bims-ecemfi 2024-10-06 papers

bims-ecemfi

Biomed News

on ECM and fibroblasts

Issue of 2024–10–06
fourteen papers selected by
Badri Narayanan Narasimhan, University of California, San Diego

Microtubules Disruption Alters the Cellular Structures and Mechanics Depending on Underlying Chemical Cues.
Geometric constraint of mechanosensing by modification of hydrogel thickness prevents stiffness-induced differentiation in bone marrow stromal cells.
Photochemical Control of Network Topology in PEG Hydrogels.
Protrusion force and cell-cell adhesion play a critical role in collective tumor cluster migration.
Matrix stiffness regulates mitochondria-lysosome contacts to modulate the mitochondrial network, alleviate the senescence of MSCs.
Porosity dominates over microgel stiffness for promoting chondrogenesis in zwitterionic granular hydrogels.
Clustered macrophages cooperate to eliminate tumors via coordinated intrudopodia.
Interpenetrating networks of fibrillar and amorphous collagen promote cell spreading and hydrogel stability.
A pancreatic cancer organoid incorporating macrophages reveals the correlation between the diversity of tumor-associated macrophages and cancer cell survival.
Notch-1 regulates collective breast cancer cell migration by controlling intercellular junction and cytoskeletal organization.
Competition between cross-linking and force-induced local conformational changes determines the structure and mechanics of labile protein networks.
Elucidating the unexpected cell adhesive properties of agarose substrates. The effect of mechanics, fetal bovine serum and specific peptide sequences.
Organization of a cytoskeletal superstructure in the apical domain of intestinal tuft cells.
Three-dimensional bioprinted cell-adaptive hydrogel with anisotropic micropores for enhancing skin wound healing.

Small. 2024 Sep 29. e2312282

Microtubules Disruption Alters the Cellular Structures and Mechanics Depending on Underlying Chemical Cues.

Shimaa A Abdellatef, Hongxin Wang, Jun Nakanishi.

  The extracellular matrix determines cell morphology and stiffness by manipulating the cytoskeleton. The impacts of extracellular matrix cues, including the mechanical and topographical cues on microtubules and their role in biological behaviors, are previously studied. However, there is a lack of understanding about how microtubules (MTs) are affected by environmental chemical cues, such as extracellular matrix density. Specifically, it is crucial to understand the connection between cellular morphology and mechanics induced by chemical cues and the role of microtubules in these cellular responses. To address this, surfaces with high and low cRGD (cyclic Arginine-Glycine-Aspartic acid) peptide ligand densities are used. The cRGD is diluted with a bioinert ligand to prevent surface native cellular remodeling. The cellular morphology, actin, and microtubules differ on these surfaces. Confocal fluorescence microscopes and atomic force microscopy (AFM) are used to determine the structural and mechanical cellular responses with and without microtubules. Microtubules are vital as an intracellular scaffold in elongated morphology correlated with low cRGD compared to rounded morphology in high cRGD substrates. The contributions of MTs to nucleus morphology and cellular mechanics are based on the underlying cRGD densities. Finally, this study reveals a significant correlation between MTs, actin networks, and vimentin in response to the underlying densities of cRGD.

Keywords:  ECM chemical cues; cellular stiffness; cytoskeletal crosstalk; microtubules

DOI:  https://doi.org/10.1002/smll.202312282
J R Soc Interface. 2024 Oct;21(219): 20240485

Geometric constraint of mechanosensing by modification of hydrogel thickness prevents stiffness-induced differentiation in bone marrow stromal cells.

Maria L Hernandez-Miranda, Dichu Xu, Aya A Ben Issa, David A Johnston, Martin Browne, Richard B Cook, Bram G Sengers, Nicholas Evans.

