Biomedical subjects

Li-Sheng Wang

Publications and source records attributed to Li-Sheng Wang.

26 records · Page 2Linked to original sources

PubMed2003

[Cultivation of human mesenchymal stem cells on macroporous CultiSpher G microcarriers].

Adult human bone marrow-derived mesenchymal stem cells (MSCs) were cultured on microcarriers in spinner flasks and were compared with those in conventional culture in 12-well plates. For the production of adherently growing MSCs, macroporous CultiSpher G gelatin microcarriers were used in concentration of 1 g/L. The cells were seeded in a density of 5 x 10(4) cells/ml in both spinner culture and conventional stationary culture. The result showed that after 7 days of cultivation a maximum viable cell concentration of 5.15 x 10(5) cells/ml was obtained in spinner culture. Whereas the cell density increased to a maximum of 1.675 x 10(5) cells/ml on day 5 in conventional stationary culture. Lactate was produced up to 12.06 mmol/L in spinner culture and up to 13.10 mmol/L in stationary culture, and glucose was consumed up to 7.38 mmol/L and 5.37 mmol/L respectively. The average lactate yield on glucose consumption in spinner culture was only 1.63, lower than that in stationary culture 2.44. This indicated that the energy metabolism in spinner culture was significantly more efficient than that in conventional culture. After spinner culture for 12 days, the MSCs maintain the characteristics of stem cells. It is concluded that the microcarrier culture system is a suitable way to expand the seeding cells for tissue engineering.

Adult↗

PubMed2003

[Progress in the study of physiological function of sphingosine 1-phosphate].

Sphingosine 1-phosphate, a bioactive sphingolipid produced from the metabolism of sphingomyelin, play important roles in diverse biological process, including cell proliferation, survival, cytoskeleton changes, migration, angiogenesis, wound healing and embryonic development. Here we review the role of sphingosine 1-phosphate in cell biological function regulation and signal transduction.

Animals↗

PubMed2003

[cDNA cloning, subcellular localization and tissue expression of a new human Krüppel-like transcription factor: human basic Krüppel-like factor (hBKLF)].

The FLD4585 clone from the cDNA library of human fetal liver may encode a hematopoietic related transcription factor. Here we tried to clone its full-length cDNA from the 22 weeks-gestation human fetal liver and study its functional domains, genomic structure, chromosomal localization, subcellular site and expression pattern. To obtain the full-length cDNA of FLD4585 clone, 5' RACE technique was used. Bioinformatics was used to analyze its genomic structure, chromosomal localization and potential functional domains. Its subcellular localization was shown by GFP fusion technique. The expression pattern was studied by Northern blot, RT-PCR and Western blot. The results show the full-length cDNA encoded by FLD4585 clone is 1810 bp long and encodes a 345 amino acids protein with high homology to mouse BKLF (basic Krüppel-like factor). Its characteristic C-terminal three contiguous C2H2 zinc fingers place it within the family of Krüppel-like factors. Bioinformatics studies show hBKLF gene spans over 33 kb on chromosome 4p15.2-4p16.1 and contains 6 exons and 5 introns. GFP-hBKLF fusion technique showed hBKLF was present in the nuclei of COS-7 cells in a punctate pattern, whereas it was absent in the nucleoli. By Northern blot, hBKLF has two transcripts, one between 4.4 kb-7.5 kb and the other between 1.35 kb-2.4 kb. The larger transcript exists widely in human tissues. However, the smaller transcript was more restricted in blood leukocytes, liver and bone marrow. RT-PCR showed erythrocytes and granulocytes could both express hBKLF and its level increased as they matured. The expression level in fetal liver decreased as it developed towards adult liver and its hematopoietic function gradually lost. Taken together, in this paper we have successfully cloned the full length cDNA of hBKLF. Expression study suggests it may have broad functions in vivo, especially the functions in hematopoietic tissues.

Amino Acid Sequence↗

PubMed2003

[The extracellular domain of human delta-like-1 expressed and purified from CHO cells promotes expansion of hematopoietic progenitor cells].

