Complex Scaffolds Research Articles

Abstract 1260: Collapse of cancer cell micronuclei from oxidative damage

Abstract Chromosomal instability, a hallmark of aggressive cancers, disrupts genome integrity through multiple hits by ongoing missegregation of chromosomes. These chromosomes, inherited only by one daughter cell, are subsequently encapsulated in micronuclei (MNi). Micronucleation is detrimental for replication fidelity not only because it sustains chromosomal missegregation, but also because MNi frequently undergo irreversible collapse during interphase exposing their enclosed chromatin to the cytosol. This exposure catalyzes chromosomal rearrangements and heritable epigenetic abnormalities that have been shown to further bolster cancer evolution and therapeutic resistance. Moreover, MNi collapse is known to promote distant metastasis and poor prognosis through eliciting a non-canonical response of otherwise inflammatory signaling pathways. Despite the fundamental role played by MNi catastrophe in compromising genome integrity and sustaining cancer progression, and the subsequent therapeutic potential of targeting this process, the mechanisms underlying MNi collapse are poorly understood. Here, we identify mitochondria-derived reactive oxygen species (ROS) as the main cause of MNi rupture. Notably, we observe that MNi that locate closer to mitochondria are more prone to rupture. Accordingly, increasing ROS chemically and by H2O2 addition increment rupture in a panel of 5 different tumor cell lines, while decreasing ROS using pan-cellular or mitochondrial specific scavengers reduce the frequency of ruptured MNi. By using a combination of advanced super-resolution microscopy, proteomics, transcriptomics, in vitro biochemistry assays, and extensive mutagenesis, we reveal the exact pathway leading to MNi collapse. We demonstrate that ROS promote a noncanonical function of the membrane repair ESCRT-III complex scaffolding protein, CHMP7. ROS reduce CHMP7 interaction with ESCRT-III promoting CHMP7 oligomerization and its binding to the inner nuclear membrane protein, LEMD2. CHMP7, while aggregating, physically pulls the micronuclear envelope together with the LEMD2-associated lamina, thereby disrupting MNi integrity. Finally, we show that hypoxic conditions promote ROS-dependent CHMP7-LEMD2 interaction, inducing MNi rupture and inflammatory signaling. Thus, we observe that human tumors characterized by hypoxia have a significantly increased predominance of ruptured MNi, providing a mechanistic link between tumor hypoxia and downstream processes that drive cancer progression. Citation Format: Melody Di Bona, Yanyang Chen, Albert Agustinus, Matthew Deyell, Mercedes A. Duran, Christy Hong, James Hickling, Daniel Bronder, Sara Martin, Nadeem Riaz, Bill Diplas, Manisha Jalan, Nancy Lee, Alban Ordureau, Benjamin Izar, Ashley Laughney, Simon Powell, Stefano Santaguida, John Maciejowski, Thomas Jeitner, Samuel Bakhoum. Collapse of cancer cell micronuclei from oxidative damage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1260.

Soy conglycinin amyloid fibril and chitosan complex scaffold for cultivated meat application

This study addresses the critical need in cultivated meat production for suitable scaffolds that support the growth and differentiation of muscle cells. We explore the synergy of soy conglycinin (7S) amyloid protein fibrils and chitosan to create three-dimensional (3D) porous scaffolds, specifically designed for this application. By varying the molecular weight and deacetylation degrees of chitosan, we employed a controlled temperature water annealing method to produce these complex scaffolds. The formation mechanism of the 7S-chitosan scaffolds was elucidated through molecular simulation and Fourier-transform infrared (FTIR) analysis. Characterization of the scaffolds revealed pore sizes within the 50–250 μm range, porosities from 71% to 78%, and compressive moduli varying between 4.8 and 15.3 kPa, dependent on the chitosan's deacetylation degree and molecular weight. Notably, these scaffolds maintained structural integrity in refrigerated Phosphate Buffered Saline (PBS) for up to three months and effectively supported the growth and differentiation of C2C12 mouse skeletal muscle cells without necessitating additional cell adhesion enhancements. Their mechanical properties, comparable to natural muscle tissue, and compatibility with high-temperature sterilization processes, underscore their potential as innovative solutions in the field of cultivated meat production.

