Diverse Tissues Research Articles

Targeting APC/C Ubiquitin E3-Ligase Activation with Pyrimidinethylcarbamate Apcin Analogues for the Treatment of Breast Cancer

Activation of the ubiquitin ligase APC/C by the protein Cdc20 is an essential requirement for proper cell division in higher organisms, including humans. APC/C is the ultimate effector of the Spindle Assembly Checkpoint (SAC), the signalling system that monitors the proper attachment of chromosomes to microtubules during cell division. Defects in this process result in genome instability and cancer. Interfering with APC/C substrate ubiquitylation in cancer cells delays mitotic exit, which induces cell death. Therefore, impairing APC/C function represents an opportunity for the treatment of cancer and malignancies associated with SAC dysregulation. In this study, we report a new class of pyrimidinethylcarbamate apcin analogues that interfere with APC/C activity in 2D and 3D breast cancer cells. The new pyrimidinethylcarbamate apcin analogues exhibited higher cytotoxicity than apcin in all breast cancer cell subtypes investigated, with much lower cytotoxicity observed in fibroblasts and RPE-1 cells. Further molecular rationalisation of apcin and its derivatives was conducted using molecular docking studies. These structural modifications selected from the in silico studies provide a rational basis for the development of more potent chemotypes to treat highly aggressive breast cancer and possibly other aggressive tumour types of diverse tissue origins.

Sodium Alginate/Poly (Acrylicacid) Hydrogel Composite, Potential Carrier for Fibroblast Growth Factor1 (FGF1) Delivery.

Fibroblast growth factor1 is a powerful signaling molecule that plays a critical role in injury repair of diverse tissue by stimulating cell growth and angiogenesis. FGF1 has significant role in the cell fate and regulating inflammation with short half-life and poor in vivo stability. The encapsulation of the growth factor in the hydrogel led to peptide protect from the degradation and/or immune recognition and enable controlled drug delivery over a longer period of time. The aim of this study is to develop and evaluate a hydrogel carrier with adjustable release rate while maintaining bioactivity of FGF1. Here we describe an optimal ratio of sodium alginate and polyacrylic acid without additional cross linker containing optimum amount of FGF1 with the potential of sustained release to be used as a therapeutic agent. The carrier was characterized by FTIR, contact angle and swelling ratio. The activity of FGF1 after release from the hydrogel was confirmed by ELISA and Western blot. Further assessment of genes related to inflammation were evaluated by RTPCR. This hydrogel is able to deliver growth factors by restricting the essential proteins within the matrix to prevent rapid proteolysis and explosive release and is therefore widely applicable.

An outcome-defining role for the triple-helical domain in regulating collagen-I assembly

Collagens are the foundational component of diverse tissues, including skin, bone, cartilage, and basement membranes, and are the most abundant protein class in animals. The fibrillar collagens are large, complex, multidomain proteins, all containing the characteristic triple helix motif. The most prevalent collagens are heterotrimeric, meaning that cells express at least two distinctive procollagen polypeptides that must assemble into specific heterotrimer compositions. The molecular mechanisms ensuring correct heterotrimeric assemblies are poorly understood - even for the most common collagen, type-I. The longstanding paradigm is that assembly is controlled entirely by the ~30 kDa globular C-propeptide (C-Pro) domain. Still, this dominating model for procollagen assembly has left many questions unanswered. Here, we show that the C-Pro paradigm is incomplete. In addition to the critical role of the C-Pro domain in templating assembly, we find that the amino acid sequence near the C terminus of procollagen's triple-helical domain plays an essential role in defining procollagen assembly outcomes. These sequences near the C terminus of the triple-helical domain encode conformationally stabilizing features that ensure only desirable C-Pro-mediated trimeric templates are committed to irreversible triple-helix folding. Incorrect C-Pro trimer assemblies avoid commitment to triple-helix formation thanks to destabilizing features in the amino acid sequences of their triple helix. Incorrect C-Pro assemblies are consequently able to dissociate and search for new binding partners. These findings provide a distinctive perspective on the mechanism of procollagen assembly, revealing the molecular basis by which incorrect homotrimer assemblies are avoided and setting the stage for a deeper understanding of the biogenesis of this ubiquitous protein.

