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Biomedical subjects

Lingsong Li

Publications and source records attributed to Lingsong Li.

At least 19 recordsLinked to original sources
PubMed2007

Upregulation of Flk-1 by bFGF via the ERK pathway is essential for VEGF-mediated promotion of neural stem cell proliferation.

Neural stem cells (NSCs) constitute the cellular basis for embryonic brain development and neurogenesis. The process is regulated by NSC niche including neighbor cells such as vascular and glial cells. Since both vascular and glial cells secrete vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), we assessed the effect of VEGF and bFGF on NSC proliferation using nearly homogeneous NSCs that were differentiated from mouse embryonic stem cells. VEGF alone did not have any significant effect. When bFGF was added, however, VEGF stimulated NSC proliferation in a dose-dependent manner, and this stimulation was inhibited by ZM323881, a VEGF receptor (Flk-1)-specific inhibitor. Interestingly, ZM323881 also inhibited cell proliferation in the absence of exogenous VEGF, suggesting that VEGF autocrine plays a role in the proliferation of NSCs. The stimulatory effect of VEGF on NSC proliferation depends on bFGF, which is likely due to the fact that expression of Flk-1 was upregulated by bFGF via phosphorylation of ERK1/2. Collectively, this study may provide insight into the mechanisms by which microenvironmental niche signals regulate NSCs.

Animals↗
PubMed2006

Differentiation plasticity of human fetal articular chondrocytes.

OBJECTIVE: To test chondrogenic differentiation potential, we examined the differentiation plasticity of isolated human fetal articular chondrocytes (HFACs). STUDY AND DESIGN SETTING: Culture-expanded human fetal articular chondrocytes (HFACs) were analyzed for chondrogenic, adipogenic, osteogenic capacity and neural differentiation ability in defined in vitro culture systems. RESULTS: The different assays demonstrated that culture-expanded HFACs have potential to form cartilage in pellet mass culture, to form adipose cells, osteogenic cells, and neural cells in monolayer culture. CONCLUSIONS: These results suggest that within human fetal articular cartilages there are MSC-like cells that exhibit differentiation plasticity that is comparable with that of BM-MSCs and they may be a new kind of seeding cells for head and neck cartilage reconstruction.

Cartilage, Articular↗
PubMed2005

Association between monoamine oxidase gene polymorphisms and smoking behaviour in Chinese males.

Monoamine oxidase (MAO) is a critical metabolic enzyme of dopamine, which is a key neurotransmitter of the mesolimbic reward pathway in the human brain. Consequently, the gene encoding MAO is an important candidate gene in the genetics of smoking behaviour. We investigated the association between MAOA polymorphisms (a VNTR polymorphism and an EcoRV polymorphism) and smoking status. A community-based cross-sectional study was conducted with 203 current smoking subjects and 168 non-current smoking subjects in Beijing, China. Genotyping for these polymorphisms was performed using PCR and restriction fragment length polymorphism. Multiple logistic regression models were used to analyse the association of MAOA gene polymorphisms with smoking status. We found that individuals with the 1460T/O genotype had a significantly increased the risk of smoking compared to those with 1460C/O. The adjusted odds ratios (aORs) were 3.2 (95% CI 2.0-5.2) in current vs. non-current smokers group, 1.7 (95% CI 1.1-2.8) in ever vs. never smokers group, 2.5 (95% CI 1.4-4.3) in current vs. never smokers group, and 5.3 (95% CI 2.5-11.2) in current vs. former smokers group respectively. We also found that individuals with the 3-repeat genotype of the VNTR polymorphism had a significantly increased risk of smoking significantly compared to those with the 4-repeat genotype. The aORs were 2.0 (95% CI 1.0-4.1) in the current vs. former smokers group, and 1.9 (95% CI 1.0-3.6) in the nicotine dependent vs. non-nicotine dependent group respectively. Moreover, MAOA gene haplotypes were associated significantly with nicotine dependence in every group. In conclusion, there is an important association between MAOA polymorphisms and smoking status, suggesting a possible role of MAOA gene variants in nicotine dependence.

Adult↗
PubMed2005

Reconstruction of chemically burned rat corneal surface by bone marrow-derived human mesenchymal stem cells.

