Adhesion Of Cells Research Articles

A Novel Strategy for Fabrication of Polyamide 66/Nanohydroxyapatite Composite Bone Repair Scaffolds by Low-Temperature Three-Dimensional Printing.

Due to the decomposition temperature of Polyamide 66 (PA66) in the environment is close to its thermoforming temperature, it is difficult to construct porous scaffolds of PA66/nanohydroxyapatite (PA66/HAp) by fused deposition modeling (FDM) three-dimensional (3D) printing. In this study, we demonstrated for the first time a method for 3D printing PA66/HAp composites at room temperature, prepared PA66/HAp printing ink using a mixed solvent of formic acid/dichloromethane (FA/DCM), and constructed a series of composite scaffolds with varying HAp content. This printing system can print composite materials with a high HAp content of 60 wt %, which is close to the mineral content in natural bone. The physicochemical evaluation presented that the hydroxyapatite was uniformly distributed within the PA66 matrix, and the PA66/HAp composite scaffold with 30 wt % HAp content exhibited optimal mechanical properties and printability. The results of in vitro cell culture experiments indicated that the incorporation of HAp into the PA66 matrix significantly improved the cell adhesion, proliferation, and osteogenic differentiation of bone marrow stromal cells (BMSCs) cultured on the scaffold. In vivo animal experiments suggested that the PA66/HAp composite material with 30 wt % HAp content had the best structural maintenance and osteogenic performance. The three-dimensional PA66/HAp composite scaffold prepared by low temperature printing in the current study holds great potential for the repair of large-area bone defects.

Layer-by-layer self-assembly of PLL/CPP-ACP multilayer on SLA titanium surface: Enhancing osseointegration and antibacterial activity in vitro and in vivo

Dental Implants are expected to possess both excellent osteointegration and antibacterial activity because poor osseointegration and infection are two major causes of titanium implant failure. In this study, we constructed layer-by-layer self-assembly films consisting of anionic casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) and cationic poly (L-lysine) (PLL) on sandblasted and acid etched (SLA) titanium surfaces and evaluated their osseointegration and antibacterial performance in vitro and in vivo. The surface properties were examined, including microstructure, elemental composition, wettability, and Ca2+ ion release. The impact the surfaces had on the adhesion, proliferation and differentiation abilities of MC3T3-E1 cells were investigated, as well as the material’s antibacterial performance after exposure to the oral microorganisms such as Porphyromonas gingivalis (P. g) and Actinobacillus actinomycetemcomitans (A. a). For the in vivo studies, SLA and Ti (PLL/CA-3.0)10 implants were inserted into the extraction socket immediately after extracting the rabbit mandibular anterior teeth with or without exposure to mixed bacteria solution (P. g & A. a). Three rabbits in each group were sacrificed to collect samples at 2, 4, and 6 weeks of post-implantation, respectively. Radiographic and histomorphometry examinations were performed to evaluate the implant osseointegration. The modified titanium surfaces were successfully prepared and appeared as a compact nano-structure with high hydrophilicity. In particular, the Ti (PLL/CA-3.0)10 surface was able to continuously release Ca2+ ions. From the in vitro and in vivo studies, the modified titanium surfaces expressed enhanced osteogenic and antibacterial properties. Hence, the PLL/CPP-ACP multilayer coating on titanium surfaces was constructed via a layer-by-layer self-assembly technology, possibly improving the biofunctionalization of Ti-based dental implants.

Acoustofluidics enables direct ink writing of vascular scaffolds with intrinsically patterned porous microstructures

