cell-ECM Interactions Research Articles

A 3D Self-Assembly Platform Integrating Decellularized Matrix Recapitulates In Vivo Tumor Phenotypes and Heterogeneity.

Three-dimensional (3D) in vitro cell culture models are invaluable tools for investigating the tumor microenvironment (TME). However, analyzing the impact of critical stromal elements, such as extracellular matrix (ECM), remains a challenge. Here, we developed a hydrogel-free self-assembly platform to establish ECM-rich 3D "MatriSpheres" to deconvolute cancer cell-ECM interactions. Mouse and human colorectal cancer (CRC) MatriSpheres actively incorporated microgram quantities of decellularized small intestine submucosa ECM, which proteomically-mimicked CRC tumor ECM compared to traditional formulations like Matrigel. Solubilized ECM, at sub-gelation concentrations, was organized by CRC cells into intercellular stroma-like regions within 5 days, displaying morphological similarity to CRC clinical pathology. MatriSpheres featured ECM-dependent transcriptional and cytokine profiles associated with malignancy, lipid metabolism, and immunoregulation. Model benchmarking with scRNA sequencing demonstrated that MatriSpheres enhanced correlation with in vivo tumor cells over traditional ECM-poor spheroids. This facile approach enables tumor-specific tissue morphogenesis, promoting cell-ECM communication to improve fidelity for disease modeling applications.

Renal and Peripheral Blood Transcriptome Signatures That Predict Treatment Response in Proliferative Lupus Nephritis-A Prospective Study.

Mechanisms contributing to non-response to treatment in lupus nephritis (LN) are unclear. We characterised the transcriptome of paired peripheral blood mononuclear cells (PBMCs) and renal tissues in LN before and after cyclophosphamide (CYC) treatment and identified markers that predicted treatment response. Total RNA isolated from paired PBMCs (n = 32) and renal tissues (n = 25) of 16 proliferative LN before CYC treatment, 6 months post-treatment, and during renal flare, was sequenced on Illumina Novaseq-6000 platform. Post-treatment, eight patients were clinical responders (CR), of whom four flared (FL), and eight were non-responders (NR). Comparative transcriptomic analyses before and after treatment within CR, NR, and FL groups was performed using DESeq2. Weighted gene co-expression network analysis (WGCNA) and ROC analysis was performed to identify and validate hub genes predictive of treatment response. Based on this, we observed that pathways such as degradation of cell cycle proteins, expression of G0 and G1 phase proteins, and apoptosis, were upregulated in CR PBMCs post-treatment, while IFN-γ signalling and ECM organisation were downregulated. In NR PBMCs, ECM molecules, neddylation and BCR signalling were upregulated post-CYC treatment, while in NR renal tissue, TLR, IFN and NF-κB signalling pathways were upregulated. In FL PBMCs, neutrophil degranulation and ROS and RNS production in phagocytes were downregulated following treatment, whereas, in the corresponding renal tissue, cell-ECM interactions and ISG15 antiviral mechanism were downregulated. After WGCNA and subsequent ROC analysis, TENM2, NLGN1 and AP005230.1 from PBMCs each predicted NR (AUC-0.91; p = 0.03), while combined model improved prediction (AUC-0.94; p = 0.02). AP005230.1 from renal tissue also predicted non-response (AUC-0.94; p = 0.01) and AC092436.3 from PBMCs predicted renal flare (AUC-0.81; p = 0.04). Our study identified significant DEGs/pathways specific to different treatment outcomes and hub genes that predicted non-response and renal flare.

MatriCom: a scRNA-Seq data mining tool to infer ECM-ECM and cell-ECM communication systems.

The ECM is a complex and dynamic meshwork of proteins that forms the framework of all multicellular organisms. Protein interactions within the ECM are critical to building and remodeling the ECM meshwork, while interactions between ECM proteins and cell surface receptors are essential for the initiation of signal transduction and the orchestration of cellular behaviors. Here, we report the development of MatriCom, a web application (https://matrinet.shinyapps.io/matricom) and a companion R package (https://github.com/Izzilab/MatriCom), devised to mine scRNA-Seq datasets and infer communications between ECM components and between different cell populations and the ECM. To impute interactions from expression data, MatriCom relies on a unique database, MatriComDB, that includes over 25,000 curated interactions involving matrisome components, with data on 80% of the ~1,000 genes that compose the mammalian matrisome. MatriCom offers the option to query open-access datasets sourced from large sequencing efforts (Tabula Sapiens, The Human Protein Atlas, HuBMAP) or to process user-generated datasets. MatriCom is also tailored to account for the specific rules governing ECM protein interactions and offers options to customize the output through stringency filters. We illustrate the usability of MatriCom with the example of the human kidney matrisome communication network. Last, we demonstrate how the integration of 46 scRNA-Seq datasets led to the identification of both ubiquitous and tissue-specific ECM communication patterns. We envision that MatriCom will become a powerful resource to elucidate the roles of different cell populations in ECM-ECM and cell-ECM interactions and their dysregulations in the context of diseases such as cancer or fibrosis.

