed to determine the 3D arrangement and nanostructure within the critical-sized bone. Both newly developed scaffold types, seeded with cells or decellularized, showed high osseointegration, higher bone quality, increased alignment of collagen fibers and optimal alignment and size of hydroxyapatite minerals.

Method for manufacture and cryopreservation of cartilage microtissues

The financial viability of a cell and tissue-engineered therapy may depend on the compatibility of the therapy with mass production and cryopreservation. Herein, we developed a method for the mass production and cryopreservation of 3D cartilage microtissues. Cartilage microtissues were assembled from either 5000 human bone marrow-derived stromal cells (BMSC) or 5000 human articular chondrocytes (ACh) each using a customized microwell platform (the Microwell-mesh). Microtissues rapidly accumulate homogenous cartilage-like extracellular matrix (ECM), making them potentially useful building blocks for cartilage defect repair. Cartilage microtissues were cultured for 5 or 10 days and then cryopreserved in 90% serum plus 10% dimethylsulfoxide (DMSO) or commercial serum-free cryopreservation media. Cell viability was maximized during thawing by incremental dilution of serum to reduce oncotic shock, followed by washing and further culture in serum-free medium. When assessed with live/dead viability dyes, thawed microtissues demonstrated high viability but reduced immediate metabolic activity relative to unfrozen control microtissues. To further assess the functionality of the freeze-thawed microtissues, their capacity to amalgamate into a continuous tissue was assess over a 14 day culture. The amalgamation of microtissues cultured for 5 days was superior to those that had been cultured for 10 days. Critically, the capacity of cryopreserved microtissues to amalgamate into a continuous tissue in a subsequent 14-day culture was not compromised, suggesting that cryopreserved microtissues could amalgamate within a cartilage defect site. The quality ECM was superior when amalgamation was performed in a 2% O2 atmosphere than a 20% O2 atmosphere, suggesting that this process may benefit from the limited oxygen microenvironment within a joint. In summary, cryopreservation of cartilage microtissues is a viable option, and this manipulation can be performed without compromising tissue function.

A distinct M2 macrophage infiltrate and transcriptomic profile decisively influence adipocyte differentiation in lipedema

Lipedema is a chronic and progressive adipose tissue disorder, characterized by the painful and disproportionate increase of the subcutaneous fat in the lower and/or upper extremities. While distinct immune cell infiltration is a known hallmark of the disease, its role in the onset and development of lipedema remains unclear. To analyze the macrophage composition and involved signaling pathways, anatomically matched lipedema and control tissue samples were collected intra-operatively from gender- and BMI-matched patients, and the Stromal Vascular Fraction (SVF) was used for Cytometry by Time-of-Flight (CyTOF) and RNA sequencing. The phenotypic characterization of the immune component of lipedema versus control SVF using CyTOF revealed significantly increased numbers of CD163 macrophages. To gain further insight into this macrophage composition and molecular pathways, RNA sequencing of isolated CD11b+ cells was performed. The analysis suggested a significant modification of distinct gene ontology clusters in lipedema, including cytokine-mediated signaling activity, interleukin-1 receptor activity, extracellular matrix organization, and regulation of androgen receptor signaling. As distinct macrophage populations are known to affect adipose tissue differentiation and metabolism, we evaluated the effect of M2 to M1 macrophage polarization in lipedema using the selective PI3Kγ inhibitor IPI-549. Surprisingly, the differentiation of adipose tissue-derived stem cells with conditioned medium from IPI-549 treated SVF resulted in a significant decreased accumulation of lipids in lipedema versus control SVF. In conclusion, our results indicate that CD163+ macrophages are a critical component in lipedema and re-polarization of lipedema macrophages can normalize the differentiation of adipose-derived stem cells in vitro evaluated by the cellular lipid accumulation. These data open a new chapter in understanding lipedema pathophysiology and may indicate potential treatment options.

