Construction and biological assessment of tissue engineering intervertebral disc / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the value of bone marrow-mesenchymal stem cells (BM-MSCs) transformed by nucleus pulposus (NPs) for construction of tissue engineering disc.</p><p><b>METHODS</b>BM-MSCs and fetal NPs were cultured in vitro, planted on polylactic acid-polyglycolic acid copolymer (PLGA), and observed with inverted microscope and scanning electronic microscope. PLGA scaffolds with adherent BM-MSCs and NPs, as well as BM-MSCs and NPs suspension were implanted into intervertebral discs of New Zealand white rabbits, respectively. Intervertebral signal intensity was evaluated by Thompson grading 12 weeks later. Proteoglycan and type IIcollagen were determined by spectrophotometric method and immunohistochemistry, respectively.</p><p><b>RESULTS</b>Spindle or multi-angular BM-MSCs turned into fibro-like phenotype coculture of BM-MSCs and NPs, which grew well with normal morphology when they attached on PLGA scaffolds. There was statistical difference in intervertebral signal intensity, and the expression of proteoglycan and type IIcollagen between PLGA scaffolds group and control group (P < 0.05), the content of proteoglycan was (3.93 ± 0.31) mg/100 mg in the PLGA scaffolds group whereas (3.52 ± 0.26) mg/100 mg in the control group.</p><p><b>CONCLUSIONS</b>BM-MSCs can be induced into NPs by cocultivation, and PLGA scaffolds can provide good growing conditions, and maintain high mechanical properties and spacial structure which meet the requirement of tissue engineering disc to prevent degeneration.</p>

Effect of biopure MTAD on removing smear layer in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the ability of Biopure MTAD in removing smear layer in vitro.</p><p><b>METHODS</b>Forty extracted single-rooted human teeth were randomly divided into five groups: Distilled water in group A, 5.25% NaClO and 17% EDTA in group B, 1.3% NaClO in group C, 1.3% NaClO and Biopure MTAD in group D, 1.3% NaClO and 3% EDTA in group E. The canals were prepared and irrigated with one of the five different irrigating agent respectively. The amount of smear layer and erosion on the surface of the root canal walls were examined with scanning electron microscope.</p><p><b>RESULTS</b>The whole surfaces of root canals in group A and C were covered by smear layer. The surfaces of root canals in the coronal and middle thirds of samples in group B, D, E were free of smear layer (P>0.05) and the apical third of canals in the group D were significantly cleaner (P<0.05) than that in group B and E. The coronal and middle sections were significantly eroded in group B compared with group D and E (P<0.05). The degree of erosion in the apical section was not statistically different among group B, D and E (P>0.05).</p><p><b>CONCLUSION</b>Biopure MTAD and 1.3% NaClO are effective irrigating agents for removal of the smear layer on the surface of root canal. There is no significant change in the structure of the surface of root canal.</p>