Fibroblastic Morphology Research Articles

Atomic force microscopy reveals the influence of substrate collagen concentration and TGF-β on lung fibroblast mechanics

Understanding how extracellular matrix (ECM) stiffness and biochemical factors such as TGF-β affect cell behaviour is critical for elucidating mechanisms underlying several pathologic conditions such as tissue fibrosis and cancer metastasis. This study investigates the effects of varying collagen substrate concentration and consequently varying stiffness conditions along with TGF-β treatment on the morphology, nanomechanical properties, and gene expression of normal human lung fibroblasts (NHLF). Our results reveal that increased substrate stiffness leads to more elongated cell morphology, decreased cellular stiffness, and significant alterations in gene expression related to cytoskeletal organization and myofibroblast activation genes. TGF-β treatment further induces myofibroblast differentiation, as evidenced by increased α-SMA and collagen expression, while also reducing cellular stiffness and promoting a more elongated, invasive phenotype. These findings highlight the critical role of both mechanical and biochemical cues in modulating fibroblast behaviour, with significant implications in fibrosis development and cancer progression.

PTB Regulates Keloid Fibroblast Migration and Proliferation Through Autophagy.

Keloid disease is a chronic fibroproliferative disease that occurs after tissue injury, and the currently available treatments are unsatisfactory. We aimed to explore the level of autophagy in keloid fibroblasts (KFbs) and adjacent normal fibroblasts (NFbs). In addition, whether polypyrimidine tract-binding protein (PTB) regulates the biological functions of KFbs via autophagy was also investigated. The morphology of fibroblasts in normal skin and keloids was observed transmission electron microscopy. We silenced PTB with PTB-specific siRNA to determine whether PTB-regulated KFb proliferation. Acridine orange and LysoTracker Red staining was performed to label acidic compartments. Interestingly, when autophagy was inhibited by wortmannin, the PTB knockdown-mediated decrease in KFb migration and proliferation was abolished, while the collagen I and III levels were not altered; these results indicated that PTB regulated the migration and proliferation of KFbs via autophagy, while collagen synthesis occurred independently of PTB regulation. Many activities related to the survival and function of KFbs are controlled by PTB. Transmission electron microscopy revealed more autophagosomes and autolysosomes in KFbs than in NFbs. PTB induced autophagy in KFbs, as demonstrated by the significantly greater number of autophagosomes in KFbs after PTB knockdown, which was revealed by acridine orange and LysoTracker staining. Our study is the first to show that PTB regulates the migration and proliferation of KFbs via autophagy and that PTB regulates collagen synthesis in KFbs in an autophagy-independent manner. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of three different root canal sealants on human dental pulp stem cells

The cytotoxic effects of three root canal sealers with different bases on human dental pulp stem cells were assessed in this study using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test. The cytotoxic effects of three root canal sealers with different bases on human dental pulp stem cells (DPSCs) were assessed in this study using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test. The cytotoxicity of the sealers was tested after one, 4, and 7 d. Human dental pulp stem cell proliferation was concluded using an MTT assay. Cells not treated with sealer extract were used as controls. The absorption levels were measured using an Eliza spectrophotometer. P was set at 0.05 when the percentage of cell proliferation was matched between groups and observation times using one-way analysis of variance (ANOVA).During the second passage (P2), human dental pulp stem cells displayed a single morphological and phenotypic trait, with fibroblast morphology being the most common. There were no appreciable variations between the four groups after a day. There was a notable variation in the average percentage of cell proliferation between the groups after 4 and 7 days. The control group had the highest percentage, followed by the GuttaFlow Bioseal group, the Well Root St group, and the AH-Plus group, which had the lowest percentage. For every sealing group, after one day, the highest mean percentage of cell proliferation was recorded, followed by day four, and after day seven, the lowest mean percentage. The observation periods showed minimal cytotoxic effects of GuttaFlow Bioseal, whereas AH-Plus was the most cytotoxic to human dental pulp stem cells. The highest mean percentage of cell proliferation for all sealers was recorded on day one.

