Collagen Matrix Research Articles

Generating human skeletal myoblast spheroids for vascular myogenic tissue engineering

Engineered myogenic microtissues derived from human skeletal myoblasts offer unique opportunities for varying skeletal muscle tissue engineering applications, such as in vitro drug-testing and disease modelling. However, more complex models require the incorporation of vascular structures, which remains to be challenging. In this study, myogenic spheroids were generated using a high-throughput, non-adhesive micropatterned surface. Since monoculture spheroids containing human skeletal myoblasts were unable to remain their integrity, co-culture spheroids combining human skeletal myoblasts and human adipose-derived stem cells were created. When using the optimal ratio, uniform and viable spheroids with enhanced myogenic properties were achieved. Applying a pre-vascularization strategy, through addition of endothelial cells, resulted in the formation of spheroids containing capillary-like networks, lumina and collagen in the extracellular matrix, whilst retaining myogenicity. Moreover, sprouting of endothelial cells from the spheroids when encapsulated in fibrin was allowed. The possibility of spheroids, from different maturation stages, to assemble into a more large construct was proven by doublet fusion experiments. The relevance of using three-dimensional microtissues with tissue-specific microarchitecture and increased complexity, together with the high-throughput generation approach, makes the generated spheroids a suitable tool for in vitro drug-testing and human disease modeling.

The Long-Term Esthetic and Radiographic Outcome of Implants Placed in the Anterior Maxilla after Ridge Preservation, Combining Bovine Xenograft with Collagen Matrix.

The objective of the study was to evaluate the long-term esthetic and radiographic results of implants placed in the anterior maxilla after ridge preservation, combining bovine xenograft with collagen matrix. Fifteen patients who required a single tooth extraction because of fracture, root resorption, or extended caries were included in the study. After extraction, all sites were grafted using Deproteinized Bovine Bone Mineral (DBBM) with collagen and covered by a resorbable collagen matrix (CM). Five months after socket grafting, implants were successfully installed. The implant diameter range was between 3.8 and 4.2 mm. All patients were monitored for over 7 years, both clinically and radiographically. Three independent observers evaluated the long-term esthetic outcome, employing the Pink Esthetic Score (PES) technique. Over a period exceeding seven years, a 100% survival rate was observed for all 15 implants, with minimal marginal bone loss. The mean PES was 11.40 (±1.44) at the first assessment and 11.38 (±1.63) at the second assessment. The difference was not statistically significant (p = 0.978), and the scores of PES measurements indicated excellent esthetic results even after seven years. Based on these preliminary results, it seems that placing collagen bovine bone in a fresh extraction socket, covered with a collagen matrix, can preserve the alveolar ridge and provide long-term stable esthetic results.

Implant Stability and Histomorphometric Analysis Comparing Two Different Implant Macrogeometries Placed in Fresh Sockets: An Experimental Study in Sheep.

The aim of the present animal study was to examine the impact of two implant designs that promote different insertion torque values on implant stability and evaluate, histomorphometrically, the bone healing for immediate implant placement in fresh sockets. Twelve female sheep (35.0±5.0kg) and 48 conical Morse-taper dental implants divided into two groups (n = 24 per group): G1 group, where the implants present a design that can provide high insertion torque values; and G2 group, where the implants present a design that can provide low insertion torque values. Both had the same surface treatment, and dimensions (4.0 mm in diameter and 10 mm in length). The first two posterior teeth (both sides) were extracted carefully. Sequentially, there were osteotomies in the mesial socket of each molar tooth. The final implant position was 2 mm below the buccal bone crest level. On the right side, implants of the G1 were placed anteriorly, followed by implants of the G2; and, on the left side, it was the reverse. A digital torquemeter was used to measure the maximum final insertion torque value (f-IT). The initial implant stability quotient (ISQ) was measured immediately after the implant insertion (T0) and immediately after the euthanasia and removing the mandibles with the implants. The animals were euthanized (n=6 animals/ time) at 21 days (T1) and 35 days (T2). The t-test was used to compare statistical differences for each intragroup parameter analyzed. Pearson's correlation was used to analyze possible correlations: f-IT and BIC%, f-IT and ISQ, and ISQ and %BIC. Regarding the insertion torque, the G1 presented higher values than the G2, with a statistically significant difference (p<0.0001). The ISQ mean values were higher in the B-L direction than those obtained for M-D for both groups. %BIC measurements showed higher values in samples from G2 than G1 at both times and in both directions. New bone, medullary spaces, and collagen matrix had statistical differences between the groups at each evaluation time. Using implants with a modified macrogeometry plays a significant role in implant stability and the healing process of bone tissue around the implant. It is important for clinicians to carefully consider implant macrogeometry when planning dental implant surgery to achieve optimal implant stability and successful osseointegration, mainly in cases of immediate implant placement.

