Tongyi Chen

Evaluation of the biocompatibility of a nonceramic hydroxyapatite

In this study, the biocompatibility of calcium phosphate cement (CPC) was systematically investigated, which included systemic injection acute toxicity assay, cell culture cytotoxicity assay, gene mutation assay (Ames test), chromosome aberration assay (micronucleus test), DNA damage assay (unscheduled DNA synthesis test) and implant histological evaluation. The results showed that the CPC had no toxicity and all tests for mutagenicity and potential carcinogenicity of CPC extracts are negative. CPC was implanted into the femurs of rabbits under no-load condition and the histology of specimens revealed that the implant tightly joined with the surrounding bone, only a very slight histological inflammatory reaction occurred. Thus, CPC is a highly biocompatible material and seems to be safe for application in humans.

Dextran-g-PEI nanoparticles as a carrier for co-delivery of adriamycin and plasmid into osteosarcoma cells.

Combination of chemotherapy and gene therapy of cancer has synergistic effects on overcoming drug resistance. Macromolecular materials such as dextran and PEI have been a potential module for chemotherapeutics and gene delivery. Herein, we hypothesize the combinational strategy of chemotherapy and gene therapy in a single dextran-PEI nanoplatform. The physicochemical properties, cytotoxicity, transfection efficiency were investigated in vitro. Ultra-violet spectrum and (1)H NMR revealed adriamycin and PEI were grafted to dextran chain. Agarose gel electrophoresis demonstrated that the migration of plasmid was completely retarded when the N/P ratio of complex was 4. The sizes of DEX-ADM-PEI/DNA nanoparticles decreased and the zeta potentials enhanced with the increasing N/P ratio. Transmission electron microscope indicated a round morphology of the nanoparticles. DEX-ADM-PEI conjugation has higher cytotoxicity, compared to free adriamycin, in MG-63 and Saos-2 osteosarcoma cells but DEX-PEI maintained over 65% cell viability at the concentration of 8 mg/mL. The transfection efficiency of DEX-ADM-PEI/pEGFP-N1 at N/P ratio of 4:1 both in MG-63 and Saos-2 cell were slightly low than that of PEI 25k. But our nanoplatform efficiently delivered both plasmid pEGFP-N1 and adriamycin into osteosarcoma cells. This study demonstrated that DEX-ADM-PEI efficiently and selectively delivered both plasmid pEGFP-N1 and adriamycin to osteosarcoma cells with low cytotoxicity.

Study of sensory and motor fascicles in brachial plexus and establishment of a digital three-dimensional graphic model.

To investigate a 3-dimensional (3D) model of human brachial plexus including its topography of sensory and motor fascicles with the assistance of the computer technology, 2 brachial plexus were serially horizontally sliced. Each slice was stained by Karnovsky–Roots acetylcholinesterase histochemical method. The stained sections were scanned, and the image was put into the computer serially. At last, the 3D diagram of brachial plexus was made. The internal structure of the brachial plexus was found to be very complicated. The fascicles bifurcated and recombined with one another with no fixed rules. All fascicles were mixed sensory and motor fibers. Acetylcholinesterase histochemical staining from a serial tissue section is a useful technique to distinguish sensory fibers from motor ones. The 3D visualization of the brachial plexus may help to develop a computerized database of the fascicle topography to provide an anatomical reference in fascicular repair of brachial plexus.

Repair of partial nerve injury by bypass nerve grafting with end-to-side neurorrhaphy.

The purpose of this study was to investigate the efficacy of bypass nerve grafting with end-to-side neurorrhaphy in repair of the partial nerve injury in a rabbit model. Thirty-six adult male New Zealand rabbits were divided into three groups. A partial nerve injury was created by removal of a segment of the lateral fascicle of the left peroneal nerve. In group one, the injured nerve was repaired with nerve graft bypassing the injury site in an end-to-side fashion 4 weeks after injury. In group two, the injured nerve was repaired with end-to-end interpositional nerve grafting 6 weeks after injury. The injured nerve without repair was used as the control. Sixteen weeks after nerve repair, in groups one and two, and 20 weeks after the initial nerve injury in the control group, the nerves were dissected for electrophysiological examination and biopsied for histology and molecular markers expression. The nerve repair with interpositional nerve grafting achieved maximal functional recovery. However, motor nerve conduction velocity and compound motor action potential in nerve repair with bypass nerve grafting were significantly higher than that in the nerve injury without repair. Histologically, the regenerated myelinated axons and unmyelinated axons were present in the distal peroneal nerves in the bypass nerve grafts. The axon counts in nerve repair with the bypass nerve grafting were also significantly higher than that in the nerve injury without repair. The comparisons of the ciliary neurotrophic factor and the calcitonin gene-related peptide gene expressions between nerves with and without repair were significantly different. End-to-side bypass nerve grafting can significantly improve functional recovery in the nerve with partial injury and may be a useful repair strategy in neuromas-in-continuity.

Expression of Livin and PlGF in human osteosarcoma is associated with tumor progression and clinical outcome

Baculoviral IAP repeat containing 7 (BIRC7/Livin/ML-IAP/KIAP; referred to as Livin throughout the present study) and placental growth factor (PlGF) are not detectable in the majority of normal differentiated tissues, but are present in a number of types of cancer, including hepatocellular carcinoma, ovarian cancer and renal cell carcinoma. The aim of the present study was to assess the expression levels of Livin and PlGF in human osteosarcoma specimens and cell lines, and to analyze the functions of Livin and PIGF in the prognosis of osteosarcoma. The expression levels of Livin and PlGF in 48 osteosarcoma specimens and three osteosarcoma cells were determined using immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. The positivity rates of Livin and PlGF in osteosarcoma specimens were 58.3 and 60.4%, respectively, but were 0% in normal bone tissues. The expression levels of Livin and PlGF were increased in MG-63 cells, compared with those in the other cell lines evaluated in the present study. In addition, the expression levels of Livin and PlGF were significantly associated with tumor diameter and Enneking staging, but were independent of tumor site, age and sex of patients. The expression level of Livin was not associated with PlGF. Furthermore, the 5-year overall survival rate was decreased in the Livin or PlGF expression group, compared with that in the non-expression group (P=0.034 and P=0.012, respectively). The expression levels of Livin and PlGF were independent prognostic factors for patients with osteosarcoma. The results of the present study demonstrated that Livin and PlGF may participate in the pathogenesis of osteosarcoma. Therefore, pharmacological inhibition of Livin or PlGF may provide a novel strategy for osteosarcoma treatment.

Three-dimensional reconstruction of human median, ulnar and radial nerve

This study was undertaken to implement the three-dimensional (3D) reconstruction of the intraneural structure in the upper limb peripheral nerves. Three fresh cadaver peripheral nerves (one median, one ulnar and one radial nerve) were located with human hair, embedded in OCT, sectioned consecutively every 100 mum at a 20 mum thickness. Then all slices were stained with the acetylcholinesterase histochemical (AChe) method. 2D information of these slices were obtained through high resolution scanner. A special software (3D nerve visualization system) was used for 3D reconstruction of these nerves. Finally, 3D microstructure inside these nerves were reproduced in the computer. 3D nerve visualization system can show exactly the 3D microstructure inside these nerves and the rules of the regrouping and redistribution of the fasciculus. In addition, the reconstructed nerves could rotate at any angle along any axis, which might help us to observe the shape, position and relationships of fasciculus from different positions. It might do a great help to provide a anatomic basis for the approach in treating peripheral nerve injuries.