Junjie Deng

Dendronized chitosan derivative as a biocompatible gene delivery carrier.

To improve the transfection efficiency of chitosan as a nonviral gene delivery vector, a dendronized chitosan derivative was prepared by a copper-catalyzed azide alkyne cyclization reaction of propargyl focal point poly(amidoamine) dendron with 6-azido-6-deoxy-chitosan. Its structure was characterized by (1)H NMR and FTIR analyses and its buffering capacity was evaluated by acid-base titration. In particular, its complexation with plasmid DNA was investigated by agarose gel electrophoresis, zeta potential, and particle size analyses as well as transmission electron microscopy observation. Compared to unmodified chitosan, such a chitosan derivative has better water solubility and buffering capacity. Compared to commonly used polyethyleneimine (PEI, 25 kDa), it could exhibit enhanced transfection efficiency in some cases and lower cell toxicity, as confirmed by in vitro transfection and cytotoxicity tests in human kidney 293T and human nasopharyngeal carcinoma CNE2 cell lines. In addition, the effect of serum on its transfection efficiency was also studied.

Hyaluronidase Embedded in Nanocarrier PEG Shell for Enhanced Tumor Penetration and Highly Efficient Antitumor Efficacy.

One of the major challenges in applying nanomedicines to cancer therapy is their low interstitial diffusion in solid tumors. Although the modification of nanocarrier surfaces with enzymes that degrade extracellular matrix is a promising strategy to improve nanocarrier diffusion in tumors, it remains challenging to apply this strategy in vivo via systemic administration of nanocarriers due to biological barriers, such as reduced blood circulation time of enzyme-modified nanocarriers, loss of enzyme function in vivo, and life-threatening side effects. Here, we report the conjugation of recombinant human hyaluronidase PH20 (rHuPH20), which degrades hyaluronic acid, on the surfaces of poly(lactic-co-glycolic acid)-b-polyethylene glycol (PLGA-PEG) nanoparticles followed by anchoring a relatively low density layer of PEG, which reduces the exposure of rHuPH20 for circumventing rHuPH20-mediated clearance. Despite the extremely short serum half-life of rHuPH20, our unique design maintains the function of rHuPH20 and avoids its effect on shortening nanocarrier blood circulation. We also show that rHuPH20 conjugated on nanoparticles is more efficient than free rHuPH20 in facilitating nanoparticle diffusion. The facile surface modification quadruples the accumulation of conventional PLGA-PEG nanoparticles in 4T1 syngeneic mouse breast tumors and enable their uniform tumor distribution. The rHuPH20-modified nanoparticles encapsulating doxorubicin efficiently inhibit the growth of aggressive 4T1 tumors under a low drug dose. Thus, our platform technology may be valuable to enhance the clinical efficacy of a broad range of drug nanocarriers. This study also provides a general strategy to modify nanoparticles with enzymes that otherwise may reduce nanoparticle circulation or lose function in the blood.

Star-shaped polymers consisting of a β-cyclodextrin core and poly(amidoamine) dendron arms: binding and release studies with methotrexate and siRNA

To develop multifunctional polymeric carrier for small interfering RNA (siRNA) and drug delivery, novel star-shaped polymers were synthesized by the copper catalyzed azide alkyne cyclization reactions of propargyl focal point poly(amidoamine) dendrons with per-6-azido-β-cyclodextrin, and were characterized by 1H NMR, FTIR and GPC analyses. Their physicochemical properties such as buffering capability, siRNA binding ability and in vitro cytotoxicity as well as their complexation with siRNA in aqueous system were also investigated. Under the optimized conditions, such cationic polymers could exhibit high siRNA transfection efficiency and low cytotoxicity in fibroblast cells. Moreover, their β-cyclodextrin core with internal hydrophobic cavities could be used simultaneously for the entrapment and sustained release of a poorly water-soluble anti-cancer drug (methotrexate).

Cationic star-shaped polymer as an siRNA carrier for reducing MMP-9 expression in skin fibroblast cells and promoting wound healing in diabetic rats.