Validation of a color deconvolution method to quantify MSC tri-lineage differentiation across species

Mesenchymal stem cells (MSCs) are a promising candidate for both human and veterinary regenerative medicine applications because of their abundance and ability to differentiate into several lineages. Mesenchymal stem cells are however a heterogeneous cell population and as such, it is imperative that they are unequivocally characterized to acquire reproducible results in clinical trials. Although the tri-lineage differentiation potential of MSCs is reported in most veterinary studies, a qualitative evaluation of representative histological images does not always unambiguously confirm tri-lineage differentiation. Moreover, potential differences in differentiation capacity are not identified. Therefore, quantification of tri-lineage differentiation would greatly enhance proper characterization of MSCs. In this study, a method to quantify the tri-lineage differentiation potential of MSCs is described using digital image analysis, based on the color deconvolution plug-in (ImageJ). Mesenchymal stem cells from three species, i.e., bovine, equine, and porcine, were differentiated toward adipocytes, chondrocytes, and osteocytes. Subsequently, differentiated MSCs were stained with Oil Red O, Alcian Blue, and Alizarin Red S, respectively. Next, a differentiation ratio (DR) was obtained by dividing the area % of the differentiation signal by the area % of the nuclear signal. Although MSCs isolated from all donors in all species were capable of tri-lineage differentiation, differences were demonstrated between donors using this quantitative DR. Our straightforward, simple but robust method represents an elegant approach to determine the degree of MSC tri-lineage differentiation across species. As such, differences in differentiation potential within the heterogeneous MSC population and between different MSC sources can easily be identified, which will support further optimization of regenerative therapies.

A comparison of human dental pulp stem cell activity cultured on sandblasted titanium discs decontaminated with Er:YAG laser and air-powder abrasion: an in vitro study

Decontamination of implant surfaces is important to the treatment of peri-implantitis. Er:YAG laser and air-powder abrasion system are regarded as the most effective means of decontamination of implant surfaces. The aim of this in vitro study was to compare the activity of human dental pulp stem cells (hDPSCs) cultured on decontaminated sandblasted titanium discs using Er:YAG laser irradiation and air-powder abrasion. Forty-five titanium discs were contaminated with Escherichia coli (E. coli) bacteria and fifteen titanium discs served as sterile control groups. Thirty contaminated titanium discs were decontaminated with Er:YAG laser or air-powder abrasion system and fifteen contaminated discs were used as contaminated control group. Afterwards, hDPSCs were seeded on all sixty experimental titanium discs. The effects of two decontamination tools on hDPSCs viability were evaluated by MTT assay. Alkaline phosphatase (ALP) activity assay, quantitative real-time PCR analysis and alizarin red staining method were performed to assess hDPSCs osteogenic differentiation. Scanning microscope electron (SEM) was also used to evaluate the effects of two different decontaminated methods on cellular morphology. Our study showed that decontamination using Er:YAG laser caused maximum cell viability. However, the ALP activity was not different in laser and air-abrasion groups. The significant expression of an osteoblastic marker and stronger Alizarin red staining were observed in laser irradiation groups. In addition, SEM observation indicated that grown cells were more stretched and more filopodia in Er:YAG-treated discs. In the present study, Er:YAG laser and air-powder abrasion improved the activity of the cells cultured on the decontaminated titanium discs. However, in comparison with air-powder abrasion, Er:YAG laser was more effective.

Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.

Rapid Prototypable Biomimetic Peristalsis Bioreactor Capable of Concurrent Shear and Multi-Axial Strain