Foreign Body Immune Response to Zwitterionic and Hyaluronic Acid Granular Hydrogels Made with Mechanical Fragmentation.

Granular hydrogels have recently attracted the attention for diverse tissue engineering applications due to their versatility and modularity. Despite previous studies showing enhanced viability and metabolism of cells encapsulated in these hydrogels, the in vitro immune response and long-term fibrotic response of these scaffolds have not been well characterized. Here, bulk and granular hydrogels are studied based on synthetic zwitterionic (ZI) and natural polysaccharide hyaluronic acid (HA) made with mechanical fragmentation. In vitro, immunomodulatory studies show an increased stimulatory effect of HA granular hydrogels compared to bulk, while both bulk and granular ZI hydrogels do not induce an inflammatory response. Subcutaneous implantation in mice shows that both ZI and HA granular hydrogels resulted in less collagen capsule deposition around implants compared to bulk HA hydrogels 10 weeks after implantation. Moreover, the HA granular hydrogels are infiltrated by host cells, including macrophages and mature blood vessels, in a porosity-dependent manner. However, a large number of cells, including multinucleated giant cells as well as blood vessels, surround bulk and granular ZI hydrogels and are not able to infiltrate. Overall, this study provides new insights on the long-term stability and fibrotic response of granular hydrogels, paving the way for future studies and applications.

Screening and validating the optimal panel of housekeeping genes for 4T1 breast carcinoma and metastasis studies in mice

The 4T1 model is extensively employed in murine studies to elucidate the mechanisms underlying the carcinogenesis of triple-negative breast cancer. Molecular biology serves as a cornerstone in these investigations. However, accurate gene expression analyses necessitate data normalization employing housekeeping genes (HKGs) to avert spurious results. Here, we initially delve into the characteristics of the tumor evolution induced by 4T1 in mice, underscoring the imperative for additional tools for tumor monitoring and assessment methods for tracking the animals, thereby facilitating prospective studies employing this methodology. Subsequently, leveraging various software platforms, we assessed ten distinct HKGs (GAPDH, 18 S, ACTB, HPRT1, B2M, GUSB, PGK1, CCSER2, SYMPK, ANKRD17) not hitherto evaluated in the 4T1 breast cancer model, across tumors and diverse tissues afflicted by metastasis. Our principal findings underscore GAPDH as the optimal HKG for gene expression analyses in tumors, while HPRT1 emerged as the most stable in the liver and CCSER2 in the lung. These genes demonstrated consistent expression and minimal variation among experimental groups. Furthermore, employing these HKGs for normalization, we assessed TNF-α and VEGF expression in tissues and discerned significant disparities among groups. We posit that this constitutes the inaugural delineation of an ideal HKG for experiments utilizing the 4T1 model, particularly in vivo settings.

Osteoarthritis year in review 2024: genetics, genomics, and epigenetics

ObjectiveThe purpose of this narrative review is to highlight the advances made in the past 12 months in the field of osteoarthritis genetics, genomics and epigenetics. MethodsThe Medline and Embase databases were systematically searched for original publications using terminology, and combinations of terminology, relating to: “osteoarthritis”, “genetics”, “genomics”, and “epigenetics”. Only original research articles published in the English language between the OARSI congresses of April 2032 and April 2024 were considered. ResultsThis narrative review focuses only on studies using genome-wide omics techniques in human material. There was a rise in functional genomics studies across different osteoarthritis-relevant tissues, which have robustly identified an additional 26 genes involved in osteoarthritis pathology. Two of such previously identified genes (MGP, ALDH1A2) are currently the target of ongoing clinical trials for osteoarthritis. This past year also saw the use of single-cell transcriptomics and two relatively new omics: epitranscriptomics and mitochondrial genomics. ConclusionThis past year of genomics research has led to multiple exciting findings involving genes and mechanisms linked to osteoarthritis. Moreover, the comprehensive genome-wide omics datasets generated for diverse osteoarthritis tissues will prove invaluable for future research aimed at elucidating more causal biological mechanisms and possible therapeutic targets for osteoarthritis.