To examine whether transplantation of human mesenchymal stem cells (MSCs) could reconstruct the corneal damage and also whether grafted MSCs could differentiate into corneal epithelial cells, we isolated MSCs from healthy donors. After growth and expansion on amniotic membrane, cells were transplanted into rat corneas 7 days after chemical burns. Reconstruction of the damaged cornea and the rat vision were measured once a week by slit lamp and by an optokinetic head-tracking instrument, respectively. Corneas were then cut out, fixed, and imbedded for immunofluorescent study of the expression of keratin 3 and keratin-pan as epithelial cell markers. Expression of CD45, interleukin 2, and metalloproteinase-2 was also investigated for inflammation and inflammation-related angiogenesis. The data showed that transplantation of MSCs, like limbal epithelial stem cells, successfully reconstructed damaged rat corneal surface. Interestingly, the therapeutic effect of the transplantation may be associated with the inhibition of inflammation and angiogenesis after transplantation of MSCs rather than the epithelial differentiation from MSCs. This study provides the first line of evidence that MSCs can be used for reconstruction of damaged corneas, presenting a new source for autotransplantation in the treatment of corneal disorders.

Animals↗
PubMed2005

A novel PAX6 gene mutation in a Chinese family with aniridia.

PURPOSE: The PAX6 gene mutation in aniridia has been studied in various ethnic patients, but not well studied in the Chinese population. In the present study, we have investigated the PAX6 gene mutation in a Chinese family with congenital aniridia. METHODS: Total genomic DNA was isolated from peripheral blood of three aniridia patients (who also suffered from bilateral congenital cataracts) and two non-carriers in a Chinese family. Fourteen exons of the PAX6 gene were amplified by polymerase chain reaction (PCR). PCR products of each exon were analyzed by single strand conformational polymorphism (SSCP). The PCR products with abnormal SSCP patterns were subcloned and sequenced to identify the mutation. RESULTS: Abnormal SSCP patterns were found in all affected patients but not in non-carrier family members. A novel mutation (c.857delG) in exon 7 was detected by sequencing analysis. This frame shift mutation was predicted to lead to a pre-stop codon in exon 8, and generate a novel 40 amino acid peptide from codon 165. CONCLUSIONS: A novel PAX6 gene mutation was identified in a Chinese aniridia family. This mutation may also contribute to congenital cataracts in these aniridia patients.

Adult↗
PubMed2005

In vitro neuronal differentiation of cultured human embryonic germ cells.

Human embryonic germ (hEG) cells, which have been advanced as one of the most important sources of pluripotent stem cells [the other one being human embryonic stem cells], can be propagated in vitro indefinitely in the primitive undifferentiated state while being capable of developing into all three germ layer derivatives, hence have become anticipated developing novel strategies of tissue regeneration and transplantation in the treatment of degenerative diseases. In the experiments here, we derived hEG cells from cultured human primordial germ cells (PGCs) of 6- to 9-week-post-fertilization embryos. They satisfied the criteria previously used to define hEG cells, including the expression of markers characteristic of pluripotent cells-abundant alkaline phosphatase (AP) activity, stage specific embryonic antigen (SSEA)-1(+), SSEA-3(-), SSEA-4(+), TRA-1-60(+), TRA-1-81(+), Oct-4(+), and hTERT(+), the retention of normal karyotypes, and possessing pluripotency by forming embryoid bodies (EBs) in vitro. Furthermore, these derived cells tended to neurally differentiate in vitro, especially under high-density culture conditions. We successfully isolated neural progenitor cells from differentiating hEG cultures and about 10% cells induced by 2microM all-trans-retinoic acid (RA) or 0.1mM dibutyryl cyclic AMP (dbcAMP)/1mM forskolin to mature neurons expressing microtubule-associated protein 2ab (MAP2ab), synaptophysin, beta-tubulin III, neuron-specific enolase (NSE), tyrosine hydroxylase (TH), but no glial fibrillary acid protein (GFAP) and choline acetyl transferase (ChAT). The data suggested that hEG cells may provide a potential source of cells for use in transplantation therapy for neurological degenerative diseases.

Biomarkers↗
PubMed2005

Isolation and characterization of neural stem cells from human fetal striatum.