Vascular scaffolds with well-organized pore characteristics are crucial for promoting infiltration, adhesion, growth, tissue-specific arrangement, and substance-exchanges of biological cells. However, their controllable fabrication is extremely challenging, especially for those with specially designed three-dimensional (3D) tubular and porous microstructures. In this paper, a new methodology based on acoustofluidics-assisted direct ink writing (DIW) technique is developed to fabricate vascular scaffolds with controlled porosity distributions and well-defined porous microstructures. Calcium carbonate (CaCO3) particles and alginate are uniformly mixed as the printing ink, which is printed along a rotating rod to form a vessel-like structure. Distributions of these CaCO3 particles in the printed structure are precisely controlled using bulk acoustic waves. The particles within the vessel-like structure are dissolved in situ using hydrochloric acid, resulting in the formation of 3D vascular scaffolds with intrinsically patterned porous microstructures. The scaffolds printed by the acoustofluidics-assisted DIW method exhibit a 69% improvement in pore connectivity compared to conventional 3D-printed scaffolds. Fibroblast cells are successfully seeded onto these scaffolds, achieving distinctive distributions along the patterned porous microstructures. This innovative methodology, with its excellent microfabrication capabilities, holds great promise for applications in tissue engineering, drug release, composite formation, microfluidic chips, and biosensors.

Investigations on microstructure and properties of five TiZr-based refractory multi-principal element alloys for clinical metallic biomaterials

The development of new materials with high strength, ductility, low modulus, wear resistance, and good biocompatibility remains a requirement in the field of clinical biomaterials. Based on the concept of high-entropy alloys, five TiZr-based refractory multi-principal element alloys (RMPEAs), i.e. MoTiZr, NbTiZr, MoTiVZr, NbTiVZr, and NbMoTiZr were designed and their microstructure, mechanical properties, elastic properties, and biocompatibility were assessed in this study. Results indicate that NbTiZr and NbTiVZr RMPEAs are single-phase BCC alloys, while the other alloys exhibit multiphase structures. In terms of mechanical behaviors, NbMoTiZr RMPEA has the highest hardness (496±15 HV) among the five alloys and also combines a high yield strength and good ductility, with values of 1275 MPa and 21.66%, respectively. According to atomic calculations, the ideal shear strengths of the five alloys on the {110} plane are all lower than those on the {112} plane. Furthermore, NbMoTiZr RMPEA also exhibits a lower Young’s modulus than that of Ti6Al4V, which can reduce “stress shielding” effects. The in vitro biocompatibility evaluation revealed that NbMoTiZr RMPEA can support cell adhesion and proliferation of MC3T3-E1 cells and exhibits good biocompatibility comparable to Ti6Al4V. These results demonstrate the remarkable potential of NbMoTiZr RMPEA for orthopedic bioimplant applications.

In situ densification and heparin immobilization of bacterial cellulose vascular patch for potential vascular applications

Nowadays, developing vascular grafts (e.g., vascular patches and tubular grafts) is challenging. Bacterial cellulose (BC) with 3D fibrous network has been widely investigated for vascular applications. In this work, different from BC vascular patch cultured with the routine culture medium, dopamine (DA)-containing culture medium is employed to in situ synthesize dense BC fibrous structure with significantly increased fiber diameter and density. Simultaneously, BC fibers are modified by DA during in situ synthesis process. Then DA on BC fibers can self-polymerize into polydopamine (PDA) accompanied with the removal of bacteria in NaOH solution, obtaining PDA-modified dense BC (PDBC) vascular patch. Heparin (Hep) is subsequently covalently immobilized on PDBC fibers to form Hep-immobilized PDBC (Hep@PDBC) vascular patch. The obtained results indicate that Hep@PDBC vascular patch exhibits remarkable tensile and burst strength due to its dense fibrous structure. More importantly, compared with BC and PDBC vascular patches, Hep@PDBC vascular patch not only displays reduced platelet adhesion and improved anticoagulation activity, but also promotes the proliferation, adhesion, spreading, and protein expression of human umbilical vein endothelial cells, contributing to the endothelialization process. The combined strategy of in situ densification and Hep immobilization provides a feasible guidance for the construction of BC-based vascular patches.

UFM1 inhibits hypoxia-induced angiogenesis via promoting proteasome degradation of HIF-1α.