Development of an optimized SEC method for characterization of genome DNA leakage from adeno-associated virus products.

Adeno-associated virus (AAV) vectors are widely used to deliver therapeutic transgenes due to their superior safety, relatively low immunogenicity, and ability to target diverse tissues. AAV gene therapy products are typically formulated as frozen liquid and stored below - 60 °C, and therefore are subjected to multiple freeze/thaw cycles during manufacturing and administration. Recent studies have shown that genome DNA leakage could be induced by freeze/thaw stress. DNA leakage from AAV capsids has been reported to potentially impact product stability, induce immune responses, and compromise product efficacy. Thus, further characterization to improve the understanding of genome DNA leakage is necessary for mitigating the risks associated with genome DNA leakage during AAV product development. In this work, we developed an optimized size-exclusion chromatography (SEC) method for quantifying the leakage of genome DNA across multiple different AAV serotypes and demonstrated satisfactory assay performance in sensitivity, precision, and linearity. Furthermore, we showed that this method could also be applied to quantifying additional quality attributes of AAV, including the percentage of full capsids and quantification of AAV dimers. By using this optimized SEC method, we demonstrated that significantly increased free DNA was observed with increasing freeze/thaw cycles or at a temperature approaching the onset temperature for genome DNA ejection, which was effectively mitigated by the addition of 1.5% w/v sucrose in the AAV formulation. Thus, this optimized SEC method can serve as an invaluable tool for AAV formulation, product, and process development in ensuring the quality and stability of AAV gene therapy products.

SARS-CoV-2 variants mediated tissue-specific metabolic reprogramming determines the disease pathophysiology in a hamster model

Despite significant effort, a clear understanding of host tissue-specific responses and their implications for immunopathogenicity against the severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) variant infection has remained poorly defined. To shed light on the interaction between tissues and SARS-CoV-2 variants, we sought to characterize the complex relationship among acute multisystem manifestations, dysbiosis of the gut microbiota, and the resulting implications for SARS-CoV-2 variant-specific immunopathogenesis in the Golden Syrian Hamster (GSH) model using multi-omics approaches. Our investigation revealed the presence of increased SARS-CoV-2 genomic RNA in diverse tissues of delta-infected GSH compared to the omicron variant. Multi-omics analyses uncovered distinctive metabolic responses between the delta and omicron variants, with the former demonstrating dysregulation in synaptic transmission proteins associated with neurocognitive disorders. Additionally, delta-infected GSH exhibited an altered fecal microbiota composition, marked by increased inflammation-associated taxa and reduced commensal bacteria compared to the omicron variant. These findings underscore the SARS-CoV-2-mediated tissue insult, characterized by modified host metabolites, neurological protein dysregulation, and gut dysbiosis, highlighting the compromised gut-lung-brain axis during acute infection.

Speckle decorrelation rate as a robust indicator for visualizing the therapeutic thermal field with OCT.