This paper described that neural stem cells (hsNSCs) were isolated and expanded rapidly from human fetal striatum in adherent culture. The population was serum- and growth factor-dependent and expressed neural stem cell markers. They were capable of multi-differentiation into neurons, astrocytes, and oligodendrocytes. When plated in the dopaminergic neuron inducing medium, human striatum neural stem cells could differentiate into tyrosine hydroxylase positive neurons. hsNSCs were morphologically homogeneous and possessed high proliferation ability. The population doubled every 44.28h and until now it has divided for more than 82 generations in vitro. Normal human diploid karyotype was unchanged throughout the in vitro culture period. Together, this study has exploited a method for continuous and rapid expansion of human neural stem cells as pure population, which maintained the capacity to generate almost fifty percent neurons. The availability of such cells may hold great interest for basic and applied neuroscience.

Astrocytes↗
PubMed2004

Cartilage-derived morphogenetic protein-1 promotes the differentiation of mesenchymal stem cells into chondrocytes.

Mesenchymal stem cells (MSCs) are able to differentiate into many types of cells including chondrocytes. Transforming growth factor beta1 (TGF-beta1) is very important in the regulation of chondrogenesis. Since cartilage-derived morphogenetic protein-1 (CDMP-1) belongs to the TGF-beta superfamily, we tested whether CDMP-1 plays any role in the regulation of the differentiation of MSCs into chondrocytes using a high density pellet culture system. Based on the histological staining of glycosaminoglycan using toluidine blue dye-binding method we found that CDMP-1 could initiate chondrogenic differentiation of MSCs as did TGF-beta1. However, CDMP-1 was less stimulatory than TGF-beta1. The combination of CDMP-1 and TGF-beta1 synergically induced chondrogenesis of MSCs. This synergic chondrogenic effect of CDMP-1 together with TGF-beta1 was further confirmed by quantification of GAG using dimethylmethylene blue dye-binding assay and immunohistochemical analysis of the expression of cartilage-specific protein collagen II. This study may provide an improved induction approach using MSCs for repairing damaged cartilage.

Aborted Fetus↗
PubMed2004

Radionuclide imaging of mesenchymal stem cells transplanted into spinal cord.

In vivo tracking of stem cells implanted to spinal cord by radionuclide imaging was investigated. The high expression of transferrin receptor on human mesenchymal stem cells (hMSCs) was verified by flow cytometry, radioligand binding and immunofluorescence. Radiolabelled transferrin was chosen as a tracer for scintigraphic imaging of the hMSCs transplanted into spinal cord of rabbits. Comparative experiments with radiolabelled human serum albumin as tracer and PBS as graft as well as ex vivo autoradiography demonstrated the specific uptake of radiolabelled transferrin of hMSCs. hMSCs could be detected in vivo with radiolabelled transferrin targeting at cellular transferrin receptors at an early stage after transplantation into spinal cord.

Animals↗
PubMed2004

Mid-trimester fetal blood-derived adherent cells share characteristics similar to mesenchymal stem cells but full-term umbilical cord blood does not.

Stem cell transplantation is a promising treatment for many conditions. Although stem cells can be isolated from many tissues, blood is the ideal source of these cells due to the ease of collection. Mesenchymal stem cells (MSCs) have been paid increased attention because of their powerful proliferation and pluripotent differentiating ability. But whether MSCs reside in blood (newborn umbilical cord blood and fetal or adult peripheral blood) is also debatable. The present study showed that MSC-like cells could be isolated and expanded from 16-26 weeks fetal blood but were not acquired efficiently from full-term infants' umbilical cord blood (UCB). Adherent cells separated from postnatal UCB were heterogeneous in cell morphology. Their proliferation capacity was limited and they were mainly CD45+, which indicated their haematopoietic derivation. On the contrary, MSC-like cells shared a similar phenotype to bone marrow MSCs. They were CD34- CD45- CD44+ CD71+ CD90+ CD105+. They could be induced to differentiate into osteogenic, adipogenic and neural lineage cells. Single cell clones also showed similar phenotype and differentiation ability. Our results suggest that early fetal blood is rich in MSCs but term UCB is not.

Cell Differentiation↗
PubMed2004

Characterization of stage-specific embryonic antigen-1 expression during early stages of human embryogenesis.

