Water Transport-Induced Liquid-Liquid Phase Separation Facilitates Gelation for Controllable and Facile Fabrication of Physically Crosslinked Microgels.

Physically crosslinked microgels (PCMs) offer a biocompatible platform for various biomedical applications. However, current PCM fabrication methods suffer from their complexity and poor controllability, due to their reliance on altering physical conditions to initiate gelation and their dependence on specific materials. To address this issue, a novel PCM fabrication method is devised, which employs water transport-induced liquid-liquid phase separation (LLPS) to trigger the intermolecular interaction-supported sol-gel transition within aqueous emulsion droplets. This method enables the controllable and facile generation of PCMs through a single emulsification step, allowing for the facile production of PCMs with various materials and sizes, as well as controllable structures and mechanical properties. Moreover, this PCM fabrication method holds great promise for diverse biomedical applications. The interior of the PCM not only supports the encapsulation and proliferation of bacteria but also facilitates the encapsulation of eukaryotic cells after transforming the system into an all-aqueous emulsion. Furthermore, through appropriate surface functionalization, the PCMs effectively activate T cells in vitro upon coculturing. This work represents an advancement in PCM fabrication and offers new insights and perspectives for microgel engineering.

Biophysical cues of bone marrow-inspired scaffolds regulate hematopoiesis of hematopoietic stem and progenitor cells.

Hematopoietic stem cells (HSCs) are adult multipotential stem cells with the capacity to differentiate into all blood cells and immune cells, which are essential for maintaining hematopoietic homeostasis throughout the lifespan and reconstituting damaged hematopoietic system after myeloablation. However, the clinical application of HSCs is hindered by the imbalance of its self-renewal and differentiation during in vitro culture. Considering the fact that HSC fate is uniquely determined by natural bone marrow microenvironment, various elaborate cues in this hematopoietic micro-niche provide an excellent reference for the regulation of HSCs. Inspired by the bone marrow extracellular matrix (ECM) network, we designed degradable scaffolds by orchestrating the physical parameters to investigate the decoupling effects of Young's modulus and pore size of three-dimensional (3D) matrix materials on the fate of hematopoietic stem and progenitor cells (HSPCs). We ascertained that the scaffold with larger pore size (80 µm) and higher Young's modulus (70 kPa) was more favorable for HSPCs proliferation and the maintenance of stemness related phenotypes. Through in vivo transplantation, we further validated that scaffolds with higher Young's modulus were more propitious in maintaining the hematopoietic function of HSPCs. We systematically screened an optimized scaffold for HSPC culture which could significantly improve the cell function and self-renewal ability compared with traditional two-dimensional (2D) culture. Together, these results indicate the important role of biophysical cues in regulating HSC fate and pave the way for the parameter design of 3D HSC culture system.

Injectable bone marrow microniches by co-culture of HSPCs with MSCs in 3D microscaffolds promote hematopoietic reconstitution from acute lethal radiation.

Hematopoietic syndrome of acute radiation syndrome (h-ARS) is an acute illness resulted from the damage of bone marrow (BM) microenvironment after exposure to radiation. Currently, the clinical management of h-ARS is limited to medication-assisted treatment, while there is still no specific therapy for the hematopoietic injury from high-dose radiation exposure. Our study aimed to assemble biomimetic three-dimensional (3D) BM microniches by co-culture of hematopoietic stem and progenitor cells (HSPCs) and mesenchymal stem cells (MSCs) in porous, injectable and viscoelastic microscaffolds in vitro. The biodegradable BM microniches were then transplanted in vivo into the BM cavity for the treatment of h-ARS. We demonstrated that the maintenance of HSPCs was prolonged by co-culture with MSCs in the porous 3D microscaffolds with 84 µm in pore diameter and 11.2 kPa in Young's modulus compared with 2D co-culture system. Besides, the minimal effective dose and therapeutic effects of the BM microniches were investigated on a murine model of h-ARS, which showed that the intramedullary cavity-injected BM microniches could adequately promote hematopoietic reconstitution and mitigate death from acute lethal radiation with a dose as low as 1000 HSPCs. Furthermore, the mRNA expression of Notch1 and its downstream target gene Hes1 of HSPCs were increased when co-cultured with MSCs, while the Jagged1 expression of the co-cultured MSCs was upregulated, indicating the significance of Notch signaling pathway in maintenance of HSPCs. Collectively, our findings provide evidence that biomimetic and injectable 3D BM microniches could maintain HSPCs, promote hematopoiesis regeneration and alleviate post-radiation injury, which provides a promising approach to renovate conventional HSPCs transplantation for clinical treatment of blood and immune disorders.

Upconversion Nanoparticles-Based Multiplex Protein Activation to Neuron Ablation for Locomotion Regulation.