Adipose stem cell exosomes promote mitochondrial autophagy through the PI3K/AKT/mTOR pathway to alleviate keloids

BackgroundFibrosis with unrelieved chronic inflammation is an important pathological change in keloids. Mitochondrial autophagy plays a crucial role in reducing inflammation and inhibiting fibrosis. Adipose stem cell-derived exosomes, a product of adipose stem cell paracrine secretion, have pharmacological effects, such as anti-inflammatory and antiapoptotic effects, and mediate autophagy. Therefore, this study aims to investigate the function and mechanism of adipose stem cell exosomes in the treatment of keloids.MethodWe isolated adipose stem cell exosomes under normoxic and hypoxic condition to detect their effects on keloid fibroblast proliferation, migration, and collagen synthesis. Meanwhile, 740YPDGFR (PI3K/AKT activator) was applied to detect the changes in autophagic flow levels and mitochondrial morphology and function in keloid fibroblasts. We constructed a human keloid mouse model by transplanting human keloid tissues into six-week-old (20–22 g; female) BALB/c nude mice, meanwhile, we applied adipose stem cell exosomes to treat the mouse model and observed the retention and effect of ADSC exosomes in vivo.ResultsADSC exosomes can inhibit the PI3K/AKT/mTOR signaling pathway. The exosomes of ADSCs decreased the inflammatory level of KFs, enhanced the interaction between P62 and LC3, and restored the mitochondrial membrane potential. In the human keloid mouse model, ADSC exosomes can exist stably, promote mitochondrial autophagy in keloid tissue, improve mitochondrial morphology, reduce inflammatory reaction and fibrosis. Meanwhile, At the same time, the exosomes derived from hypoxic adipose stem cells have played a more effective role in both in vitro and in vivo experiments.ConclusionsAdipose stem cell exosomes inhibited the PI3K/AKT/mTOR pathway, activated mitochondrial autophagy, and alleviated keloid scars.Graphical

3D-printed surfaces of titanium implant: the fibroblasts response

Ti-6Al-4V (wt%) is the most widely used titanium alloy and its additive manufactured (or 3D printed) parts with near net-shape have provided great advantages for biomedical applications. While the impact of surface roughness on the biocompatibility of 3D-printed Ti-6Al-4V part is recognized, further exploration is needed to fully understand this complex relationship. Hence, this study presents a comprehensive evaluation of as-printed Ti-6Al-4V structures, both with and without surface texturing, with particular focus on the fibroblast response. Alongside a flat surface, or as-printed surface, two different types of surface textures: diamond texture and diamond crystal texture, were meticulously designed and printed through laser powder bed fusion (LPBF). The viability, cell adhesion, and morphology of human and murine fibroblasts seeded on the surface patterns was investigated, as well as the distribution of extracellular matrix (ECM) proteins (collagen I, fibronectin). The results demonstrated that the as-fabricated surface morphologies did not impact fibroblast viability, however, a reduced density of human fibroblasts was observed on the diamond texture surface, likely owing to the upright strut structure preventing cell adhesion. Interestingly, spreading of the human, but not murine, fibroblasts was limited by the remaining partially-sintered powders. The relative intensity of ECM protein signals was unaffected, however, ECM protein distribution across the surfaces was also altered. Thus, the as-printed substrates, particularly with diamond crystal struts, present a promising avenue for the cost-effective and efficient fabrication of Ti-6Al-4V components for medical applications in the future.

An investigation of the dose-dependent safety of bemiparin sodium: A cell culture study

Aim: Fibroblasts are common cells in subcutaneous tissue and they have an important role on healing process. Although patients who are receiving first-generation low molecular weight heparins are more likely to experience skin responses, there is no study evaluating the effect of bemiparin sodium on subcutaneous fibroblasts following administration. In the present study, we aimed to evaluate the effects of bemiparin sodium on fibroblast cell viability in cell culture model. Material and Methods: The L929 cells were incubated for 12 hours in 96-well culture dishes. Fresh medium containing different concentrations of bemiparin was added in five different concentrations (Dilution I: 3,500 IU; Dilution II: 1,750 IU; Dilution III: 875 IU; Dilution IV: 437.5 IU; Dilution V: 218.75 IU). A control group was established with drug-free culture medium. Cell viability analysis was performed after 48 hours of incubation by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The change in cell morphology was examined at each dilution by direct and acridine orange/propidium iodide staining. Results: The highest cytotoxic effect was observed in dilution I compared to the control group (p<0.05). There is a clear deviation from the fibroblastic morphology of the cells in dilution I. The cells have a round morphology with degeneration and nuclear condensation. Conclusion: Although it seems that high doses of bemiparin may have a negative effect on fibroblast cells in subcutaneous tissue, it can be considered that the cytotoxic effects of high concentrations of the drug at the application site will not be clinically significant due to using a single dose per day.

