An experimental study on rabbit's radial bone defect healed by application of mimetic periosteum with tissue-engineered bone / 中华整形外科杂志

<p><b>OBJECTIVE</b>The purpose of this study is to investigate the osteogenic potential and possibility of combination application of mimetic osteoinductive periosteum with tissue-engineered bone.</p><p><b>METHODS</b>The three-dimensional construction of tissue-engineered bone was made by implantation of adipose derived stromal cells (ADSCs) into rhBMP-2 mediated bio-derived carrier, and mimetic periosteum was constructed by loading ADSCs into Cs-Col-beta3-TCP with rhBMP-2. 10 mm defects of right radiuses were established in adult New Zealand rabbits, group A was transplanted by tissue-engineered bone with mimetic periosteum, group B was implanted by tissue-engineered bone, and group C was implanted by mimetic periosteum, group D was transplanted by bio-derived compound bone as blank scaffold. X-ray, histology, immunohistochemistry stain, dural energy X-ray absorptiometry (DEXA) and transmission electron microscopy (TEM) examinations were performed at different periods.</p><p><b>RESULTS</b>Group A played a predominant role in process of new tissue regeneration and mature bone reconstitution, defect completely healed at 12 weeks. Group B showed primary repair, group C also existed in modeling stage. While, group D displayed retard regeneration with poor osteogenic capacity. DEXA result showed that group A had statistical significance over control group according to data of BMC and BMD ( P < 0.05).</p><p><b>CONCLUSIONS</b>Enhanced osteogenic potential can be obtained by using tissue-engineered bone with mimetic osteoinductive periosteum. Defect can be healed with concord pattern of osteoinductive and osteopromotive and osteoconductive effects.</p>

Cellular uptake and cytotoxicity of modified chitosans as gene carriers / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the effects of arginine modified chitosan or hexadecylated modified chitosan as gene carriers on the cellular uptake by vascular smooth muscle cells and its in vitro cytotoxicity. METHODS Plasmid DNA was labeled with alpha-32P-dATP and complexed with the modified chitosans or unmodified chitosan to form nanoparticle complexes by complex coacervation method. Uptake of all kinds of chitosan/ DNA nanoparticle complexes (CNC) by A10 cells was measured by beta-liquid scintillation counting. The in vitro cytotoxicity of the CNC was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay.</p><p><b>RESULTS</b>The diameters of the CNC ranged from 55.9-174.9 nm and the zeta potentials were from 10. 8 mV for the arginine modified chitosan/DNA nanoparticle complexes (ACNC) to 1.8 mV for the hexadecylated chitosan/DNA nanoparticle complexes (HCNC). The cellular uptake of the modified chitosan/ DNA nanoparticle complexes (MCNC) by A10 cells increased significantly when compared with the unmodified chitosan/DNA nanoparticle complexes (UCNC) (P < 0.05), with the HCNC at N/P ratio of 1:1 and the ACNC at ratio of 8:1 showing the highest cellular uptake (1.3 fold higher than UCNC, P < 0.05). MCNC were much less cytotoxic when compared with Lipofectamine 2000-DNA nanoparticles.</p><p><b>CONCLUSION</b>DNA nanoparticle complexes prepared with either arginine or hexadecylated modified chitosan can improve the cellular uptake of the DNA, while the in vitro cytotoxicity of both of the modified chitosan is much less than that of Lipofectamine 2000.</p>