The optogenetic neuron ablation approach enables noninvasive remote decoding of specific neuron function within a complex living organism in high spatiotemporal resolution. However, it suffers from shallow tissue penetration of visible light with low ablation efficiency. This study reports a upconversion nanoparticle (UCNP)-based multiplex proteins activation tool to ablate deep-tissue neurons for locomotion modulation. By optimizing the dopant contents and nanoarchitecure, over 300-fold enhancement of blue (450-470 nm) and red (590-610 nm) emissions from UCNPs is achieved upon 808 nm irradiation. Such emissions simultaneously activate mini singlet oxygen generator and Chrimson, leading to boosted near infrared (NIR) light-induced neuronal ablation efficiency due to the synergism between singlet oxygen generation and intracellular Ca2+ elevation. The loss of neurons severely inhibits reverse locomotion, revealing the instructive role of neurons in controlling motor activity. The deep penetrance NIR light makes the current system feasible for in vivo deep-tissue neuron elimination. The results not only provide a rapidly adoptable platform to efficient photoablate single- and multiple-cells, but also define the neural circuits underlying behavior, with potential for development of remote therapy in diseases.

An Upconversion Nanoparticle Enables Near Infrared-Optogenetic Manipulation of the Caenorhabditis elegans Motor Circuit.

Near-infrared (NIR) light penetrates tissue deeply, but its application to motor behavior stimulation has been limited by the lack of known genetic NIR light-responsive sensors. We designed and synthesized a Yb3+/Er3+/Ca2+-based lanthanide-doped upconversion nanoparticle (UCNP) that effectively converts 808 nm NIR light to green light emission. This UCNP is compatible with Chrimson, a cation channel activated by green light; as such, it can be used in the optogenetic manipulation of the motor behaviors of Caenorhabditis elegans. We show that this UCNP effectively activates Chrimson-expressing, inhibitory GABAergic motor neurons, leading to reduced action potential firing in the body wall muscle and resulting in locomotion inhibition. The UCNP also activates the excitatory glutamatergic DVC interneuron, leading to potentiated muscle action potential bursts and active reversal locomotion. Moreover, this UCNP exhibits negligible toxicity in neural development, growth, and reproduction, and the NIR energy required to elicit these behavioral and physiological responses does not activate the animal's temperature response. This study shows that UCNP provides a useful integrated optogenetic toolset, which may have wide applications in other experimental systems.

Synergizing Upconversion Nanophotosensitizers with Hyperbaric Oxygen to Remodel the Extracellular Matrix for Enhanced Photodynamic Cancer Therapy.

Photodynamic therapy (PDT) holds great promise as a noninvasive and selective cancer therapeutic treatment in preclinical research and clinical practice; however, it has limited efficacy in the ablation of deep-seated tumor because of hypoxia-associated circumstance and poor penetration of photosensitizers to cancer cells away from the blood vessels. To tackle the obstacles, we propose a therapeutic strategy that synergizes upconversion nanophotosensitizers (UNPSs) with hyperbaric oxygen (HBO) to remodel the extracellular matrix for enhanced photodynamic cancer therapy. The UNPSs are designed to have an Nd3+-sensitized sandwiched structure, wherein the upconversion core serves as light transducers to transfer energy to the neighboring photosensitizers to produce reactive oxygen species (ROS). With HBO, photodynamic process can generate abundant ROS in the intrinsically hypoxic tumor. It is revealed for the first time that HBO-assisted PDT decomposes collagen in the extracellular matrix of tumor and thus facilitates the diffusion of oxygen and penetration of UNPSs into the deeper area of tumor. Such a synergic effect eventually results in a significantly enhanced therapeutic efficacy at a low laser power density as compared with that using UNPSs alone. In view of its good biosafety, the HBO-assisted and UNPSs-mediated PDT provides new possibilities for treatment of solid tumors.

α-Amylase- and Redox-Responsive Nanoparticles for Tumor-Targeted Drug Delivery.

Paclitaxel (PTX) is an effective antineoplastic agent and shows potent antitumor activity against a wide spectrum of cancers. Yet, the wide clinical use of PTX is limited by its poor aqueous solubility and the side effects associated with its current therapeutic formulation. To tackle these obstacles, we report, for the first time, α-amylase- and redox-responsive nanoparticles based on hydroxyethyl starch (HES) for the tumor-targeted delivery of PTX. PTX is conjugated onto HES by a redox-sensitive disulfide bond to form HES-SS-PTX, which was confirmed by results from NMR, high-performance liquid chromatography-mass spectrometry, and Fourier transform infrared spectrometry. The HES-SS-PTX conjugates assemble into stable and monodispersed nanoparticles (NPs), as characterized with Dynamic light scattering, transmission electron microscopy, and atomic force microscopy. In blood, α-amylase will degrade the HES shell and thus decrease the size of the HES-SS-PTX NPs, facilitating NP extravasation and penetration into the tumor. A pharmacokinetic study demonstrated that the HES-SS-PTX NPs have a longer half-life than that of the commercial PTX formulation (Taxol). As a consequence, HES-SS-PTX NPs accumulate more in the tumor compared with the extent of Taxol, as shown in an in vivo imaging study. Under reductive conditions, the HES-SS-PTX NPs could disassemble quickly as evidenced by their triggered collapse, burst drug release, and enhanced cytotoxicity against 4T1 tumor cells in the presence of a reducing agent. Collectively, the HES-SS-PTX NPs show improved in vivo antitumor efficacy (63.6 vs 52.4%) and reduced toxicity in 4T1 tumor-bearing mice compared with those of Taxol. These results highlight the advantages of HES-based α-amylase- and redox-responsive NPs, showing their great clinical translation potential for cancer chemotherapy.