Gene-engineered polypeptide hydrogels with on-demand oxygenation and ECM-cell interaction mimicry for diabetic wound healing

The treatment of infected diabetic wounds remains a significant clinical challenge due to pathogen infection, excessive inflammation, and impaired angiogenesis with troubled extracellular matrix (ECM) - cell and cell - cell interaction. Herein, we prepared a Janus polypeptide-engineered hydrogel with programmable function driven by self-assembly of the same A domain. The hydrogel was composed of a V8-degradable AC10A layer loaded with hybrid phages for precise bacterial inhibition (ABC) and a PC10ARGD layer loaded with Mn-based mineralized erythrocyte for continuous supply oxygen on demand (PEM). The results of laser speckle contrast imaging, photoacoustic imaging, and hyperspectral imaging demonstrated that the AC10A@BP-Ce6/PC10AR@EM hydrogel (ABC/PEM) accelerated the reconstruction of normal skin structure by breaking the oxygen diffusion barrier and supplying oxygen on demand to promote angiogenesis and functionalization. In addition, in vitro and in vivo experiment results showed that the ABC/PEM hydrogel can mimic positive ECM - cell interaction to inhibit the polarization of macrophage towards M1-type to slow down the inflammatory process by down-regulated yes-associated protein (YAP), and relieve the mechanical tension of fibroblasts to reduce scar formation. Finally, the ABC/PEM hydrogel promotes a healing rate of 98.83% on day 21 and results in the number of dermal appendages being eight times that of the negative group. This work presents an effective strategy for diabetes-related chronic infected wound management.

Extracellular Matrix as a Target in Melanoma Therapy: From Hypothesis to Clinical Trials.

Melanoma is a malignant, highly metastatic neoplasm showing increasing morbidity and mortality. Tumor invasion and angiogenesis are based on remodeling of the extracellular matrix (ECM). Selective inhibition of functional components of cell-ECM interaction, such as hyaluronic acid (HA), matrix metalloproteinases (MMPs), and integrins, may inhibit tumor progression and enhance the efficacy of combination treatment with immune checkpoint inhibitors (ICIs), chemotherapy, or immunotherapy. In this review, we combine the results of different approaches targeting extracellular matrix elements in melanoma in preclinical and clinical studies. The identified limitations of many approaches, including side effects, low selectivity, and toxicity, indicate the need for further studies to optimize therapy. Nevertheless, significant progress in expanding our understanding of tumor biology and the development of targeted therapies holds great promise for the early approaches developed several decades ago to inhibit metastasis through ECM targeting.

Matrix Architecture and Mechanics Regulate Myofibril Organization, Costamere Assembly, and Contractility in Engineered Myocardial Microtissues.

The mechanical function of the myocardium is defined by cardiomyocyte contractility and the biomechanics of the extracellular matrix (ECM). Understanding this relationship remains an important unmet challenge due to limitations in existing approaches for engineering myocardial tissue. Here, they established arrays of cardiac microtissues with tunable mechanics and architecture by integrating ECM-mimetic synthetic, fiber matrices, and induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), enabling real-time contractility readouts, in-depth structural assessment, and tissue-specific computational modeling. They found that the stiffness and alignment of matrix fibers distinctly affect the structural development and contractile function of pure iPSC-CM tissues. Further examination into the impact of fibrous matrix stiffness enabled by computational models and quantitative immunofluorescence implicates cell-ECM interactions in myofibril assembly, myofibril maturation, and notably costamere assembly, which correlates with improved contractile function of tissues. These results highlight how iPSC-CM tissue models with controllable architecture and mechanics can elucidate mechanisms of tissue maturation and disease.