Highly Compressible, Superabsorbent, and Biocompatible Hybrid Cryogel Constructs Comprising Functionalized Chitosan and St. John's Wort Extract.

Biobased porous hydrogels enriched with phytocompounds-rich herbal extracts have aroused great interest in recent years, especially in healthcare. In this study, new macroporous hybrid cryogel constructs comprising thiourea-containing chitosan (CSTU) derivative and a Hypericum perforatum L. extract (HYPE), commonly known as St John's wort, were prepared by a facile one-pot ice-templating strategy. Benefiting from the strong interactions between the functional groups of the CSTU matrix and those of polyphenols in HYPE, the hybrid cryogels possess excellent liquid absorption capacity, mechanical resilience, antioxidant performance, and a broad spectrum of antibacterial activity simultaneously. Thus, owing to their design, the hybrid constructs exhibit an interconnected porous architecture with the ability to absorb over 33 and 136 times their dry weight, respectively, when contacted with a phosphate buffer solution (pH 7.4) and an acidic aqueous solution (pH 2). These cryogel constructs have extremely high compressive strengths ranging from 839 to 1045 kPa and withstand elevated strains of over 70% without developing fractures. Moreover, the water-swollen hybrid cryogels with the highest HYPE content revealed a complete and instant shape recovery after uniaxial compression. The incorporation of HYPE into CSTU cryogels enabled substantial improvement in scavenging reactive oxygen species and an expanded antibacterial spectrum toward multiple pathogens, including Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungi (Candida albicans). Cell viability experiments demonstrated the cytocompatibility of the 3D cryogel constructs, which did not induce changes in the fibroblast morphology. This work showcases a simple and effective strategy to immobilize HYPE extracts on CSTU 3D networks, allowing the development of novel multifunctional platforms with promising potential in hemostasis, wound dressing, and dermal regeneration scaffolds.

ELFN1 is a new extracellular matrix (ECM)-associated protein

AimsThe ELFN1, discovered in 2007, is a single-pass transmembrane protein. Studies conducted thus far to elucidate the function of the Elfn1 have been limited only to animal studies. These studies have reported that ELFN1 is a universal binding partner of metabotropic glutamate receptors (mGluRs) in the central nervous system and its functional deficiency has been associated with the pathogenesis of neurological and neuropsychiatric diseases. In 2021, we described the first disease-associated human ELFN1 pathogenic gene mutation. Severe joint laxity, which was the most striking finding of this new disease and was clearly seen in the patients since early infancy, showed that the ELFN1 may have a possible function in the connective tissue besides the nervous system. Here, we present the first experimental evidence of the extracellular matrix (ECM)-related function of the ELFN1. Materials and methodsPrimary skin fibroblasts were isolated from the skin biopsies of ELFN1 mutated patients and healthy foreskin donors. For the clinical trial in a dish, in vitro ECM and DEM (decellularized ECM) models were created from skin fibroblasts. All the in vitro models were comparatively characterized and analyzed. Key findingsThe mutation in the ELFN1 signal peptide region of patients resulted in a severe lack of ELFN1 expression and dramatically altered the characteristic morphology and behavior (growth, proliferation, and motility) of fibroblasts. SignificanceWe propose that ELFN1 is involved in the cell-ECM attachment, and its deficiency is critical enough to cause a loss of cell motility and soft ECM stiffness.

