Rational Design of All-Organic Nanoplatform for Highly Efficient MR/NIR-II Imaging-Guided Cancer Phototheranostics.

Organic theranostic nanomedicine has precision multimodel imaging capability and concurrent therapeutics under noninvasive imaging guidance. However, the rational design of desirable multifunctional organic theranostics for cancer remains challenging. Rational engineering of organic semiconducting nanomaterials has revealed great potential for cancer theranostics largely owing to their intrinsic diversified biophotonics, easy fabrication of multimodel imaging platform, and desirable biocompatibility. Herein, a novel all-organic nanotheranostic platform (TPATQ-PNP NPs) is developed by exploiting the self-assembly of a semiconducting small molecule (TPATQ) and a new synthetic high-density nitroxide radical-based amphiphilic polymer (PNP). The nitroxide radicals act as metal-free magnetic resonance imaging agent through shortened longitudinal relaxation times, and the semiconducting molecules enable ultralow background second near-infrared (NIR-II, 1000-1700 nm) fluorescence imaging. The as-prepared TPATQ-PNP NPs can light up whole blood vessels of mice and show precision tumor-locating ability with synergistic (MR/NIR-II) imaging modalities. The semiconducting molecules also undergo highly effective photothermal conversion in the NIR region for cancer photothermal therapy guided by complementary tumor diagnosis. The designed multifunctional organic semiconducting self-assembly provides new insights into the development of a new platform for cancer theranostics.

Regulation of AKT phosphorylation by GSK3ß and PTEN to control chemoresistance in breast cancer.

BACKGROUND: Phosphorylated AKT is highly expressed or overexpressed in chemoresistant tumor samples. However, the precise molecular mechanism involved in AKT phosphorylation-related chemoresistance in breast cancer is still elusive. The present research was designed to estimate the effect of AKT phosphorylation on cell viability and chemoresistance in breast cancer. METHODS: We utilized MCF-7 and MDA-MB468 human breast cancer cell lines and developed multidrug-resistant MCF-7/MDR and cisplatin-resistant MDA-MB-468 cells. Immunofluorescence analysis and Western blotting were employed to test the level of glycogen synthase kinase 3 beta (GSK3ß), phosphorylated phosphatase and tension homologue (p-PTEN) and phosphorylated AKT (p-AKT) in MCF-7/MDR and MDA-MB468 cells. Xenograft assays in nude mice were performed with MCF-7/MDR cells to verify chemoresistance and the signaling pathway upstream of phosphatidylinositide 3-kinase (PI3K)/AKT. RESULTS: An increase in GSK3ß, p-PTEN and p-AKT expression was strongly induced in MCF-7/MDR and cisplatin-resistant MDA-MB-468 cells, and augmented GSK3ß phosphorylation and PTEN inactivation enhanced AKT signaling. The elevation in GSK3ß, p-PTEN and p-AKT was associated with cell viability based on a CCK-8 assay. The results of in vivo and in vitro assays indicated that GSK3ß knockdown with lentiviral shRNA (shRNA-GSK3ß) promoted apoptosis and suppressed the migration of cisplatin-resistant MCF-7/MDR cells, while these effects were reversed by activating p-AKT with the PTEN inhibitor bpV(pic). CONCLUSIONS: AKT phosphorylation mediated by GSK3ß and PTEN were correlated with cell viability, migration and apoptosis, which may promote chemoresistance in breast cancer. Furthermore, GSK3ß can regulate cell viability through the PTEN/PI3K/AKT signaling pathway and induce chemoresistance, serving as a valuable molecular strategy for breast cancer therapy.

Enwrapping Polydopamine on Doxorubicin-Loaded Lamellar Hydroxyapatite/Poly(lactic-co-glycolic acid) Composite Fibers for Inhibiting Bone Tumor Recurrence and Enhancing Bone Regeneration.

