Tumor targeted siRNA delivery by adenosine receptor-specific curdlan nanoparticles

Curdlan-Mediated Syngeneic RNAi against NF-κB in Glial Cells Protects Cerebral Vessels in the TBI Mouse Model

Traumatic brain injury (TBI) activates the NF-κB pathway in microglia and astrocytes, which secrete pro-inflammatory cytokines that disrupt the blood-brain barrier (BBB). Curdlan derivatives are promising carriers for the delivery of siRNA drugs. Herein, we evaluated the glial cell specificity, siRNA delivery efficiency, and the subsequent phenotypic regulation of glial cells by the Curdlan derivatives in the TBI mouse model. Our in vitro and in vivo studies confirmed that the (1) pAVC4 or CuMAN polymer encapsulating siRNA were internalized by astrocytes and microglia in a receptor-dependent manner; (2) systemic administration of the pAVC4 or CuMAN polymer encapsulating siRNA resulted in significant gene silencing efficiency, altered the phenotypic polarization of glial cells, and regulated the secretion of inflammatory cytokines; (3) this lessened neuroinflammation, ameliorated BBB destruction, and improved vascular recovery. These data suggested that pAVC4 and CuMAN polymers are promising RNA delivery vehicles that can efficiently deliver siRNA to the target cells.

Oral Piwi-Interacting RNA Delivery Mediated by Green Tea-Derived Exosome-Like Nanovesicles for the Treatment of Aortic Dissection

Aortic dissection (AD) is a severe cardiovascular disease necessitating active therapeutic strategies for early intervention and prevention. Nucleic acid drugs, known for their potent molecule-targeting therapeutic properties, offer potential for genetic suppression of AD. Piwi-interacting RNAs, a class of small RNAs, hold promise for managing cardiovascular diseases. Limited research on these RNAs and AD exists. This study demonstrates that an antagomir targeting heart-apoptosis-associated piRNA (HAAPIR) effectively regulates vascular remodeling, mitigating AD occurrence and progression through the myocyte enhancer factor 2D (Mef2D) and matrix metallopeptidase 9 (MMP9) pathways. Green tea-derived plant exosome-like nanovesicles (PELNs) are used for oral administration of antagomir. The antagomir-HAAPIR-nanovesicle complex, after purification and optimization, exhibits a high packing rate, while the antagomir is resistant to enzyme digestion. Administered to mice, the complex targets the aortic lesion, reducing AD incidence and improving survival. Moreover, MMP9 and Mef2D expression decrease significantly, inhibiting the phenotypic conversion of human aortic smooth muscle cells. PELNs encapsulate the antagomir-HAAPIR complex, maintaining stability, mediating transport into the bloodstream, and delivering Piwi-interacting RNAs to AD sites. Thus, HAAPIR is a potential target for persistent clinical AD prevention and treatment, and nanovesicle-encapsulated nucleic acids offer a promising cardiovascular disease treatment, providing insights for other therapeutic targets.

Tumor-Targeted Codelivery of CpG and siRNA by a Dual-Ligand-Functionalized Curdlan Nanoparticle

The simultaneous delivery of CpG oligonucleotide along with short interfering RNA (siRNA) has the potential to significantly boost the anticancer impact of siRNA medications. Our previous research demonstrated that Curdlan nanoparticles functionalized with adenosine are capable of selectively delivering therapeutic siRNA to cancerous cells through endocytosis mediated by adenosine receptors. Herein, we synthesized a dual-ligand-functionalized Curdlan polymer (denoted by CuMAN) to simultaneously target tumor cells and tumor-associated macrophages (TAMs). CuMAN nanoparticles containing CpG and siRNA demonstrated enhanced uptake by B16F10 tumor cells and bone marrow-derived macrophages, which are facilitated by AR on tumor cells and mannose receptor on macrophages. This led to increased release of pro-inflammatory cytokines in both in vitro and in vivo settings. The synergistic effect of CpG on TAMs and RNAi on tumor cells mediated by the CuMAN nanoparticle not only suppressed the tumor growth but also strongly inhibited the lung metastasis. Our findings indicate that the CuMAN nanoparticle has potential as an effective dual-targeting delivery system for nucleic acid therapeutics.