Cell response to extracellular matrix viscous energy dissipation outweighs high-rigidity sensing.

The mechanics of the extracellular matrix (ECM) determine cell activity and fate through mechanoresponsive proteins including Yes-associated protein 1 (YAP). Rigidity and viscous relaxation have emerged as the main mechanical properties of the ECM steering cell behavior. However, how cells integrate coexisting ECM rigidity and viscosity cues remains poorly understood, particularly in the high-stiffness regime. Here, we have exploited engineered stiff viscoelastic protein hydrogels to show that, contrary to current models of cell-ECM interaction, substrate viscous energy dissipation attenuates mechanosensing even when cells are exposed to higher effective rigidity. This unexpected behavior is however readily captured by a pull-and-hold model of molecular clutch-based cell mechanosensing, which also recapitulates opposite cellular response at low rigidities. Consistent with predictions of the pull-and-hold model, we find that myosin inhibition can boost mechanosensing on cells cultured on dissipative matrices. Together, our work provides general mechanistic understanding on how cells respond to the viscoelastic properties of the ECM.

Gene expression-based modeling of overall survival in Black or African American patients with lung adenocarcinoma.

Lung cancer is a leading cause of cancer-related deaths worldwide. Black/African American (B/AA) populations, in particular, exhibit the highest incidence and mortality rates of lung adenocarcinoma (LUAD) in the United States. This study aims to explore gene expression patterns linked to LUAD in B/AA and case-matched white patients, with the goal of developing predictive models for prognosis. Leveraging RNA sequencing data from The Cancer Genome Atlas (TCGA) database, genes and pathways associated with overall survival (OS) were identified. The OS-associated genes in B/AA patients were distinct from those in white patients, showing predominant enrichment in immune-related pathways. Furthermore, mRNA co-expression network analysis revealed that OS-associated genes in B/AA patients had higher levels of interaction with various pathways, including those related to immunity, cell-ECM interaction, and specific intracellular signaling pathways. Notably, a potential B/AA-specific biomarker, C9orf64, demonstrated significant correlations with genes involved in immune response. Unsupervised machine learning algorithms stratified B/AA patients into groups with distinct survival outcomes, while supervised algorithms demonstrated a higher accuracy in predicting survival for B/AA LUAD patients compared to white patients. In total, this study explored OS-associated genes and pathways specific for B/AA LUAD patients. Further validation and clinical application of these findings are warranted to address disparities and improve outcomes in diverse patient populations.

Identification of CD44 as a key engager to hyaluronic acid-rich extracellular matrices for cell traction force generation and tumor invasion in 3D

Mechanical properties of the extracellular matrix (ECM) critically regulate a number of important cell functions including growth, differentiation and migration. Type I collagen and glycosaminoglycans (GAGs) are two primary components of ECMs that contribute to mammalian tissue mechanics, with the collagen fiber network sustaining tension, and GAGs withstanding compression. The architecture and stiffness of the collagen network are known to be important for cell-ECM mechanical interactions via cell surface adhesion receptor integrin. In contrast, studies of GAGs in modulating cell-ECM interactions are limited. Here, we present experimental studies on the roles of hyaluronic acid (HA) in single tumor cell traction force generation using a recently developed 3D cell traction force microscopy method. Our work reveals that CD44, a cell surface receptor to HA, is engaged in cell traction force generation in conjunction with β1-integrin. We find that HA significantly modifies the architecture and mechanics of the collagen fiber network, decreasing tumor cells’ propensity to remodel the collagen network, attenuating traction force generation, transmission distance, and tumor invasion. Our findings point to a novel role for CD44 in traction force generation, which can be a potential therapeutic target for diseases involving HA rich ECMs such as breast cancer and glioblastoma.

Design and Applications of Supramolecular Peptide Hydrogel as Artificial Extracellular Matrix.

Supramolecular peptide hydrogels (SPHs) consist of peptides containing hydrogelators and functional epitopes, which can first self-assemble into nanofibers and then physically entangle together to form dynamic three-dimensional networks. Their porous structures, excellent bioactivity, and high dynamicity, similar to an extracellular matrix (ECM), have great potential in artificial ECM. The properties of the hydrogel are largely dependent on peptides. The noncovalent interactions among hydrogelators drive the formation of assemblies and further transition into hydrogels, while bioactive epitopes modulate cell-cell and cell-ECM interactions. Therefore, SPHs can support cell growth, making them ideal biomaterials for ECM mimics. This Review outlines the classical molecular design of SPHs from hydrogelators to functional epitopes and summarizes the recent advancements of SPHs as artificial ECMs in nervous system repair, wound healing, bone and cartilage regeneration, and organoid culture. This emerging SPH platform could provide an alternative strategy for developing more effective biomaterials for tissue engineering.