  Extracellular matrix (ECM) stiffness is fundamental in cell division, movement and differentiation. The stiffness that cells sense is determined not only by the elastic modulus of the ECM material but also by ECM geometry and cell density. We hypothesized that these factors would influence cell traction-induced matrix deformations and cellular differentiation in bone marrow stromal cells (BMSCs). To achieve this, we cultivated BMSCs on polyacrylamide hydrogels that varied in elastic modulus and geometry and measured cell spreading, cell-imparted matrix deformations and differentiation. At low cell density BMSCs spread to a greater extent on stiff compared with soft hydrogels, or on thin compared with thick hydrogels. Cell-imparted matrix deformations were greater on soft compared with stiff hydrogels or thick compared with thin hydrogels. There were no significant differences in osteogenic differentiation relative to hydrogel elastic modulus and thickness. However, increased cell density and/or prolonged culture significantly reduced matrix deformations on soft hydrogels to levels similar to those on stiff substrates. This suggests that at high cell densities cell traction-induced matrix displacements are reduced by both neighbouring cells and the constraint imposed by an underlying stiff support. This may explain observations of the lack of difference in osteogenic differentiation as a function of stiffness.

Keywords:  bone marrow stromal cells; differentiation; elastic modulus; hydrogel; osteogenic; stiffness; thickness

DOI:  https://doi.org/10.1098/rsif.2024.0485
Adv Mater. 2024 Sep 28. e2409603

Photochemical Control of Network Topology in PEG Hydrogels.

Bruce E Kirkpatrick, Grace K Hach, Benjamin R Nelson, Nathaniel P Skillin, Joshua S Lee, Lea Pearl Hibbard, Abhishek P Dhand, Henry S Grotheer, Connor E Miksch, Violeta Salazar, Tayler S Hebner, Sean P Keyser, Joshua T Kamps, Jasmine Sinha, Laura J Macdougall, Benjamin D Fairbanks, Jason A Burdick, Timothy J White, Christopher N Bowman, Kristi S Anseth.

  Hydrogels are often synthesized through photoinitiated step-, chain-, and mixed-mode polymerizations, generating diverse network topologies and resultant material properties that depend on the underlying network connectivity. While many photocrosslinking reactions are available, few afford controllable connectivity of the hydrogel network. Herein, a versatile photochemical strategy is introduced for tuning the structure of poly(ethylene glycol) (PEG) hydrogels using macromolecular monomers functionalized with maleimide and styrene moieties. Hydrogels are prepared along a gradient of topologies by varying the ratio of step-growth (maleimide dimerization) to chain-growth (maleimide-styrene alternating copolymerization) network-forming reactions. The initial PEG content and final network physical properties (e.g., modulus, swelling, diffusivity) are tailored in an independent manner, highlighting configurable gel mechanics and reactivity. These photochemical reactions allow high-fidelity photopatterning and 3D printing and are compatible with 2D and 3D cell culture. Ultimately, this photopolymer chemistry allows facile control over network connectivity to achieve adjustable material properties for broad applications.

Keywords:  hydrogels; maleimide; network topology; photochemistry; poly(ethylene glycol)

DOI:  https://doi.org/10.1002/adma.202409603
bioRxiv. 2024 Sep 22. pii: 2024.09.18.613706. [Epub ahead of print]

Protrusion force and cell-cell adhesion play a critical role in collective tumor cluster migration.

Huijing Wang, Catalina Ardila, Ajita Jindal, Vaishali Aggarwal, Weikang Wang, Jonathan Vande Geest, Yi Jiang, Jianhua Xing, Shilpa Sant.

While collective migration is shown to enhance invasive and metastatic potential in cancer, the mechanisms driving this behavior and regulating tumor migration plasticity remain poorly understood. This study provides a mechanistic framework explaining the emergence of different modes of collective migration under hypoxia-induced secretome. We focus on the interplay between cellular protrusion force and cell-cell adhesion using collectively migrating three-dimensional microtumors as models with well-defined microenvironment. Large microtumors show directional migration due to intrinsic hypoxia, while small microtumors exhibit radial migration in response to hypoxic secretome. Here, we developed the minimal multi-scale microtumor model (MSMM) to elucidate underlying mechanisms. We identified distinct migration modes within specific regions of protrusion force and cell-cell adhesion parameter space. We show that sufficient cellular protrusion force is crucial for both, radial and directional collective microtumor migration. Radial migration emerges when sufficient cellular protrusion force is generated, driving neighboring cells to move collectively in diverse directions. Within migrating tumors, strong cell-cell adhesion enhances the alignment of cell polarity, breaking the symmetric angular distribution of protrusion forces, and leading to directional microtumor migration. The integrated results from the experimental and computational models provide fundamental insights into collective migration in response to different microenvironment stimuli.