Extensive expression of stage-specific embryonic antigen-1 (SSEA-1) has been documented in some animal species, but not in human embryos. In this study, SSEA-1 was detected during human embryogenesis by whole-mount immunohistochemistry. Alkaline phosphatase (Ap) activity was detected to identify human primordial germ cells. SSEA-1 was expressed steadily and restrictedly in some cells/tissues, especially in the nephric duct and nephric tubule (including the pronephric duct and tubule, mesonephric duct and tubule, metanephric tissues) besides embryonic ectodermal cells and yolk sac from 3 to 7 weeks. High level of Ap activity was observed in vessels, part of the mesonephric duct, especially in embryonic primordial germ cells localized in the yolk sac, primitive gut, dorsal mesenteries and genital ridges. No colocalization of AP and SSEA-1 cells was observed. SSEA-1 was expressed in human embryos in a different pattern at early stages compared to that in mouse embryos. It was expressed in the nephric duct, nephric tubule, yolk sac and on the surface of embryonic ectodermal cells of the epidermis, but not in human primordial germ cells.

Animals↗
PubMed2004

Improving recovery of spinal cord-injured rats by telomerase-driven human neural progenitor cells.

PURPOSE: Human neural progenitor cells hold great promise for treating a variety of human neurological diseases such as spinal cord injury. One of the issues limiting this technology is how to expand neural progenitor cells in vitro to obtain sufficient number of cells for clinical transplantation. We have established a homogeneous population of human neural progenitor cells (hNPC-TERT) immortalized by the human telomerase reverse transcriptase (hTERT) gene. Then we studied whether these cells could differentiate into neural cells in vivo and improve the recovery of spinal cord-injured rats. METHODS: The hNPC-TERT cells had been transplanted into the injured spinal cord and the functional recovery of the rats with spinal cord contusion injury was evaluated through BBB locomotor scale and Motor Evoked Potentials. Additionally, the differentiation of hNPC-TERT cells was shown by immunocytochemistry. RESULTS: As revealed by this animal model, hNPC-TERT cells developed into functional cells in the injured spinal cord and improved recovery from spinal cord injury in both locomotor scores and electrophysiological parameter in this animal model. CONCLUSIONS: This study is the first demonstration of the use of telomerase-driven human progenitor cells to treat spinal cord injury and should provide a new cell source for research of clinical application.

Analysis of Variance↗
PubMed2003

Functional reconstruction of rabbit corneal epithelium by human limbal cells cultured on amniotic membrane.

PURPOSE: To investigate the phenotype of fetal and adult human limbal cells cultured on human amniotic membrane and the ability of cultured adult human limbal cells to repair limbal stem cell deficiency in a rabbit model. METHODS: Human adult and fetal limbal cells were isolated and cultured either on plastic plates or on human amniotic membrane. Connexin43, p63, and keratins 3 and 12 (K3 and K12) were detected by immunofluorescence and RT-PCR. Limbal stem cell deficiency was established in rabbits using chemical ablation and mechanical debridement. Cultured adult human limbal cells were transplanted onto rabbit corneas one month after injury, then fixed and imbedded in paraffin forty days later. Immunofluorescent staining of human-nuclear antigen, p63, K3, and connexin43 identified human-specific cells, progenitor cells, and differentiated corneal epithelial cells, respectively. RESULTS: Adult and fetal cultured limbal cells appeared similar in morphology. RT-PCR results showed that cells cultured from the human adult and fetal limbal area expressed both p63 and K12, whereas cells from central adult epithelium expressed K12 only. Immunofluorescent staining showed that more cells were p63 positive when cultured on human amniotic membrane than on plastic. Double staining for p63 and connexin43 showed some p63-positive cells co-expressing connexin43. After transplantation of adult human limbal cells cultured on human amniotic membrane, injured rabbit corneas were completely reconstructed exhibiting epithelial integrity, improved corneal clarity, and little or no neovascularization. The majority of repopulated epithelial cells expressed anti-human nuclear antibody. Cells expressing p63 occurred throughout the new epithelium. CONCLUSIONS: During healing, expression of p63 is not limited to epithelial stem cells but may also mark transient amplifying progenitor cells. Culture on human amniotic membrane suppresses differentiation of limbal epithelial cells and promotes the proliferation of p63 expressing cells. Amniotic membrane-cultured human limbal cells fully reconstructed rabbit corneas having limbal stem cell deficiency, with human cells providing most of the cells of the new epithelium. Expression p63 is distributed throughout the reconstructed tissue.

Amnion↗
PubMed2003

[The induction of neuronal differentiation in the glial fibrillary acid protein positive human neural progenitor cell line].