Notch signal path plays important roles in the regulation of proliferation and differentiation of hematopoietic stem cells. An extracellular domain of human Delta-like-1 (hDll-1(ext)), one of Notch ligands, was cloned and expressed in CHO cells, and the effect of hDll-1(ext) on expansion of hematopoietic stem/progenitor cells was investigated in this study. Total RNA was isolated from human marrow mononuclear cells. hDll-1(ext) was amplified by RT-PCR and cloned to T vector, then the gene was sequenced and subcloned to pcDNA3.1/Myc-His(+)A expression vector. The constructed plasmid was transfected into CHO cells with lipofectin and the expression of secreted hDll-1(ext) in G418-resistant clones was assayed by Western blot. hDll-1(ext) high-expressed clone was cultured to collect supernatant. Fusion protein hDll-1(ext) was purified from the supernatant by immobilized metal affinity chromatography (IMAC). The results showed that expression of Notch-1 receptor was detected in cord blood-derived CD34(+) cells by RT-PCR. Human umbilical blood CD34(+) cells were cultured in serum-free medium containing SCF, IL-3, VEGF, and with or without purified hDll-1(ext) for 4 or 8 days. Effect of hDll-1(ext) on the expansion of progenitor cells was analyzed then by clonogenic assays. The number of CFU-Mix and HPP-CFC generated from the culture system containing hDll-1(ext) was 1.5 times of that from the control. In conclusion, the recombinant hDll-1(ext) promotes the expansion of primitive hematopoietic progenitors.

Animals↗

PubMed2002

Purging effect of dibutyl phthalate on leukemia cells involves fas independent activation of caspase-3/CPP32 protease.

We previously found that dibutyl phthalate (DBP) had a pharmacological activity in eliminating tumor cells and could be used as a purging agent in autologous bone marrow transplantation. In this study, we show that DBP can induce apoptosis in MO7e and U937 leukemia cell lines. Treatment of these cells with DBP up-regulates cellular activity of caspase-3/CPP32 and causes apoptosis rapidly as determined by cell viability and dUTP nick end labeling assay. Activation of caspase-3/CPP32 and cleavage of poly(ADP-ribose) polymerase were determined in DBP-induced apoptosis of leukemia cells. However, DBP treatment did not induce the expression of fas. Two caspase inhibitors, z-VAD-fmk and N-acetyl-Asp-Glu-Val-Asp-aldehyde partly blocked the cell death of MO7e cells induced by DBP. These results suggest that fas-independent activation of caspase-3 protease plays important roles in the purging effect of DBP on leukemia cells.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Tetra[2,3-thienylene]: a building block for single-molecule electromechanical actuators.

Tetra(2,3-thienylene) is a thiophene-fused [8]annulene capable of undergoing redox-induced dimensional changes. The feasibility of efficiently translating this intrinsic function into a single polymeric electromechanical actuator is investigated by both experiment and density functional theory (B3LYP 6-31G[d,p]). A study of tetra(2,3-thienylene) and its homodimer reveal that redox-induced conformational change is conserved upon dimerization, a result that implicates similar behavior in the corresponding polymer. Theoretical predictions yield a maximum redox-induced dimensional change of 5.92% per repeat unit for the homodimer. Cyclic voltammetry reveals complete reversibility for the corresponding redox cycle. The latter two facts establish tetra(2,3-thienylene) as a suitable building block for single-molecule electromechanical actuators.

Journal Article↗

PubMed2002

[Stem cell factor enhances the adhesion of hematopoietic cells to fibronectin].

