(±)-Quassidine K, a pair of cytotoxic bis-ß-carboline alkaloid enantiomers from Picrasma quassioides.

(±)-Quassidine K (1), a pair of new bis-ß-carboline alkaloid enantiomers, were isolated from Picrasma quassioides. Their structures were determined on the basis of detailed spectroscopic data analysis. The absolute configurations of (+)-S-quassidine K (1a) and (-)-R-quassidine K (1b) were determined by comparing with the reported experimental ECD spectra after chiral separation. The cytotoxicity assay showed activity against HeLa cells with IC50 values of 15.8 and 20.1 µM, respectively.

Free radicals generated by tantalum implants antagonize the cytotoxic effect of doxorubicin.

Little is known about the interaction between antineoplastic drugs and implants in bone cancer patients. We investigated the interaction between commercially available porous tantalum (Ta) implants and the chemotherapeutic drug, Doxorubicin (DOX). DOX solutions were prepared in the presence of Ta implant. The changes in fluorescence intensity of the DOX chromophore were measured by spectrofluorometry and the efficacy of DOX was evaluated by viability of rabbit rectal tumor cells (VX2). After 5 min interaction of the DOX solution (5 µg/ml) with the Ta implant, the fluorescent intensity of the DOX solution was 85% degraded, and only 20% the drug efficacy to kill VX2 cells was retained. However, after adding a reducing agent, Dithiothreitol (DTT, 10 µg/ml), 80% of the original fluorescence and 50% of the drug efficacy were restored while UV irradiation enhanced drug degradation in the presence of Ta implant. The action of DTT and UV irradiation indicated that reactive oxygen species (ROS) were involved in the drug degradation mechanism. We detected that Ta implants in aqueous medium produced hydroxyl radicals. Cells showed higher intracellular ROS activity when culture medium was incubated with the Ta implant prior to cell culture. It is concluded that the porous Ta implant antagonizes the cytotoxicity of DOX via ROS generation of the porous Ta implant.

Electrostatic self-assembly of multilayer copolymeric membranes on the surface of porous tantalum implants for sustained release of doxorubicin.

Many studies in recent years have focused on surface engineering of implant materials in order to improve their biocompatibility and other performance. Porous tantalum implants have increasingly been used in implant surgeries, due to their biocompatibility, physical stability, and good mechanical strength. In this study we functionalized the porous tantalum implant for sustained drug delivery capability via electrostatic self-assembly of polyelectrolytes of hyaluronic acid, methylated collagen, and terpolymer on the surface of a porous tantalum implant. The anticancer drug doxorubicin was encapsulated into the multilayer copolymer membranes on the porous tantalum implants. Results showed the sustained released of doxorubicin from the functionalized porous tantalum implants for up to 1 month. The drug release solutions in 1 month all had inhibitory effects on the proliferation of chondrosarcoma cell line SW1353. These results suggest that this functionalized implant could be used in reconstructive surgery for the treatment of bone tumor as a local, sustained drug delivery system.

A traditional Chinese medicine formula extracts stimulate proliferation and inhibit mineralization of human mesenchymal stem cells in vitro.

AIM OF THE STUDY: To investigate the effects of a traditional Chinese medicine (TCM) formula extract, named as ZD-I, on the proliferation and osteogenic differentiation of human mesenchymal stem cells (hMSCs) in vitro. MATERIALS AND METHODS: When hMSCs cultivated in the basal medium with ZD-I, cell viability was assessed by MTT assay and cellular proliferation was assessed by SYBR green I assay. The effects of ZD-I on osteogenic differentiation of hMSCs were assessed by alkaline phosphatase (ALP) activity, mineralization assay and real-time RT-PCR. RESULTS: ZD-I (0.78-100 microg/ml) was non-cytotoxic. The 50% inhibitory concentration (IC50) of hMSCs was 200 microg/ml. ZD-I (0.78-50 microg/ml) stimulated the proliferation of hMSCs. ZD-I did not change ALP activity of hMSCs cultivated in osteogenic medium in the early stage (4 and 7 days), but ZD-I inhibited the mineralization of hMSCs through down-regulation of several osteogenic markers (e.g. osteocalcin, bone morphogenetic protein 2 and osteopontin) in the late stage. CONCLUSIONS: ZD-I stimulate cellular proliferation and decrease the bone mineral deposition of hMSCs. These results suggest ZD-I may play an important therapeutic role in osteoarthritic patients by improving proliferative capacity of hMSCs and inhibiting the mineralization of hMSCs.

