[Study of apoptosis gene expression in U937 cells induced by adhesion culture with mesenchymal stem cell].

Objective: To compare apoptosis gene expression profiling of U937 cells in suspension culture with that cultivated with mesenchymal stem cells (MSCs), and find out the relationship between drug resistance of leukemia cells and hemopoietic microenvironment.

Methods: U937 cells were cultivated in adhesion culture with MSCs and in suspension culture for 48 hours. Cell cycle was determined by flow cytometry and gene expression profiling by cDNA microarray.

Study on the bone marrow mesenchymal stem cells induced drug resistance in the U937 cells and its mechanism.

Background: The hematopoietic microenvironment (HM) plays a critical role in malignant cell growth, patient survival, and response to chemotherapy in hematologic malignancies. However, mechanisms associated with this environmental influence remain unclear. In this study, we investigated the role of bone marrow derived mesenchymal stem cells (MSCs) in U937 cell line, to find out the relations between leukemia drug resistance and the MSCs.

Reversal of MDR1 gene-dependent multidrug resistance using short hairpin RNA expression vectors.

Background: RNA interference using short hairpin RNA (shRNA) can mediate sequence-specific inhibition of gene expression in mammalian cells. A vector-based approach for synthesizing shRNA has been developed recently. Overexpression of P-glycoprotein (P-gp), the MDR1 gene product, confers multidrug resistance (MDR) to cancer cells.

[Study on multipotential differentiation of human bone marrow mesenchymal stem cells in vitro].

Objective: To study the capability of human bone marrow mesenchymal stem cells (MSCs) to differentiate into adipocyte, osteoblasts, and neurocytes under different experimental conditions in vitro.

Methods: The induced human bone marrow MSCs were examined by cytochemistry staining and immunohistochemistry staining.

Results: Induced human bone marrow MSCs formed alkaline phosphatase-positive aggregates and Von Kossa stain-positive nodules under the condition of osteogenic differentiation.

[Effects of fluoride on osteoclastic activity of rats in vitro].

Objective: To investigate the effects of fluoride on activities of tartrate-resistant acid phosphate (TRAP) and matrix metalloproteinase-9 (MMP-9) in rat osteoclasts cultured in vitro.

Methods: Osteoclast was isolated mechanically from long bones of neonatal rats and cultured in vitro. Histochemical stain was applied to detect the effects of fluoride on activities of TRAP and in-situ hybridization was used to study the expression of MMP-9 mRNA in rat osteoclasts in vitro.