Simultaneous prevention of bone tumor recurrence and promotion of repairing bone defects resulting from tumorectomy remain a challenge. Herein, we report a polydopamine (PDA)-coated composite scaffold consisting of doxorubicin (DOX)-loaded lamellar hydroxyapatite (LHAp) and poly(lactic-co-glycolic acid) (PLGA) in an attempt to reach dual functions of tumor inhibition and bone repair. The DOX was intercalated into LHAp, and the DOX-loaded LHAp was incorporated into PLGA solution to prepare a DOX-intercalated LHAp/PLGA (labeled as DH/PLGA) scaffold that was coated with PDA to obtain a PDA@DH/PLGA scaffold. The morphology, structure, wettability, mechanical properties, drug release, biocompatibility, and in vitro and in vivo bioactivities of the PDA@DH/PLGA scaffold were evaluated. It is found that PDA coating not only improves hydrophilicity and mechanical properties, but also leads to more sustainable drug release. More importantly, the PDA@DH/PLGA scaffold shows significantly inhibited growth of tumor cells initially and subsequent improved adhesion and proliferation of osteoblasts. In addition, the PDA coating improves the bioactivity of the DH/PLGA scaffold as suggested by the in vitro biomineralization. Further in vivo study demonstrates the improved bone growth around PDA@DH/PLGA over DH/PLGA after 20 days of drug release. The dual functional PDA@DH/PLGA scaffold shows great promise in the treatment of bone tumor.

PPAR-γ Is Critical for HDAC3-Mediated Control of Oligodendrocyte Progenitor Cell Proliferation and Differentiation after Focal Demyelination.

Disruption of remyelination contributes to neurodegeneration and cognitive impairment in chronically disabled patients. Valproic acid (VPA) inhibits histone deacetylase (HDAC) function and probably promotes oligodendrocyte progenitor cell (OPC) proliferation and differentiation; however, the relevant molecular mechanisms remain unknown. Here, focal demyelinating lesions (FDLs) were generated in mice by two-point stereotactic injection of lysophosphatidylcholine (LPC) into the corpus callosum. Cognitive functions, sensorimotor abilities and histopathological changes were assessed for up to 28 days post-injury with or without VPA treatment. Primary OPCs were harvested and used to study the effect of VPA on OPC differentiation under inflammatory conditions. VPA dose-dependently attenuated learning and memory deficits and robustly protected white matter after FDL induction, as demonstrated by reductions in SMI-32 and increases in myelin basic protein staining. VPA also promoted OPC proliferation and differentiation and increased subsequent remyelination efficiency by day 28 post-FDL induction. VPA treatment did not affect HDAC1, HDAC2 or HDAC8 expression but reduced HDAC3 protein levels. In vitro, VPA improved the survival of mouse OPCs and promoted their differentiation into oligodendrocytes following lipopolysaccharide (LPS) stimulation. LPS caused OPCs to overexpress HDAC3, which translocated from the cytoplasm into the nucleus, where it directly interacted with the nuclear transcription factor PPAR-γ and negatively regulated PPAR-γ expression. VPA decreased the expression of HDAC3 and promoted remyelination and functional neurological recovery after FDL. These findings may support the use of strategies modulating HDAC3-mediated regulation of protein acetylation for the treatment of demyelination-related cognitive dysfunction.

Hypoxic preconditioning enhances the differentiation of bone marrow stromal cells into mature oligodendrocytes via the mTOR/HIF-1α/VEGF pathway in traumatic brain injury.

OBJECTIVE: Traumatic brain injury (TBI) results not only in gray matter damage, but also in severe white matter injury (WMI). Previous findings support hypoxic preconditioning (HP) could augment the efficacy of bone marrow stromal cell (BMSC) transplantation in a TBI mouse model. However, whether HP-treated BMSCs (H-BMSCs) could overcome remyelination failure after WMI is unclear, and the molecular mechanisms remain to be explored. Here, we focused on the therapeutic benefits of H-BMSC transplantation for treating WMI, as well as its underlying mechanisms. METHODS: In vitro, BMSCs were incubated at passage 4 in the hypoxic preconditioning (1.0% oxygen) for 8 hr. In vivo, a TBI mouse model was established, and DMEM cell culture medium (control), normal cultured BMSCs (N-BMSCs), or H-BMSCs were transplanted to mice 24 hr afterward. Neurobehavioral function, histopathological changes, and oligodendrogenesis were assessed for up to 35 days post-TBI. RESULTS: Compared with the control group, improvement of cognitive functions and smaller lesion volumes was observed in the two BMSC-transplanted groups, especially the H-BMSC group. H-BMSC transplantation resulted in a greater number of neural/glial antigen 2 (NG2)-positive and adenomatous polyposis coli (APC)-positive cells than N-BMSC transplantation in both the corpus callosum and the striatum. In addition, we observed that the expression levels of hypoxia-inducible factor-1a (HIF-1α), phosphorylated mechanistic target of rapamycin (p-mTOR), and vascular endothelial growth factor (VEGF) were all increased in H-BMSC-transplanted mice. Furthermore, the mTOR pathway inhibitor rapamycin attenuated the impact of HP both in vivo and in vitro. CONCLUSION: The results provided mechanistic evidences suggesting that HP-treated BMSCs promoted remyelination partly by modulating the pro-survival mTOR/HIF-1α/VEGF signaling pathway.