3D cell culture models in research: applications to lung cancer pharmacology.

Lung cancer remains one of the leading causes of cancer-related mortality worldwide, necessitating innovative research methodologies to improve treatment outcomes and develop novel strategies. The advent of three-dimensional (3D) cell cultures has marked a significant advancement in lung cancer research, offering a more physiologically relevant model compared to traditional two-dimensional (2D) cultures. This review elucidates the various types of 3D cell culture models currently used in lung cancer pharmacology, including spheroids, organoids and engineered tissue models, having pivotal roles in enhancing our understanding of lung cancer biology, facilitating drug development, and advancing precision medicine. 3D cell culture systems mimic the complex spatial architecture and microenvironment of lung tumours, providing critical insights into the cellular and molecular mechanisms of tumour progression, metastasis and drug responses. Spheroids, derived from commercialized cell lines, effectively model the tumour microenvironment (TME), including the formation of hypoxic and nutrient gradients, crucial for evaluating the penetration and efficacy of anti-cancer therapeutics. Organoids and tumouroids, derived from primary tissues, recapitulate the heterogeneity of lung cancers and are instrumental in personalized medicine approaches, supporting the simulation of in vivo pharmacological responses in a patient-specific context. Moreover, these models have been co-cultured with various cell types and biomimicry extracellular matrix (ECM) components to further recapitulate the heterotypic cell-cell and cell-ECM interactions present within the lung TME. 3D cultures have been significantly contributing to the identification of novel therapeutic targets and the understanding of resistance mechanisms against conventional therapies. Therefore, this review summarizes the latest findings in drug research involving lung cancer 3D models, together with the common laboratory-based assays used to study drug effects. Additionally, the integration of 3D cell cultures into lung cancer drug development workflows and precision medicine is discussed. This integration is pivotal in accelerating the translation of laboratory findings into clinical applications, thereby advancing the landscape of lung cancer treatment. By closely mirroring human lung tumours, these models not only enhance our understanding of the disease but also pave the way for the development of more effective and personalized therapeutic strategies.

Methylglyoxal alters collagen fibril nanostiffness and surface potential

Collagen fibrils are fundamental to the mechanical strength and function of biological tissues. However, they are susceptible to changes from non-enzymatic glycation, resulting in the formation of advanced glycation end-products (AGEs) that are not reversible. AGEs accumulate with aging and disease and can adversely impact tissue mechanics and cell-ECM interactions. AGE-crosslinks have been related, on the one hand, to dysregulation of collagen fibril stiffness and damage and, on the other hand, to altered collagen net surface charge as well as impaired cell recognition sites. While prior studies using Kelvin probe force microscopy (KPFM) have shown the effect glycation has on collagen fibril surface potential (i.e., net charge), the combined effect on individual and isolated collagen fibril mechanics, hydration, and surface potential has not been documented. Here, we explore how methylglyoxal (MGO) treatment affects the mechanics and surface potential of individual and isolated collagen fibrils by utilizing atomic force microscopy (AFM) nanoindentation and KPFM. Our results reveal that MGO treatment significantly increases nanostiffness, alters surface potential, and modifies hydration characteristics at the collagen fibril level. These findings underscore the critical impact of AGEs on collagen fibril physicochemical properties, offering insights into pathophysiological mechanical and biochemical alterations with implications for cell mechanotransduction during aging and in diabetes. Statement of significanceCollagen fibrils are susceptible to glycation, the irreversible reaction of amino acids with sugars. Glycation affects the mechanical properties and surface chemistry of collagen fibrils with adverse alterations in biological tissue mechanics and cell-ECM interactions. Current research on glycation, at the level of individual collagen fibrils, is sparse and has focused either on collagen fibril mechanics, with contradicting evidence, or surface potential. Here, we utilized a multimodal approach combining Kelvin probe force (KPFM) and atomic force microscopy (AFM) to examine how methylglyoxal glycation induces structural, mechanical, and surface potential changes on the same individual and isolated collagen fibrils. This approach helps inform structure-function relationships at the level of individual collagen fibrils.

