High quality haplotype-resolved genome assemblies of Populus tomentosa Carr., a stabilized interspecific hybrid species widespread in Asia.

Populus has a wide ecogeographical range spanning the Northern Hemisphere, and interspecific hybrids are common. Populus tomentosa Carr. is widely distributed and cultivated in the eastern region of Asia, where it plays multiple important roles in forestry, agriculture, conservation, and urban horticulture. Reference genomes are available for several Populus species, however, our goals were to produce a very high quality de novo chromosome-level genome assembly in P. tomentosa genome that could serve as a reference for evolutionary and ecological studies of hybrid speciation throughout the genus. Here, combining long-read sequencing and Hi-C scaffolding, we present a high-quality, haplotype-resolved genome assembly. The genome size was 740.2 Mb, with a contig N50 size of 5.47 Mb and a scaffold N50 size of 46.68 Mb, consisting of 38 chromosomes, as expected with the known diploid chromosome number (2n = 2x = 38). A total of 59,124 protein-coding genes were identified. Phylogenomic analyses revealed that P. tomentosa is comprised of two distinct subgenomes, which we deomonstrate is likely to have resulted from hybridization between Populus adenopoda as the female parent and Populus alba var. pyramidalis as the male parent, with an origin of approximately 3.93 Ma. Although highly colinear, significant structural variation was found between the two subgenomes. Our study provides a valuable resource for ecological genetics and forest biotechnology.

Facilitated brain delivery of poly (ethylene glycol)-poly (lactic acid) nanoparticles by microbubble-enhanced unfocused ultrasound.

Nanotechnology plays a unique instrumental role in the revolutionary development of brain-specific drug delivery, imaging, and diagnosis, but is highly limited by the existence of blood-brain barrier (BBB). In this study, microbubble-enhanced unfocused ultrasound (MEUUS) was developed as an approach to mediate an extensive brain delivery of poly (ethylene glycol) - poly (lactic acid) (PEG-PLA) nanoparticles. Following the MEUUS treatment, the nanoparticles signals were found to penetrate through the vascular walls and distributed deeply into the parenchyma at a significantly higher level (more than 250%) than those of the non-MEUUS treated control. Such effect was reversible and dependent on nanoparticles injection timing, sonication mode and mechanical index. Together with the transmission electron microscopy analysis, the increased brain accumulation of nanoparticles was claimed to be largely mediated by an ultrasound-induced stable cavitation of the microbubble which resulted in mechanical stretching of the vessel wall and consequently induced cellular transcytosis of the nanoparticles. The MEUUS technique was also used to facilitate the brain delivery of PEG-PLA nanoparticles functionalized with amyloid beta-specific antibody 6E10 for enabling the recognition of the hallmarks of Alzheimer's disease that widely distributed in the brain. No erythrocytes extravasation and other visible damages in the brain were detected following the MEUUS treatment. These findings together indicated that unfocused ultrasound with the aid of microbubble could effectively improve the brain delivery of nanoparticles, and this approach might serve as a safe and flexible platform for the potential application of nanoparticles in the diagnosis and therapy of brain diseases.

Co-administration of dual-targeting nanoparticles with penetration enhancement peptide for antiglioblastoma therapy.

Chemotherapy is an indispensable auxiliary treatment for glioma but highly limited by the existence of both blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). The dysfunctional brain tumor blood vessels and high interstitial pressure in glioma also greatly hindered the accumulation and deep penetration of chemotherapeutics into the glioma. Lactoferrin (Lf), with its receptor overexpressed on both the brain endothelial cells and glioma cells, was here functionalized to the surface of poly(ethylene glycol)-poly(lactic acid) nanoparticles to mediate BBB/BBTB and glioma cell dual targeting. tLyP-1, a tumor-homing peptide, which contains a C-end Rule sequence that can mediate tissue penetration through the neuropilin-1-dependent internalization pathway, was coadministrated with Lf-functionalized nanoparticles (Lf-NP) to enhance its accumulation and deep penetration into the glioma parenchyma. Enhanced cellular association in both BCEC and C6 cells, increased cytotoxicity of the loaded paclitaxel, and deep penetration in the 3D glioma spheroids was achieved by Lf-NP. Following coadministration with tLyP-1, the functionalized nanoparticles obtained improved tumor targeting, glioma vascular extravasation, and antiglioma efficacy. The findings here suggested that the strategy by coadministrating BBB/BBTB and glioma cells dual-targeting nanocarriers with a tumor penetration enhancement peptide represent a promising platform for antiglioma drug delivery.