DOI: https://doi.org/10.1101/2024.09.18.613706
Cell Prolif. 2024 Oct 01. e13746

Matrix stiffness regulates mitochondria-lysosome contacts to modulate the mitochondrial network, alleviate the senescence of MSCs.

Kang Wang, Chingchun Ho, Xiangyu Li, Jianfeng Hou, Qipei Luo, Jiahong Wu, Yuxin Yang, Xinchun Zhang.

The extracellular microenvironment encompasses the extracellular matrix, neighbouring cells, cytokines, and fluid components. Anomalies in the microenvironment can trigger aging and a decreased differentiation capacity in mesenchymal stem cells (MSCs). MSCs can perceive variations in the firmness of the extracellular matrix and respond by regulating mitochondrial function. Diminished mitochondrial function is intricately linked to cellular aging, and studies have shown that mitochondria-lysosome contacts (M-L contacts) can regulate mitochondrial function to sustain cellular equilibrium. Nonetheless, the influence of M-L contacts on MSC aging under varying matrix stiffness remains unclear. In this study, utilizing single-cell RNA sequencing and atomic force microscopy, we further demonstrate that reduced matrix stiffness in older individuals leads to MSC aging and subsequent decline in osteogenic ability. Mechanistically, augmented M-L contacts under low matrix stiffness exacerbate MSC aging by escalating mitochondrial oxidative stress and peripheral division. Moreover, under soft matrix stiffness, cytoskeleton reorganization facilitates rapid movement of lysosomes. The M-L contacts inhibitor ML282 ameliorates MSC aging by reinstating mitochondrial network and function. Overall, our findings confirm that MSC aging is instigated by disruption of the mitochondrial network and function induced by matrix stiffness, while also elucidating the potential mechanism by which M-L Contact regulates mitochondrial homeostasis. Crucially, this presents promise for cellular anti-aging strategies centred on mitochondria, particularly in the realm of stem cell therapy.

DOI: https://doi.org/10.1111/cpr.13746
Biomater Sci. 2024 Sep 30.

Porosity dominates over microgel stiffness for promoting chondrogenesis in zwitterionic granular hydrogels.

Maryam Asadikorayem, Lucia G Brunel, Patrick Weber, Sarah C Heilshorn, Marcy Zenobi-Wong.

Granular hydrogels comprised of jammed, crosslinked microgels offer great potential as biomaterial scaffolds for cell-based therapies, including for cartilage tissue regeneration. As stiffness and porosity of hydrogels affect the phenotype of encapsulated cells and the extent of tissue regeneration, the design of tunable granular hydrogels to control and optimize these parameters is highly desirable. We hypothesized that chondrogenesis could be modulated using a granular hydrogel platform based on biocompatible, zwitterionic materials with independent intra- and inter-microgel crosslinking mechanisms. Microgels are made with mechanical fragmentation of photocrosslinked zwitterionic carboxybetaine acrylamide (CBAA) and sulfobetaine methacrylate (SBMA) hydrogels, and secondarily crosslinked in the presence of cells using horseradish peroxide (HRP) to produce cell-laden granular hydrogels. We varied the intra-microgel crosslinking density to produce microgels with varied stiffnesses (1-3 kPa) and swelling properties. These microgels, when resuspended at the same weight fraction and secondarily crosslinked, resulted in granular hydrogels with distinct porosities (5-40%) due to differing swelling properties. The greatest extent of chondrogenesis was achieved in scaffolds with the highest microgel stiffness and highest porosity. However, when scaffold porosity was kept constant and just microgel stiffness varied, cell phenotype and chondrogenesis were similar across scaffolds. These results indicate the dominant role of granular scaffold porosity on chondrogenesis, whereas microgel stiffness appears to play a relatively minor role. These observations are in contrast to cells encapsulated within conventional bulk hydrogels, where stiffness has been shown to significantly affect chondrocyte response. In summary, we introduce chemically-defined, zwitterionic biomaterials to fabricate versatile granular hydrogels allowing for tunable scaffold porosity and microgel stiffness to study and influence chondrogenesis.