Numerical analysis of scaffold degradation in cryogenic environment: impact of cell migration and cell apoptosis

The analysis of degradation in the presence of cell death and migration is a critical aspect of research in various biological fields, such as tissue engineering, regenerative medicine, and disease pathology. In present study, numerical study of degradation of scaffold were performed in present of cells, cell apoptosis and cell migration. A poly electrolyte complex (PEC) silk fibroin scaffold was used for degradation study. Degradation study in the presence of cells and migration were performed at fixed pH concentration 7.2. Similarly, degradation study of scaffold were performed at different pH cell apoptosis. A transient analysis of scaffold was evaluated in COMSOL 5.5 in presence of cryogenic temperature at different temperature gradient. The parameters; temperature, stress, strain tensor and deformation gradient associated with the degradation of polyelectrolyte complex scaffold were evaluated. Result shows that in both geometries minimum temperature had been achieved as 230.051 K at point P4 in series view and parallel view and at a point P3 for cell migration study for −5 k min−1 and −1 k min−1, respectively. The maximum stress had been generated for 5.57 × 107 N m−2 for the temperature gradient of −2 K min−1 at T cycle in the case of cell migration study. In contrast in series view the maximum stress 2.9 × 107 N m−2 were observed at P4 which was higher as compare to P3. Similarly, for a parallel view, maximum stress (3.93 × 107 N m−2) was obtained for point P3. It had been observed that the maximum strain tensor 5.21 × 10−3, 5.15 × 10−3 and 5.26 × 10−3 was generated in series view at 230 k on a point P3 for − 1, −2 and −5 K min−1, respectively. Similarly, the maximum strain tensor 8.16 × 10−3, 8.09 × 10−3 and 8.09 × 10−3 was generated in parallel view at 230 k on a point P3 for −1, −2 and −5 K min−1, respectively. In the presence of cells, at a point P4 for temperature gradient of −1 and −2 K min−1, it had been closed to the scaffold wall, which had a different temperature profile than the point P3 and scaffold comes to the contact with the cells. The analysis of PEC scaffold degradation in the presence of cells, including cell apoptosis and migration, offers significant insights into the relationship between scaffold properties, cell behaviour, and tissue regeneration.

Structured Tandem Repeats in Protein Interactions.

Tandem repeats (TRs) in protein sequences are consecutive, highly similar sequence motifs. Some types of TRs fold into structural units that pack together in ensembles, forming either an (open) elongated domain or a (closed) propeller, where the last unit of the ensemble packs against the first one. Here, we examine TR proteins (TRPs) to see how their sequence, structure, and evolutionary properties favor them for a function as mediators of protein interactions. Our observations suggest that TRPs bind other proteins using large, structured surfaces like globular domains; in particular, open-structured TR ensembles are favored by flexible termini and the possibility to tightly coil against their targets. While, intuitively, open ensembles of TRs seem prone to evolve due to their potential to accommodate insertions and deletions of units, these evolutionary events are unexpectedly rare, suggesting that they are advantageous for the emergence of the ancestral sequence but are early fixed. We hypothesize that their flexibility makes it easier for further proteins to adapt to interact with them, which would explain their large number of protein interactions. We provide insight into the properties of open TR ensembles, which make them scaffolds for alternative protein complexes to organize genes, RNA and proteins.

Precise, low-intensity triggered release in biological systems using ultrasound-responsive antibubbles

Antibubbles are an emerging carrier for low-intensity, ultrasound-triggered release that can carry large payloads in their liquid cores. As we have previously shown, antibubbles can release their payloads at adjustable pressures, ranging from as low as a few kPa (MI < 0.01) to above a few hundred kPa (MI > 0.2). The specific release threshold and behavior can be determined during fabrication, making it possible to realize either single-shot release or multi-stage dosing of a payload. These characteristics make antibubbles an attractive alternative to conventional microbubble delivery agents particularly in sensitive tissues where risks of ultrasound need to be kept to a minimum. In this talk, we discuss recent experiments in which we demonstrate triggered release from antibubbles in in vitro biological systems. We show that payload release can be controlled using patterned or focused ultrasound fields, and we characterize the distribution and cellular uptake of payloads inside cell-laden matrices. These results not only demonstrate the potential of antibubbles for therapeutic applications but also open the door to targeted delivery in complex tissue scaffolds for tissue engineering.