Angiogenesis is crucial for blood flow recovery and ischemic tissue repair of peripheral artery disease (PAD). Exploration of new mechanisms underlying angiogenesis will shed light on the treatment of PAD. Ubiquitin-fold modifier 1 (UFM1), a newly identified ubiquitin-like molecule, has been discovered to be involved in various pathophysiological processes. However, the role of UFM1 in the pathogenesis of PAD, especially in endothelial angiogenesis remains obscure, and we aimed to clarify this issue in this study. We initially found UFM1 was significantly upregulated in gastrocnemius muscles of PAD patients and hind limb ischemia mice. And UFM1 was mainly colocalized with endothelial cells in ischemic muscle tissues. Further, elevated expression of UFM1 was observed in hypoxic endothelial cells. Subsequent genetic inhibition of UFM1 dramatically enhanced migration, invasion, adhesion, and tube formation of endothelial cells under hypoxia. Mechanistically, UFM1 reduced the stability of hypoxia-inducible factor-1α (HIF-1α) and promoted the von Hippel-Lindau-mediated K48-linked ubiquitin-proteasome degradation of HIF-1α, which in turn decreased angiogenic factor VEGFA expression and suppressed VEGFA related signaling pathway. Consistently, overexpression of UFM1 inhibited the angiogenesis of endothelial cells under hypoxic conditions, whereas overexpression of HIF-1α reversed this effect. Collectively, our data reveal that UFM1 inhibits the angiogenesis of endothelial cells under hypoxia through promoting ubiquitin-proteasome degradation of HIF-1α, suggesting UFM1 might serve as a potential therapeutic target for PAD.

Anodic oxidation- and hydrogenation-produced TiO2 nanotubes on titanium and its effect on gingival epithelial cell adhesion ability

The gingival epithelium plays a crucial role in achieving long-term stability of dental implants, and the hydrogenated TiO2 nanotubes with a superhydrophilic surface exhibit more excellent biological activity than pure titanium implants. However, the effects of the hydrogenated TiO2 nanotubes on human gingival epithelial cells remain unclear. Here, we fabricated hydrogenated TiO2 nanotubes using anodization and hydrogenation to investigate the adhesion of human gingival epithelial cells (HGEs) on structured surfaces in vitro. The topography, roughness, and wettability of three sample types—titanium (Ti), TiO2 nanotubes (TNTs), and hydrogenated TiO2 nanotubes (H2-TNTs)—were characterized. To evaluate cell adhesion, the HGEs were co-cultured with these specimens. This allowed for the examination of both the adhesion morphology and the number of cells adhering to each material’s surface. Expression levels of genes and proteins related to cell adhesion were also assessed. H2-TNTs demonstrated nanoscale topography similar to TNTs in terms of diameter and height and maintained a superhydrophilic surface (with a static water contact angle of < 5°). The number of HGEs adhering to H2-TNTs was notably higher. Furthermore, HGEs on H2-TNTs displayed a more stretched morphology in comparison to the other two groups. Notably, the expression levels of adhesion-related genes and proteins in H2-TNTs surpassed those of the other two groups. Hence superhydrophilic H2-TNTs significantly enhance the adhesion ability of HGEs on the material surface.

A comparative study of 3D-printed scaffolds fabricated from different hydroxyapatite sources for bone tissue engineering applications