152 Three-Dimensional Printing Bespoke Polycaprolactone Tracheal Splint for Treatment of Tracheomalacia

Abstract Aim Tracheomalacia can be a fatal airway disease with limited treatment options. Three-dimensional (3D) printing has led to various patient-specific tracheal stents and splints. However, these are limited by mismatched stiffness and resulting granulation tissue formation and fibrosis. We aimed to develop a non-toxic and biodegradable polycaprolactone expandable tracheal splint by 3D printing. By fine-tuning mechanical properties, we hypothesised that the splint would match the native trachea and accommodate tracheal growth in tracheomalacia patients. Method We designed splints consisting of concave topological patterns with varying angles and aspect ratios. Fabrication occurred using polycaprolactone filaments in a 3D fuse deposition modelling printer. Uniaxial tensile studies were performed on splints to assess Young’s Modulus, Toughness, Ultimate strain, Strength, and Poisson ratio. Splints displaying optimal mechanical properties were tested for human lung fibroblast cell viability, proliferation, and morphology. Results On a mechanical testing rig, uniaxial tensile studies confirmed that splint designs with smaller angles and negative Poisson ratios of up to strains of 25%, better mimicked mechanical properties of native human trachea, accommodating tracheal growth. In vitro studies using these tracheal splints demonstrated successful human lung cell proliferation with low cell toxicity. Conclusions This study characterised 3D printed bespoke tracheal splints with various 2D structures, showing mechanical properties that match the native trachea. However, in vivo studies investigating cellular interactions on our splint must be performed to further evaluate the ability for endogenous tissue formation.

The Role of Vimentin in Human Corneal Fibroblast Spreading and Myofibroblast Transformation.

Vimentin has been reported to play diverse roles in cell processes such as spreading, migration, cell-matrix adhesion, and fibrotic transformation. Here, we assess how vimentin impacts cell spreading, morphology, and myofibroblast transformation of human corneal fibroblasts. Overall, although knockout (KO) of vimentin did not dramatically impact corneal fibroblast spreading and mechanical activity (traction force), cell elongation in response to PDGF was reduced in vimentin KO cells as compared to controls. Blocking vimentin polymerization using Withaferin had even more pronounced effects on cell spreading and also inhibited cell-induced matrix contraction. Furthermore, although absence of vimentin did not completely block TGFβ-induced myofibroblast transformation, the degree of transformation and amount of αSMA protein expression was reduced. Proteomics showed that vimentin KO cells cultured in TGFβ had a similar pattern of protein expression as controls. One exception included periostin, an ECM protein associated with wound healing and fibrosis in other cell types, which was highly expressed only in Vim KO cells. We also demonstrate for the first time that LRRC15, a protein previously associated with myofibroblast transformation of cancer-associated fibroblasts, is also expressed by corneal myofibroblasts. Interestingly, proteins associated with LRRC15 in other cell types, such as collagen, fibronectin, β1 integrin and α11 integrin, were also upregulated. Overall, our data show that vimentin impacts both corneal fibroblast spreading and myofibroblast transformation. We also identified novel proteins that may regulate corneal myofibroblast transformation in the presence and/or absence of vimentin.

Stability of starch-folic acid/ polyethylene glycol particles for gastrointestinal drug delivery

This study takes a novel approach by exploring the potential of starch/polyethylene glycol core/shell particles, where folic acid was encapsulated, as effective gastrointestinal drug delivery systems. The results demonstrate the successful encapsulation of folic acid within the starch/PEG particles, with sizes ranging from 18 to 45 μm depending on the type of starch used (corn, potato, rice). Importantly, applying PEG coating had no negative impact on cell viability and did not induce alterations in fibroblast morphology. The investigation of stability in gastric and intestinal fluids revealed that the particles underwent different degrees of degradation. In simulated gastric fluid, a partial degradation of the PEG layer by 30–37% was observed, while the starch-folic acid core remained intact. However, the PEG layer underwent a 50% degradation in simulated intestinal fluid. This degradation of the PEG layer allowed the controlled and gradual release of folic acid. These findings underscore the role of fluid composition in influencing the stability and degradation behavior of the particles, with significant implications for their functionality as drug delivery systems in the gastrointestinal tract.

Repurposing nitrofurantoin as a stimulant of fibroblast extracellular matrix repair for the treatment of emphysema