The influence of the penetrating peptide iRGD on the effect of paclitaxel-loaded MT1-AF7p-conjugated nanoparticles on glioma cells.

Low permeability across the blood-brain tumor barrier (BTB) and poor penetration into the glioma parenchyma represent key obstacles for anti-glioblastoma drug delivery. In this study, MT1-AF7p peptide, which presents high binding affinity to membrane type-1 matrix metalloproteinase (MT1-MMP) that over-expressed on both angiogenic blood vessels and glioma cells, was employed to decorate the paclitaxel-loaded PEG-PLA nanoparticles (MT1-NP-PTX) to mediate glioblastoma targeting. Tumor-homing and penetrating peptide iRGD was co-administrated to further facilitate nanoparticles extravasation from the tumor vessels and penetration into the glioma parenchyma. MT1-NP-PTX showed satisfactory encapsulated efficiency, loading capacity and size distribution. In C6 glioma cells, MT1-NP was found to exhibit significantly enhanced cellular accumulation than that of unmodified NP via both energy-dependent macropinocytosis and lipid raft-mediated endocytosis. The anti-proliferative and apoptosis-induction activity of PTX was significantly enhanced following its encapsulation in MT1-NP. In vivo imaging and glioma distribution together confirmed that MT1-AF7p functionalization and iRGD co-administration significantly improved the nanoparticles extravasation across BTB and accumulation in glioma parenchyma. Furthermore, in vitro C6 glioma spheroid assays evidenced that MT1-NP effectively penetrated into the glioma spheroids and significantly improved the growth inhibitory effects of loaded PTX on glioma spheroids. More importantly, the median survival time of those nude mice bearing intracranial C6 glioma received MT1-NP-PTX and iRGD combination regimen was 60 days, significantly longer than that of other groups. The findings suggested that the BTB/glioma cells dual-targeting DDS co-administrated with iRGD peptide might provide a both practical and feasible solution to highly efficient anti-glioblastoma drug delivery.

Lactoferrin-modified PEG-co-PCL nanoparticles for enhanced brain delivery of NAP peptide following intranasal administration.

Development of effective non-invasive drug delivery systems is of great importance to the treatment of Alzheimer's diseases and has made great progress in recent years. In this work, lactoferrin (Lf), a natural iron binding protein, whose receptor is highly expressed in both respiratory epithelial cells and neurons is here utilized to facilitate the nose-to-brain drug delivery of neuroprotection peptides. The Lf-conjugated PEG-PCL nanoparticle (Lf-NP) was constructed via a maleimide-thiol reaction with the Lf conjugation confirmed by CBQCA Protein Quantitation and XPS analysis. Other important parameters such as particle size distribution, zeta potential and in vitro release of fluorescent probes were also characterized. Compared with unmodified nanoparticles (NP), Lf-NP exhibited a significantly enhanced cellular accumulation in 16HBE14o-cells through both caveolae-/clathrin-mediated endocytosis and direct translocation. Following intranasal administration, Lf-NP facilitated the brain distribution of the coumarin-6 incorporated with the AUC0-8h in rat cerebrum (with hippocampus removed), cerebellum, olfactory tract, olfactory bulb and hippocampus 1.36, 1.53, 1.70, 1.57 and 1.23 times higher than that of coumarin-6 carried by NP, respectively. Using a neuroprotective peptide - NAPVSIPQ (NAP) as the model drug, the neuroprotective and memory improvement effect of Lf-NP was observed even at lower dose than that of NP in a Morris water maze experiment, which was also confirmed by the evaluation of acetylcholinesterase, choline acetyltransferase activity and neuronal degeneration in the mice hippocampus. In conclusion, Lf-NP may serve as a promising nose-to-brain drug delivery carrier especially for peptides and proteins.

Activatable cell penetrating peptide-conjugated nanoparticles with enhanced permeability for site-specific targeting delivery of anticancer drug.