Biodegradable and 3D printable lysine functionalized polycaprolactone scaffolds for tissue engineering applications

Tissue engineering (TE) has sparked interest in creating scaffolds with customizable properties and functional bioactive sites. However, due to limitations in medical practices and manufacturing technologies, it is challenging to replicate complex porous frameworks with appropriate architectures and bioactivity in vitro. To address these challenges, herein, we present a green approach that involves the amino acid (l-lysine) initiated polymerization of ɛ-caprolactone (CL) to produce modified polycaprolactone (PCL) with favorable active sites for TE applications. Further, to better understand the effect of morphology and porosity on cell attachment and proliferation, scaffolds of different geometries with uniform and interconnected pores are designed and fabricated, and their properties are evaluated in comparison with commercial PCL. The scaffold morphology and complex internal micro-architecture are imaged by micro-computed tomography (micro-CT), revealing pore size in the range of ~300–900 μm and porosity ranging from 30 to 70 %, while based on the geometry of scaffolds the compressive strength varied from 143 ± 19 to 214 ± 10 MPa. Additionally, the degradation profiles of fabricated scaffolds are found to be influenced by both the chemical nature and product design, where Lys-PCL-based scaffolds with better porosity and lower crystallinity degraded faster than commercial PCL scaffolds. According to in vitro studies, Lys-PCL scaffolds have produced an environment that is better for cell adhesion and proliferation. Moreover, the scaffold design affects the way cells interact; Lys-PCL with zigzag geometry has demonstrated superior in vitro vitality (>90 %) and proliferation in comparison to other designs. This study emphasizes the importance of enhancing bioactivity while meeting morphology and porosity requirements in the design of scaffolds for tissue engineering applications.

Apoptotic extracellular vesicles derived from hypoxia-preconditioned mesenchymal stem cells within a modified gelatine hydrogel promote osteochondral regeneration by enhancing stem cell activity and regulating immunity

Due to its unique structure, articular cartilage has limited abilities to undergo self-repair after injury. Additionally, the repair of articular cartilage after injury has always been a difficult problem in the field of sports medicine. Previous studies have shown that the therapeutic use of mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) has great potential for promoting cartilage repair. Recent studies have demonstrated that most transplanted stem cells undergo apoptosis in vivo, and the apoptotic EVs (ApoEVs) that are subsequently generated play crucial roles in tissue repair. Additionally, MSCs are known to exist under low-oxygen conditions in the physiological environment, and these hypoxic conditions can alter the functional and secretory properties of MSCs as well as their secretomes. This study aimed to investigate whether ApoEVs that are isolated from adipose-derived MSCs cultured under hypoxic conditions (hypoxic apoptotic EVs [H-ApoEVs]) exert greater effects on cartilage repair than those that are isolated from cells cultured under normoxic conditions. Through in vitro cell proliferation and migration experiments, we demonstrated that H-ApoEVs exerted enhanced effects on stem cell proliferation, stem cell migration, and bone marrow derived macrophages (BMDMs) M2 polarization compared to ApoEVs. Furthermore, we utilized a modified gelatine matrix/3D-printed extracellular matrix (ECM) scaffold complex as a carrier to deliver H-ApoEVs into the joint cavity, thus establishing a cartilage regeneration system. The 3D-printed ECM scaffold provided mechanical support and created a microenvironment that was conducive to cartilage regeneration, and the H-ApoEVs further enhanced the regenerative capacity of endogenous stem cells and the immunomodulatory microenvironment of the joint cavity; thus, this approach significantly promoted cartilage repair. In conclusion, this study confirmed that a ApoEVs delivery system based on a modified gelatine matrix/3D-printed ECM scaffold together with hypoxic preconditioning enhances the functionality of stem cell-derived ApoEVs and represents a promising approach for promoting cartilage regeneration.Graphical

4D printed hydrogel scaffold with swelling-stiffening properties and programmable deformation for minimally invasive implantation.