Preparation of Single-Helical Curdlan Hydrogel and Its Activation with Coagulation Factor G

β-1,3-glucans are a kind of natural polysaccharide with immunomodulatory, antitumor, and anti-inflammatory properties. Curdlan, as the simplest linear β-1,3-glucan, possesses a variety of biological activities and thermogelation properties. However, due to the complexity and variability of the conformations of curdlan, the exact structure-activity relationship remains unclear. We prepare a chemically crosslinked curdlan hydrogel with the unique single-helical skeleton (named S gel) in 0.4 wt% NaOH at 40 °C, confirmed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). X-ray diffractometry (XRD) data show that S gel maintains the single-helical crystal structure, and the degree of crystallinity of the S gel is ~24%, which is slightly lower than that of the raw powder (~31%). Scanning electron microscopy (SEM) reveals that S gel has a continuous network structure, with large pores measuring 50-200 μm, which is consistent with its high swelling property. Using the 13C high-resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) method, we determine that most of the single-helical skeleton carbon signals in the swollen S gel are visible, suggesting that the single-helical skeleton of S gel exhibits fascinating mobility at room temperature. Finally, we reveal that the binding of S gel to coagulation Factor G from tachypleus amebocyte lysate increases and saturates at 20 μL tachypleus amebocyte lysate per mg of S gel. Our prepared S gel can avoid the transformation of curdlan conformations and retain the bioactivity of binding to coagulation Factor G, making it a valuable material for use in the food industry and the pharmaceutical field. This work deepens the understanding of the relationship between the single-helical structure and the activity of curdlan, promoting the development and application of β-1,3-glucans.

Recent innovations (2020-2023) in the approaches for the chemical functionalization of curdlan and pullulan: A mini-review

Chemical modification represents a highly efficacious approach for enhancing the physicochemical characteristics and biological functionalities of natural polysaccharides. However, not all polysaccharides have considerable pharmacologic activity; so, appropriate chemical modification strategies can be selected in accordance with the distinct structural properties of polysaccharides to aid in improving and encouraging the presentation of their biological activities. Hence, there has been a growing interest in the chemical alteration of polysaccharides due to their various properties such as antioxidant, anticoagulant, antiviral, anticancer, biomedical, antibacterial, and immunomodulatory effects. This paper offers a comprehensive examination of recent scientific advancements produced over the past four years in the realm of unique chemical and functional modifications in curdlan and pullulan structures. This review aims to provide readers with an overview of the structural activity correlations observed in the backbone structures of curdlan and pullulan, as well as the diverse chemical modification processes employed for these polysaccharides. Additionally, the review aims to examine the effects of combining various bioactive molecules with chemically modified curdlan and pullulan and explore their potential applications in various important fields.

Astrocyte-targeted siRNA delivery by adenosine-functionalized LNP in mouse TBI model

Traumatic brain injury (TBI) induces pro-inflammatory polarization of astrocytes and causes secondary disruption of the blood-brain barrier (BBB) and brain damage. Herein, we report a successful astrocyte-targeted delivery of small interfering RNA (siRNA) by ligand functionalized lipid nanoparticles (LNPs) formulated from adenosine-conjugated lipids and a novel ionizable lipid (denoted by Ad4 LNPs). Systemic administration of Ad4 LNPs carrying siRNA against TLR4 to the mice TBI model resulted in the specific internalization of the LNPs by astrocytes in the vicinity of damaged brain tissue. A substantial knockdown of TLR4 at both mRNA and protein levels in the brain was observed, which led to a significant decrease of key pro-inflammatory cytokines and an increase of key anti-inflammatory cytokines in serum. Dye leakage measurement suggested that the Ad4-LNP-mediated knockdown of TLR4 attenuated the TBI-induced BBB disruption. Together, our data suggest that Ad4 LNP is a promising vehicle for astrocyte-specific delivery of nucleic acid therapeutics.