Effects of TET2-mediated methylation reconstruction on A2058 melanoma cell sensitivity to matrix stiffness in a 3D culture system

Matrix stiffness is a crucial factor in the tumor microenvironment, impacting tumor progression and development. TET2 is vital for epigenetic regulation in melanoma and is significantly reduced in advanced melanomas compared with nevi and thin melanomas. However, it is unclear how TET2 mediates the effect of matrix stiffness on melanoma cells. This study utilized A2058 cell lines and prepared different stiffness collagen hydrogels to evaluate TET2 overexpression (TET2OE) and mutant (TET2M) melanoma cells' activity, proliferation, and invasion. A2058 melanoma cells' viability and invasion decreased with increased matrix stiffness, with TET2OE cells experiencing a more significant impact than TET2M cells. Methylation analysis revealed that TET2 determines gene methylation levels, influencing cell-ECM interactions. Transcriptome analysis confirmed that TET2 promotes matrix stiffness's effect on melanoma cell fate. This research provides promising directions and opportunities for melanoma treatment.

Liquid Crystalline Hydroxyapatite Nanorods Orchestrate Hierarchical Bone-Like Mineralization.

Bone matrix exhibits exceptional mechanical properties due to its unique nanocomposite structure of type I collagen fibrils and hydroxyapatite (HAp) nanoparticles in hierarchical liquid crystalline (LC) order. However, the regeneration mechanism of this LC structure is elusive. This study investigates the role of the LC structure of HAp nanorods in guiding aligned mineralization and its underlying molecular mechanism. A unidirectionally oriented LC phase of HAp nanorods is developed through engineering-assisted self-assembling. This is used to study the growth direction of long-range aligned extracellular matrix (ECM) and calcium deposit formation during the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells. It is found that 2 key regulatory genes, COL1A1 and COL4A6, lead to the formation of aligned ECM. Activation of the PI3K-Akt pathway enhances osteogenesis and promotes ordered calcium deposits. This study provides evidence for elucidating the mechanism of LC-induced ordered calcium deposition at hierarchical levels spanning from the molecular to macro-scale, as well as the switch from ordered to disordered mineralization. These findings illuminate bone regeneration, contribute to the development of biomimetic artificial bone with long-range ordered structures, and suggest a basis for therapeutic targeting of microstructure-affected bone disorders and the broader field of cell-ECM interactions.

Abstract Mo044: Minimally Invasive Delivery of Mesenchymal Stem Cell-derived Exosomes Improves Heart Repair in Pigs

Myocardial infarction (MI) is one of the primary manifestations of cardiovascular events. Human mesenchymal stem cell-derived exosomes (hMSC-Exo) were shown to promote cardiac repair after MI. To harness the therapeutic effect, prolong the therapeutic window, and achieve minimally invasive delivery, hMSC-Exo was embedded in hyaluronic acid (HA) hydrogel. The intrapericardial cavity (iPC) is a natural “pocket” surrounding the myocardium. Clinically, iPC procedures were used to treat heart diseases, which could make iPC injection a viable route for drug delivery. In addition, porcine models were highly relevant for pre-clinical studies due to their physiological and anatomical similarities to human patients. Therefore, we hypothesized that minimally invasive delivery of MSC-Exo in HA gel via iPC injection in a porcine MI model could improve pig cardiac function and cardiomyocyte (CM) proliferation. Here, a pig MI model was created using percutaneous coronary balloon catheter occlusion with C-arm fluoroscopy. Yorkshire pigs underwent video-assisted thoracoscopic surgery for iPC injection of MSC-Exo. Cardiac function studies were conducted using echocardiography (echo) to measure left ventricle ejection fraction (LVEF) and left ventricle fractional shortening (LVFS). Histology and immunohistochemistry (IHC) analyses were performed to investigate CM proliferation. Single nucleus RNA-sequencing (snRNA-sq) analysis was performed to identify key gene features and phenotype changes that may be affected by the MSC-Exo treatment. As a result, the iPC injection of MSC-Exo improved cardiac function, enhanced cardiomyocyte proliferation, and induced phenotype alteration in the pig MI model. Echo depicted significantly enhanced LVEF and LVFS on Day 28 in the MSC-Exo group. Histology showed reduced fibrotic percentage and improved infarct wall thickness. IHC analysis showed a significant increase in CM proliferation. SnRNA-seq gene and pathway enrichment elucidated upregulated CM gene features involved in cell proliferation and ECM interaction. In conclusion, these results demonstrated significant improvements in pig cardiac function and CM proliferation. Interestingly, immature cardiomyocytes of a different phenotype emerged in the MSC-Exo group. These findings provide an unprecedented dataset to facilitate the clinical translation of minimally invasive cardiac repair therapeutics.

