Current landscape of mRNA technologies and delivery systems for new modality therapeutics.

Realizing the immense clinical potential of mRNA-based drugs will require continued development of methods to safely deliver the bioactive agents with high efficiency and without triggering side effects. In this regard, lipid nanoparticles have been successfully utilized to improve mRNA delivery and protect the cargo from extracellular degradation. Encapsulation in lipid nanoparticles was an essential factor in the successful clinical application of mRNA vaccines, which conclusively demonstrated the technology's potential to yield approved medicines. In this review, we begin by describing current advances in mRNA modifications, design of novel lipids and development of lipid nanoparticle components for mRNA-based drugs. Then, we summarize key points pertaining to preclinical and clinical development of mRNA therapeutics. Finally, we cover topics related to targeted delivery systems, including endosomal escape and targeting of immune cells, tumors and organs for use with mRNA vaccines and new treatment modalities for human diseases.

Multiple amplification detection of microRNA based on the host-guest interaction between ß-cyclodextrin polymer and pyrene.

MicroRNAs (miRNAs) participate in various biological processes during the course of life. The levels of miRNAs can be useful biomarkers for cellular events or cancer diagnosis, thus sensitive and accurate analysis of miRNA expression is crucial for better understanding its functions and the early diagnosis of human disease. Here, we developed a multiple amplification detection method for miRNA based on the host-guest interaction between ß-cyclodextrin polymer and pyrene, which takes advantage of the polymerase-aided strand displacement amplification and λ exonuclease-assisted cyclic enzymatic amplification. The proposed method allowed quantitative detection of miRNA-21 in a dynamic range of 1 pM to 5 nM with a detection limit of 0.3 pM and demonstrated good ability to discriminate the target sequence from the single-base mismatched miRNA sequence. Moreover, the assay was applied successfully in a complex biological matrix. We believe that this proposed sensitive and specific assay has great potential as a quantification method for miRNA detection in biomedical research and clinical diagnosis.

A multiple amplification strategy for nucleic acid detection based on host-guest interaction between the ß-cyclodextrin polymer and pyrene.

A multiple amplification strategy has been developed for nucleic acid detection based on host-guest interaction between the ß-cyclodextrin polymer (ß-CDP) and pyrene. Briefly, the detection system consists of three parts: the polymerase and nicking enzyme-assisted isothermal strand displacement amplification (SDA) activated by a target DNA or microRNA; the exonuclease III-aided cyclic enzymatic amplification (CEA); and the fluorescence enhancement effect based on host-guest interaction between ß-CDP and pyrene. This strategy showed a good positive linear correlation with target DNA concentrations in the range from 75 fM to 1 pM with a detection limit of 41 fM. Significantly, our amplification platform was further validated and evaluated successfully by assaying miRNA-21 in human serum. The proposed assay has great potential as a nucleic acid quantification method for use in biomedical research, clinical analysis and disease diagnostics.

Effect of bone mass density and alveolar bone resorption on stress in implant restoration of free-end edentulous posterior mandible: Finite element analysis of double-factor sensitivity.

BACKGROUND: Osseous condition of the mandible was regarded as a key factor influencing stability of implants in the early stage. Finite element analysis was used to assess the effect of bone mass density and alveolar bone resorption (double factors) on stress in a four-unit implant restoration of a free-end edentulous posterior mandible. METHODS: A 3D finite element model was constructed for a single-sided free-end edentulous mandible (from mandibular first premolar to mandibular second molar) containing threaded dental implants. Mandible sensitivity modes were constructed with different alveolar bone resorption levels for normal conditions as well as mild, moderate and severe periodontitis, respectively. Based on the mass density of cancellous bone for four types of bones as the sensitivity parameter, two implant design modes were constructed: Model A (four-unit fixed bridge supported by three implants, implant positions were 34, 36 and 37) and model B: 34 × 36, 37 (37: a single implant crown) (34 × 36: three-unit fixed bridge supported by two implants, implant positions were 34 and 36). A total of 32 sensitivity-based finite element models, grouped in two groups, were constructed. Stress distribution and maximum von Mises stress on cortical bone and cancellous bone around the implant, as well as the surface of implant were investigated by using ABAQUS when vertical loading and 45° oblique loading were applied, respectively. RESULTS: When vertical loading was applied on the implant, maximum von Mises stress on the cortical bone around the implant was assessed to be 4.726 MPa - 13.15 MPa and 6.254 MPa - 13.79 MPa for groups A and B, respectively; maximum stress on the cancellous bone around the implant was 2.641 MPa - 3.773 MPa and 2.864 MPa - 4.605 MPa, respectively; maximum stress on the surface of implant was 14.7 MPa - 21.17 MPa and 21.64 MPa - 30.70 MPa, respectively. When 45° oblique loading was applied on the implant restoration, maximum von Mises stress on the cortical bone around the implant was assessed to be 42.08 MPa - 92.71 MPa and 50.84 MPa - 102.5 MPa for groups A and B, respectively; maximum stress on the cancellous bone around the implant was 4.88 MPa - 25.95 MPa and 5.227 MPa - 28.43 MPa, respectively; maximum stress on the surface of implant was 77.91 MPa - 124.8 MPa and 109.2 MPa - 150.7 MPa, respectively. Stress peak on the cortical bone and that on cancellous bone around the implant increased and decreased with the decrease in bone mass density, respectively. Stress peak on alveolar bone increased with alveolar bone resorption when oblique loading was applied. CONCLUSION: 1. Both alveolar bone resorption and bone mass density (double factors) are critical to implant restoration. Bone mass density may exhibit a more pronounced impact than alveolar bone resorption. 2. From the biomechanical perspective, types I and II bones are preferred for implant restoration, while implantation should be considered carefully in the case of type III bones, or those with less bone mass density accompanied by moderate to severe alveolar bone loss. 3. Splinting crowns restoration is biomechanically superior to single crown restoration.