Peristalsis is a nuanced mechanical stimulus comprised of multi-axial strain (radial and axial strain) and shear stress. Forces associated with peristalsis regulate diverse biological functions including digestion, reproductive function, and urine dynamics. Given the central role peristalsis plays in physiology and pathophysiology, we were motivated to design a bioreactor capable of holistically mimicking peristalsis. We engineered a novel rotating screw-drive based design combined with a peristaltic pump, in order to deliver multi-axial strain and concurrent shear stress to a biocompatible polydimethylsiloxane (PDMS) membrane "wall." Radial indentation and rotation of the screw drive against the wall demonstrated multi-axial strain evaluated via finite element modeling. Experimental measurements of strain using piezoelectric strain resistors were in close alignment with model-predicted values (15.9 ± 4.2% vs. 15.2% predicted). Modeling of shear stress on the "wall" indicated a uniform velocity profile and a moderate shear stress of 0.4 Pa. Human mesenchymal stem cells (hMSCs) seeded on the PDMS "wall" and stimulated with peristalsis demonstrated dramatic changes in actin filament alignment, proliferation, and nuclear morphology compared to static controls, perfusion, or strain, indicating that hMSCs sensed and responded to peristalsis uniquely. Lastly, significant differences were observed in gene expression patterns of calponin, caldesmon, smooth muscle actin, and transgelin, corroborating the propensity of hMSCs toward myogenic differentiation in response to peristalsis. Collectively, our data suggest that the peristalsis bioreactor is capable of generating concurrent multi-axial strain and shear stress on a "wall." hMSCs experience peristalsis differently than perfusion or strain, resulting in changes in proliferation, actin fiber organization, smooth muscle actin expression, and genetic markers of differentiation. The peristalsis bioreactor device has broad utility in the study of development and disease in several organ systems.

Comparison of Semi-Quantitative Scoring and Artificial Intelligence Aided Digital Image Analysis of Chromogenic Immunohistochemistry

Semi-quantitative scoring is a method that is widely used to estimate the quantity of proteins on chromogen-labelled immunohistochemical (IHC) tissue sections. However, it suffers from several disadvantages, including its lack of objectivity and the fact that it is a time-consuming process. Our aim was to test a recently established artificial intelligence (AI)-aided digital image analysis platform, Pathronus, and to compare it to conventional scoring by five observers on chromogenic IHC-stained slides belonging to three experimental groups. Because Pathronus operates on grayscale 0-255 values, we transformed the data to a seven-point scale for use by pathologists and scientists. The accuracy of these methods was evaluated by comparing statistical significance among groups with quantitative fluorescent IHC reference data on subsequent tissue sections. The pairwise inter-rater reliability of the scoring and converted Pathronus data varied from poor to moderate with Cohen’s kappa, and overall agreement was poor within every experimental group using Fleiss’ kappa. Only the original and converted that were obtained from Pathronus original were able to reproduce the statistical significance among the groups that were determined by the reference method. In this study, we present an AI-aided software that can identify cells of interest, differentiate among organelles, protein specific chromogenic labelling, and nuclear counterstaining after an initial training period, providing a feasible and more accurate alternative to semi-quantitative scoring.

Application of a deep learning-based image analysis and live-cell imaging system for quantifying adipogenic differentiation kinetics of adipose-derived stem/stromal cells

Quantitative methods for assessing differentiative potency of adipose-derived stem/stromal cells may lead to improved clinical application of this multipotent stem cell, by advancing our understanding of specific processes such as adipogenic differentiation. Conventional cell staining methods are used to determine the formation of adipose areas during adipogenesis as a qualitative representation of adipogenic potency. Staining methods such as oil-red-O are quantifiable using absorbance measurements, but these assays are time and material consuming. Detection methods for cell characteristics using advanced image analysis by machine learning are emerging. Here, live-cell imaging was combined with a deep learning-based detection tool to quantify the presence of adipose areas and lipid droplet formation during adipogenic differentiation of adipose-derived stem/stromal cells. Different detection masks quantified adipose area and lipid droplet formation at different time points indicating kinetics of adipogenesis and showed differences between individual donors. Whereas CEBPA and PPARG expression seems to precede the increase in adipose area and lipid droplets, it might be able to predict expression of ADIPOQ. The applied method is a proof of concept, demonstrating that deep learning methods can be used to investigate adipogenic differentiation and kinetics in vitro using specific detection masks based on algorithm produced from annotation of image data.