As a naturally occurring mineral component of bone, hydroxyapatite (HA) is a preferred bone-repair material in clinical medicine. This adaptable biomaterial is developed from synthetic or biological sources. The goal of this study was to investigate the physicochemical and biological properties of scaffolds made from diverse hydroxyapatite sources. We prepared hydroxyapatite powders either from naturally occurring sources, using decellularized bone extracellular matrix (DBECM) and deproteinized bovine bone (DBB), or in the laboratory using the co-precipitation method. Although XRD analysis confirmed the pure phase of HA in all three powders, XRF data found some other trace elements in bone-derived biomaterials, such as magnesium and strontium. Further, FTIR spectra showed DBECM-associated macromolecule peaks. In the second phase of this study, the particles were mixed with sodium alginate to produce bioink for 3D printing via extrusion. SEM photographs of the printed scaffolds showed a grid-like porous structure with large, interconnected pores. Although all of the scaffolds retained their structural integrity after 28 days submerged in the culture medium, DBECM-based scaffolds degraded the most. The test of Young’s modulus and compressive strength of scaffolds revealed that all scaffolds are strong enough to be employed in non-weight-bearing applications. The biological characteristics of the scaffolds were then evaluated via cytotoxicity analysis, SEM examination of cell attachment, MTT assay, ALP activity assessment, immunofluorescence staining, and Alizarin red staining. The results indicated that all three scaffolds provided a surface that promoted adhesion and proliferation of rat bone marrow mesenchymal stem cells (rMSCs), as well as stimulated the production of mineralized extracellular matrices. Additionally, our findings showed that scaffolds made from DBECM powders offer the best environment for cell activity. This is most likely due to the presence of trace elements and protein macromolecules in DBECM powders that are not found in DBB and synthetic HA. In conclusion, our comparative study revealed that while all three scaffolds are suitable for bone tissue engineering, DBECM-based scaffolds outperform DBB and synthetic HA.

Glucopeptide Superstructure Hydrogel Promotes Surgical Wound Healing Following Neoadjuvant Radiotherapy by Producing NO and Anticellular Senescence.

Neoadjuvant radiotherapy, a preoperative intervention regimen for reducing the stage of primary tumors and surgical margins, has gained increasing attention in the past decade. However, radiation-induced skin damage during neoadjuvant radiotherapy exacerbates surgical injury, remarkably increasing the risk of refractory wounds and compromising the therapeutic effects. Radiation impedes wound healing by increasing the production of reactive oxygen species and inducing cell apoptosis and senescence. Here, a self-assembling peptide (R-peptide) and hyaluronic-acid (HA)-based and cordycepin-loaded superstructure hydrogel is prepared for surgical incision healing after neoadjuvant radiotherapy. Results show that i) R-peptide coassembles with HA to form biomimetic fiber bundle microstructure, in which R-peptide drives the assembly of single fiber through π-π stacking and other forces and HA, as a single fiber adhesive, facilitates bunching through electrostatic interactions. ii) The biomimetic superstructure contributes to the adhesion and proliferation of cells in the surgical wound. iii) Aldehyde-modified HA provides dynamic covalent binding sites for cordycepin to achieve responsive release, inhibiting radiation-induced cellular senescence. iv) Arginine in the peptides provides antioxidant capacity and a substrate for the endogenous production of nitric oxide to promote wound healing and angiogenesis of surgical wounds after neoadjuvant radiotherapy.

Physicochemical and biological characterization of propolis-loaded composite polyamide-6/soybean protein nanofibers for wound healing applications

Dressings are pivotal in aiding wound recovery, yet they are burdened by significant constraints. In addition to possessing antibacterial properties, the effectiveness of a wound dressing must be rigorously assessed for its potential utility across diverse medical applications. Propolis (Pro) is widely acknowledged for its antioxidant, antibacterial, and anti-inflammatory properties, positioning it as a promising candidate for wound healing and tissue engineering applications. This study presents a novel composite nanofiber (NF) material comprising polyamide-6 (PA6) and soybean protein as matrix components, incorporating Pro as a payload. We aimed to mimic the extracellular matrix, thus promotion the proliferation and adhesion of mouse embryonic fibroblast cells (NIH3T3) on the scaffold's surface. The morphology and composition of the NFs, examined through scanning electron microscopy (SEM) imaging and Fourier-transform infrared (FTIR) spectroscopy. The Pro-loaded fibers exhibited diameters ranging from 102 to 270 nm. Notably, the NFs demonstrated a dose-dependent increase in porosity, water vapor transmission rate, and fluid uptake capacity. However, the hydrophilic categorized nanofibers (NFs) did not exhibit a concentration-dependent effect on contact angle measurements. After a 15-day period, the Pro-loaded fibers experienced degradation within the range of 39–53 %. Using UV–visible spectrophotometry, the amount of pro released was measured. The rates of release were found to be 29.93 %, 41.02 %, and 60.06 % within 24 h for PA6/Soy/Pro5 %, PA6/Soy/Pro10 %, and PA6/Soy/Pro20 % NFs, respectively. Importantly, our study showcased the significant inhibitory effects of Pro-loaded fibers on the growth of E. coli and S. aureus, with inhibition increasing proportionally with higher Pro concentrations. This observation underscores the potential of Pro-based composite NFs as effective antimicrobial agents for wound dressings and tissue scaffolds. Furthermore, the biocompatibility of the fabricated nanofibrous mats was confirmed through the MTT test, affirming the non-toxic nature of all formulations. SEM imaging further demonstrated the optimal adhesion of cells on the NFs, confirming the findings of the MTT test and highlighting the suitability of Pro-loaded NFs for cell attachment and proliferation.