Interpenetrated nano- and submicro-fibrous biomimetic scaffolds towards enhanced mechanical and biological performances.

Developing fibrous scaffolds with hierarchical structures that closely mimic natural extracellular matrix (ECM) is highly desirable. However, fabricating scaffolds with true nanofibers (<100 nm) and submicrofibers (<1 µm) remains a big challenge. In this work, to mimic the fibrillar structure of natural ECM, bacterial cellulose (BC) nanofibers were hybridized with cellulose acetate (CA) submicrofibers for the first time. The interpenetrated nano-submicron fibrous BC/CA scaffold was fabricated using the combined electrospinning and modified in situ biosynthesis method. The BC/CA scaffold has an integrated symmetrical nanostructure in which BC nanofibers (42 nm in diameter) penetrate into the submicrofibrous CA (820 nm in diameter) scaffold. The BC/CA scaffold shows an interconnected porous structure with a high porosity of >90%. Additionally, the combination of CA submicrofibers with BC nanofibers leads to significantly improved mechanical properties over nanofibrous BC and submicrofibrous CA scaffolds and enlarged pores over nanofibrous BC scaffold. In addition, the biological behaviors of prepared BC/CA on MC3T3-E1 cells were investigated. Results suggested that BC/CA scaffold is beneficial for cell migration and proliferation. Moreover, the BC/CA scaffold shows higher alkaline phosphatase (ALP) activity, and calcium depositions. In addition, the hierarchical structures can effectively improve the expression of osteogenic gene (ALP mRNA and Runx2 mRNA) and protein (ALP). We believe that the methodology might provide biomimetic morphological microenvironments for enhanced tissue regeneration.

Neuroprotective effect of l-serine against white matter demyelination by harnessing and modulating inflammation in mice.

Demyelination in white matter is the end product of numerous pathological processes. This study was designed to evaluate the neuroprotective effect of l-serine and the underlying mechanisms against the demyelinating injury of white matter. A model of focal demyelinating lesions (FDL) was established using the two-point stereotactic injection of 0.25% lysophosphatidylcholine (LPC, 10 µg per point) into the corpus callosum of mice. Mice were then intraperitoneally injected with one of three doses of l-serine (114, 342, or 1026 mg/kg) 2 h after FDL, and then twice daily for the next five days. Behavior tests and histological analysis were assessed for up to twenty-eight days post-FDL induction. Electron microscopy was used for ultrastructural investigation. In vitro, we applied primary co-cultures of microglia and oligodendrocytes for oxygen glucose deprivation (OGD). After establishing FDL, l-serine treatment: 1) improved spatial learning, memory and cognitive ability in mice, and relieved anxiety for 4 weeks post-FDL induction; 2) reduced abnormally dephosphorylated neurofilament proteins, increased myelin basic protein, and preserved anatomic myelinated axons; 3) inhibited microglia activation and reduced the release of inflammatory factors; 4) promoted recruitment and proliferation of oligodendrocyte progenitor cells, and the efficiency of subsequent remyelination on day twenty-eight post-FDL induction. In vitro experiments, showed that l-serine not only directly protected against oligodendrocytes from OGD damage, but also provided an indirect protective effect by regulating microglia. In our study, l-serine offered long-lasting behavioral and oligodendrocyte protection and promoted remyelination. Therefore, l-serine may be an effective clinical treatment aganist white matter injury.