Quantification of increased MUC5AC expression in airway mucus of smoker using an automated image-based approach

Microscopic analysis of mucus quantity and composition is crucial in research and diagnostics on muco-obstructive diseases. Currently used image-based methods are unable to extract concrete numeric values of mucosal proteins, especially on the expression of the key mucosal proteins MUC5AC and MUC5B. Since their levels increase under pathologic conditions such as extensive exposure to cigarette smoke, it is imperative to quantify them to improve treatment strategies of pulmonary diseases. This study presents a simple, image-based, and high-processing computational method that allows determining the ratio of MUC5AC and MUC5B within the overall airway mucus while providing information on their spatial distribution. The presented pipeline was optimized for automated downstream analysis using a combination of bright field and immunofluorescence imaging suitable for tracheal and bronchial tissue samples, and air-liquid interface (ALI) cell cultures. To validate our approach, we compared tracheal tissue and ALI cell cultures of isolated primary normal human bronchial epithelial cells derived from smokers and nonsmokers. Our data indicated 18-fold higher levels of MUC5AC in submucosal glands of smokers covering about 8% of mucosal areas compared to <1% in nonsmoking individuals, confirming results of previous studies. We further identified a subpopulation of nonsmokers with slightly elevated glandular MUC5AC levels suggesting moderate exposure to second-hand smoke or fine particulate air pollution. Overall, this study demonstrates a novel, user-friendly and freely available tool for digital pathology and the analysis of therapeutic interventions tested in ALI cell cultures.

Development of an electrical impedance tomography set-up for the quantification of mineralization in biopolymer scaffolds

Objective. 3D cell cultures are becoming a fundamental resource forin-vitrostudies, as they mimic more closelyin-vivobehavior. The analysis of these constructs, however, generally rely on destructive techniques, that prevent the monitoring over time of the same construct, thus increasing the results variability and the resources needed for each experiment.Approach. In this work, we focus on mineralization, a crucial process during maturation of artificial bone models, and propose electrical impedance tomography (EIT) as an alternative non-destructive approach. In particular, we discuss the development of an integrated hardware/software system capable of acquiring experimental data from 3D scaffolds and reconstructing the corresponding conductivity maps. We also show how the same software can test how the measurement is affected by biological features such as scaffold shrinking during the culture.Main results. An initial validation, comprising the acquisition of both a non-conductive phantom and alginate/gelatin scaffolds with known calcium content will be presented, together with thein-silicostudy of a cell-induced mineralization process. This analysis will allow for an initial verification of the systems functionality while limiting the effects of biological variability due to cell number and activity.Significance. Our results show the potential of EIT for the non-destructive quantification of matrix mineralization in 3D scaffolds, and open to the possible long term monitoring of this fundamental hallmark of osteogenic differentiation in hybrid tissue engineered constructs.

Calcium Carbonate Nanoparticles-Toxicity and Effect of In Ovo Inoculation on Chicken Embryo Development, Broiler Performance and Bone Status

Simple Summary

Intensive selection in broiler chicken flocks has led do several leg disorders. The injection of nanoparticles, with high specificity to the bone, into the egg is a potential method to improve bone quality. The objective of our study was to evaluate the potential effect of calcium carbonate nanoparticles injected to the egg on chicken embryo development and bone quality of broiler chickens after 42 day of life. The calcium carbonate nanoparticles were not toxic to embryo and even improved the bone quality of embryos and later broilers without negative impact on production results. Thus, the application of calcium carbonate nanoparticles to the egg may be the potential solution for improving the bone mineralization of broiler chickens.

Abstract

The use of intensive selection procedure in modern broiler chicken lines has led to the development of several skeletal disorders in broiler chickens. Therefore, current research is focused on methods to improve the bone quality in birds. In ovo technology, using nanoparticles with a high specificity to bones, is a potential approach. The present study aimed to evaluate the effect of in ovo inoculation (IOI) of calcium carbonate nanoparticles (CCN) on chicken embryo development, health status, bone characteristics, and on broiler production results and bone quality. After assessing in vitro cell viability, the IOI procedure was performed with an injection of 500 μg/mL CCN. The control group was not inoculated with CCN. Hatchability, weight, and selected bone and serum parameters were measured in embryos. Part of hatchlings were reared under standard conditions until 42 days, and production results, meat quality, and bone quality of broilers were determined. CCN did not show cytotoxicity to cells and chicken embryo and positively influenced bone parameters of the embryos and of broilers later (calcification) without negatively affecting the production results. Thus, the IOI of CCN could modify the molecular responses at the stage of embryogenesis, resulting in better mineralization, and could provide a sustained effect, thereby improving bone quality in adult birds.