Ultrasmall-Superbright Neodymium-Upconversion Nanoparticles via Energy Migration Manipulation and Lattice Modification: 808 nm-Activated Drug Release.

Nd3+-sensitized upconversion nanoparticles are among the most promising emerging fluorescent nanotransducers. They are activated by 808 nm irradiation, which features merits such as limited tissue overheating and deeper penetration depth, and hence are attractive for diagnostic and therapeutic applications. Recent studies indicate that ultrasmall nanoparticles (<10 nm) are potentially more suitable for clinical application due to their favorable biodistribution and safety profiles. However, upconversion nanoparticles in the sub-10 nm range suffer from poor luminescence due to their ultrasmall size and greater proportion of lattice defects. To reconcile these opposing traits, we adopt a combinatorial strategy of energy migration manipulation and crystal lattice modification, creating ultrasmall-superbright Nd3+-sensitized nanoparticles with 2 orders of magnitude enhancement in upconversion luminescence. Specifically, we configure a sandwich-type nanostructure with a Yb3+-enriched intermediate layer [Nd3+]-[Yb3+-Yb3+]-[Yb3+-Tm3+] to form a positively reinforced energy migration system, while introducing Ca2+ into the crystal lattice to reduce lattice defects. Furthermore, we apply the nanoparticles to 808 nm light-mediated drug release. The results indicate time-dependent cancer cells killing and better antitumor activities. These ultrasmall-superbright dots have unraveled more opportunities in upconversion photomedicine with the promise of potentially safer and more effective therapy.

Redox-Sensitive Hydroxyethyl Starch-Doxorubicin Conjugate for Tumor Targeted Drug Delivery.

Doxorubicin (DOX) is one of the most potent anticancer agents in cancer chemotherapy, but the clinical use of DOX is restricted by its severe side effects caused by nonspecific delivery. To alleviate the side effects and improve the antitumor efficacy of DOX, a novel redox-sensitive hydroxyethyl starch-doxorubicin conjugate, HES-SS-DOX, with diameter of 19.9 ± 0.4 nm was successfully prepared for tumor targeted drug delivery and GSH-mediated intracellular drug release. HES-SS-DOX was relatively stable under extracellular GSH level (∼2 µM) but released DOX quickly under intracellular GSH level (2-10 mM). In vitro cell study confirmed the GSH-mediated cytotoxicity of HES-SS-DOX. HES-SS-DOX exhibited prolonged plasma half-life time and enhanced tumor accumulation in comparison to free DOX. As a consequence, HES-SS-DOX exhibited better antitumor efficacy and reduced toxicity as compared to free DOX in the in vivo antitumor activity study. The redox-sensitive HES-SS-DOX was proved to be a promising prodrug of DOX, with clinical potentials, to achieve tumor targeted drug delivery and timely intracellular drug release for effective and safe cancer chemotherapy.

Effects of macamides on endurance capacity and anti-fatigue property in prolonged swimming mice.

CONTEXT: Lepidium meyenii Walp. (Brassicaceae), most commonly known as "maca", has been used as a food or folk medicine to improve vitality in Peru. Previous research demonstrated that lipid-soluble extract from maca improved swimming endurance capacity. Macamides are considered the typical lipid-soluble markers for maca and proved to have several pharmacological properties, such as improving sexual performance and neuroprotective activies. OBJECTIVE: The present study investigates the effects of macamides on endurance capacity and anti-fatigue property in prolonged swimming mice. MATERIALS AND METHODS: The Balb/c mice were divided into seven groups: a control group, low-dose groups of N-benzyllinoleamide, N-benzyloleamide, and N-benzylpalmitamide, high-dose groups of these macamides. The macamides groups received the commercial products (12 and 40 mg/kg, ig), while the control group received vehicle for 21 d. On the 14th day, the mice were given the weight-loaded swimming test. On the 21st day, the mice were sacrificed immediately after 90 min swimming, and some biochemical parameters were measured. RESULTS AND DISCUSSION: Compared with the control group, exhaustive swimming time was significantly prolonged in high-dose group of N-benzyloleamide (p < 0.05); the levels of lactic acid (LD), blood ammonia (BA), and lactate dehydrogenase (LDH) were significantly decreased (p < 0.05), whereas the levels of liver glycogen (LG) and non-esterified fatty acid (NEFA) were significantly increased (p < 0.05) in high-dose group of N-benzyloleamide. The malondialdehyde (MDA) contents in the brain, muscle, and liver were significantly decreased (p < 0.05), whereas superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities in the brain, muscle, and liver were significantly increased in high-dose group of N-benzyloleamide (p < 0.05). CONCLUSION: The results indicate that N-benzyloleamide has pharmaceutical property against exercise-induced fatigue, and this effect can be explained by the modulated energy metabolism and improved antioxidant status.