Porous microspheres as promising vehicles for the topical delivery of poorly soluble asiaticoside accelerate wound healing and inhibit scar formation in vitro &in vivo.

Asiaticoside is a natural compound possessing diverse pharmacological effects with great potential for clinical use. However, the low solubility and oil-water partition coefficient of asiaticoside lead to reduced effect and limited application. This study aims to construct a porous microsphere for the sustained release of asiaticoside to improve its absorption and enhance the therapeutic effects. Parameters of the formulations, including the drug to polymer ratio, solvent amounts of the inner and external phases, the stirring speed for preparation, and the drug entrapment efficiency were investigated and optimized. Particle size, morphology, pores structure, and Fourier transform infrared spectrum of the microsphere were characterized. The release kinetics and cellular uptake profiles of the asiaticoside-microspheres were examined. The therapeutic effects of asiaticoside-microspheres on wound healing and skin appendages regeneration were investigated in vitro & in vivo. Results showed that the optimized asiaticoside-microspheres possess spherical spongy structure with cylindrical holes. Asiaticoside can be loaded in the microsphere with high efficiency and released with sustained manner. The cellular uptake of asiaticoside from the microspheres was increased with 9.1 folds higher than that of free solution. Asiaticoside-microspheres expressed the strong promotion in the proliferation, migration of keratinocytes and wound scratching healing in vitro. More importantly, they significantly accelerated the re-epithelization, collagen synthesis and pro-angiogenesis in the rat full-skin wound healing. Porous microsphere was shown a novel carrier for the sustained delivery of poorly soluble asiaticoside, with absorption and therapeutic effects improved. Asiaticoside-microsphere is a promising topical preparation with excellent regenerative effects for the wound therapy.

Integration of antimicrobial peptides with gold nanoparticles as unique non-viral vectors for gene delivery to mesenchymal stem cells with antibacterial activity.

Gold nanoparticles (AuNPs) have emerged as attractive non-viral gene vectors. However their application in regenerative medicine is still limited partially due to a lack of an intrinsic capacity to transfect difficult-to-transfect cells such as primary cells or stem cells. In current study, we report the synthesis of antimicrobial peptide conjugated cationic AuNPs (AuNPs@PEP) as highly efficient carriers for gene delivery to stem cells with antibacterial ability. The AuNPs@PEP integrate the advantages of cationic AuNPs and antibacterial peptides: the presence of cationic AuNPs can effectively condense DNA and the antimicrobial peptides are essential for the cellular & nucleus entry enhancement to achieve high transfection efficiency and antibacterial ability. As a result, antimicrobial peptides conjugated AuNPs significantly promoted the gene transfection efficiency in rat mesenchymal stem cells than pristine AuNPs, with a similar extent to those expressed by TAT (a well-known cell-penetrating peptide) modified AuNPs. More interestingly, the combinational system has better antibacterial ability than free antimicrobial peptides in vitro and in vivo, possibly due to the high density of peptides on the surface of AuNPs. Finally we present the concept-proving results that AuPs@PEP can be used as a carrier for in vivo gene activation in tissue regeneration, suggesting its potential as a multifunctional system with both gene delivery and antibacterial abilities in clinic.

ß-Cyclodextrin-Linked Polyethylenimine Nanoparticles Facilitate Gene Transfer and Enhance the Angiogenic Capacity of Mesenchymal Stem Cells for Wound Repair and Regeneration.

Repair of deep wounds by cell transplantation strongly depends on angiogenesis and on the regeneration of skin and appendages. In this study, plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165) was transduced into bone-marrow mesenchymal stem cells (MSCs) using a nonviral vector, ß-cyclodextrin-linked polyethylenimine, to enhance angiogenic capacity. The effects of MSCs administered by intradermal injection or transplantation on wound closure were compared in a full-thickness excision wound model. The results showed that the MSC-seeded sponge had significantly stronger acceleration in wound closure than the MSC injection. The effects on wound repair and regeneration of transplanted MSCs and pDNA-VEGF1 65-transfected MSCs (TMSCs) with gelatin/ß-tricalcium phosphate scaffold were also investigated. Compared with MSC transplantation, TMSC transplantation showed higher efficacy in stimulating wound closure, promoting dermal collagen synthesis and regulating the deposition of newly formed collagen. In addition, the angiogenic capacity of the TMSCs was higher than that of the MSCs. The results indicate that the nonviral genetic engineering of the MSCs is a promising strategy to enhance the angiogenic capacity of MSCs for wound repair and angiogenesis. Functional gene-activated MSCs may be used as cost-effective and accessible seed cells for skin tissue engineering and as novel carriers for wound gene therapy.