O146: Investigating the cell-matrix interplay in fibrotic remodelling using renal 3D in vitro models

Abstract Introduction The dynamic biophysical microenvironment of the renal extracellular matrix is integral in regulating tissue homeostasis. Matrix remodelling is an iterative process, which guides cell behaviour and pathological fibrosis occurs due to aberrant tissue repair. Fibrosis, characterised by the desmoplastic ECM deposition and tissue stiffening, is prominent in CKD and renal carcinomas. We engineered biomimetic 3D constructs to recapitulate cell-matrix interactions in fibrotic disease progression. Methods Soft collagen-I and laminin constructs (0.2%w/v) were engineered with renal cancer cells (786-O or ACHN) or renal fibroblasts (TK188). Plastic compression was used to generate dense collagen constructs, at 6%w/v collagen density. Mechanical properties were analysed using shear rheology. Gene expression of markers defining the healthy/diseased kidney matrix was determined using qPCR. Results Over 21 days, 786-O cancer cells softened the collagen matrix. Matrix degradation was supported by collagen-I downregulation and MMP7 and vimentin upregulation. Whereas metastatic cancer cells (ACHN) stiffened the dense matrix to ∼1.25kPa, with significant gene upregulation of collagen-I, collagen-IV and LOX. Fibrotic fibroblasts soften the dense matrix by ∼1kPa, with α-SMA and MMP9 upregulation. However, matrix stiffness significantly increases with cancer cell co-cultures. Discussion Renal cancer cells remodel their biophysical environment, altering the construct’s material properties. In our models, collagen density and stromal complexity influences cell behaviour, causing alterations in biomechanics and gene expression. These models can generate physiologically relevant stiffness, enabling investigation between key cell types and the physical environment. Drugs targeting MMPs and LOX will be used to determine if we can disrupt the fibrotic remodelling.

First person – Emily D. McParland and T. Amber Butcher

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Emily D. McParland and T. Amber Butcher are co-first authors on ‘ The Dilute domain in Canoe is not essential for linking cell junctions to the cytoskeleton but supports morphogenesis robustness’, published in JCS. Emily and Amber conducted the research described in this article while they were postbaccalaureate research assistants in the labs of Dr Mark Peifer (E.D.M. and T.A.B.) and Dr Kevin Slep (T.A.B.) at Chapel Hill Department of Biology, University of North Carolina, USA. Emily is now a PhD student in the lab of Dr Thomas Roberts at Brown University, Providence, USA, where she is broadly interested in functional morphology and muscle biomechanics, and focuses on the function of the collagenous extracellular matrix in muscle force production. Amber is a PhD student in the lab of Dr Eric Greene at Columbia University Department of Biochemistry and Molecular Biophysics, New York, USA, where she uses biochemical and biophysical techniques to investigate protein function, most recently within the context of homologous recombination.

