Regulation Of Cell Fate By Smart Nanomaterials For Biomedical Applications

Smart nanomaterials can respond to biological endogenous environmental factors(pH,osmotic pressure,enzyme,redox,etc.)and exogenous environmental stimuli(ultrasonic,light,mechanical force,electricity,temperature,magnetic field,etc.)and generate dynamic changes in physical and chemical properties.Smart nanomaterials have been widely used in tissue engineering,immune modulation,tumor theranostics,and drug delivery,due to their outstanding nanoscale,targeting,controllable,and localized properties.Cell fate is a general term including cell proliferation,differentiation,aging,death,etc.Cells can respond to environmental signals and adjust their fate decision,and cell fate is also an important part of biomedical applications for disease treatment.In recent years,great progress has been made in the investigations on cell fate regulation by nanoparticles or scaffold materials with various structures and functions.However,most of these materials are non-stimuli-responsive with low intelligence and poor safety for long-term application in vivo.Therefore,in view of the characteristics of endogenous biochemical factors and exogenous physical stimulation,it is urgent to design a variety of smart nanomaterials with endogenous environmental response and exogenous stimulus response to regulate cell fate more accurately,efficiently and controllable.In this dissertation,the author uses several active polyphenols for designation of endogenous environmental responsive smart materials and exogenous environmental stimuli-responsive piezoelectric materials with ultrasound stimulation,and investigates these materials-mediated biochemical signals and physical signals for cell fate regulation,respectively.In vivo experiments are conducted to explore the further biomedical application.This dissertation mainly includes the following aspects:(1)pH-responsive iron-polyphenol smart nanoparticles for the promotion of osteogenic differentiation and exerting an immunomodulatory role in bone tissue repair.Mesenchymal stem cells with self-renewal and oriented differentiation ability play an important role in bone defect repair.Due to the urgent need of bone tissue engineering,osteogenesis of stem cells is more expected rather than adipogenesis,which is also one of important research areas in bone tissue engineering.In addition,there are a large number of inflammatory cells infiltration in bone defect area,such as pro-inflammatory(M1)macrophages,resulting in excessive inflammatory immune microenvironment,which impairs bone tissue repair and regeneration.Therefore,it is of great significance to design multifunctional smart nanomaterials with bone regeneration/adipogenesis inhibition and synergistic immune regulation to accelerate bone repair.To meet these requirements,a simple and efficient self-assembly method of ferric ion-catechin coordination is used to synthesize biological endogenous pH-responsive Fe-cat smart nanoparticles with various biological functions.After uptake by cells,the nanoparticles exhibit pH-responsive disassembly and release functional catechin molecules in the weak acid environment of lysosomes.Fe-cat nanoparticles can regulate the fate of stem cells and immune cells,promote the osteogenic differentiation of human adipose-derived stem cells and inhibit their adipogenic differentiation,and inhibit the inflammatory response of macrophages.Fe-cat nanoparticles promote subcutaneous ectopic osteogenesis in nude mice,and also effectively inhibit chronic inflammation in rat femur defect model and promote femoral tissue regeneration.Therefore,a non-toxic,degradable and low-cost bioendogenous environment-responsive smart nanomaterial is proposed in this project,which has a broad application prospect in bone tissue engineering and further clinical translation.It can be used as living cell-filling material and bone scaffold material with promoting osteogenic/inhibiting adipogenic abilities.This principle of pH-responsiveness can also be applied to the design other agents.Solid-phase multifunctional smart nano-biomaterials can be fabricated by the combination of the different active components,and then intervention can be conducted according to different characteristics of the disease to obtain better therapeutic effects.