Background Excessive expression of matrix metalloproteinase-9 (MMP-9) is deleterious to the cutaneous wound-healing process in the context of diabetes. The aim of the present study was to explore whether a cationic star-shaped polymer consisting of β-cyclodextrin (β-CD) core and poly(amidoamine) dendron arms (β-CD-[D3]7) could be used as the gene carrier of small interfering RNA (siRNA) to reduce MMP-9 expression for enhanced diabetic wound healing. Methods The cytotoxicity of β-CD-(D3)7 was investigated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MMT) method in the rat CRL1213 skin fibroblast cell line. The transfection efficiency of β-CD-(D3)7/MMP-9-small interfering RNA (siRNA) complexes was determined by confocal microscopy and flow cytometry. Quantitative real time (RT) polymerase chain reaction was performed to measure the gene expression of MMP-9 after the transfection by β-CD-(D3)7/MMP-9-siRNA complexes. The β-CD-(D3)7/MMP-9-siRNA complexes were injected on the wounds of streptozocin-induced diabetic rats. Wound closure was measured on days 4 and 7 post-wounding. Results β-CD-(D3)7 exhibited low cytotoxicity in fibroblast cells, and easily formed the complexes with MMP-9-siRNA. The β-CD-(D3)7/MMP-9-siRNA complexes were readily taken up by fibroblast cells, resulting in the downregulation of MMP-9 gene expression (P<0.01). Animal experiments revealed that the treatment by β-CD-(D3)7/MMP-9-siRNA complexes enhanced wound closure in diabetic rats on day 7 post-wounding (P<0.05). Conclusion β-CD-(D3)7 may be used as an efficient carrier for the delivery of MMP-9-siRNA to reduce MMP-9 expression in skin fibroblast cells and promote wound healing in diabetic rats.

PEGylated polyamidoamine dendron-assisted encapsulation of plasmid DNA into in situ forming supramolecular hydrogel

For the first time, PEGylated polyamidoamine dendron was used to condense plasmid DNA (pDNA) into the nanoparticles (polyplexes) and subsequently used to interact with α-cyclodextrin in an aqueous system. The resultant pDNA polyplexes could be encapsulated into the in situ forming supramolecuar hydrogel and exhibit sustained release and gene transfection properties.

Efficiency and Safety of β-CD-(D3)7 as siRNA Carrier for Decreasing Matrix Metalloproteinase-9 Expression and Improving Wound Healing in Diabetic Rats

Overexpression of matrix metalloproteinase-9 (MMP-9) is critical for diabetic chronic wounds involved in the refractory wound healing process. We aimed to develop a strategy through RNAi to decrease MMP-9 expression and improve diabetic wound healing. We had explored β-CD-(D3)7 as a gene carrier to take siRNA and effectively interfere with MMP-9 expression. It has been proven that β-CD-(D3)7 could be used as an effective siRNA delivery system. In this study, we want to know about the efficiency and safety of β-CD-(D3)7/MMP-9 siRNA for improving wound healing in diabetic rats. β-CD-(D3)7/MMP-9 siRNA treated animals show lower levels of MMP-9 expression, which induce faster wound-close rates. Histological evaluation indicates that β-CD-(D3)7/MMP-9 siRNA significantly increases the content of collagen around the injured tissues. The number of neutrophilic ganulocytes was significantly decreased through treatment of β-CD-(D3)7/MMP-9 siRNA. In vivo fluorescence imaging assessment shows that β-CD-(D3)7/MMP-9 siRNA could not cause organ damage and organ accumulation. The results suggest that β-CD-(D3)7/MMP-9 siRNA might be developed as a novel topical agent for the diabetic wounds treatment.

CHAPTER 10:Advances of Smart Materials for Wound Healing

Biomaterials have been widely applied in wound healing since the inception of the biomaterials field. Recent advances in smart biomaterials have led to the development of environment-responsive wound dressings and drug release systems. These materials respond to a variety of stimuli present at the site of a wound, such as reactive oxygen species, cytokines, and enzymes. Selective and precise release of growth factors, anti-inflammatory agents, and/or small molecules in response to the distinct phases of wound healing has been shown to significantly improve the healing process. Furthermore, these advances in controlled delivery have coincided with an increasingly detailed understanding of the wound healing process, creating new and more specific therapeutic targets. This chapter will present an overview of the use of stimuli-responsive smart materials in wound healing by first introducing the sequential phases and biological events in the healing process; second, summarizing key classes of stimuli-responsive materials used in wound healing; and finally, presenting the most recent and promising new directions for the field and offering perspectives for the future.