Adhesion to extracellular matrix plays important roles in the regulation of survival, proliferation, differentiation and homing of hematopoietic cells and is regulated by a wide variety of growth factors, adhesion receptors and other ligands that mediate the cell to matrix and cell to cell interaction. Stem cell factor (SCF) plays important roles in the regulating growth and self-renewal of hematopoietic stem/progenitor cells. In the report, the effects of stem cell factor on the adhesion of hematopoietic cells to fibronectin were observed by using a hematopoietic growth factor dependent cell line-Mo7e. Results showed that Mo7e cells express the very late antigen VLA-4 (beta1 alpha4) and VLA-5 (beta1 alpha5) integrins. The expression of the SCF receptor (c-kit) was also detected in the Mo7e cells. SCF enhances the adhesion of Mo7e cells to fibronectin in a concentration dependent manner. SCF enhanced adhesion of Mo7e cells to fibronectin was blocked by anti-beta1, alpha4 and alpha5 antibodies. Addition of PI-3 kinase inhibitors also blocked the adhesion of Mo7e cells to fibronectin induced by SCF. It was concluded that SCF enhances the adhesion of Mo7e cells to fibronectin, and this process is mediated by integrins and PI-3 kinase pathway.

Antibodies, Monoclonal↗

PubMed1998

Synthesis, Characterization, and Molecular Structures of Diethylnitrosamine Metalloporphyrin Complexes of Iron, Ruthenium, and Osmium.

Diethylnitrosamine reacts with [(TPP)Fe(THF)(2)]ClO(4) (TPP = 5,10,15,20-tetraphenylporphyrinato dianion) in toluene to generate the bis-nitrosamine complex, [(TPP)Fe(Et(2)NNO)(2)]ClO(4), in 96% isolated yield. The related [(TTP)Fe(Et(2)NNO)(2)]SbF(6) (TTP = 5,10,15,20-tetra-p-tolylporphyrinato dianion) complex is prepared in 70% isolated yield via a similar reaction in CH(2)Cl(2). Reaction of [(TPP)Fe(Et(2)NNO)(2)]ClO(4) in CH(2)Cl(2) with NO gas results in the displacement of one of the Et(2)NNO ligands to give the air-sensitive and thermally sensitive [(TPP)Fe(NO)(Et(2)NNO)]ClO(4) derivative. Reaction of (OEP)Ru(CO) (OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion) with NOBF(4) in CH(2)Cl(2) gives [(OEP)Ru(NO)(H(2)O)]BF(4) as the final isolated product (after exposure to air) in 71% isolated yield. The aqua ligand is then displaced by Et(2)NNO in CH(2)Cl(2) to give [(OEP)Ru(NO)(Et(2)NNO)]BF(4) in 82% isolated yield. The valence isoelectronic (OEP)Ru(CO)(Et(2)NNO) compound is prepared in 71% isolated yield by the addition of excess Et(2)NNO to (OEP)Ru(CO) in CH(2)Cl(2). The nitrosyl amine complex [(OEP)Ru(NO)(HNEt(2))]BF(4) is prepared (i) in 78% yield by diethylamine addition to [(OEP)Ru(NO)(H(2)O)]BF(4) or (ii) in 71% isolated yield by diethylamine addition to [(OEP)Ru(NO)(Et(2)NNO)]BF(4). The osmium nitrosamine complexes, (TTP)Os(CO)(Et(2)NNO) and (OEP)Os(CO)(Et(2)NNO), are prepared in 74% and 66% yields, respectively, by diethylnitrosamine addition to the precursor (porphyrin)Os(CO) compounds in CH(2)Cl(2). The nitrosyl [(OEP)Os(NO)(Et(2)NNO)]BF(4) derivative is prepared in quantitative yield (by IR and (1)H NMR spectroscopy) by the reaction of (OEP)Os(CO)(Et(2)NNO) with NOBF(4). Labeling studies using (15)NOBF(4), Et(2)N(15)NO, and Et(2)NN(18)O have been used to assign the nitrosyl and nitrosamine bands in the IR spectra of several of the complexes. The solid-state structures of [(TPP)Fe(THF)(2)]ClO(4), [(TPP)Fe(Et(2)NNO)(2)]ClO(4), [(OEP)Ru(NO)(H(2)O)]BF(4), (OEP)Ru(CO)(Et(2)NNO), and (TTP)Os(CO)(Et(2)NNO) have also been determined by single-crystal X-ray diffraction. The Et(2)NNO ligands display a rare eta(1)-O binding mode in all three nitrosamine complexes.

Journal Article↗