(2)pH-responsive iron-polyphenol ultrasmall smart nanocarriers for the delivery of nicotinamide adenine dinucleotide(NAD+)to reverse inflammation in the treatment of acute kidney injury(AKI).Base on the principle of organic-inorganic coordination for synthesizing iron-polyphenols nanoparticles,it is proposed to combine gallic acid(GA)and NAD+to form organic ligands,and prepare GA-NAD ultrasmall nanoparticles loaded with NAD+by metal-organic coordination assembly.This strategy improves the utilization of GA and NAD+molecules,combines with their high anti-inflammatory effect and physiological regulation of kidney by fabricating multifunctional smart nano-biomaterials,to achieve the reversal of the acute inflammatory response and the treatment of AKI.The ultrasmall size of Ga-NAD nanoparticles facilitates their transport from the glomerulus to the site of injured renal tubule and can release NAD+molecules in the weak acid environment of acute inflammation,supplementing the intracellular level of NAD+ and reversing the death of renal tubular epithelial cells.GA-NAD ultrasmall nanoparticles can also regulate the fate of macrophages,and inhibit their inflammatory response.In addition,GA-NAD ultrasmall nanoparticles treat ischemia-reperfusion induced AKI by suppressing acute inflammation and restoring mitochondrial function in vivo.This study provides a simple and efficient strategy for acute inflammation treatment.GA-NAD nanoparticles are degradable and easy to be obtained in large quantities,and have a low administration dose in animal experiments,which have great advantages in clinical translation.(3)Glutathione(GSH)-responsive polyphenol smart nanoplatforms for the treatment of malignant brain tumors and the promotion of neural differentiation.The anti-tumor and neuroprotective effects of polyphenols provide ideas for the design of polyphenols-based smart nanomaterials for cancer therapy.However,many reported polyphenols-based smart nanomaterials for tumor treatment depend on the metal-organic ligand,and metal ions may cause side effects on tissues,especially in the complex neural system.Therefore,to solve neuro-related diseases such as glioma,a metal-free strategy is proposed to synthesize Cys-EGCG nanoparticles by condensation of epigallocatechin gallate(EGCG)with amines containing disulphide bonds to achieve smart GSH-responsive disassembly in tumor cells and healthy cells.The nanoparticles not only selectively kill tumor cells,but also have good compatibility with stem cells,can regulate the fate of neural stem cells and inhibit the growth of glioblastoma in animals.The Cys-EGCG nanoparticles improve the utilization and intelligence of EGCG functional molecules and avoid the interference of metal ions on the metabolism of the nervous system,which is expected to be widely used in the treatment of nerve tumors and synergistic repair of glioma-caused nerve damage.(4)Ultrasound-driven piezoelectric P-PVDF smart discharge for promoting the pro-inflammatory phenotype polarization of macrophages.The aforementioned smart nanomaterials with endogenous environmental response have improved the utilization and intelligence of polyphenol functional molecules.However,the utilization of these smart nanomaterials is limited by specific factors,such as the strength of endogenous environmental signals.A high concentration of these nanomaterials administration may cause changes in endogenous environmental signal level,affecting the smart response ability of materials or metabolic homeostasis.Therefore,exogenous stimuli-responsive smart nanomaterials can provide more stable physical signals to stimulate cells and regulate cell fate.Nanostructure-mediated physical signals have been widely used to regulate the fate of stem cells,but few studies have focused on the role of electrical stimulation on the polarization of macrophages.In this part,ultrasound is used to drive piezoelectric β-PVDF film to generate smart charge release.Next,the author explores the effect of electrical signals on macrophages fate decision,and discusses the underlying mechanism.Ultrasound treatment significantly promotes the polarization of macrophages on β-PVDF film to a pro-inflammatory phenotype,during which electrical signals activates calcium influx through voltage-gated ion channels and promotes the expression of pro-inflammatory factors through Ca2+-CAMK2A-NF-κB signaling pathway.In addition,polarized macrophages can significantly inhibit the activity and proliferation of tumor cells.In this study,it is proposed to meditate wireless electrical signals by exogenously stimuli-responsive piezoelectric materials with ultrasound driven,revealing the central role of electrical signals in macrophages fate decision,and driving macrophage inflammatory response in an accurate,controllable,non-invasive and smart manner.This strategy is expected to provide a remote,non-contact electrical regulation technology for the immune cell electrogenetics,opens up a novel tumor immunotherapy method,and has a certain guiding significance for the treatment of voltage-gated ion channel related diseases.In summary,it is dedicated to explore the design of smart nanomaterials and their mediated-biochemical or physical response on regulating cell fate in this dissertation,offers a new thought and method for regulating cell fate.It also provides new sights into tissue injury,inflammation,and tumor diseases treatment by a nanoscale,targeting,controllable and localized strategy.