Optical coherence tomography (OCT) is evolving from a diagnostic imaging modality to one that also facilitates therapeutic procedures. However, visualizing the therapeutic thermal field during minimally invasive thermal treatments such as laser or radio frequency ablation is challenging. This difficulty arises because tissues show minimal optical property changes until they reach the coagulation threshold at approximately 50 ∘C. To address this, we introduce the speckle decorrelation rate as a new, to our knowledge, contrast mechanism for OCT, enhancing the visualization of the therapeutic thermal field. Through ex vivo tissue experiments on a laser ablation-OCT surveillance system, we demonstrate that the speckle decorrelation rate offers superior sensitivity to detect subtle temperature changes and is less sensitive to the selection of time intervals for decorrelation calculations compared to existing speckle decorrelation methods. Our approach, which is label-free and compatible with various OCT systems, has been validated across diverse biological tissues, showing potential to augment the precision and safety of thermal therapies. Additionally, we propose a GPU-accelerated pipeline to expedite processing time, making real-time thermal field visualization feasible.

RAB4A is a master regulator of cancer cell stemness upstream of NUMB–NOTCH signaling

Cancer stem cells (CSCs) are a group of specially programmed tumor cells that possess the characteristics of perpetual cell renewal, increased invasiveness, and often, drug resistance. Hence, eliminating CSCs is a major challenge for cancer treatment. Understanding the cellular programs that maintain CSCs, and identifying the critical regulators for such programs, are major undertakings in both basic and translational cancer research. Recently, we have reported that RAB4A is a major regulator of epithelial-to-mesenchymal transition (EMT) and it does so mainly through regulating the activation of RAC1 GTPase. In the current study, we have delineated a new signaling circuitry through which RAB4A transmits its control of cancer stemness. Using in vitro and in vivo studies, we show that RAB4A, as the upstream regulator, relays signal stepwise to NUMB, NOTCH1, RAC1, and then SOX2 to control the self-renewal property of multiple cancer cells of diverse tissue origins. Knockdown of NUMB, or overexpression of NICD (the active fragment NOTCH1) or SOX2, rescued the in vitro sphere-forming and in vivo tumor-forming abilities that were lost upon RAB4A knockdown. Furthermore, we discovered that the chain of control is mostly through transcriptional regulation at every step of the pathway. The discovery of the novel signaling axis of RAB4A–NUMB–NOTCH–SOX2 opens the path for further expansion of the signaling chain and for the identification of new regulators and interacting proteins important for CSC functions, which can be explored to develop new and effective therapies.

Recurrence prediction of gastric cancer based on multi-resolution feature fusion and context information

Pathological images of gastric cancer serve as the gold standard for diagnosing this malignancy. However, the recurrence prediction task often encounters challenges such as insignificant morphological features of the lesions, insufficient fusion of multi-resolution features, and inability to leverage contextual information effectively. To address these issues, a three-stage recurrence prediction method based on pathological images of gastric cancer is proposed. In the first stage, the self-supervised learning framework SimCLR was adopted to train low-resolution patch images, aiming to diminish the interdependence among diverse tissue images and yield decoupled enhanced features. In the second stage, the obtained low-resolution enhanced features were fused with the corresponding high-resolution unenhanced features to achieve feature complementation across multiple resolutions. In the third stage, to address the position encoding difficulty caused by the large difference in the number of patch images, we performed position encoding based on multi-scale local neighborhoods and employed self-attention mechanism to obtain features with contextual information. The resulting contextual features were further combined with the local features extracted by the convolutional neural network. The evaluation results on clinically collected data showed that, compared with the best performance of traditional methods, the proposed network provided the best accuracy and area under curve (AUC), which were improved by 7.63% and 4.51%, respectively. These results have effectively validated the usefulness of this method in predicting gastric cancer recurrence.

Bacterial live therapeutics for human diseases.

The genomic revolution has fueled rapid progress in synthetic and systems biology, opening up new possibilities for using live biotherapeutic products (LBP) to treat, attenuate or prevent human diseases. Among LBP, bacteria-based therapies are particularly promising due to their ability to colonize diverse human tissues, modulate the immune system and secrete or deliver complex biological products. These bacterial LBP include engineered pathogenic species designed to target specific diseases, and microbiota species that promote microbial balance and immune system homeostasis, either through local administration or the gut-body axes. This review focuses on recent advancements in preclinical and clinical trials of bacteria-based LBP, highlighting both on-site and long-reaching strategies.