AEG-1 as a Novel Therapeutic Target in Colon Cancer: A Study from Silencing AEG-1 in BALB/c Mice to Large Data Analysis.

Astrocyte elevated gene-1 (AEG-1) is overexpressed in various malignancies. Exostosin-1 (EXT-1), a tumor suppressor, is an intermediate for malignant tumors. Understanding the mechanism behind the interaction between AEG-1 and EXT-1 may provide insights into colon cancer metastasis. AOM/DSS was used to induce tumor in BALB/c mice. Using an in vivo-jetPEI transfection reagent, transient transfection of AEG-1 and EXT-1 siRNAs were achieved. Histological scoring, immunohistochemical staining, and gene expression studies were performed from excised tissues. Data from the Cancer Genomic Atlas and GEO databases were obtained to identify the expression status of AEG-1 and itsassociation with the survival. In BALB/c mice, the AOM+DSS treated mice developed necrotic, inflammatory and dysplastic changes in the colon with definite clinical symptoms such as loss of goblet cells, colon shortening, and collagen deposition. Administration of AEG-1 siRNA resulted in a substantial decrease in the disease activity index. Mice treated with EXT-1 siRNA showed diffusely reduced goblet cells. In vivo investigations revealed that PTCH-1 activity was influenced by upstream gene AEG-1, which in turn may affect EXT-1 activity. Data from The Cancer Genomic Atlas and GEO databases confirmed the upregulation of AEG-1 and downregulation of EXT-1 in cancer patients. This study revealed that AEG-1 silencing might alter EXT-1 expression indirectly through PTCH-1, influencing cell-ECM interactions, and decreasing dysplastic changes, proliferation and invasion.

Decellularized Extracellular Matrix Scaffolds for Soft Tissue Augmentation: From Host-Scaffold Interactions to Bottlenecks in Clinical Translation.

Along with a paradigm shift in looking at soft tissue fillers from space-filling to bioactive materials, decellularized extracellular matrix (DEM) fillers have gained more attention considering their superior bioactivity. However, the complex mechanisms that govern the interaction between host tissues and DEMs have been partially understood. This review first covers the mechanisms that determine immunogenicity, angiogenesis and vasculogenesis, and recellularization and remodeling after DEM implantation into host tissue, with a particular focus on related findings from filler materials. Accordingly, the review delves into the dual role of macrophages and their M1/M2 polarization paradigm to form both constructive and destructive immune responses to DEM implants. Moreover, the contribution of macrophages in angiogenesis has been elucidated, which includes but is not limited to the secretion of angiogenic growth factors and extracellular matrix (ECM) remodeling. The findings challenge the traditional view of immune cells as solely destructive entities in biomaterials and indicate their multifaceted roles in tissue regeneration. Furthermore, the review discusses how the compositional factors of DEMs, such as the presence of growth factors and matrikines, can influence angiogenesis, cell fate, and differentiation during the recellularization process. It is also shown that the biomechanical properties of DEMs, including tissue stiffness, modulate cell responses through mechanotransduction pathways, and the structural properties of DEMs, such as scaffold porosity, impact cell-cell and cell-ECM interactions. Finally, we pointed out the current clinical applications, the bottlenecks in the clinical translation of DEM biomaterials into soft tissue fillers, as well as the naïve research areas of the field.