Identification of ALP+/CD73+ defining markers for enhanced osteogenic potential in human adipose-derived mesenchymal stromal cells by mass cytometry

BACKGROUND

The impressive progress in the field of stem cell research in the past decades has provided the ground for the development of cell-based therapy. Mesenchymal stromal cells obtained from adipose tissue (AD-MSCs) represent a viable source for the development of cell-based therapies. However, the heterogeneity and variable differentiation ability of AD-MSCs depend on the cellular composition and represent a strong limitation for their use in therapeutic applications. In order to fully understand the cellular composition of MSC preparations, it would be essential to analyze AD-MSCs at single-cell level.

METHOD

Recent advances in single-cell technologies have opened the way for high-dimensional, high-throughput, and high-resolution measurements of biological systems. We made use of the cytometry by time-of-flight (CyTOF) technology to explore the cellular composition of 17 human AD-MSCs, interrogating 31 markers at single-cell level. Subcellular composition of the AD-MSCs was investigated in their naïve state as well as during osteogenic commitment, via unsupervised dimensionality reduction as well as supervised representation learning approaches.

RESULT

This study showed a high heterogeneity and variability in the subcellular composition of AD-MSCs upon isolation and prolonged culture. Algorithm-guided identification of emerging subpopulations during osteogenic differentiation of AD-MSCs allowed the identification of an ALP+/CD73+ subpopulation of cells with enhanced osteogenic differentiation potential. We could demonstrate in vitro that the sorted ALP+/CD73+ subpopulation exhibited enhanced osteogenic potential and is moreover fundamental for osteogenic lineage commitment. We finally showed that this subpopulation was present in freshly isolated human adipose-derived stromal vascular fractions (SVFs) and that could ultimately be used for cell therapies.

CONCLUSION

The data obtained reveal, at single-cell level, the heterogeneity of AD-MSCs from several donors and highlight how cellular composition impacts the osteogenic differentiation capacity. The marker combination (ALP/CD73) can not only be used to assess the differentiation potential of undifferentiated AD-MSC preparations, but also could be employed to prospectively enrich AD-MSCs from the stromal vascular fraction of human adipose tissue for therapeutic applications.

Assessment of bisphosphonate treated-osteoblast behaviors by conventional assays and a simple digital image analysis

The main objective of this study was to analyze the changes in osteoblast behaviors by two different methods, a simple digital image analysis method and conventional assays. Osteoblast progenitor cells and osteoblasts were treated with alendronate (ALN; a nitrogen-containing bisphosphonate). Osteoblast behaviors such as the uptake of ALN, cell proliferation, cell differentiation, and mineralized nodule formation were examined. Quantitative assessments were conducted using a publically available ImageJ software along with conventional methods. Furthermore, ImageJ method and conventional assay for mineralized nodule formation were performed simultaneously and were compared in order to demonstrate the reliability of ImageJ analysis. Osteoblast precursors and osteoblasts responded to ALN treatments. The software could identify various colors and allowed for the quantification of staining intensity and area coverage. Both image analysis and conventional assays detected the changes in cell behaviors between treated and untreated samples. For alizarin red S assay, the staining intensity calculated by ImageJ analysis was comparable to the absorbance measured by conventional assay. These findings showed that digital image analysis along with conventional assays could be used for quantitative assessment to evaluate osteoblast alteration by drug treatment. Image analysis method is practical and might be useful for other applications in the field of biology and medical sciences. It could also be employed in a combination with the conventional assays to strengthen the data.