The power of three-dimensional printing in designing personalized scaffolds with precise dimensions and properties is well-known. However, minimally invasive implantation of complex scaffolds is still challenging. Here, we develop amphiphilic dynamic thermoset polyurethanes catering for multi-material four-dimensional printing to fabricate supportive scaffolds with body temperature-triggered shape memory and water-triggered programmable deformation. Shape memory effect enables the two-dimensional printed pattern to be fixed into temporary one-dimensional shape, facilitating transcatheter delivery. Upon implantation, the body temperature triggers shape recovery of the one-dimensional shape to its original two-dimensional pattern. After swelling, the hydrated pattern undergoes programmable morphing into the desired three-dimensional structure because of swelling mismatch. The structure exhibits unusual soft-to-stiff transition due to the water-driven microphase separation formed between hydrophilic and hydrophobic chain segments. The integration of shape memory, programmable deformability, and swelling-stiffening properties makes the developed dynamic thermoset polyurethanes promising supportive void-filling scaffold materials for minimally invasive implantation.

Generating Molecular Fragmentation Graphs with Autoregressive Neural Networks.

The accurate prediction of tandem mass spectra from molecular structures has the potential to unlock new metabolomic discoveries by augmenting the community's libraries of experimental reference standards. Cheminformatic spectrum prediction strategies use a "bond-breaking" framework to iteratively simulate mass spectrum fragmentations, but these methods are (a) slow due to the need to exhaustively and combinatorially break molecules and (b) inaccurate as they often rely upon heuristics to predict the intensity of each resulting fragment; neural network alternatives mitigate computational cost but are black-box and not inherently more accurate. We introduce a physically grounded neural approach that learns to predict each breakage event and score the most relevant subset of molecular fragments quickly and accurately. We evaluate our model by predicting spectra from both public and private standard libraries, demonstrating that our hybrid approach offers state-of-the-art prediction accuracy, improved metabolite identification from a database of candidates, and higher interpretability when compared to previous breakage methods and black-box neural networks. The grounding of our approach in physical fragmentation events shows especially great promise for elucidating natural product molecules with more complex scaffolds.

Evidence the Isc iron–sulfur cluster biogenesis machinery is the source of iron for [NiFe]-cofactor biosynthesis in Escherichia coli

[NiFe]-hydrogenases have a bimetallic NiFe(CN)2CO cofactor in their large, catalytic subunit. The 136 Da Fe(CN)2CO group of this cofactor is preassembled on a distinct HypC–HypD scaffold complex, but the intracellular source of the iron ion is unresolved. Native mass spectrometric analysis of HypCD complexes defined the [4Fe–4S] cluster associated with HypD and identified + 26 to 28 Da and + 136 Da modifications specifically associated with HypC. A HypCC2A variant without the essential conserved N-terminal cysteine residue dissociated from its complex with native HypD lacked all modifications. Native HypC dissociated from HypCD complexes isolated from Escherichia coli strains deleted for the iscS or iscU genes, encoding core components of the Isc iron–sulfur cluster biogenesis machinery, specifically lacked the + 136 Da modification, but this was retained on HypC from suf mutants. The presence or absence of the + 136 Da modification on the HypCD complex correlated with the hydrogenase enzyme activity profiles of the respective mutant strains. Notably, the [4Fe–4S] cluster on HypD was identified in all HypCD complexes analyzed. These results suggest that the iron of the Fe(CN)2CO group on HypCD derives from the Isc machinery, while either the Isc or the Suf machinery can deliver the [4Fe–4S] cluster to HypD.

Electrospun polymeric nanofibers for dental applications

AbstractElectrospinning is an economical, efficient, and versatile process for the preparation of continuous nanofibers with desired patterns, tailored fiber diameters, and orientations. Since its invention, electrospinning has been utilized to prepare nanofibers from several natural polymers and synthetic polymers for use as scaffolds in tissue engineering, regeneration, and biomedical applications. Furthermore, complex scaffolds were prepared by electrospinning complex polymer solutions formulated by blending natural and synthetic organic polymers with bioceramics and other inorganic molecules. Lately, coaxial electrospinning has emerged as a promising technology in the preparation of drug‐loaded biodegradable core‐shell structured micro/nanofibers for sustained drug delivery applications. This paper will discuss the basic mechanism of electrospinning, parameters governing the electrospinning process, various materials investigated for use in the electrospinning process, and its recent advances.