Visible light photo-crosslinking of biomimetic gelatin-hyaluronic acid hydrogels for adipose tissue engineering

Tissue engineering (TE) of adipose tissue (AT) is a promising strategy that can provide 3D constructs to be used for in vitro modelling, overcoming the limitations of 2D cell cultures by closely replicating the complex breast tissue extracellular matrix (ECM), cell-cell, and cell-ECM interactions. However, the challenge in developing 3D constructs of AT resides in designing artificial matrices that can mimic the structural properties of native AT and support adipocytes biological functions. Herein, we developed photocrosslinkable hydrogels by employing gelatin methacrylate (GelMA) and hyaluronic acid methacrylate (HAMA) to mimic the collagenous and glycosaminoglycan components of AT microenvironment, respectively. The physico-mechanical properties of the hydrogels were tuned to target AT biomimetic properties by varying the hydrogel formulation (with or without hyaluronic acid), and the amount of photoinitiator (ruthenium/sodium persulfate) used to crosslink the hydrogels via visible light. The physical and mechanical properties of the developed hydrogels were tuned by varying the material formulation and the photoinitiator concentration. Preadipocytes were encapsulated inside the hydrogels and differentiated into mature adipocytes. Findings enlightened that HAMA addition in hybrid hydrogels boosted an increased lipid accumulation. The engineered biomimetic adipocyte-based constructs resulted promising as scaffolds or 3D in vitro models of AT.

Modeling the mechanosensitive collective migration of cells on the surface and the interior of morphing soft tissues.

Cellular contractility, migration, and extracellular matrix (ECM) mechanics are critical for a wide range of biological processes including embryonic development, wound healing, tissue morphogenesis, and regeneration. Even though the distinct response of cells near the tissue periphery has been previously observed in cell-laden microtissues, including faster kinetics and more prominent cell-ECM interactions, there are currently no models that can fully combine coupled surface and bulk mechanics and kinetics to recapitulate the morphogenic response of these constructs. Mailand et al. (Biophys J 117(5):975-986, 2019) had shown the importance of active elastocapillarity in cell-laden microtissues, but modeling the distinct mechanosensitive migration of cells on the periphery and the interior of highly deforming tissues has not been possible thus far, especially in the presence of active elastocapillary effects. This paper presents a framework for understanding the interplay between cellular contractility, migration, and ECM mechanics in dynamically morphing soft tissues accounting for distinct cellular responses in the bulk and the surface of tissues. The major novelty of this approach is that it enables modeling the distinct migratory and contractile response of cells residing on the tissue surface and the bulk, where concurrently the morphing soft tissues undergo large deformations driven by cell contractility. Additionally, the simulation results capture the changes in shape and cell concentration for wounded and intact microtissues, enabling the interpretation of experimental data. The numerical procedure that accounts for mechanosensitive stress generation, large deformations, diffusive migration in the bulk and a distinct mechanism for diffusive migration on deforming surfaces is inspired from recent work on bulk and surface poroelasticity of hydrogels involving elastocapillary effects, but in this work, a two-field weak form is proposed and is able to alleviate numerical instabilities that were observed in the original method that utilized a three-field mixed finite element formulation.

Corneal keratocytes, fibroblasts, and myofibroblasts exhibit distinct transcriptional profiles in vitro.

After stromal injury to the cornea, the release of growth factors and pro-inflammatory cytokines promotes the activation of quiescent keratocytes into a migratory fibroblast and/or fibrotic myofibroblast phenotype. Persistence of the myofibroblast phenotype can lead to corneal fibrosis and scarring, which are leading causes of blindness worldwide. This study aims to establish comprehensive transcriptional profiles for cultured corneal keratocytes, fibroblasts, and myofibroblasts to gain insights into the mechanisms through which these phenotypic changes occur. Primary rabbit corneal keratocytes were cultured in either defined serum-free media (SF), fetal bovine serum (FBS) containing media, or in the presence of TGF-β1 to induce keratocyte, fibroblast, or myofibroblast phenotypes, respectively. Bulk RNA sequencing followed by bioinformatic analyses was performed to identify significant differentially expressed genes (DEGs) and enriched biological pathways for each phenotype. Genes commonly associated with keratocytes, fibroblasts, or myofibroblasts showed high relative expression in SF, FBS, or TGF-β1 culture conditions, respectively. Differential expression and functional analyses revealed novel DEGs for each cell type, as well as enriched pathways indicative of differences in proliferation, apoptosis, extracellular matrix (ECM) synthesis, cell-ECM interactions, cytokine signaling, and cell mechanics. Overall, these data demonstrate distinct transcriptional differences among cultured corneal keratocytes, fibroblasts, and myofibroblasts. We have identified genes and signaling pathways that may play important roles in keratocyte differentiation, including many related to mechanotransduction and ECM biology. Our findings have revealed novel molecular markers for each cell type, as well as possible targets for modulating cell behavior and promoting physiological corneal wound healing.