Adult-onset intramedullary teratomas: systematic review with outcome analysis.

Intramedullary mature teratomas in adults are rare tumors that pose significant diagnostic and therapeutic challenges due to their diverse tissue composition and intramedullary location. This review, which includes an illustrative case, aims to provide a comprehensive overview of the clinical presentation, diagnosis, treatment, and outcomes of adult intramedullary mature teratomas through a systematic review of 89 cases. A systematic review was conducted following PRISMA guidelines, using keyword combinations in PubMed, MEDLINE, and Web of Science databases until June 2024. Inclusion criteria were adult patients (> 18 years) with histopathologically confirmed intramedullary mature teratomas. Statistical analyses examined relationships between the extent of resection (EoR), tumor location, and patient outcomes. Among the 89 cases, the mean age was 39.94 ± 13.52 years, with a male-to-female ratio of 1.39:1. Tumors were most commonly located in the conus region (51.2%). Surgical resection was the primary treatment, with 43 cases undergoing partial resection and 33 gross total resection. No statistically significant differences in outcomes were found between EoR, sex, associated anomalies, or specific outcomes. However, younger patients showed improved outcomes for lower limb weakness and sphincter dysfunction. Recurrence was noted in three cases, all located in the conus. Intramedullary mature teratomas require a nuanced approach that balances complete resection and neurological preservation. Early diagnosis and individualized surgical planning are crucial for optimizing outcomes. Despite the challenges, effective management is achievable, and ongoing research is essential to refining treatment strategies for this rare tumor.

Cellulose synthase-like OsCSLD4: a key regulator of agronomic traits, disease resistance, and metabolic indices in rice.

Cellulose synthase-like OsCSLD4 plays a pivotal role in regulating diverse agronomic traits, enhancing resistance against bacterial leaf blight, and modulating metabolite indices based on the multi-omics analysis in rice. To delve deeper into this complex network between agronomic traits and metabolites in rice, we have compiled a dataset encompassing genome, phenome, and metabolome, including 524 diverse accessions, 11 agronomic traits, and 841 metabolites, enabling us to pinpoint eight hotspots through GWAS. We later discovered four distinct metabolite categories, encompassing 15 metabolites that are concurrently present on the QTL qC12.1, associated with leaf angle of flag and spikelet length, and finally focused the cellulose synthase-like OsCSLD4, which was pinpointed through a rigorous process encompassing sequence variation, haplotype, ATAC, and differential expression across diverse tissues. Compared to the wild type, csld4 exhibited significant reductions in the plant height, flag leaf length, leaf width, spikelet length, 1000-grain weight, grain width, grain thickness, fertility, yield per plant, and bacterial blight resistance. However, there were significant increase in tiller numbers, degree of leaf rolling, flowering period, growth period, grain length, and empty kernel rate. Furthermore, the content of four polyphenol metabolites, excluding metabolite N-feruloyltyramine (mr1268), notably rose, whereas the levels of the other three polyphenol metabolites, smiglaside C (mr1498), 4-coumaric acid (mr1622), and smiglaside A (mr1925) decreased significantly in mutant csld4. The content of amino acid L-tyramine (mr1446) exhibited a notable increase, whereas the alkaloid trigonelline (mr1188) displayed a substantial decrease among the mutants. This study offered a comprehensive multi-omics perspective to analyze the genetic mechanism of OsCSLD4, and breeders can potentially enhance rice's yield, bacterial leaf blight resistance, and metabolite content, leading to more sustainable and profitable rice production.

The Genetics of Chiari 1 Malformation.

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2-3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years.

Dual decoding of cell types and gene expression in spatial transcriptomics with PANDA.