Emphysema is a respiratory disease that causes the progressive loss of lung extracellular matrix (ECM) organisation, subsequently undermining lung integrity and reducing lung function. Fibroblasts must constantly repair damage to the lungs to preserve lung health, however, fibroblast ECM repair is reduced during emphysema, causing ECM damage to outweigh fibroblast ECM maintenance. Current treatments for emphysema fail to address the root causes of emphysematous progression, highlighting the need for novel methods of treating emphysema. Nitrofurantoin is a broad-spectrum antibiotic indicated for the treatment of urinary tract infections that also displays potential as a novel avenue of emphysema treatment. Nitrofurantoin is known to potentially cause fibrotic effects that could be repurposed to increase fibroblast repair and outweigh the progressive ECM damage of the emphysematous lung. Therefore, this study examined the effects of nitrofurantoin treatment on primary human lung fibroblasts derived from emphysema patients to determine if the drug holds potential as a novel treatment for emphysema. Nitrofurantoin was shown to stimulate migration and alter fibroblast morphology by increasing cell area and reducing roundness, suggesting that it could induce an ECM-repair primed phenotype in fibroblasts. Interestingly, nitrofurantoin treatment did not alter collagen-IV, perlecan, periostin or tenascin-C deposition, though fibronectin deposition was significantly upregulated at a higher dosage (20 μg/mL). This study highlighted the nitrofurantoin induced changes to fibroblast motility and morphology that facilitate ECM repair. Thus, nitrofurantoin induced pulmonary fibrosis could be caused by a change in cell phenotype that subsequently upregulates ECM repair, indicating its potential as a treatment for emphysema.

Extracellular matrices of stromal cell subtypes regulate phenotype and contribute to the stromal microenvironment in vivo

BackgroundBone marrow stromal cells (BMSCs) are highly heterogeneous, which may reflect their diverse biological functions, including tissue maintenance, haematopoietic support and immune control. The current understanding of the mechanisms that drive the onset and resolution of heterogeneity, and how BMSCs influence other cells in their environment is limited. Here, we determined how the secretome and importantly the extracellular matrix of BMSCs can influence cellular phenotype.MethodsWe used two immortalised clonal BMSC lines isolated from the same heterogeneous culture as model stromal subtypes with distinct phenotypic traits; a multipotent stem-cell-like stromal line (Y201) and a nullipotent non-stem cell stromal line (Y202), isolated from the same donor BMSC pool. Label-free quantitative phase imaging was used to track cell morphology and migration of the BMSC lines over 96 h in colony-forming assays. We quantified the secreted factors of each cell line by mass spectrometry and confirmed presence of proteins in human bone marrow by immunofluorescence.ResultsTransfer of secreted signals from a stem cell to a non-stem cell resulted in a change in morphology and enhanced migration to more closely match stem cell-like features. Mass spectrometry analysis revealed a significant enrichment of extracellular matrix (ECM) proteins in the Y201 stem cell secretome compared to Y202 stromal cells. We confirmed that Y201 produced a more robust ECM in culture compared to Y202. Growth of Y202 on ECM produced by Y201 or Y202 restored migration and fibroblastic morphology, suggesting that it is the deficiency of ECM production that contributes to its phenotype. The proteins periostin and aggrecan, were detected at 71- and 104-fold higher levels in the Y201 versus Y202 secretome and were subsequently identified by immunofluorescence at rare sites on the endosteal surfaces of mouse and human bone, underlying CD271-positive stromal cells. These proteins may represent key non-cellular components of the microenvironment for bona-fide stem cells important for cell maintenance and phenotype in vivo.ConclusionsWe identified plasticity in BMSC morphology and migratory characteristics that can be modified through secreted proteins, particularly from multipotent stem cells. Overall, we demonstrate the importance of specific ECM proteins in co-ordination of cellular phenotype and highlight how non-cellular components of the BMSC microenvironment may provide insights into cell population heterogeneity and the role of BMSCs in health and disease.

Development of Novel Antibacterial Ti-Nb-Ga Alloys with Low Stiffness for Medical Implant Applications.

