Two-dimensional nanomaterials, an ultrathin class of materials such as graphene, nanoclays, transition metal dichalcogenides (TMDs), and transition metal oxides (TMOs), have emerged as a new ...generation of materials due to their unique properties relative to macroscale counterparts. However, little is known about the transcriptome dynamics following exposure to these nanomaterials. Here, we investigate the interactions of 2D nanosilicates, a layered clay, with human mesenchymal stem cells (hMSCs) at the wholetranscriptome level by high-throughput sequencing (RNA-seq). Analysis of cell–nanosilicate interactions by monitoring changes in transcriptome profile uncovered key biophysical and biochemical cellular pathways triggered by nanosilicates. A widespread alteration of genes was observed due to nanosilicate exposure as more than 4,000 genes were differentially expressed. The change in mRNA expression levels revealed clathrin-mediated endocytosis of nanosilicates. Nanosilicate attachment to the cell membrane and subsequent cellular internalization activated stress-responsive pathways such as mitogen-activated protein kinase (MAPK), which subsequently directed hMSC differentiation toward osteogenic and chondrogenic lineages. This study provides transcriptomic insight on the role of surface-mediated cellular signaling triggered by nanomaterials and enables development of nanomaterials-based therapeutics for regenerative medicine. This approach in understanding nanomaterial–cell interactions illustrates how change in transcriptomic profile can predict downstream effects following nanomaterial treatment.
Despite bone’s impressive ability to heal after traumatic injuries and fractures, a significant need still exists for developing strategies to promote healing of nonunion defects. To address this ...issue, we developed collagen-based hydrogels containing two-dimensional nanosilicates. Nanosilicates are ultrathin nanomaterials with a high degree of anisotropy and functionality that results in enhanced surface interactions with biological entities compared to their respective three-dimensional counterparts. The addition of nanosilicates resulted in a 4-fold increase in compressive modulus along with an increase in pore size compared to collagen-based hydrogels. In vitro evaluation indicated that the nanocomposite hydrogels are capable of promoting osteogenesis in the absence of any osteoinductive factors. A 3-fold increase in alkaline phosphatase activity and a 4-fold increase in the formation of a mineralized matrix were observed with the addition of the nanosilicates to the collagen-based hydrogels. Overall, these results demonstrate the multiple functions of nanosilicates conducive to the regeneration of bone in nonunion defects, including increased network stiffness and porosity, injectability, and enhanced mineralized matrix formation in a growth-factor-free microenvironment.
Bioprinting is an emerging additive manufacturing approach to the fabrication of patient-specific, implantable three-dimensional (3D) constructs for regenerative medicine. However, developing ...cell-compatible bioinks with high printability, structural stability, biodegradability, and bioactive characteristics is still a primary challenge for translating 3D bioprinting technology to preclinical and clinal models. To overcome this challenge, we developed a nanoengineered ionic covalent entanglement (NICE) bioink formulation for 3D bone bioprinting. The NICE bioinks allow precise control over printability, mechanical properties, and degradation characteristics, enabling custom 3D fabrication of mechanically resilient, cellularized structures. We demonstrate cell-induced remodeling of 3D bioprinted scaffolds over 60 days, demonstrating deposition of nascent extracellular matrix proteins. Interestingly, the bioprinted constructs induce endochondral differentiation of encapsulated human mesenchymal stem cells (hMSCs) in the absence of osteoinducing agent. Using next-generation transcriptome sequencing (RNA-seq) technology, we establish the role of nanosilicates, a bioactive component of NICE bioink, to stimulate endochondral differentiation at the transcriptome level. Overall, the osteoinductive bioink has the ability to induce formation of osteo-related mineralized extracellular matrix by encapsulated hMSCs in growth factor-free conditions. Furthermore, we demonstrate the ability of NICE bioink to fabricate patient-specific, implantable 3D scaffolds for repair of craniomaxillofacial bone defects. We envision development of this NICE bioink technology toward a realistic clinical process for 3D bioprinting patient-specific bone tissue for regenerative medicine.
•Fe3O4-RGO sheets shows higher drug loading efficiency due to surface area.•Efficient nanohybrid for drug delivery system for targeted therapy.•Magnetic nanohybrid shows excellent chemo-thermal ...therapy.