Single step synthesis of β- and γ- aryl-substituted ß- and γ-amino acid derivatives by electrochemistry

Electrochemical transformations are a subject of increasing interest in early drug discovery due to its ability to assemble complex scaffolds under rather mild reaction conditions. In this context, we became interested in electrochemical decarboxylative cross-coupling (DCC) protocols of redox-active esters (RAEs) and halo(hetero)arenes. Starting with the one-step electrochemical synthesis of novel methylamino-substituted heterocycles we recognized the potential of this methodology to deliver a novel approach to β- and γ- amino acids by starting from the corresponding RAEs. Our work finally resulted in the delivery of novel and highly valuable trifunctional building blocks based on ß- and γ-amino-acid scaffolds.

Rapid Access to Densely Functionalized Cyclopentenyl Sulfoximines through a Sc-Catalyzed Aza-Piancatelli Reaction.

Sulfoximines make up a class of compounds of growing interest for crop science and medicinal chemistry, but methods for directly incorporating them into complex molecular scaffolds are lacking. Here we report a scandium-catalyzed variant of the aza-Piancatelli cyclization that can directly incorporate sulfoximines as nucleophiles rather than the classical aniline substrates. Starting from 2-furylcarbinols and sulfoximines, the reaction provides direct access to 4-sulfoximinocyclopentenones, a new scaffold bearing cyclopentenone and sulfoximine motifs, both of interest for bioactive compounds.

Trifluoromethyl-β-dicarbonyls as Versatile Synthons in Synthesis of Heterocycles.

Trifluoromethyl group relishes a privileged position in the realm of medicinal chemistry because its incorporation into organic molecules often enhances the bioactivity by altering pharmacological profile of molecule. Trifluoromethyl-β-dicarbonyls have emerged as pivotal building blocks in synthetic organic chemistry due to their facile accessibility, stability and remarkable versatility. Owing to presence of nucleophilic and electrophilic sites, they offer multifunctional sites for the reaction. This review covers a meticulous exploration of their multifaceted role, encompassing an in-depth analysis of mechanism, extensive scope, limitations and wide-ranging applications in diverse organic synthesis, covering the literature from the 21st century. This comprehensive review encapsulates the applications of trifluoromethyl-β-dicarbonyls and their synthetic equivalents as precursors of complex and diverse heterocyclic scaffolds, fused heterocycles and spirocyclic compounds having medicinal and material importance. Their potent synthetic utility in cyclocondensation reactions with binucleophiles, cycloaddition reactions, C-C bond formations, asymmetric multicomponent reactions using classical/solvent-free/catalytic synthesis have been presented. Influence of unsymmetrical trifluoromethyl-β-diketones on regioselectivity of transformation is also reviewed. This review will benefit the synthetic and pharmaceutical communities to explore trifluoromethyl-β-dicarbonyls as trifluoromethyl building blocks for fabrication of heterocyclic scaffolds having implementation into drug discovery programs in the imminent future.

Selective biosynthesis of a rhamnosyl nosiheptide by a novel bacterial rhamnosyltransferase.

Nosiheptide (NOS) is a thiopeptide antibiotic produced by the bacterium Streptomyces actuosus. The hydroxyl group of 3-hydroxypyridine in NOS has been identified as a promising site for modification, which we therefore aimed to rhamnosylate. After screening, Streptomyces sp. 147326 was found to regioselectively attach a rhamnosyl unit to the 3-hydroxypyridine site in NOS, resulting in the formation of a derivative named NOS-R at a productivity of 24.6%. In comparison with NOS, NOS-R exhibited a 17.6-fold increase in aqueous solubility and a new protective effect against MRSA infection in mice, while maintaining a similar invitro activity. Subsequently, SrGT822 was identified as the rhamnosyltransferase in Streptomyces sp. 147326 responsible for the biosynthesis of NOS-R using dTDP-L-rhamnose. SrGT822 demonstrated an optimal reaction pH of 10.0 and temperature of 55°C, which resulted in a NOS-R yield of 74.9%. Based on the catalytic properties and evolutionary analysis, SrGT822 is anticipated to be a potential rhamnosyltransferase for use in the modification of various complex scaffolds.

Review of application of the I2 and dimethyl sulfoxide combined reagent system to aryl methyl ketones for diverse transformations

The synthesis of small molecules and complex scaffolds is one of the most important topics in organic synthesis.