DOI: https://doi.org/10.1039/d4bm00233d
bioRxiv. 2024 Sep 20. pii: 2024.09.19.613918. [Epub ahead of print]

Clustered macrophages cooperate to eliminate tumors via coordinated intrudopodia.

Lawrence J Dooling, Alişya A Anlaş, Michael P Tobin, Nicholas M Ontko, Tristan Marchena, Maximilian Wang, Jason C Andrechak, Dennis E Discher.

Macrophages often pervade solid tumors, but their nearest neighbor organization is understudied and potentially enables key functions such as phagocytosis. Here, we observe dynamic macrophage clusters in tumors under conditions that maximize cancer cell phagocytosis and use reductionist approaches to uncover pathways to cluster formation and roles for tumor-intrusive pseudopodia, which we term 'intrudopodia'. Macrophage clusters form over hours on low- adhesion substrates after M1 polarization with interferons, including T cell-derived cytokines, and yet clusters prove fluid on timescales of minutes. Clusters also sort from M2 macrophages that disperse on the same substrates. M1 macrophages upregulate specific cell-cell adhesion receptors but suppress actomyosin contractility, and while both pathways contribute to cluster formation, decreased cortical tension was predicted to unleash pseudopodia. Macrophage neighbors in tumor spheroids indeed extend intrudopodia between adjacent cancer cell junctions - at least when phagocytosis conditions are maximized, and coordinated intrudopodia help detach and individualize cancer cells for rapid engulfment. Macrophage clusters thereby provide a cooperative advantage for phagocytosis to overcome solid tumor cohesion.

DOI: https://doi.org/10.1101/2024.09.19.613918
bioRxiv. 2024 Sep 16. pii: 2024.09.11.612534. [Epub ahead of print]

Interpenetrating networks of fibrillar and amorphous collagen promote cell spreading and hydrogel stability.

Lucia G Brunel, Chris M Long, Fotis Christakopoulos, Betty Cai, Patrik K Johansson, Diya Singhal, Annika Enejder, David Myung, Sarah C Heilshorn.

Hydrogels composed of collagen, the most abundant protein in the human body, are widely used as scaffolds for tissue engineering due to their ability to support cellular activity. However, collagen hydrogels with encapsulated cells often experience bulk contraction due to cell-generated forces, and conventional strategies to mitigate this undesired deformation often compromise either the fibrillar microstructure or cytocompatibility of the collagen. To support the spreading of encapsulated cells while preserving the structural integrity of the gels, we present an interpenetrating network (IPN) of two distinct collagen networks with different crosslinking mechanisms and microstructures. First, a physically self-assembled collagen network preserves the fibrillar microstructure and enables the spreading of encapsulated human corneal mesenchymal stromal cells. Second, an amorphous collagen network covalently crosslinked with bioorthogonal chemistry fills the voids between fibrils and stabilizes the gel against cell-induced contraction. This collagen IPN balances the biofunctionality of natural collagen with the stability of covalently crosslinked, engineered polymers. Taken together, these data represent a new avenue for maintaining both the fiber-induced spreading of cells and the structural integrity of collagen hydrogels by leveraging an IPN of fibrillar and amorphous collagen networks.
Statement of significance: Collagen hydrogels are widely used as scaffolds for tissue engineering due to their support of cellular activity. However, collagen hydrogels often undergo undesired changes in size and shape due to cell-generated forces, and conventional strategies to mitigate this deformation typically compromise either the fibrillar microstructure or cytocompatibility of the collagen. In this study, we introduce an innovative interpenetrating network (IPN) that combines physically self-assembled, fibrillar collagen-ideal for promoting cell adhesion and spreading-with covalently crosslinked, amorphous collagen-ideal for enhancing bulk hydrogel stability. Our IPN design maintains the native fibrillar structure of collagen while significantly improving resistance against cell-induced contraction, providing a promising solution to enhance the performance and reliability of collagen hydrogels for tissue engineering applications.
Graphical abstract:

DOI: https://doi.org/10.1101/2024.09.11.612534
Biomaterials. 2024 Sep 18. pii: S0142-9612(24)00372-7. [Epub ahead of print]314 122838

A pancreatic cancer organoid incorporating macrophages reveals the correlation between the diversity of tumor-associated macrophages and cancer cell survival.