In this work, an efficient superparamagnetic iron oxide-reduced graphene oxide (Fe3O4-RGO) nanohybrid has been synthesized following one-step co-precipitation method. The phase identification, microstructure and magnetic behavior of nanohybrid were characterized by X-ray diffraction, transmission electron microscopy (TEM), raman spectroscopy and vibrating sample magnetometer (VSM), respectively. TEM micrograph confirms the presence of well-segregated Fe3O4 nanoparticles in RGO layers. The layered RGO minimizes the agglomeration in Fe3O4 nanoparticles with slight reduction in magnetic behavior. Doxorubicin (DOX) has been used as a model drug to investigate the loading efficiency of nanohybrid and chemo-thermo therapeutic effect on human cervical cancer (HeLa cells). The DOX loaded nanohybrid (DOX-Fe3O4-RGO) shows maximum inhibition of human cervical cancer cell lines during magnetic field assisted hyperthermia treatment. The synergistic effect of nanohybrid demonstrated the potential for cancer cell proliferation prevention up to 90% when treated at the concentration of 2mgmL−1 for one million cells and exposed to AC field of 335 Oe at a fixed frequency of 265kHz for 35min.
Although hydrogels are able to mimic native tissue microenvironments, their utility for biomedical applications is severely hampered due to limited mechanical stiffness and low toughness. Despite ...recent progress in designing stiff and tough hydrogels, it is still challenging to achieve a cell-friendly, high modulus construct. Here, we report a highly efficient method to reinforce collagen-based hydrogels using extremely low concentrations of a nanoparticulate-reinforcing agent that acts as a cross-link epicenter. Extraordinarily, the addition of these nanoparticles at a 10 000-fold lower concentration relative to polymer resulted in a more than 10-fold increase in mechanical stiffness and a 20-fold increase in toughness. We attribute the high stiffness of the nanocomposite network to the chemical functionality of the nanoparticles, which enabled the cross-linking of multiple polymeric chains to the nanoparticle surface. The mechanical stiffness of the nanoengineered hydrogel can be tailored between 0.2 and 200 kPa simply by manipulating the size of the nanoparticles (4, 8, and 12 nm), as well as the concentrations of the nanoparticles and polymer. Moreover, cells can be easily encapsulated within the nanoparticulate-reinforced hydrogel network, showing high viability. In addition, encapsulated cells were able to sense and respond to matrix stiffness. Overall, these results demonstrate a facile approach to modulate the mechanical stiffness of collagen-based hydrogels and may have broad utility for various biomedical applications, including use as tissue-engineered scaffolds and cell/protein delivery vehicles.
The Epidermal Growth Factor Receptor (EGFR) signaling pathway plays a critical role in regulating tissue patterning. Drosophila EGFR signaling achieves specificity through multiple ligands and ...feedback loops to finetune signaling outcomes spatiotemporally. The principal Drosophila EGF ligand, cleaved Spitz, and the negative feedback regulator, Argos are diffusible and can act both in a cell autonomous and non-autonomous manner. The expression dose of Spitz and Argos early in photoreceptor cell fate determination has been shown to be critical in patterning the Drosophila eye, but the exact identity of the cells expressing these genes in the larval eye disc has been elusive. Using single molecule RNA Fluorescence in situ Hybridization (smFISH), we reveal an intriguing differential expression of spitz and argos mRNA in the Drosophila third instar eye imaginal disc indicative of directional non-autonomous EGFR signaling. By genetically tuning EGFR signaling, we show that rather than absolute levels of expression, the ratio of expression of spitz-to-argos to be a critical determinant of the final adult eye phenotype. Proximate effects on EGFR signaling in terms of cell cycle and differentiation markers are affected differently in the different perturbations. Proper ommatidial patterning is robust to thresholds around a tightly maintained wildtype spitz-to-argos ratio, and breaks down beyond. This provides a powerful instance of developmental buffering against gene expression fluctuations.
Reactive oxygen species (ROS) and mitochondrial defects in neurons are implicated in neurodegenerative disease. Here, we find that a key consequence of ROS and neuronal mitochondrial dysfunction is ...the accumulation of lipid droplets (LD) in glia. In Drosophila, ROS triggers c-Jun-N-terminal Kinase (JNK) and Sterol Regulatory Element Binding Protein (SREBP) activity in neurons leading to LD accumulation in glia prior to or at the onset of neurodegeneration. The accumulated lipids are peroxidated in the presence of ROS. Reducing LD accumulation in glia and lipid peroxidation via targeted lipase overexpression and/or lowering ROS significantly delays the onset of neurodegeneration. Furthermore, a similar pathway leads to glial LD accumulation in Ndufs4 mutant mice with neuronal mitochondrial defects, suggesting that LD accumulation following mitochondrial dysfunction is an evolutionarily conserved phenomenon, and represents an early, transient indicator and promoter of neurodegenerative disease.