Different mechanisms of spinal fusion using equine bone protein extract, rhBMP-2 and autograft during the process of anterior lumbar interbody fusion.

To elucidate the molecular mechanisms of spinal fusion with different graft materials during an anterior lumbar interbody fusion, we examined the gene-expression profiles after implantation of equine bone protein extract, rhBMP-2 and autograft using microarray technology and data analysis, including hierarchical clustering, self-organizing maps (SOM), KEGG pathway and Biological process GO analyses in a porcine model. The results suggest that equine bone protein extract exhibited a more similar expression pattern with autograft than that of rhBMP-2. rhBMP-2 recruits progenitor cells, proliferation and differentiation possibly by inducing various factors including PGHS-2, IFGBP-2, VEGF and chemokines and then leads to preferable membranous ossification and bone remodeling. Conversely, equine bone protein extract results in endochondral ossification via upregulation of cartilage-related genes. Ossification by inducing direct osteoblastic differentiation and obviating the cartilaginous intermediate phases may increase spinal fusion rate.

[Characteristics of osteoblastic differentiation in mesenchymal stem cells from porcine bone marrow in vitro].

OBJECTIVE: To observe the characteristics and related gene expression of osteoblastic differentiation in porcine bone marrow mesenchymal stem cells (MSCs) during. METHODS: Bone marrow from 6 landrace pigs, 3-month-old about 50 kg, was aspirated from the medullary cavity of the proximal tibia. The MSCs were isolated, and purified by Ficoll density gradient centrifugation combined with adherent culture method. The MSCs from passage 1 were cultivated in DMEM with 1 x 10(-8) mmol/L dexamethasone (Dex), 10 mmol/L beta-glycerophosphate (beta-GP), 82 microg/ml ascorbic acid (Asc) and 10% inactivated fetal bovine serum (FBS) up to 21 days. The MSCs were cultivated in basic DMEM as a control. Cell morphology was observed by microscope. Cell proliferation was tested by using the fluorescent dye SYBR green I measurement. Osteoblastic differentiation was evaluated by alkaline phosphatase (ALP) histochemical staining, quantitative calcium deposit, and real-time PCR technology. RESULTS: Characterization of primary MSCs: At day 1, most cells depicted round and floating hematopoietic cells. Colonies consisting of fibroblastlike cells were observed at day 3 after removal of non-adherent cells, colonies grew to various sizes at day 7. Thirteen population doublings took place in primary culture. Osteoblastic differentiation: During osteogenic stimulation, cellular morphology of MSCs changed from a fibroblastic shape to a cubical form. Cell proliferation had no impact in osteogenic medium compared to basic medium (P>0.05). At day 14, ALP staining presented strong positive. Calcium deposit pronouncedly increased at day 21 (P<0.01). Furthermore, the mRNA levels of core binding factor alpha1 (Cbfalpha1), osterix, ALP, collagen I (Col I ), osteonectin (ON) and osteocalcin (OC) increased gradually. Cbfalpha1, ON and ALP genes increased at early stage of osteoblastic differentiation. Osterix and OC at day 21 were significantly increased when compared with that at day 7 (P<0.05). Col I was increased at day 14 (P<0.05). CONCLUSION: Porcine MSCs harvested from bone marrow by density gradient centrifugation are capable of osteoblastic differentiation in vitro. The potential of osteoblastic differentiation relies upon upregulation of genes specific to this lineage under the ostcogenic conditions.