Sequencing-based spatial transcriptomics technologies have revolutionized our understanding of complex biological systems by enabling transcriptome profiling while preserving spatial context. However, spot-level expression measurements often amalgamate signals from diverse cells, obscuring potential heterogeneity. Existing methods aim to deconvolute spatial transcriptomics data into cell type proportions for each spot using single-cell RNA sequencing references but overlook cell-type-specific gene expression, essential for uncovering intra-type heterogeneity. We present PANDA (ProbAbilistic-based decoNvolution with spot-aDaptive cell type signAtures), a novel method that concurrently deciphers spot-level gene expression into both cell type proportions and cell-type-specific gene expression. PANDA integrates archetypal analysis to capture within-cell-type heterogeneity and dynamically learns cell type signatures for each spot during deconvolution. Simulations demonstrate PANDA's superior performance. Applied to real spatial transcriptomics data from diverse tissues, including tumor, brain, and developing heart, PANDA reconstructs spatial structures and reveals subtle transcriptional variations within specific cell types, offering a comprehensive understanding of tissue dynamics.

Retroperitoneal Myoepithelial Carcinoma with Heterologous Bone Formation and EWSR1::ZNF444

Abstract Introduction/Objective Soft tissue myoepithelial tumors are rare tumors that affect a wide age range and diverse tissue sites. Fewer than five cases have been reported in the retroperitoneum. Most tumors are benign with the only histologic criterion for malignancy being cytologic atypia. The morphology is broad ranging from spindled to epithelioid cells of varying cellularity in sclerotic to myxoid stroma. Heterologous differentiation may be present. These tumors usually express cytokeratin, EMA, S100, and GFAP and show EWSR1 and FUS rearrangements. Here we present an unusual case of retroperitoneal myoepithelial carcinoma. Methods/Case Report A 29-year-old female presented with rash and painless jaundice. CT and MRCP revealed a relatively circumscribed 3.7 cm mass in the porta hepatis. On fine needle aspiration, a possible gastrointestinal stromal tumor was considered due to DOG1 expression. The patient underwent a Whipple procedure with negative margins showing tumor in soft tissue adjacent to the common bile duct. The tumor was multinodular and consisted predominantly of mild to moderately pleomorphic epithelioid cells in fibromyxoid stroma with interspersed woven bone. Mitoses were not appreciated, and necrosis not seen. The tumor was focally positive for CK AE1/AE3, GFAP, and DOG1 and negative for S100, SOX10, p63, and CD117. INI1 was retained. NGS identified EWSR1::ZNF44 and a diagnosis of myoepithelial carcinoma was rendered. The patient received no adjuvant therapy and has not shown any evidence of metastasis or recurrence for 17 months. Results (if a Case Study enter NA) NA Conclusion Soft tissue myoepithelial carcinomas are aggressive tumors with approximately 40% recurrence and over 50% metastasis. Standard treatment is complete surgical resection. The efficacy of radiation and chemotherapy is not clear. EWSR1 fusions with various partners including POU5F1, PBX1/3, and ZNF44 have been identified. Due to their rarity and varying histology and immunohistochemical expression, identification of gene fusions can be invaluable in diagnosing soft tissue myoepithelial tumors, especially in unusual locations.

Depot-specific mRNA expression programs in human adipocytes suggest physiological specialization via distinct developmental programs.

Adipose tissue is distributed in diverse locations throughout the human body. Not much is known about the extent to which anatomically distinct adipose depots are functionally distinct, specialized organs, nor whether depot-specific characteristics result from intrinsic developmental programs, as opposed to reversible physiological responses to differences in tissue microenvironment. We used DNA microarrays to compare mRNA expression patterns of isolated human adipocytes and cultured adipose stem cells, before and after ex vivo adipocyte differentiation, from seven anatomically diverse adipose tissue depots. Adipocytes from different depots display distinct gene expression programs, which are most closely shared with anatomically related depots. mRNAs whose expression differs between anatomically diverse groups of depots (e.g., subcutaneous vs. internal) suggest important functional specializations. These depot-specific differences in gene expression were recapitulated when adipocyte progenitor cells from each site were differentiated ex vivo, suggesting that progenitor cells from specific anatomic sites are deterministically programmed to differentiate into depot-specific adipocytes. Many developmental transcription factors show striking depot-specific patterns of expression, suggesting that adipocytes in each anatomic depot are programmed during early development in concert with anatomically related tissues and organs. Our results support the hypothesis that adipocytes from different depots are functionally distinct and that their depot-specific specialization reflects distinct developmental programs.