Analysis of the treatment of RT2 recessions with a xenogeneic collagen matrix vs. connective tissue graft combined with a coronally advanced flap. A double-blinded randomized clinical trial

ObjectivesTo compare the clinical efficacy in terms of mean root coverage in RT2 recession treated with a coronally advanced flap combined with a xenogeneic collagen matrix versus a connective tissue graft.Materials and methodsA total of 20 patients were randomized to receive one of two treatments: coronally advanced flap + xenogeneic collagen matrix (test group) and coronally advanced flap + connective tissue graft (control group). Patient-related outcomes measures and professional aesthetic assessment by root esthetic score were performed. A descriptive and analytical statistical analysis of the variables was performed.ResultsAt 12 months, the mean root coverage was 56.48% in the test group and 69.72% in the control group (p = 0.048), with a 35% and 40% complete root coverage in the xenogeneic collagen matrix and connective tissue graft, respectively. Test group presented less pain (3.65 vs. 5.2 VAS units) (p = 0.015) and less surgical time (45 vs. 49.15 min) (p = 0.004) than control group.ConclusionThe use of xenogeneic collagen matrix in RT2 recessions was effective for recession reduction to those obtained using autologous grafts; with the advantage that the duration of surgery and patient morbidity decreased. Therefore, xenogeneic collagen matrix in RT2 recessions could be an alternative to autologous grafts.Clinical relevanceThe use of xenogeneic collagen matrix decreases the surgery time and patient morbidity but connective tissue graft results in significantly better mean root coverage and complete root coverage. Xenogeneic collagen matrix can be used in the treatment of RT2 gingival recessions.Study registrationNCT 03344315.

Acute exposure to ultraviolet radiation targets proteins involved in collagen fibrillogenesis.

Introduction: Exposure to chronic, low-dose UV irradiation (UVR) can lead to premature ageing of the skin. Understanding which proteins are affected by acute UVR and photo-dynamically produced reactive oxygen species (ROS) could help to inform strategies to delay photoageing. Conventional biochemical analyses can be used to characterize UVR/ROS-induced damage on a protein-by-protein basis and we have previously shown using SDS-PAGE that collagen I and plasma fibronectin are respectively resistant and susceptible to physiological doses of UVR. The aim of this study was to screen a complex proteome for UVR-affected proteins. Methods: This study employed a sensitive mass spectrometry technique (peptide location fingerprinting: PLF) which can identify structure associated differences following trypsin digestion to characterize the impact of UVR exposure on purified collagen I and tissue fibronectin and to identify UVR-susceptible proteins in an ECM-enriched proteome. Results: Using LC/MS-MS and PLF we show that purified mature type-I collagen is resistant to UVR, whereas purified tissue fibronectin is susceptible. UV irradiation of a human dermal fibroblast-deposited ECM-enriched proteome in vitro, followed by LC/MS-MS and PLF analysis revealed two protein cluster groups of UV susceptible proteins involved in i) matrix collagen fibril assembly and ii) protein translation and motor activity. Furthermore, PLF highlighted UV susceptible domains within targeted matrix proteins, suggesting that UV damage of matrix proteins is localized. Discussion: Here we show that PLF can be used to identify protein targets of UVR and that collagen accessory proteins may be key targets in UVR exposed tissues.

A multi-centre randomized controlled trial comparing connective tissue graft with collagen matrix to increase soft tissue thickness at the buccal aspect of single implants: 3-Year results.

