Zhaofeng Zhang

Ciliary neurotrophic factor‐coated polylactic‐polyglycolic acid chitosan nerve conduit promotes peripheral nerve regeneration in canine tibial nerve defect repair

A variety of nerve conduits incorporated with chemical and biological factors have been developed to further stimulate nerve regeneration. Although most of the nerve guides in studies are basically limited to bridge a short gap of nerve defect in rat models, it is vital to evaluate effects of conduits on nerve regeneration over distance greater than 20 mm, or more clinically relevant nerve gap lengths in higher mammals. In this study, a poly(lactide-co-glycolide) (PLGA) nerve conduit, treated with pulsed plasma and coated with ciliary neurotrophic factor (CNTF) as well as chitosan, was used to repair 25-mm-long canine tibial nerve defects in eighteen cross-bred dogs. The canines were randomly divided into three groups (n = 6), a 25-mm segment of the tibial nerve was removed and replaced by a PLGA/chitosan-CNTF nerve conduit, PLGA/chitosan conduit and autologous nerve grafts were performed as the control. The results were evaluated by general observation, electromyogram testing, S-100 histological immunostaining, and image analysis at 3 months after operation. The histological results demonstrated that the PLGA/chitosan-CNTF conduits and PLGA/chitosan conduits were capable of leading the damaged axons through the lesioned area. Through the comparison of the three groups, the results in PLGA/chitosan-CNTF conduits group were better than that of PLGA/chitosan conduits group, while they were similar to autologous nerve grafts group. Therefore, CNTF-coated PLGA/chitosan nerve conduits could be an alternative artificial nerve conduit for nerve regeneration.

Facile fabrication of dextran-based fluorescent nanogels as potential glucose sensors

Glucose-responsive nanogels based on dextran and poly(3-acrylamidophenylboronic acid) (PAAPBA) were fabricated by a facile self-assembly assisted (SAA) strategy. Further introduction of the fluorescent agent 2-[4-(3-hydroxy-4-oxo-4H-chromen-2-yl)phenoxy]ethylacrylamide (3HF-AM) allowed visualization of this glucose sensitivity, thus ensuring their potential use as glucose sensors.

Fluorescent dextran-based nanogels: efficient imaging nanoprobes for adipose-derived stem cells

For the efficient tracking of adipose-derived stem cells (ADSCs), nano-sized probes provide convenient platforms and have many advantages over the induction of reporter genes. Despite their great potential for various applications, investigations on macromolecular nanogels acting as stem cell tracking probes remain limited due to the difficulties encountered with synthesizing macromolecular nanogels with controllable diameters and surface charges. In this report, we describe a self-assembly assisted (SAA) methodology for the efficient preparation of fluorescent dextran-based nanogels as ADSC imaging nanoprobes. Through a three step procedure involving the fabrication of dextran-based nanogels, the conjugation of fluorescent molecules with the nanogels, and the surface modification of the fluorescent nanogels, novel fluorescent nanogels with various diameters ranging from 165 to 241 nm and surface potentials ranging from −10 to 10 mV were fabricated. The feasibility of these nanogels for ADSC imaging applications was also investigated. We demonstrate that negatively charged nanogels provide effective ADSC imaging without requiring any cell-uptake enhancers. Additionally, we observed that the capabilities of these nanogels to provide ADSC imaging is closely related to both their size and surface charge. Our study suggests that the fluorescent nanogels generated by the SAA approach have great potential for ADSC imaging applications due to their excellent cell imaging capabilities and low cytotoxicity.

Highly fluorescent quantum dot@silica nanoparticles by a novel post-treatment for live cell imaging

Highly fluorescent CdSe/CdS/ZnS core/shell/shell QD@SiO2 NPs have been synthesized via a reverse microemulsion approach with a novel post-treatment process by combining annealing with photoactivation. The QD@SiO2 NPs have a high photoluminescent quantum yield of up to 56% and were successfully applied to cellular uptake by HeLa cells.

The effect of co-transplantation of nerve fibroblasts and Schwann cells on peripheral nerve repair

Combinations of fibroblasts (Fbs) and corresponding epithelial cells have been widely used in many tissues, such as the skin and breast tissues, to augment tissue repair and remodeling. Recently, a large amount of new data has indicated that nerve Fbs play critical roles in Schwann cells (SCs) and axons in vitro. However, little is known regarding the effects of co-transplanting nerve Fbs and SCs on peripheral nerve repair in vivo. The aim of this study was to investigate the effect of co-transplanting sciatic nerve Fbs (SN-Fbs) and sciatic nerve SCs (SN-SCs) on nerve regeneration. We developed a 5 mm nerve-defect model in mice using a polyurethane (PUR) catheter and then injected one of four different mixtures of cells into the catheters to form the following four groups: pure Matrigel (Control group), SN-Fbs alone (SN-Fb group), SN-Fbs combined with SN-SCs at a ratio of 1:2 (Fb&SC group) and SN-SCs alone (SN-SC group). Histological and functional analyses were performed 3 months later. The results indicated that in vitro, the expression levels of NGF, BDNF and GDNF were significantly higher, and in vivo, a more moderate amount of extracellular matrix was produced in the Fb&SC group than in the SN-SC group. Compared to the other groups, co-transplanting SN-Fbs with SCs at a 1:2 ratio had significantly positive effects on nerve regeneration and functional recovery.