Activating Angiogenesis and Immunoregulation to Propel Bone Regeneration via Deferoxamine-Laden Mg-Mediated Tantalum Oxide Nanoplatform.

Vascularization and inflammation management are essential for successful bone regeneration during the healing process of large bone defects assisted by artificial implants/fillers. Therefore, this study is devoted to the optimization of the osteogenic microenvironment for accelerated bone healing through rapid neovascularization and appropriate inflammation inhibition that were achieved by applying a tantalum oxide (TaO)-based nanoplatform carrying functional substances at the bone defect. Specifically, TaO mesoporous nanospheres were first constructed and then modified by functionalized metal ions (Mg2+) with the following deferoxamine (DFO) loading to obtain the final product simplified as DFO-Mg-TaO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the product was homogeneously dispersed hollow nanospheres with large specific surface areas and mesoporous shells suitable for loading Mg2+ and DFO. The biological assessments indicated that DFO-Mg-TaO could enhance the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The DFO released from DFO-Mg-TaO promoted angiogenetic activity by upregulating the expressions of hypoxia-inducible factor-1 (HIF-1α) and vascular endothelial growth factor (VEGF). Notably, DFO-Mg-TaO also displayed anti-inflammatory activity by reducing the expressions of pro-inflammatory factors, benefiting from the release of bioactive Mg2+. In vivo experiments demonstrated that DFO-Mg-TaO integrated with vascular regenerative, anti-inflammatory, and osteogenic activities significantly accelerated the reconstruction of bone defects. Our findings suggest that the optimized DFO-Mg-TaO nanospheres are promising as multifunctional fillers to speed up the bone healing process.

Cobalt-containing calcium silicate nanowires incorporated scaffolds for the repair of osteochondral defect induced by chondrosarcoma

Considering the difficulty in the treatment of chondrosarcoma in clinic, multifunctional composite hydrogel scaffolds were designed with excellent photothermal ability for the regeneration of damaged bone and cartilage tissue. The chitosan solution/polyvinyl alcohol (CP) hydrogels with different contents of cobalt doped calcium silicate (Co-CSH) nanowires were prepared via 3D printing method. Attributing to the excellent photothermal performance of Co-CSH nanowires, the average survival rate of human chondrosarcoma cells in the CP-5Co-13.4 % and CP-5Co-16.2 % scaffolds with near infrared laser irradiation was about 10.5 % and 9.9 %, respectively. At the same time, the prepared composite hydrogel scaffolds possessed satisfactory biocompatibility and could support the adhesion and spread of rabbit bone mesenchymal stem cells (rBMSCs) and rabbit chondrocytes in the hydrogel scaffolds, and further promoted the formation of new bone and cartilage tissue in vivo, on account of the stimulation effect of released bioactive ions. Therefore, the prepared composite hydrogel scaffolds is expected to provide a new therapeutic strategy for the postoperative adjuvant treatment of chondrosarcoma.

Reendothelialization of Acellular Adipose Flaps under Mimetic Physiological Dynamic Conditions.