To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of increase in buccal soft tissue profile (BSP) when applied at single implant sites. Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre randomized controlled trial. All were fully healed sites with a bucco-palatal bone dimension of at least 6 mm, and received an immediately restored single implant using a full digital workflow. Patients were randomly allocated to the control (CTG) or test group (CMX: Geistlich Fibro-Gide, Geistlich Pharma AG, Wolhusen, Switzerland) to increase buccal soft tissue thickness. Primary endpoints were increase in BSP at T1 (immediately postop), T2 (3 months), T3 (1 year) and T4 (3 years) based on superimposed digital surface models. Secondary endpoints included patient-reported, clinical and aesthetic outcomes. Thirty patients were included per group (control group: 15 males, 15 females, mean age 50.1 years; test group: 14 males, 16 females, mean age 48.2 years) and 50 could be re-examined at T4. The changes in BSP over time were significantly different between the groups (p < .001). At T4, the estimated mean increase in BSP amounted to 0.83 mm (95% confidence interval [CI]: 0.58-1.08) in the control group and 0.48 mm (95% CI: 0.22-0.73) in the test group. The estimated mean difference of 0.35 mm (95% CI: 0.06-0.65) in favour of the control group was significant (p = .021). No significant differences between the groups could be observed in terms of patients' aesthetic satisfaction (p = .563), probing depth (p = .286), plaque (p = .676), bleeding on probing (p = .732), midfacial recession (p = .667), Pink Esthetic Score (p = .366) and Mucosal Scarring Index (p = .438). However, CMX resulted in significantly more marginal bone loss (-0.43 mm; 95% CI: -0.77 to -0.09; p = .015) than CTG. CTG was more effective in increasing buccal soft tissue profile and resulted in less marginal bone loss than CMX. Therefore, CTG remains the gold standard to increase soft tissue thickness at implant sites. This study was registered in ClinicalTrials.gov (NCT04210596).

Effects of dexamethasone and IGF-1 on post-traumatic osteoarthritis-like catabolic changes in a human cartilage-bone-synovium microphysiological system in space and ground control tissues on earth

Post-traumatic Osteoarthritis (PTOA) results from traumatic joint injuries (such as an ACL rupture). Mechanical impact and an immediate synovial inflammatory response can result in joint tissue degradation and longer-term progression to PTOA. Astronauts are susceptible to increased exercise-related joint injuries leading to altered musculoskeletal physiology, further escalated due to microgravity and increased exposure to ionizing radiation. We applied a human Cartilage-Bone-Synovium (CBS) coculture model to test the potential of low-dose dexamethasone (Dex) and IGF-1 in ameliorating PTOA-like degeneration on Earth and the International Space Station-National Laboratory (ISS-NL, ISS for short). CBS cocultures were established using osteochondral plugs (CB) subjected to compressive impact injury (INJ) followed by coculture with synovium (S) explants. Study groups consisted of control (CB); disease [CBS + INJ]; treatment [CBS + INJ + Dex + IGF-1]; and drug-safety [CB + Dex + IGF-1]. Outcome measures included cell viability, altered matrix glycosaminoglycans (GAG) and collagens, multiplex-ELISA quantification of released cytokines, histopathology, and metabolomic and proteomic analyses of spent media. A 21-day study on ISS-NL explored PTOA-like pathogenesis and treatment in microgravity. Tissue cards for study groups were cultured in custom-built culture chambers within multi-use variable-g platforms (MVPs). A marked upregulation in the release of inflammatory cytokines and tissue-GAG loss was observed in CBS + INJ groups in space and ground controls utilizing tissues from the same donors, similar to that reported in a previous multi-donor study on Earth; these changes were partly ameliorated by Dex + IGF-1, but with donor variability. Metabolomic and proteomic analyses revealed an array of distinct differences between metabolites/proteins released to the medium in Space versus on Earth.

Surgical Outcomes of Laminectomy, Durotomy and a Non-Synthetic Dura Substitute Application in Ten Dogs with a Spinal Subarachnoid Diverticulum.

This retrospective study aimed to report the surgical treatment and outcomes of laminectomies followed by durotomy and the application of a non-synthetic collagen matrix dura substitute (DurepairTM) in ten dogs with a spinal subarachnoid diverticulum (SAD). The medical records of these ten client-owned dogs with SAD diagnosed by magnetic resonance imaging (MRI) were reviewed. All patients had chronic and progressive deficits. At presentation, common neurological signs were proprioceptive ataxia, ambulatory spastic paraparesis or tetraparesis, and faecal incontinence. Dorsal thoracolumbar laminectomy was performed in eight dogs; one dog underwent cervical dorsolateral laminectomy, and one patient had thoracic hemilaminectomy. Laminectomies were followed by durotomy, allowing the dissection of the pia-arachnoid adhesions. A rectangular patch of a non-synthetic dura substitute was applied as an onlay graft over the durotomy site before routine closure. Proprioceptive ataxia, paraparesis, and tetraparesis improved in all patients. Faecal incontinence in one patient resolved postoperatively. Laminectomy, durotomy, and the application of a non-synthetic dura substitute was a safe procedure facilitating postoperative improvement over a long-term follow-up period (from 9 to 40 months).