Liposomal paclitaxel induces fewer hematopoietic and cardiovascular complications than bioequivalent doses of Taxol.

Paclitaxel (PTX) exhibits potent antineoplastic activity against various human malignancies; however, clinical application must overcome the inherent hydrophobicity of this molecule. The commercialized Taxol formulation utilizes Cremophor EL (CrEL)/ethanol as a solvent to stabilize and dispense PTX in an aqueous solution. However, adverse CrEL­induced hypersensitivity reactions have been reported in ~30% of recipients, and 40% of patients receiving premedication may also experience this adverse effect. Therefore, the development of a CrEL-free delivery system is crucial, in order to fully exploit the therapeutic efficacy of PTX. In the present study, a novel liposomal PTX (lipo­PTX) formulation was optimized with regards to encapsulation rate and long­term stability, arriving at a molar constituent ratio of soybean phosphatidylcholine:cholesterol:N-(carbonyl-methoxy-poly-ethylene glycol 2000)­1,2­distearoyl­sn-glycero­3-phosphoethanolamine, sodium salt:PTX at 95:2:1:2. Comparable doses of lipo­PTX and Taxol were bioequivalent in terms of therapeutic efficacy in xenograft tumor models. However, the systemic side effects, including hematopoietic toxicity, acute hypersensitivity reactions and cardiac irregularities, were significantly reduced in lipo­PTX­treated mice compared with those infused with reference formulations of PTX. In conclusion, the present study reported that lipo­PTX exhibited a higher therapeutic index than clinical PTX formulations.

Nano-Diamino-Tetrac (NDAT) Enhances Resveratrol-Induced Antiproliferation by Action on the RRM2 Pathway in Colorectal Cancers.

Cancer resistance to chemotherapeutic agents is a major issue in the management of cancer patients. Overexpression of the ribonucleotide reductase regulatory subunit M2 (RRM2) has been associated with aggressive cancer behavior and chemoresistance. Nano-diamino-tetrac (NDAT) is a nanoparticulate derivative of tetraiodothyroacetic acid (tetrac), which exerts anticancer properties via several mechanisms and downregulates RRM2 gene expression in cancer cells. Resveratrol is a stilbenoid phytoalexin which binds to a specific site on the cell surface integrin αvß3 to trigger cancer cell death via nuclear translocation of COX-2. Here we report that resveratrol paradoxically activates RRM2 gene expression and protein translation in colon cancer cells. This unanticipated effect inhibits resveratrol-induced COX-2 nuclear accumulation. RRM2 downregulation, whether achieved by RNA interference or treatment with NDAT, enhanced resveratrol-induced COX-2 gene expression and nuclear uptake which is essential to integrin αvß3-mediated-resveratrol-induced antiproliferation in cancer cells. Elsewhere, NDAT downregulated resveratrol-induced RRM2 expression in vivo but potentiated the anticancer effect of the stilbene. These findings suggest that RRM2 appears as a cancer cell defense mechanism which can hinder the anticancer effect of the stilbene via the integrin αvß3 axis. Furthermore, the antagonistic effect of RRM2 against resveratrol is counteracted by the administration of NDAT.

Amplified fluorescence detection of DNA based on catalyzed dynamic assembly and host-guest interaction between ß-cyclodextrin polymer and pyrene.

The detection of nucleic acids is fundamental for studying their functions and for the development of biological studies and medical diagnostics. Herein, we report a new strategy for nucleic acid amplified detection by combining target-catalyzed dynamic assembly with host-guest interaction between ß-cyclodextrin polymer (ß-CDP) and pyrene. In this strategy, a metastable pyrene-labeled hairpin DNA probe (probe H1) and a metastable unlabeled hairpin DNA probe (probe H2) were elaborately designed as the assembly components, which were kinetically handicapped from cross-opening in the absence of target DNA. In this state, pyrene labled at the 5'-termini of single-stranded stem of probe H1 would be easily trapped into the hydrophobic cavity of ß-CDP because of weak steric hindrance, leading to significant fluorescence enhancement. Once the dynamic assembly was catalyzed by target DNA, a hybridized DNA duplex H1-H2 would be created continuously. In this state, it is difficult for pyrene to enter the cavity of ß-CDP due to steric hindrance and weak-binding interaction, leading to a weak fluorescent signal. Thus, target DNA could be detected by this simple mix-and-detect amplification method without the need of expensive and perishable protein enzymes. As low as 10 pM of the target DNA was detected by this assay, which was comparable to that of some reported enzyme-dependent amplification methods. Meanwhile, the proposed method was further successfully applied to detect DNA in cell lysate samples, showing great potential for target detection from complex fluids. In addition, as a novel transformation of dynamic DNA assembly technology into enzyme-free signal-amplification analytical application, the proposed strategy has shown great potential for applications in a wide range of fields, such as aptamer-based non-nucleic acid target sensing, biomedicine and bioimaging.