The extensive soft-tissue defects resulting from trauma and tumors pose a prevalent challenge in clinical practice, characterized by a high incidence rate. Autologous tissue flap transplantation, considered the gold standard for treatment, is associated with various drawbacks, including the sacrifice of donor sources, postoperative complications, and limitations in surgical techniques, thereby impeding its widespread applicability. The emergence of tissue-engineered skin flaps, notably the acellular adipose flap (AAF), offers potential alternative solutions. However, a critical concern confronting large-scale tissue-engineered skin flaps currently revolves around the reendothelialization of internal vascular networks. In our study, we have developed an AAF utilizing perfusion decellularization, demonstrating excellent physical properties. Cytocompatibility experiments have confirmed its cellular safety, and cell adhesion experiments have revealed spatial specificity in facilitating endothelial cells adhesion within the adipose flap scaffold. Using a novel mimetic physiological fluid shear stress setting, endothelial cells were dynamically inoculated and cultured within the acellular vascular network of the pedicled AAF in our research. Histological and gene expression analyses have shown that the mimetic physiological fluid dynamic model significantly enhanced the reendothelialization of the AAF. This innovative platform of acellular adipose biomaterials combined with hydrodynamics may offer valuable insights for the design and manufacturing of 3D vascularized tissue constructs, which can be applied to the repair of extensive soft-tissue defects.

Cancer-Derived Small Extracellular Vesicles Affect Vascular Endothelial Cells and Promote Adhesiveness of Pancreatic Cancer Cells.

Pancreatic cancer (PC) is one of the most aggressive malignancies due to the high rate of metastasis. The mechanisms underlying metastasis need to be elucidated. Small extracellular vesicles (sEVs) mediate cell-to-cell communication, and cancer-derived sEVs contribute to the formation of premetastatic niches. The present study examined changes in adhesiveness by the internalization of PC-derived sEVs into vascular endothelial cells, and investigated the molecular mechanisms underlying metastasis. Pancreatic cancer-derived sEVs were internalized into vascular endothelial cells, and changes in adhesiveness were evaluated. We evaluated the effects of sEVs on the formation of liver metastasis in vivo. We also assessed molecular changes in vascular endothelial cells by the internalization of PC-derived sEVs. The internalization of PC-derived sEVs into vascular endothelial cells promoted the adhesiveness of vascular endothelial cells and PC cells. Pancreatic cancer-derived sEVs contained high levels of transforming growth factor β1 mRNA and acted as its transporter. Once PC-derived sEVs were internalized into vascular endothelial cells, the expression of fibronectin 1 increased on the cell surface, and the adhesiveness of vascular endothelial cells was enhanced. We investigated association between PC-derived sEVs and adhesiveness. Regulation of PC-derived sEVs has potential as a therapeutic modality to suppress the metastasis of PC.

Woodfordia fruticosa fermented with lactic acid bacteria impact on foodborne pathogens adhesion and cytokine production in HT-29 cells

Woodfordia fruticosa fermented with lactic acid bacteria impact on foodborne pathogens adhesion and cytokine production in HT-29 cells

Innovative Vancomycin-Loaded Hydrogel-Based Systems - New Opportunities for the Antibiotic Therapy.

Surgical site infections pose a significant challenge for medical services. Systemic antibiotics may be insufficient in preventing bacterial biofilm development. With the local administration of antibiotics, it is easier to minimize possible complications, achieve drugs' higher concentration at the injured site, as well as provide their more sustained release. Therefore, the main objective of the proposed herein studies was the fabrication and characterization of innovative hydrogel-based composites for local vancomycin (VAN) therapy. Presented systems are composed of ionically gelled chitosan particles loaded with vancomycin, embedded into biomimetic collagen/chitosan/hyaluronic acid-based hydrogels crosslinked with genipin and freeze-dried to serve in a flake/disc-like form. VAN-loaded carriers were characterized for their size, stability, and encapsulation efficiency (EE) using dynamic light scattering technique, zeta potential measurements, and UV-Vis spectroscopy, respectively. The synthesized composites were tested in terms of their physicochemical and biological features. Spherical structures with sizes of about 200 nm and encapsulation efficiencies reaching values of approximately 60% were obtained. It was found that the resulting particles exhibit stability over time. The antibacterial activity of the developed materials against Staphylococcus aureus was established. Moreover, in vitro cell culture study revealed that the surfaces of all prepared systems are biocompatible as they supported the proliferation and adhesion of the model MG-63 cells. In addition, we have demonstrated significantly prolonged VAN release while minimizing the initial burst effect for the composites compared to bare nanoparticles and verified their desired physicochemical features during swellability, and degradation experiments. It is expected that the developed herein system will enable direct delivery of the antibiotic at an exposed to infections surgical site, providing drugs sustained release and thus will reduce the risk of systemic toxicity. This strategy would both inhibit biofilm formation and accelerate the healing process.