Effects of implant placement timingand type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical canine model.

To determine the effects of implant timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical model. Four implant placement protocols were randomly applied at the mesial root sites of the third and fourth mandibular premolars in 10 mongrel dogs: immediate placement (group IP), early placement (group EP), delayed placement with/without alveolar ridge preservation (groups ARP and DP, respectively). A connective-tissue graft (CTG) or porcine-derived volume-stable collagen matrix (VCMX) was applied to enhance the ridge profile (simultaneously with implant placement in group IP and staged for others), resulting in five sites for each combination. All dogs were sacrificed 3 months after soft-tissue grafting. Histological and histomorphometric analyses were performed, and the data were analysed descriptively. CTG and VCMX were difficult to differentiate from the augmented area. The median total tissue thickness on the buccal aspect of the implant was largest in group IP/CTG (between 2.78 and 3.87 mm). The soft-tissue thickness was generally favourable with CTG at all implant placement timings. Within the DP groups, CTG yielded statistically significantly larger total and soft-tissue thickness than VCMX (p < .05). Among the groups with VCMX, group EP/VCMX showed the largest soft-tissue thickness at apical levels to the implant shoulder. CTG generally led to greater tissue thickness than VCMX.

Nitric oxide nano-reactor DNMF/PLGA enables tumor vascular microenvironment and chemo-hyperthermia synergetic therapy

BackgroundBreast cancer ranks first among malignant tumors, of which triple-negative breast cancer (TNBC) is characterized by its highly invasive behavior and the worst prognosis. Timely diagnosis and precise treatment of TNBC are substantially challenging. Abnormal tumor vessels play a crucial role in TNBC progression and treatment. Nitric oxide (NO) regulates angiogenesis and maintains vascular homeostasis, while effective NO delivery can normalize the tumor vasculature. Accordingly, we have proposed here a tumor vascular microenvironment remodeling strategy based on NO-induced vessel normalization and extracellular matrix collagen degradation with multimodality imaging-guided nanoparticles against TNBC called DNMF/PLGA.ResultsNanoparticles were synthesized using a chemotherapeutic agent doxorubicin (DOX), a NO donor L-arginine (L-Arg), ultrasmall spinel ferrites (MnFe2O4), and a poly (lactic-co-glycolic acid) (PLGA) shell. Nanoparticle distribution in the tumor was accurately monitored in real-time through highly enhanced magnetic resonance imaging and photoacoustic imaging. Near-infrared irradiation of tumor cells revealed that MnFe2O4 catalyzes the production of a large amount of reactive oxygen species (ROS) from H2O2, resulting in a cascade catalysis of L-Arg to trigger NO production in the presence of ROS. In addition, DOX activates niacinamide adenine dinucleotide phosphate oxidase to generate and supply H2O2. The generated NO improves the vascular endothelial cell integrity and pericellular contractility to promote vessel normalization and induces the activation of endogenous matrix metalloproteinases (mainly MMP-1 and MMP-2) so as to promote extravascular collagen degradation, thereby providing an auxiliary mechanism for efficient nanoparticle delivery and DOX penetration. Moreover, the chemotherapeutic effect of DOX and the photothermal effect of MnFe2O4 served as a chemo-hyperthermia synergistic therapy against TNBC.ConclusionThe two therapeutic mechanisms, along with an auxiliary mechanism, were perfectly combined to enhance the therapeutic effects. Briefly, multimodality image-guided nanoparticles provide a reliable strategy for the potential application in the fight against TNBC.Graphical

Biodegradable polydioxanone stents: histologic and structural effects in an experimental model of tracheal stenosis.