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•Lipid droplets (LD) are transient and occur prior to neurodegeneration in flies and mice•LD are present in glia and induced by neuronal increase of ROS, JNK, and SREBP•Reduction of ROS by antioxidants, lipases, or lower JNK or SREBP, delay degeneration•Neurodegeneration in mice with ROS/lipid droplets can be delayed with antioxidants
Lipid droplet accumulation in glial cells, driven by mitochondrial defects and ROS in neurons, contribute to neurodegeneration in a Drosophila model, with evidence of a conserved mechanism in mice.
Our current understanding of the mechanical properties of nanostructured biomaterials is rather limited to invasive/destructive and low-throughput techniques such as atomic force microscopy, optical ...tweezers, and shear rheology. In this report, we demonstrate the capabilities of recently developed dual Brillouin/Raman spectroscopy to interrogate the mechanical and chemical properties of nanostructured hydrogel networks. The results obtained from Brillouin spectroscopy show an excellent correlation with the conventional uniaxial and shear mechanical testing. Moreover, it is confirmed that, unlike the macroscopic conventional mechanical measurement techniques, Brillouin spectroscopy can provide the elasticity characteristic of biomaterials at a mesoscale length, which is remarkably important for understanding complex cell–biomaterial interactions. The proposed technique experimentally demonstrated the capability of studying biomaterials in their natural environment and may facilitate future fabrication and inspection of biomaterials for various biomedical and biotechnological applications.
Two-dimensional (2D) molybdenum disulfide (MoS₂) nanomaterials are an emerging class of biomaterials that are photoresponsive at near-infrared wavelengths (NIR). Here, we demonstrate the ability of ...2D MoS₂ to modulate cellular functions of human stem cells through photothermal mechanisms. The interaction of MoS₂ and NIR stimulation of MoS₂ with human stem cells is investigated using whole-transcriptome sequencing (RNA-seq). Global gene expression profile of stem cells reveals significant influence of MoS₂ and NIR stimulation of MoS₂ on integrins, cellular migration, and wound healing. The combination of MoS₂ and NIR light may provide new approaches to regulate and direct these cellular functions for the purposes of regenerative medicine as well as cancer therapy.
Light‐responsive biomaterials are an emerging class of materials used for developing noninvasive, noncontact, precise, and controllable biomedical devices. Long‐wavelength near‐infrared (NIR) ...radiation is an attractive light source for in situ gelation due to its higher penetration depth and minimum side effects. The conventional approach to obtain crosslinked biomaterials relies heavily on the use of a photoinitiator by generating reactive species when exposed to short‐wavelength radiation, which is detrimental to surrounding cells and tissue. Here, a new class of NIR‐triggered in situ gelation system based on defect‐rich 2D molybdenum disulfide (MoS2) nanoassemblies and thiol‐functionalized thermoresponsive polymer in the absence of a photoinitiator is introduced. Exposure to NIR radiation activates the dynamic polymer–nanomaterials interactions by leveraging the photothermal characteristics of MoS2 and intrinsic phase transition ability of the thermoresponsive polymer. Specifically, upon NIR exposure, MoS2 acts as a crosslink epicenter by connecting with multiple polymeric chains via defect‐driven click chemistry. As a proof‐of‐concept, the utility of NIR‐triggered in situ gelation is demonstrated in vitro and in vivo. Additionally, the crosslinked gel exhibits the potential for NIR light‐responsive release of encapsulated therapeutics. These light‐responsive biomaterials have strong potential for a range of biomedical applications, including artificial muscle, smart actuators, 3D/4D printing, regenerative medicine, and therapeutic delivery.
Light‐triggered in situ gelation of nanoengineered hydrogels using 2D molybdenum disulfide (MoS2) nanoassemblies is demonstrated. The in situ gelation of nanoengineered hydrogels has strong potential for a range of biomedical applications, including phototherapy, 3D printing, and therapeutic delivery.
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