Shunsuke Tabe, Kenta Takeuchi, Kenji Aoshima, Ayumu Okumura, Yuya Yamamoto, Kazuki Yanagisawa, Ryotaro Eto, Megumi Matsuo, Yasuharu Ueno, Takanori Konishi, Yoichi Furukawa, Kiyoshi Yamaguchi, Soichiro Morinaga, Yohei Miyagi, Masayuki Ohtsuka, Naoki Tanimizu, Hideki Taniguchi.

  Pancreatic ductal adenocarcinoma (PDAC) is a progressive cancer with a poor prognosis. It contains a complex tumor microenvironment (TME) that includes various stromal cell types. Comprehending cellular communications within the TME is difficult due to a lack of research models that can recapitulate human PDAC-TME. Previously, we recapitulated, in part, the PDAC-TME containing a diversity of cancer-associated fibroblasts (CAFs) in vitro. This was done by establishing a PDAC organoid by co-culturing patient-derived cancer cells with human induced pluripotent stem cell (hiPSC)-derived mesenchymal and endothelial cells, which was designated the fused pancreatic cancer organoid (FPCO). We further incorporated macrophages derived from the THP-1 cell line, which are the source of tumor-associated macrophages (TAMs), a major TME component, into FPCO, which was designated M0-FPCO. Bulk RNA sequencing (RNAseq) analysis revealed that macrophages in M0-FPCO (FPCO-Mac) lost their pro-inflammatory features but acquired pro-angiogenic features. Consistently, the formation of an endothelial cell network was enhanced in M0-FPCO. Single-cell RNA-seq (scRNA-seq) analysis revealed that M0-FPCO contained five TAM subpopulations similar to the corresponding TAM in human PDAC tissue in the integrated analysis, including SPP1+-TAM, which has been correlated with tumor angiogenesis and cell proliferation. Focusing on PDAC cells, we found that they could survive longer within the organoid in the presence of TAM. Consistent with the prolonged proliferation and survival of PDAC cells, PDAC subclusters were characterized by proliferative features, such as increased M0-FPCO. Therefore, by establishing a PDAC organoid with macrophages, we recapitulated the diversity of TAMs and identified the role of TAM in endothelial network formation as well as in the modulation of PDAC cell properties. SIGNIFICANCE: PDAC organoids, including macrophages using hiPSC, showed that PDAC-TAM has angiogenic features and contributes to PDAC cell survival.

Keywords:  Macrophages; Organoids; PDAC; hiPSC

DOI:  https://doi.org/10.1016/j.biomaterials.2024.122838
Cell Prolif. 2024 Sep 29. e13754

Notch-1 regulates collective breast cancer cell migration by controlling intercellular junction and cytoskeletal organization.

Yixi Zhang, Xiang Qin, Ronghua Guo, Xiyue Sun, Zihan Zhao, Hanyu Guo, Meng Wang, Shun Li, Tingting Li, Dong Lv, Yiyao Liu.

Pathological observations show that cancer cells frequently invade the surrounding normal tissue in collective rather than individual cell migration. However, general principles governing collective cell migration remain to be discovered. Different from individual cell migration, we demonstrated that the Notch-1-activation reduced collective cells speed and distances. In particular, Notch-1-activation induced cellular cytoskeletal remodelling, strengthened the intercellular junctions and cell-matrix adhesions. Mechanistically, Notch-1 activation prevented the phosphorylation of GSK-3β and the translocation of cytoplasmic free β-catenin to the nucleus, which increased E-cadherin expression and tight intercellular junctions. Moreover, Notch-1 signalling also activated the RhoA/ROCK pathway, promoting reorganization of F-actin and contractile forces produced by myosin. Further, Notch-1 activation increased cell adhesion to the extracellular substrate, which inhibited collective cell migration. These findings highlight that cell adhesions and cell-cell junctions contribute to collective cell migration and provide new insights into mechanisms of the modulation of Notch-1 signalling pathway on cancer cell malignancy.