To evaluate the biologic impact of polydioxanone (PDO) stenting in an animal model of inflammatory tracheal stenosis (TS). Additionally, to compare these results with those obtained in the same model without a stent and after placing one PDO stent in a healthy trachea. 40 adult NZ rabbits were distributed into 3 groups: Group A, 8 animals with a healthy trachea and a PDO stent; group B, 17 rabbits with a TS and no stent; and group C, 15 animals with TS and a PDO stent. Histopathological studies included Masson's trichrome staining for submucosal fibrosis and Safranin O to assess structural integrity of cartilage. Morphometric analyses were performed in the 3 groups. Stent placement was successful in every case. Histological studies did not show a significant increase in tracheal wall collagen area and cartilage structure was not modified in those rabbits with a PDO stent, even in a TS scenario. Stent implantation permitted recovery of normal tracheal lumen levels in the TS model. PDO stenting in the normal trachea and in a model of TS neither caused increase in the collagen matrix nor modification of the cartilaginous support. Additionally, radial force exhibited by PDO stents was effective in restoring normal tracheal lumen when placed in a stenotic lesion. These findings suggest that they may be safe and useful in the setting of an acquired TS.

Substrate Stiffness Modulates Stemness and Differentiation of Rabbit Corneal Endothelium Through the Paxillin-YAP Pathway.

To explore the role of substrate stiffness and the mechanism beneath corneal endothelial cells' (CECs') stemness maintenance and differentiation. CECs were divided into central zone (8mm trephined boundary) and peripheral zone (8mm trephined edge with attached limbal). Two zones were analyzed by hematoxylin-eosin staining and scanning electron microscopy for anatomic structure. The elastic modulus of Descemet's membrane (DM) was analyzed by atomic force microscopy. Compressed type I collagen gels with different stiffness were constructed as an in vitro model system to test the role of stiffness on phenotype using cultured rabbit CECs. Cell morphology, expression and intracellular distribution of Yes-associated protein (YAP), differentiation (ZO-1, Na+/K+-ATPase), stemness (FOXD3, CD34, Sox2, Oct3/4), and endothelial-mesenchymal transition (EnMT) markers were analyzed by immunofluorescence, quantitative RT-PCR, and Western blot. The results showed that the peripheral area of rabbit and human DM is softer than the central area ex vivo. Using the biomimetic extracellular matrix collagen gels in vitro model, we then demonstrated that soft substrate weakens the differentiation and EnMT in the culture of CECs. It was further proved by the inhibitor experiment that soft substrate enhances stemness maintenance via inhibition of paxillin-YAP signaling, which was activated on a stiff substrate. Our findings confirm that substrate stiffness modulates the stemness maintenance and differentiation of CECs and suggest a potential strategy for CEC-based corneal tissue engineering.

The role of Sirtuin 1 in regulation of fibrotic genes expression in pre-adipocytes.