With the rising demand for medical implants and the dominance of implant-associated failures including infections, extensive research has been prompted into the development of novel biomaterials that can offer desirable characteristics. This study develops and evaluates new titanium-based alloys containing gallium additions with the aim of offering beneficial antibacterial properties while having a reduced stiffness level to minimise the effect of stress shielding when in contact with bone. The focus is on the microstructure, mechanical properties, antimicrobial activity, and cytocompatibility to inform the suitability of the designed alloys as biometals. Novel Ti-33Nb-xGa alloys (x = 3, 5 wt%) were produced via casting followed by homogenisation treatment, where all results were compared to the currently employed alloy Ti-6Al-4V. Optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) results depicted a single beta (β) phase microstructure in both Ga-containing alloys, where Ti-33Nb-5Ga was also dominated by dendritic alpha (α) phase grains in a β-phase matrix. EDS analysis indicated that the α-phase dendrites in Ti-33Nb-5Ga were enriched with titanium, while the β-phase was richer in niobium and gallium elements. Mechanical properties were measured using nanoindentation and microhardness methods, where the Young's modulus for Ti-33Nb-3Ga and Ti-33Nb-5Ga was found to be 75.4 ± 2.4 and 67.2 ± 1.6 GPa, respectively, a significant reduction of 37% and 44% with respect to Ti-6Al-4V. This reduction helps address the disproportionate Young's modulus between titanium implant components and cortical bone. Importantly, both alloys successfully achieved superior antimicrobial properties against Gram-negative P. aeruginosa and Gram-positive S. aureus bacteria. Antibacterial efficacy was noted at up to 90 ± 5% for the 3 wt% alloy and 95 ± 3% for the 5 wt% alloy. These findings signify a substantial enhancement of the antimicrobial performance when compared to Ti-6Al-4V which exhibited very small rates (up to 6.3 ± 1.5%). No cytotoxicity was observed in hGF cell lines over 24 h. Cell morphology and cytoskeleton distribution appeared to depict typical morphology with a prominent nucleus, elongated fibroblastic spindle-shaped morphology, and F-actin filamentous stress fibres in a well-defined structure of parallel bundles along the cellular axis. The developed alloys in this work have shown very promising results and are suggested to be further examined towards the use of orthopaedic implant components.

Pharmacologic Activation of Integrated Stress Response Kinases Inhibits Pathologic Mitochondrial Fragmentation.

Excessive mitochondrial fragmentation is associated with the pathologic mitochondrial dysfunction implicated in the pathogenesis of etiologically-diverse diseases, including many neurodegenerative disorders. The integrated stress response (ISR) - comprising the four eIF2α kinases PERK, GCN2, PKR, and HRI - is a prominent stress-responsive signaling pathway that regulates mitochondrial morphology and function in response to diverse types of pathologic insult. This suggests that pharmacologic, stress-independent activation of the ISR represents a potential strategy to mitigate pathologic mitochondrial fragmentation associated with human disease. Here, we show that pharmacologic, stress-independent activation of the ISR kinases HRI or GCN2 promotes adaptive mitochondrial elongation and prevents mitochondrial fragmentation induced by the calcium ionophore ionomycin. Further, we show that stress-independent activation of these ISR kinases reduces mitochondrial fragmentation and restores basal mitochondrial morphology in patient fibroblasts expressing the pathogenic D414V variant of the pro-fusion mitochondrial GTPase MFN2 associated with neurological dysfunctions including ataxia, optic atrophy, and sensorineural hearing loss. These results identify pharmacologic, stress-independent activation of ISR kinases as a potential strategy to prevent pathologic mitochondrial fragmentation induced by disease-relevant chemical and genetic insults, further motivating the pursuit of highly selective ISR kinase-activating compounds as a therapeutic strategy to mitigate mitochondrial dysfunction implicated in diverse human diseases.

Sustainably cultured coral scaffold supports human bone marrow mesenchymal stromal cell osteogenesis

The current gold standard grafting material is autologous bone due to its osteoinductive and osteoconductive properties. Autograft harvesting results in donors site morbidity. Coral scaffolds offer a natural autograft alternative, sharing the density and porosity of human bone. This study investigated the biocompatibility and osteogenic potential of a novel, sustainably grown Pocillopora scaffold with human bone marrow-derived mesenchymal stromal cells (MSCs). The coral-derived scaffold displays a highly textured topography, with concavities of uniform size and a high calcium carbonate content. Large scaffold samples exhibit compressive and diametral tensile strengths in the range of trabecular bone, with strengths likely increasing for smaller particulate samples. Following the in vitro seeding of MSCs adjacent to the scaffold, the MSCs remained viable, continued proliferating and metabolising, demonstrating biocompatibility. The seeded MSCs densely covered the coral scaffold with organized, aligned cultures with a fibroblastic morphology. In vivo coral scaffolds with MSCs supported earlier bone and blood vessel formation as compared to control constructs containing TCP-HA and MSCs. This work characterized a novel, sustainably grown coral scaffold that was biocompatible with MSCs and supports their in vivo osteogenic differentiation, advancing the current repertoire of biomaterials for bone grafting.

The HOCl dry fog-is it safe for human cells?

