[Construction and biological assessment of tissue engineering intervertebral disc].

OBJECTIVE: To investigate the value of bone marrow-mesenchymal stem cells (BM-MSCs) transformed by nucleus pulposus (NPs) for construction of tissue engineering disc. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Syntheses, structures, and magnetic properties of heterobimetallic clusters with tricyanometalate and pi-conjugated ligands containing 1,3-dithiol-2-ylidene.

Two new pi-conjugated 1,3-dithiol-2-ylidene-containing ligands, 4,5-[1',4']dithiino[2',3'-b]quinoxaline-2-bis(2-pyridyl)methylene-1,3-dithiole (L(1)) and 4,5-bis(methylthio)-2-bis(2-pyridyl)methylene-1,3-dithiole (L(2)), have been synthesized and characterized. Using L(1), L(2), or dimethyl 2-[di(pyridin-2-yl)methylene]-1,3-dithiole-4,5-dicarboxylate (L(3)) as the auxiliary ligand and [(Tp)Fe(CN)(3)](-) or [(i-BuTp)Fe(CN)(3)](-) [Tp = tris(pyrazolyl)borate; i-BuTp = 2-methylpropyltris(pyrazolyl)borate] as the building block, two rectangular-square Fe(2)Ni(2) clusters [(Tp)Fe(CN)(3)Ni(L(1))(2)](2).2ClO(4).6H(2)O (1) and [(i-BuTp)Fe(CN)(3)Ni(L(3))(2)](2).2ClO(4).6H(2)O (2) and two trinuclear clusters [(Tp)(2)Fe(2)(CN)(6)Ni(L(2))(2)].8H(2)O (3) and [(Tp)(2)Fe(2)(CN)(6)Co(L(3))(2)].5H(2)O (4) have been prepared in parallel and structurally characterized. Complexes 1 and 2 show similar square structures, and weaker intermolecular pi-pi-stacking interactions through the pyrazolyl groups of the Tp(-) ligands are observed. 2D sheet structures are formed in complexes 3 and 4 through intermolecular pi-pi-stacking interactions. In 3, shorter S...S contacts further connect the 2D sheets to 3D supramolecular structures. Magnetic studies show intramolecular ferromagnetic coupling in complexes 1-4. Complexes 1 and 2 show obvious frequency dependencies in the alternating-current magnetic susceptibility data, indicating single-molecule-magnet behavior with effective spin-reversal barriers of 8.7 K for 1 and 13.5 K for 2, respectively.