Considering inhibition of pre-adipocyte cells differentiation in adipose tissue fibrosis, we aimed to explore whether Sirt1 and Hif-1α in pre-adipocytes have a significant effect on fibrotic gene expression. 3T3-L1 pre-adipocytes were transfected with SIRT1-specific siRNA, confirmed by real-time polymerase chain reaction (RT-PCR) and western blotting. Additionally, cells were treated with varying concentrations of resveratrol and sirtinol as the activator and inhibitor of Sirt1, respectively. Involvement of Hif-1α was evaluated by treatment with echinomycin. Subsequently, we assessed the gene and protein expressions related to fibrosis in the extracellular matrix of adipose tissue, including collagen VI (Col VI), lysyl oxidase (Lox), matrix metalloproteinase-2 (Mmp-2), Mmp-9, and osteopontin (Opn) in pre-adipocytes through RT-PCR and western blot. The current study demonstrated that Sirt1 knockdown and reduced enzyme activity significantly increased the expression of Col VI, Lox, Mmp-2, Mmp-9, and Opn genes in the treated 3T3-L1 cells compared to the control group. Interestingly, resveratrol significantly decreased the gene expression related to the fibrosis pathway. Inhibition of Hif-1α by echinomycin led to a significant reduction in Col VI, Mmp-2, and Mmp-9 gene expression in the treated group compared to the control. This study highlights that down-regulation of Sirt1 might be a predisposing factor in the emergence of adipose tissue fibrosis by enhancing the expression of extracellular matrix (ECM) components. Activation of Sirt1, similar to suppressing of Hif-1α in pre-adipocytes may be a beneficial approach for attenuating fibrotic gene expression. The online version contains supplementary material available at 10.1007/s40200-024-01389-4.

Sulfated hyaluronic acid/collagen-based biomimetic hybrid nanofiber skin for diabetic wound healing: Development and preliminary evaluation

Diabetic foot ulcers (DFUs) are one of the most serious and devastating complication of diabetes, manifesting as foot ulcers and impaired wound healing in patients with diabetes mellitus. To solve this problem, sulfated hyaluronic acid (SHA)/collagen-based nanofibrous biomimetic skins was developed and used to promote the diabetic wound healing and skin remodeling. First, SHA was successfully synthetized using chemical sulfation and incorporated into collagen (COL) matrix for preparing the SHA/COL hybrid nanofiber skins. The polyurethane (PU) was added into those hybrid scaffolds to make up the insufficient mechanical properties of SHA/COL nanofibers, the morphology, surface properties and degradation rate of hybrid nanofibers, as well as cell responses upon the nanofibrous scaffolds were studied to evaluate their potential for skin reconstruction. The results demonstrated that the SHA/COL, SHA/HA/COL hybrid nanofiber skins were stimulatory of cell behaviors, including a high proliferation rate and maintaining normal phenotypes of specific cells. Notably, SHA/COL and SHA/HA/COL hybrid nanofibers exhibited a significantly accelerated wound healing and a high skin remodeling effect in diabetic mice compared with the control group. Overall, SHA/COL-based hybrid scaffolds are promising candidates as biomimetic hybrid nanofiber skin for accelerating diabetic wound healing.

Degradable Nanohydroxyapatite-Reinforced Superglue for Rapid Bone Fixation and Promoted Osteogenesis.

Bone glue with robust adhesion is crucial for treating complicated bone fractures, but it remains a formidable challenge to develop a "true" bone glue with high adhesion strength, degradability, bioactivity, and satisfactory operation time in clinical scenarios. Herein, inspired by the hydroxyapatite and collagen matrix composition of natural bone, we constructed a nanohydroxyapatite (nHAP) reinforced osteogenic backbone-degradable superglue (O-BDSG) by in situ radical ring-opening polymerization. nHAP significantly enhances adhesive cohesion by synergistically acting as noncovalent connectors between polymer chains and increasing the molecular weight of the polymer matrix. Moreover, nHAP endows the glue with bioactivity to promote osteogenesis. The as-prepared glue presented a 9.79 MPa flexural adhesion strength for bone, 4.7 times that without nHAP, and significantly surpassed commercial cyanoacrylate (0.64 MPa). O-BDSG exhibited degradability with 51% mass loss after 6 months of implantation. In vivo critical defect and tibia fracture models demonstrated the promoted osteogenesis of the O-BDSG, with a regenerated bone volume of 75% and mechanical function restoration to 94% of the native tibia after 8 weeks. The glue can be flexibly adapted to clinical scenarios with a curing time window of about 3 min. This work shows promising prospects for clinical application in orthopedic surgery and may inspire the design and development of bone adhesives.