DOI: https://doi.org/10.1111/cpr.13754
J Colloid Interface Sci. 2024 Sep 22. pii: S0021-9797(24)02248-3. [Epub ahead of print]678(Pt C): 1259-1269

Competition between cross-linking and force-induced local conformational changes determines the structure and mechanics of labile protein networks.

Matt D G Hughes, Daniel West, Rebecca Wurr, Sophie Cussons, Kalila R Cook, Najet Mahmoudi, David Head, David J Brockwell, Lorna Dougan.

  Folded protein hydrogels are emerging as promising new materials for medicine and healthcare applications. Folded globular proteins can be modelled as colloids which exhibit site specific cross-linking for controlled network formation. However, folded proteins have inherent mechanical stability and unfolded in response to an applied force. It is not yet understood how colloidal network theory maps onto folded protein hydrogels and whether it models the impact of protein unfolding on network properties. To address this, we study a hybrid system which contains folded proteins (patchy colloids) and unfolded proteins (biopolymers). We use a model protein, bovine serum albumin (BSA), to explore network architecture and mechanics in folded protein hydrogels. We alter both the photo-chemical cross-linking reaction rate and the mechanical properties of the protein building block, via illumination intensity and redox removal of robust intra-protein covalent bonds, respectively. This dual approach, in conjunction with rheological and structural techniques, allows us to show that while reaction rate can 'fine-tune' the mechanical and structural properties of protein hydrogels, it is the force-lability of the protein which has the greatest impact on network architecture and rigidity. To understand these results, we consider a colloidal model which successfully describes the behaviour of the folded protein hydrogels but cannot account for the behaviour observed in force-labile hydrogels containing unfolded protein. Alternative models are needed which combine the properties of colloids (folded proteins) and biopolymers (unfolded proteins) in cross-linked networks. This work provides important insights into the accessible design space of folded protein hydrogels without the need for complex and costly protein engineering, aiding the development of protein-based biomaterials.

Keywords:  Biomaterial design; Colloidal networks; Force-induced unfolding; Mechanics

DOI:  https://doi.org/10.1016/j.jcis.2024.09.183
Acta Biomater. 2024 Sep 30. pii: S1742-7061(24)00566-X. [Epub ahead of print]

Elucidating the unexpected cell adhesive properties of agarose substrates. The effect of mechanics, fetal bovine serum and specific peptide sequences.

Francesco Piazza, Beatrice Ravaglia, Andrea Caporale, Ana Svetić, Pietro Parisse, Fioretta Asaro, Gabriele Grassi, Luca Secco, Riccardo Sgarra, Eleonora Marsich, Ivan Donati, Pasquale Sacco.

  2D agarose substrates have recently been surprisingly shown to be permissive for cell adhesion, depending on their mechanics and the use of the adhesive proteins of fetal bovine serum (FBS) in the cell culture medium. Here, we elucidate how the cells exhibit two anchoring mechanisms depending on the amount of FBS. Under low FBS conditions, the cells recognize the surface-coupled adhesive sequences of fibronectin via the binding of the heterodimer α5β1 integrin. Functionality of the actomyosin axis and mechanoactivation of focal adhesion kinase (FAK) are essential for the stretching of the protein, thereby accessing the "synergy" PPSRN site and enhancing cell adhesion in combination with the downstream RGD motif. Under high FBS conditions, the specific peptide sequences are much less relevant as the adsorbed serum proteins conceal the coupled fibronectin and the cells recognize the adhesive protein vitronectin, which is constitutively present in FBS, via the binding of the heterodimer αvβ3 integrin. Similarly, the intracellular tension and FAK activity are decisive, which collectively indicate that the cells stretch the partially cryptic RGD site of vitronectin and thus make it more accessible for integrin binding. Both anchoring mechanisms only work properly if the agarose substrate is mechanically compliant in terms of linear stress-strain response, unraveling a critical balance between the mechanics of the agarose substrate and the presentation of the adhesive peptides. STATEMENT OF SIGNIFICANCE: In the context of biomaterial design, agarose hydrogels are known to lack intrinsic cell-adhesive peptide motifs and are therefore commonly used for the development of non-permissive 2D substrates. However, we unexpectedly found that agarose hydrogels can become permissive substrates for cell adhesion, depending on a compliant mechanical response of the substrate and the use of fetal bovine serum (FBS) as protein reservoir in the cell culture medium. We describe here two anchoring mechanisms that cells harness to adhere to agarose substrates, depending on the amount of FBS. Our results will have a major impact on the field of mechanobiology and shed light on the central role of FBS as a natural source of adhesive proteins that could promote cell anchoring.