AJAP1 Regulates Human Epithelial Cell Behaviors Required for Epicardium and EPDC Formation During Cardiac Development

Introduction: The epicardium forms the outermost layer of the heart. It is composed of a single layer of specialized epithelial cells that make important cellular contributions to cardiovascular development. During embryonic development, the epicardium is a source of multipotent progenitor cells, growth factors and extracellular matrix (ECM) components. The epicardium gives rise to multipotent epicardial-derived cells (EPDCs) which undergo epithelial-to-mesenchymal transition and differentiate into non-myocyte cardiac lineages. It is also a source of paracrine signals essential for myocardial growth and coronary vessel formation that become dormant after gestation. Adult epicardial cells can be reactivated in response to myocardial injury or ischemia to express a fetal gene program for regenerative cardiac repair. The drive to harness epicardial cells for cardiac regeneration is tethered to its roles in cardiovascular development. Thus, it is necessary to identify molecules that regulate epicardial cell behaviors required for epicardium formation and EPDC differentiation. Using our Tbx5-deficient mouse model of defective epicardium formation ( Tbx5epi−/−), we identified a transcript that is novel to the heart. Adherens junction associated protein 1 is a cell adhesion molecule that is encoded by the AJAP1 transcript which was downregulated in Tbx5epi−/− mice with impaired epicardium formation. Our preliminary studies revealed that AJAP is expressed in epithelial cells of the epicardium during heart development. Silencing of AJAP1 in primary cultured human epithelial cells reduces their ability to migrate. A role for AJAP1 in the epicardium during cardiac development remains to be identified. Study Objective: This study was designed to investigate the impact of AJAP1 on epithelial cell functions that are required for formation of the epicardium and differentiation of EPDCs. Methods: Studies were conducted in a primary human epithelial cell line, HMEpiC, which served as an in vitro model system to examine the contributions of AJAP1 to epithelial cell behaviors. HMEpiCs were transfected with small interfering RNAs (siRNAs) targeting either human AJAP1 to knock down its endogenous expression or a non-targeting negative control siRNA. AJAP1 knockdown was confirmed by quantitative PCR and immunofluorescence. We conducted assays on control and AJAP1 knockdown (KD) cells to examine the effects on epithelial cell behaviors contributing to epicardium formation and EPDC differentiation. This included analysis of cell proliferation, apoptosis, and adhesion to extracellular matrices. Results: Endogenous AJAP1 mRNA expression was reduced significantly by siRNA-mediated knockdown in human epithelial cells. We observed changes in cell morphology that correlated with a significant increase in apoptosis in AJAP1 KD cells compared to negative control cells. Proliferation of HMEpiCs was unchanged by AJAP1 knockdown. Also, we observed a significant increase in the adhesion of AJAP1 KD cells to certain extracellular matrices versus control cells. Conclusion: These findings provide evidence for the AJAP1 cell adhesion molecule to regulate epithelial cell behaviors that are crucial to formation of the epicardium and differentiation of EPDCs during cardiac development. PCOM Center for Chronic Disorders of Aging; PCOM Division of Research. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Osteo-angiogenic activity of a micro/nano hierarchical SrSi-codoped hydroxyapatite coating on zirconium alloy