Gelatin but not type I collagen promotes bacteria phagocytosis in PMA-treated U937 human lymphoma cells

ABSTRACT Purpose Besides comprising scaffolding, extracellular matrix components modulate many biological processes including inflammation and cell differentiation. We previously found precoating cell plates with extracellular matrix collagen I, or its denatured product gelatin, causes aggregation of macrophage-like human lymphoma U937 cells, which are induced to differentiation by phorbol myristate treatment. In the present study, we investigated the influence of gelatin or collagen I precoating on the bacteria phagocytosis in PMA-stimulated U937 cells. Materials and Methods Colony forming units of phagocytosed bacteria, Giemsa-staining of cells with phagocytosed bacteria, confocal microscopic and flow cytometric analysis of cells with phagocytosed FITC-labeled bacteria and non-bioactive latex beats were conducted. Results Gelatin precoating enhances the phagocytosis of both Gram-negative and positive bacteria, as shown by the increased colony forming units of bacteria phagocytosed by cells, and increased intracellular bacteria observed after Giemsa-staining. But collagen I has no marked influence. Confocal microscopy reveals that both live and dead FITC-bacteria were phagocytosed more in the cells with gelatin-coating but not collagen-coating. Of note, both gelatin and collagen I coating had no influence on the phagocytosis of non-bioactive latex beads. Since gelatin-coating increases autophagy but collagen I has no such impact, we are curious about the role of autophagy. Inhibiting autophagy reduced the phagocytosis of bacteria, in cells with gelatin-coating, while stimulating autophagy enhanced phagocytosis. Conclusion This study finds the bacteria-phagocytosis stimulatory effect of gelatin in PMA-treated U937 cells and reveals the positive regulatory role of autophagy, predicting the potential use of gelatin products in anti-bacterial therapy.

A standardized wound infection model for antimicrobial testing of wound dressings in vitro.

To investigate the effectiveness of antimicrobial agents against wound infections, experiments using either 2D cultures with planktonic microorganisms or animal infection models are frequently carried out. However, the transferability of the results to human skin is limited by the lack of complexity of the 2D models or by the poor translation of the results from animal models. Hence, there is a need for wound infection models capable of assessing antimicrobial agents. In this study, an easily standardized wound infection model was established. This model consists of a mechanically wounded human skin model on a collagen matrix infected with various clinically relevant bacteria. Infection of the model led to recognition of the pathogens and induction of an inflammatory response. The untreated infection spread over time, causing significant tissue damage. By applying an antimicrobial-releasing wound dressing, the bacterial load could be reduced and the success of the treatment could be further measured by a decrease in the inflammatory reaction. In conclusion, this wound infection model can be used to evaluate new antimicrobial therapeutics as well as to study host-pathogen interactions.

Giant Intracranial Cavernous Malformations: A Review on Magnetic Resonance Imaging Characteristics.

Background Intracranial cavernous malformations (CMs), commonly known as cavernomas or cavernous angiomas, are low-flow, well-circumscribed vascular lesions composed of sinusoidal spaces lined by a single layer of endothelium and separated by a collagenous matrix without elastin, smooth muscle, or other vascular wall elements. A diameter greater than 3 cm for a CM is unlikely. These lesions may have atypical appearances on magnetic resonance imaging (MRI). MRI with advanced techniques such as a susceptibility-weighted image or T2-gradient echo, a diffusion-weighted image and corresponding apparent diffusion coefficient map, and diffusion tensor tractography have revolutionized the diagnostic approach to these lesions. Materials and Method The present study reviews the etiopathogenesis, clinical manifestations, MRI strategy, and MRI appearances of the CMs, with a few examples of the giant CMs from our archive. Results Intracranial giant CMs may have unexpected locations, sizes, numbers, and varied imaging appearances due to repeated hemorrhages, unusual enhancement patterns, intense perifocal edema, and unusual associations, making the differential diagnosis difficult. Conclusion Familiarity with the MRI appearances of the giant intracranial CMs and the differential diagnosis improves diagnostic accuracy and patient management.