Keywords:  RGD motif; agarose; cell adhesion; fetal bovine serum; mechanobiology

DOI:  https://doi.org/10.1016/j.actbio.2024.09.042
J Cell Biol. 2024 Dec 02. pii: e202404070. [Epub ahead of print]223(12):

Organization of a cytoskeletal superstructure in the apical domain of intestinal tuft cells.

Jennifer B Silverman, Evan E Krystofiak, Leah R Caplan, Ken S Lau, Matthew J Tyska.

Tuft cells are a rare epithelial cell type that play important roles in sensing and responding to luminal antigens. A defining morphological feature of this lineage is the actin-rich apical "tuft," which contains large fingerlike protrusions. However, details of the cytoskeletal ultrastructure underpinning the tuft, the molecules involved in building this structure, or how it supports tuft cell biology remain unclear. In the context of the small intestine, we found that tuft cell protrusions are supported by long-core bundles that consist of F-actin crosslinked in a parallel and polarized configuration; they also contain a tuft cell-specific complement of actin-binding proteins that exhibit regionalized localization along the bundle axis. Remarkably, in the sub-apical cytoplasm, the array of core actin bundles interdigitates and co-aligns with a highly ordered network of microtubules. The resulting cytoskeletal superstructure is well positioned to support subcellular transport and, in turn, the dynamic sensing functions of the tuft cell that are critical for intestinal homeostasis.

DOI: https://doi.org/10.1083/jcb.202404070
Int J Biol Macromol. 2024 Sep 27. pii: S0141-8130(24)06915-0. [Epub ahead of print]280(Pt 4): 136106

Three-dimensional bioprinted cell-adaptive hydrogel with anisotropic micropores for enhancing skin wound healing.

Baozhang Shi, Tong Zhu, Yang Luo, Xiang Zhang, Jie Yao, Xu Cao, Yingchun Zhu, Hongyue Miao, Liangliang Li, Qin Song, Hua Zhang, Liping Xu.

  Engineered matrices with aligned microarchitectures are pivotal in regulating the fibroblast-to-myofibroblast transition, a critical process for wound healing and scar reduction. However, developing a three-dimensional (3D) aligned matrix capable of effectively controlling this transition remains challenging. Herein, we developed a cell-adaptive hydrogel with highly oriented microporous structures, fabricated through bioprinting of thermo/ion/photo-crosslinked gelatin methacrylate/sodium alginate (GelMA/SA) incorporating shear-oriented polyethylene oxide (PEO) filler. The synergistic interactions among GelMA, PEO, and SA yield a homogeneous mixture conducive to the printing of biomimetic 3D constructs with anisotropic micropores. These anisotropic micropores, along with the biochemical cues provided by the GelMA/PEO/SA scaffolds, enhance the oriented spreading and organization of fibroblasts. The resultant spread and aligned cellular morphologies promote the transition of fibroblasts into myofibroblasts. By co-culturing human keratinocytes on the engineered dermal layer, we successfully create a bilayer skin construct, wherein the keratinocytes establish tight junctions accompanied by elevated expression of cytokeratin-14, while the fibroblasts display a highly spread morphology with increased fibronectin expression. The printed hydrogels accelerate full-thickness wound closure by establishing a bioactive microenvironment that mitigate inflammation and stimulate angiogenesis, myofibroblast transition, and extracellular matrix remodeling. This anisotropic hydrogel demonstrates substantial promise for applications in skin tissue engineering.

Keywords:  Myofibroblast; Oriented micropores; Wound repair

DOI:  https://doi.org/10.1016/j.ijbiomac.2024.136106