This study aims to investigate if high-concentration HOCl fogging disinfection causes cytotoxicity and genotoxicity to cultured primary human skin fibroblasts. The cells were exposed to a dry fog of HOCl produced from solutions with a concentration of 300 ppm (5.72 mM) or 500 ppm (9.53 mM). After four times when fibroblasts were exposed to aerosolized HOCl at a concentration of 500 ppm for 9 minutes, significant cytotoxicity and genotoxicity effects were observed. Significant changes in the morphology of fibroblasts and cell death due to membrane disruption were observed, independent of the number of exposures. Flow cytometry analyses performed under these experimental conditions indicated a decrease in the number of cells with an intact cell membrane in the exposed samples compared to the sham samples, dropping to 49.1% of the total cells. Additionally, under the same conditions, the neutral comet assay results demonstrated significant DNA damage in the exposed cells. However, no analogous damages were found when the cells were exposed to aerosolized HOCl generated from a 300-ppm solution for 3 minutes, whether once or four times. Therefore, we have concluded that aerosolized HOCl in dry fog, with a concentration exceeding 300 ppm, can cause cytotoxic and genotoxic effects on human skin fibroblasts.

In Vitro Investigation of Vocal Fold Cellular Response to Variations in Hydrogel Porosity and Elasticity.

Tissue regeneration is intricately influenced by the dynamic interplay between the physical attributes of tissue engineering scaffolds and the resulting biological responses. A tunable microporous hydrogel system was engineered using gelatin methacryloyl (GelMA) and polyethylene glycol diacrylate (PEGDA), with polyethylene glycol (PEG) serving as a porogen. Through systematic variation of PEGDA molecular weights, hydrogels with varying mechanical and architectural properties were obtained. The objective of the present study was to elucidate the impact of substrate mechanics and architecture on the immunological and reparative activities of vocal fold tissues. Mechanical characterization of the hydrogels was performed using tensile strength measurements and rheometry. Their morphological properties were investigated using scanning electron microscopy (SEM) and confocal microscopy. A series of biological assays were conducted. Cellular morphology, differentiation, and collagen synthesis of human vocal fold fibroblasts (hVFFs) were evaluated using immunostaining. Fibroblast proliferation was studied using the WST-1 assay, and cell migration was investigated via the Boyden chamber assay. Macrophage polarization and secretions were also examined using immunostaining and ELISA. The results revealed that increasing the molecular weight of PEGDA from 700 Da to 10,000 Da resulted in decreased hydrogel stiffness, from 62.6 to 8.8 kPa, and increased pore dimensions from approximately 64.9 to 137.4 μm. Biological evaluations revealed that hydrogels with a higher stiffness promoted fibroblast proliferation and spreading, albeit with an increased propensity for fibrosis, as indicated by a surge in myofibroblast differentiation and collagen synthesis. In contrast, hydrogels with greater molecular weights had a softer matrix with expanded pores, enhancing cellular migration and promoting an M2 macrophage phenotype conducive to tissue healing. The findings show that the hydrogels formulated with a PEGDA molecular weight of 6000 Da are best among the hydrogels considered for vocal fold repair. The microporous hydrogels could be tuned to serve in other tissue engineering applications.

Transcriptional regulation of living materials via extracellular electron transfer.

Engineered living materials combine the advantages of biological and synthetic systems by leveraging genetic and metabolic programming to control material-wide properties. Here, we demonstrate that extracellular electron transfer (EET), a microbial respiration process, can serve as a tunable bridge between live cell metabolism and synthetic material properties. In this system, EET flux from Shewanella oneidensis to a copper catalyst controls hydrogel cross-linking via two distinct chemistries to form living synthetic polymer networks. We first demonstrate that synthetic biology-inspired design rules derived from fluorescence parameterization can be applied toward EET-based regulation of polymer network mechanics. We then program transcriptional Boolean logic gates to govern EET gene expression, which enables design of computational polymer networks that mechanically respond to combinations of molecular inputs. Finally, we control fibroblast morphology using EET as a bridge for programmed material properties. Our results demonstrate how rational genetic circuit design can emulate physiological behavior in engineered living materials.

“Glia-like” cells of fibroblast morphology are present in cultures from injured human brain tissue

“Glia-like” cells of fibroblast morphology are present in cultures from injured human brain tissue