Based on the powerful cell-penetrating ability of low molecular weight protamine (LMWP) and the overexpression of matrix metalloproteinases in the tumor sites, we constructed an activatable low molecular weight protamine (ALMWP) and modified it onto the surface of poly(ethylene glycol)-poly(lactic acid) nanoparticles to develop a "smart" drug delivery system with enhanced permeability for facilitating site-specific targeting delivery of anticancer drug. The obtained ALMWP-functionalized nanoparticles (ALMWP-NP) with a particle size of 134.0 ± 4.59 nm and a zeta potential of -34.4 ± 2.7 mV, exhibited an enhanced MMP-dependent accumulation in HT-1080 cells via both energy-independent direct translocation and clathrin-mediated, cytoskeleton-dependent endocytosis. Pharmacokinetic and biodistribution study in HT-1080 tumor-bearing mice showed that ALMWP-NP significantly increased the accumulation of paclitaxel (PTX) in the tumor site but not the nontarget tissues. In addition, intratumor distribution analysis demonstrated that more ALMWP-NP penetrated deeply into the tumor parenchyma. As a result, PTX loaded by ALMWP-NP exhibited improved antitumor efficacy over that by unmodified nanoparticles and LMWP-functionalized nanoparticles. The findings suggested that ALMWP-NP could be used as a safe and effective tumor-targeting drug delivery system and opened a new gateway to the application of cell-penetrating peptides for targeted antitumor therapy.

PEG-co-PCL nanoparticles modified with MMP-2/9 activatable low molecular weight protamine for enhanced targeted glioblastoma therapy.

By taking advantage of the dramatically upregulated expression of matrix metalloproteinases MMP-2 and MMP-9 in glioblastomas and the powerful transport ability of low molecular weight protamine (LMWP), we constructed an activatable low molecular weight protamine (ALMWP) and conjugated it to PEG-PCL nanoparticles (NP) to develop a 'smart' drug delivery system for enhanced targeted glioblastoma therapy. Important parameters such as particle size distribution, zeta potential and surface content were determined, which confirmed the conjugation of ALMWP to the surface of nanoparticle. ALMWP-NP loaded with paclitaxel (PTX) exhibited a desirable pharmacokinetic and biodistribution profiles for anti-glioblastoma drug delivery. Cellular experiments showed that ALMWP-NP exhibited significantly elevated MMP-dependent cellular accumulation in C6 cells via lipid raft-mediated endocytosis and energy-dependent macropinocytosis, and improved the cytotoxicity of PTX. In vitro C6 tumor spheroid uptake confirmed the tumor penetrating ability of ALMWP-NP, in vivo imaging and glioma distribution justified its specific accumulation in the glioma. The improved glioma-targeting and tumor penetration led to an anticipated enhanced in vivo anti-glioblastoma effect: animals (nude mice bearing intracranial C6 glioma) treated with ALMWP-NP-PTX survive significantly longer than those treated with saline, Taxol(®) NP-PTX and LMWP-NP-PTX. The findings here offered strong evidence for the glioblastoma-targeting therapy of ALMWP-NP-PTX, and could also lead to a significant advancement in the application of CPPs for targeted therapy of glioma.

F3 peptide-functionalized PEG-PLA nanoparticles co-administrated with tLyp-1 peptide for anti-glioma drug delivery.

The development of a drug delivery strategy which can mediate efficient tumor targeting together with high cellular internalization and extensive vascular extravasation is essential and important for glioma treatment. To achieve this goal, F3 peptide that specifically bind to nucleolin, which is highly expressed on the surface of both glioma cells and endothelial cells of glioma angiogenic blood vessels, is utilized to decorate a nanoparticulate drug delivery system to realize glioma cell and neovasculature dual-targeting and efficient cellular internalization. Tumor homing and penetrating peptide, tLyp-1 peptide, which contains the motif of (R/K)XX(R/K) and specially binds to neuropilin is co-administrated to improve the penetration of the nanoparticles across angiogenic vasculature into glioma parenchyma. The F3 conjugation via a maleimide-thiol coupling reaction was confirmed by XPS analysis with 1.03% nitrogen detected on the surface of the functionalized nanoparticles. Enhanced cellular interaction with C6 cells, improved penetration in 3D multicell tumor spheroids, and increased cytotoxicity of the loaded paclitaxel were achieved by the F3-functionalized nanoparticles (F3-NP). Following co-administration with tLyp-1 peptide, F3-NP displayed enhanced accumulation at the tumor site and deep penetration into the glioma parenchyma and achieved the longest survival in mice bearing intracranial C6 glioma. The findings here clearly indicated that the strategy by co-administrating a tumor homing and penetrating peptide with functionalized nanoparticles dual-targeting both glioma cells and neovasculature could significantly improve the anti-glioma drug delivery, which also hold a great promise for chemotherapy of other hard-to-cure cancers.