Extracellular Vesicle Mobility in Collagen I Hydrogels Is Influenced by Matrix-Binding Integrins.

Extracellular vesicles (EVs) are a diverse population of membrane structures produced and released by cells into the extracellular space for the intercellular trafficking of cargo molecules. They are implicated in various biological processes, including angiogenesis, immunomodulation, and cancer cell signaling. While much research has focused on their biogenesis or their effects on recipient cells, less is understood about how EVs are capable of traversing diverse tissue environments and crossing biological barriers. Their interactions with extracellular matrix components are of particular interest, as such interactions govern diffusivity and mobility, providing a potential basis for organotropism. To start to untangle how EV-matrix interactions affect diffusivity, we use high speed epifluorescence microscopy, single particle tracking, and confocal reflectance microscopy to analyze particle mobility and localization in extracellular matrix-mimicking hydrogels composed of collagen I. EVs are compared with synthetic liposomes and extruded plasma membrane vesicles to better understand the importance of membrane composition on these interactions. By treating EVs with trypsin to digest surface proteins, we determine that proteins are primarily responsible for EV immobilization in collagen I hydrogels. We next use a synthetic peptide competitive inhibitor to narrow down the identity of the proteins involved to argynylglycylaspartic acid (RGD) motif-binding integrins, which interact with unincorporated or denatured nonfibrillar collagen. Moreover, the effect of integrin inhibition with RGD peptides has strong implications for the use of RGD-peptide-based drugs to treat certain cancers, as integrin inhibition appears to increase EV mobility, improving their ability to infiltrate tissue-like environments.

Response of a Blood Clot Adherent to Bone, Oral Mucosa and Hard Dental Tissues to a Uniaxial Tensile Test: An In Vitro Study.

Background and Objectives: Periodontal therapy aims to arrest the progression of periodontal diseases and possibly to regenerate the periodontal apparatus. To shift healing from repair to regeneration, the blood clot that fills the periodontal defect and remains in contact with structures such as tooth root, mucosa and bone needs to be stable, which is a reason why the treatment of non-containing periodontal bone defects, in which the clot may undergo displacement, is challenging. The gingival soft tissue, properly sutured, may act as a wall for blood clot stabilization. Knowledge on the response of the blood clot to stress and how it might vary according to the characteristics of the tissues it gets in contact with might be deepened. The aim of this study was to investigate in vitro, by means of a micro-loading device, the response of the complex formed by a blood clot and diverse tissues, simulating those involved in periodontal regeneration, to a displacing tensile test. Materials and Methods: Experimental samples made of two layers of either hard dental tissues, cancellous bone or oral mucosa, between which fresh blood was interposed, underwent a debonding experiment by means of a micro-loading device that measured their response to uniaxial tensile stress. Results: The peak of tensile stress and the overall work needed for the complete rupture of the clot's fibrin filaments were significantly higher for hard dental tissues than for other tissues. However, mucosa sustained the highest maximal strain in terms of relative displacement between the plates of the micro-loading device to accomplish the complete rupture of the fibrin filaments compared to the other tissues, suggesting that the mucosa might act as a stable interface with the clot and be able to sustain tensile stresses. Conclusions: This in vitro study seems to support the use of mucosa to act as a wall for regenerative procedures of suprabony periodontal defects given its capability to form a stable interface with the clot.