Numerous studies highlight the significance of biomimetic metallic implant surfaces for enhancing osseointegration through synergistic regulation of osteogenesis-angiogenesis. However, achieving clinical demands through singular structural or compositional biomimicry poses challenges. Therefore, the integration of both structural and compositional biomimicry, to closely emulate the host bone surface, is crucial for maximizing the biological activity of metallic implants. We synthesized a micro/nano hierarchical SrSi-codoped hydroxyapatite coating on Zr16Nb12Ti alloy through a simple microarc oxidation-hydrothermal reaction. Results revealed that Si doping enhances hydroxyapatite (HA) growth along the c-axis, forming large-sized nanorods. However, co-doping of Sr and Si inhibits grain growth by reducing crystal growth freedom, yielding a finer HA nanowire coating (MH-SrSi). MH-SrSi exhibits outstanding hydrophilicity attributed to the finer HA nanowires on the coating surface, promoting the adhesion of proteins and cells. Additionally, the released Sr and Si from MH-SrSi stimulate the secretion of osteogenesis-related proteins in osteoblasts and angiogenesis-related factors in endothelial cells, exhibiting a synergistic effect on promoting osteogenesis and angiogenesis. In vivo evaluation mirrors these results and shows that the micro/nano hierarchical structures of MH-SrSi elicited inward bone growth. Overall, MH-SrSi, combining structural biomimicry and compositional biomimicry, exhibits excellent osseointegration capability, making it a promising candidate for implant materials.

Characteristics of the Antitumor Effect of Doxorubicin and Pegylated Hyaluronidase on Models of Rat Brain Tumors.

Hyaluronidase increases tissue permeability and diffusion of the extracellular fluid by cleaving hyaluronan, the primary component of the extracellular matrix. Hyaluronidase pegylation (Hyal-PEG) decreases its clearance and enhances biodistribution. The pro- and anticancer activity of Hyal-PEG and a combination of Hyal-PEG with doxorubicin were studied in vitro (morphological analysis of rat glioblastoma 101.8 spheroids) and in vivo (by the survival time of rats after intracerebral transplantation of the tumor and morphological analysis). In the presence of doxorubicin and Hyal-PEG in the culture medium in vitro, spheroids lost their ability to adhere to the substrate and disintegrate into individual cells. Intracerebral transplantation of the tumor tissue with Hyal-PEG did not accelerate glioblastoma growth. The mean survival time for animals receiving transplantation of the tumor alone and in combination with Hyal-PEG was 13 and 20 days, respectively. In one rat with transplanted tumor and Hyal-PEG, this parameter increased by 53%. The survival time of rats receiving systemic therapy with doxorubicin and Hyal-PEG significantly increased (p=0.003). Antitumor effect of therapeutic doses of doxorubicin combined with Hyal-PEG was demonstrated on the model of rat glioblastoma 101.8 in vitro. Hyal-PEG inhibited adhesion of tumor cells, but did not cause their death. Transplantation of Hyal-PEG-treated tumor did not reduce animal survival time. Systemic administration of therapeutic doses of doxorubicin with Hyal-PEG increased survival time of rats with glioblastoma 101.8.

The hemostatic performance and mechanism of palygorskite with structural regulate by oxalic acid gradient leaching

Palygorskite (Pal) is a naturally available one-dimensional clay mineral, featuring rod-shaped morphology, nanoporous structure, permanent negative charges as well as abundant surface hydroxyl groups, exhibiting promising potential as a natural hemostatic material. In this study, the hemostatic performance and mechanisms of Pal were systematically investigated based on the structural regulate induced by oxalic acid (OA) gradient leaching from perspectives of structure, surface attributes and ion release. In vitro and in vivo hemostasis evaluation showed that Pal with OA leaching for 1 h exhibited a superior blood procoagulant effect compared with the raw Pal as well as the others leached for prolonging time. This phenomenon might be ascribed to the synergistic effect of the intact nanorod-like morphology, the increase in the surface negative charge, the release of metal ions (Fe3+ and Mg2+), and the improved blood affinity, which promoted the intrinsic coagulation pathway, the fibrinogenesis and the adhesion of blood cells, thereby accelerating the formation of robust blood clots. This work is expected to provide experimental and theoretical basis for the construction of hemostatic biomaterials based on clay minerals.