Effect of local anesthetics on viability and differentiation of various adult stem/progenitor cells

BACKGROUND

Local anesthetics (LAs) are widely used to control pain during various clinical treatments. One of the side effects of LAs, cytotoxicity, has been investigated in various cells including stem/progenitor cells. However, our understanding of the effects of LAs on the differentiation capacity of stem/progenitor cells still remains limited. Therefore, a comparative study was conducted to investigate the effects of multiple LAs on viability and multi-lineage differentiation of stem/progenitor cells that originated from various adult tissues.

METHOD

Multiple types of stem/progenitor cells, including bone marrow mesenchymal stem/progenitor cells (MSCs), dental pulp stem/progenitor cells (DPSCs), periodontal ligament stem/progenitor cells (PDLSCs), and tendon-derived stem/progenitor cells, were either obtained from a commercial provider or isolated from adult human donors. Lidocaine (LD) and bupivacaine (BP) at various doses (1×, 0.75×, 0.5×, and 0.25× of each physiological dose) were applied to the different stem/progenitor cells for an hour, followed by induction of fibrogenic, chondrogenic, osteogenic, and adipogenic differentiation. Live/dead and MTT assays were performed at 24 h after the LD or BP treatment. At 2 weeks, qRT-PCR was conducted to evaluate the gene expressions associated with differentiation. After 4 weeks, multiple biochemical staining was performed to evaluate matrix deposition.

RESULTS

At 24 h after LD or BP treatment, 1× and 0.75× physiological doses of LD and BP showed significant cytotoxicity in all the tested adult stem/progenitor cells. At 0.5×, BP resulted in higher viability than the same dose LD, with variance between cell types. Overall, the gene expressions associated with fibrogenic, chondrogenic, osteogenic, and adipogenic differentiation were attenuated in LD or BP pre-treated stem/progenitor cells, with notable dose-effect and dependence on types. In contrast, certain doses of LD and/or BP were found to increase specific gene expression, depending on the cell types.

CONCLUSION

Our data suggest that LAs such as LD and BP affect not only the viability but also the differentiation capacity of adult stem/progenitor cells from various anatomical sites. This study sheds light on stem cell applications for tissue regeneration in which isolation and transplantation of stem cells frequently involve LA administration.

Corylin, a flavonoid derived from Psoralea Fructus, induces osteoblastic differentiation via estrogen and Wnt/β-catenin signaling pathways

Corylin is a naturally occurring flavonoid isolated from the fruit of Psoralea corylifolia L. (Fabaceae), which is a Chinese medicinal herb in treating osteoporosis. Although a variety of pharmacological activities of corylin have been reported, its osteogenic action and the underlying mechanism in bone development remain unclear. In the present study, the involvement of bone-specific genes in corylininduced differentiated osteoblasts was analyzed by RT-PCR, promoter-reporter assay, and Western blotting. In cultured osteoblasts, corylin-induced cell differentiation and mineralization, as well as increased the expressions of vital biological markers for osteogenesis, such as Runx2, Osterix, Col1, and ALP. Corylin was proposed to have dual pathways in triggering the osteoblastic differentiation. First, the osteogenic function of corylin acted through the activation of Wnt/β-catenin signaling. The nuclear translocation of β-catenin of cultured osteoblasts, as determined by flow cytometry and confocal microscopy, was triggered by applied corylin, and which was blocked by DKK-1, an inhibitor of Wnt/β-catenin signaling. Second, the application of corylin-induced estrogenic response in a dose-dependent manner, and which was blocked by ICI 182 780, an antagonist of estrogen receptor. Furthermore, the activation of Runx2 promoter by corylin was abolished by both DKK-1 and ICI 182,780, indicating that the corylin exhibited its osteogenic effect via estrogen and Wnt/β-catenin signaling pathways. In addition, corylin regulated the metabolic profiles, as well as the membrane potential of mitochondria, in cultured osteoblasts. Corylin also stimulated the osteogenesis in bone micromass derived from mesenchymal progenitor cells. This study demonstrated the osteogenic activities of corylin in osteoblasts and micromass, suggesting that corylin has the potential to be developed as a novel pro-osteogenic agent in targeting for the treatment of osteoblast-mediated osteoporosis.