Cell Membrane Capsules for Encapsulation of Chemotherapeutic and Cancer Cell Targeting in Vivo.

Systemic administration of chemotherapeutic agents can cause indiscriminate drug distribution and severe toxicity. Until now, encapsulation and targeting of drugs have typically relied on synthetic vehicles, which cannot minimize the clearance by the renal system and may also increase the risk of chemical side effects. Cell membrane capsules (CMCs) provide a generic and far more natural approach to the challenges of drug encapsulation and delivery in vivo. Here aptamer AS1411, which can recognize and bind overexpressed nucleolin on a cancer cell membrane, was chemically conjugated onto CMCs. As a result, AS1411 modified CMCs showed enhanced ingestion in certain cancer cells in vitro and accumulation in mouse cancer xenografts in vivo. Chemotherapeutics and contrast agents with therapeutically significant concentrations can be packaged into CMCs by reversible permeating their plasma membranes. The systematic administration of cancer targeting CMCs loaded with doxorubicin hydrochloride can significantly inhibit tumor growth in mouse xenografts, with significantly reduced toxicity compared to free drug. These findings suggest that cancer targeting CMCs may have considerable benefits in drug delivery and cancer treatment.

Sequential release of salidroside and paeonol from a nanosphere-hydrogel system inhibits ultraviolet B-induced melanogenesis in guinea pig skin.

Melanin is the one of most important pigments for skin color in mammals. Excessive biosynthesis of melanin induces various pigment disorders. Much effort has been made to develop regulators to minimize skin pigmentation abnormalities. However, only a few of them are used, primarily because of safety concerns and low efficiency. In this study, we aimed to construct a novel nanosphere-gel for sequential delivery of salidroside and paeonol, to investigate the synergistic effects of these drugs in anti-melanogenesis, and to decrease their potential for toxicity in high dosage. Nanospheres were prepared and characterized for their particle size, polydispersity index, zeta potential, and morphological properties. The optimized nanospheres were incorporated in carbomer hydrogel with both paeonol and salidroside entrapped to form a dual drug-releasing nanosphere-gel. With this nanosphere-gel, rapid release of salidroside from the hydrogel followed by sustained release of paeonol from the nanosphere was achieved. Using a classical model of the melanogenesis response to ultraviolet exposure, it was shown that the anti-melanogenesis effects of the dual drug-releasing system, in which the doses of the individual drugs were decreased by half, was obviously enhanced when compared with the effects of the single drug preparations. Mechanistically, the burst release of salidroside from the hydrogel may enable prompt suppression of melanocyte proliferation on exposure to ultraviolet B radiation, while the paeonol released in a sustained manner can provide continuous inhibition of tyrosinase activity in melanocytes. Combined delivery of salidroside and paeonol was demonstrated to be a promising strategy for enhancing the therapeutic efficacy of these agents in anti-melanogenesis and reducing their toxicity, so may have great potential in nanomedicine.

TAT conjugated cationic noble metal nanoparticles for gene delivery to epidermal stem cells.

Most nonviral gene delivery systems are not efficient enough to manipulate the difficult-to-transfect cell types, including non-dividing, primary, neuronal or stem cells, due to a lack of an intrinsic capacity to enter the membrane and nucleus, release its DNA payload, and activate transcription. Noble metal nanoclusters have emerged as a fascinating area of widespread interest in nanomaterials. Herein, we report the synthesis of the TAT peptide conjugated cationic noble metal nanoparticles (metal NPs@PEI-TAT) as highly efficient carriers for gene delivery to stem cells. The metal NPs@PEI-TAT integrate the advantages of metal NPs and peptides: the presence of metal NPs can effectively decrease the cytotoxicity of cationic molecules, making it possible to apply them in biological systems, while the cell penetrating peptides are essential for enhanced cellular and nucleus entry to achieve high transfection efficiency. Our studies provide strong evidence that the metal NPs@PEI-TAT can be engineered as gene delivery agents for stem cells and subsequently enhance their directed differentiation for biomedical application.