Direct photochemical intramolecular [4 + 2] cycloadditions of dehydrosecodine-type substrates for the synthesis of the iboga-type scaffold and divergent [2 + 2] cycloadditions employing micro-flow system.

Photocyclisation reactions offer a convenient and versatile method for constructing complex polycyclic scaffolds, particularly in the synthesis of natural products. While the [2 + 2] photocycloaddition reaction is well-established and extensively reported, the [4 + 2] counterpart via direct photochemical means remains challenging and relatively unexplored. In this work, we devised the rapid assembly of the iboga-type scaffold through photochemical intramolecular Diels-Alder reaction using a common biomimetic dehydrosecodine-type intermediate having vinyl indole and dihydropyridine (DHP) sub-units. Exploiting a micro-flow system, the medicinally important iboga-type scaffold was obtained up to 77% yield under mild, neutral conditions at room temperature. This study demonstrated the site-selective activation of the DHP moiety by direct UV-LED irradiation, eliminating the need for external photocatalysts or photosensitisers and showing good tolerance to a wide range of stabilised dehydrosecodine-type substrates. By adjusting the spatial arrangement of the DHP ring and the vinyl indole group, this versatile photochemical approach efficiently facilitates both [4 + 2] and [2 + 2] cyclisations, assembling architecturally complex multicyclic scaffolds. Precise photoactivation of the DHP subunit, generating short-lived biradical species, enabled the new way of harnessing the hidden but innately pre-encoded reactivity of the polyunsaturated dehydrosecodine-type intermediate. These photo-mediated [4 + 2] cyclisation and divergent [2 + 2] cycloadditions are distinct from biosynthetic processes, which are mainly mediated through concerted thermal cycloadditions.

A 4D printed nanoengineered super bioactive hydrogel scaffold with programmable deformation for potential bifurcated vascular channel construction.

Four-dimensional (4D) printing of hydrogels enabled the fabrication of complex scaffold geometries out of static parts. Although current 4D fabrication strategies are promising for creating vascular parts such as tubes, developing branched networks or tubular junctions is still challenging. Here, for the first time, a 4D printing approach is employed to fabricate T-shaped perfusable bifurcation using an extrusion-based multi-material 3D printing process. An alginate/methylcellulose-based dual-component hydrogel system (with defined swelling behavior) is nanoengineered with carbonized alginate (∼100 nm) to introduce anti-oxidative, anti-inflammatory, and anti-thrombotic properties and shape-shifting properties. A computational model to predict shape deformations in the printed hydrogels with defined infill angles was designed and further validated experimentally. Shape deformations of the 3D-printed flat sheets were achieved by ionic cross-linking. An undisrupted perfusion of a dye solution through a T-junction with minimal leakage mimicking blood flow through vessels is also demonstrated. Moreover, human umbilical vein endothelial and fibroblast cells seeded with printed constructs show intact morphology and excellent cell viability. Overall, the developed strategy paves the way for manufacturing self-actuated vascular bifurcations with remarkable anti-thrombotic properties to potentially treat coronary artery diseases.

Constructing a biofunctionalized 3D-printed gelatin/sodium alginate/chitosan tri-polymer complex scaffold with improvised biological and mechanical properties for bone-tissue engineering

Constructing a biofunctionalized 3D-printed gelatin/sodium alginate/chitosan tri-polymer complex scaffold with improvised biological and mechanical properties for bone-tissue engineering

Strategies and Methods for the Catalytic Asymmetric Synthesis of Benzofuran/Benzopyran Fused Acetals: A Review

AbstractBenzofuran‐ and benzopyran‐fused polycyclic acetals are found in a variety of biologically active natural products. The synthetic methods toward this class of polycyclic heterocycles have fascinated one of the most intensive pursuits in total synthesis. Nevertheless, stereoselective methods towards the rapid construction of such skeletons still remain challenging for organic chemists. Significant progress has been made in this research area in recent years, however, literature on enantioselective approaches to construct these molecules has not fully reviewed. Driven by their intriguing and complex scaffolds with potential usefulness, we compose the recent advances in this review covering all the important works in this field. We hope this review will promote future research in this area.