OBJECTIVE: To investigate the ability of human GFAP positive neural progenitor cell line from the subventricular zone (SVZ) to differentiate into neurons. METHODS: Real-time RT-PCR, Western blot analysis and immunocytochemistry were used to examine the expression level of the neural stem cell marker and neuronal-specific marker before and after all-trans-retinoic acid (AT-RA) induction in the GFAP positive neural progenitor cell line. Immunocytochemistry was used to examine the expression of the neuronal-specific marker after transplantation the GFAP positive neural progenitor cell line into the animal model. RESULTS: After induction, in the GFAP positive neural progenitor cell line the expression levels of the neuronal-specific marker increased, while the neural stem cell marker decreased both in mRNA and protein levels. After transplantation into animal model, the GFAP positive neural progenitor cell line could differentiate into neurons. CONCLUSION: The GFAP positive neural progenitor cell line could be induced to differentiate into neurons both in vitro and in vivo.

Cell Differentiation↗
PubMed2003

[Induced expression of dopamine D2 receptor in human neuro-progenitor cell line HNG1210-E].

OBJECTIVE: To investigate whether the dopamine receptor D2 can express or can be induced to express in HNG1210-E, a monoclonal, telomerase-immortalized, human neural progenitor cell line. METHODS: By means of RT-PCR, immuno-fluorescent staining, and fluo3 Ca2+ imaging to the expression of D2 mRNA and protein as well as the reaction to dopamine were demonstrated. RESULTS: HNG1210-E cells could be induced to express D2 mRNA and its proteins. The induced cells also reacted to dopamine (5 mmol.L-1), which caused rapid rising of cytoplasm Ca2+. CONCLUSION: HNG1210-E cells can be induced to express D2 mRNA and functional proteins.

Calcium↗
PubMed2003

[Functional evaluation for neural progenitor cells transplantation to treat spinal cord injury in rats].

OBJECTIVE: To evaluate the functional recovery of acute spinal cord-injured rats treated by immortalized neural progenitor cells transplantation. METHODS: Spinal cord injury (SCI) model was built by revised Allen method. Immortalized neural progenitor cells (G3 line) transplantation was performed on day 9 after injury. Culture medium and nontreatment groups were used as control. BBB scores were checked every week to show the motor function recovery and Motor Evoked Potentials (MEPs) were recorded 8 and 12 weeks after transplantation to display the conduction of injured spinal cord. RESULTS: There were not significantly differences for BBB scores among the three groups within 12 weeks after grafting; but MEPs were significantly enhanced in G3 group compared with control and sham groups. CONCLUSION: Immortalized neural progenitor cells transplantation can significantly improve the conduction of spinal cord injured rats.

Animals↗
PubMed2003

[Transplantation of bone marrow cells upregulated vascular endothelial growth factor and its receptor and improved ischemic myocardial function].

OBJECTIVE: To investigate the possible mechanisms of improving ischemic myocardial function by transplantation of bone marrow cells in a rat ischemic heart model. METHODS: Myocardial infarction was induced in inbred Lewis rats by left anterior descending artery ligation. Bone marrow cells were injected into an ischemic zone (BMI group). On days 1, 3, 7, 14 and 28 post-transplantation, the expressions of vascular endothelial growth factor (VEGF) and its receptor (Flk-1) and the differentiation of transplanted cells were determined by immunofluorescence and RT-PCR. The number of vessels was examined by immunohistochemistry. The cardiac function was evaluated by hemodynamics. RESULTS: Immunofluorescence microscopy of hearts from BMI group revealed that expressions of VEGF and Flk-1 were promoted within cardiomyocytes in the infarction zone, the peri-infarct zone and in some transplanted bone marrow cells. RT-PCR also showed that mRNA expression levels of VEGF and Flk-1 in BMI group were significantly higher than those of the control group, reached the highest level on days 3 and 14 post-transplantation, and then gradually declined. On days 7, 14 and 28, the vessel count showed the number of blood vessels in the BMI group was greater than that of the control group at the same time, and the cardiac function in the BMI group was improved more significantly than that of the control group. After day 14, the specific markers for myocardium or vascular endothelial cells were detected in the transplanted bone marrow cells. CONCLUSIONS: BMI improved the acute ischemic cardiac function by both upregulating the expressions of VEGF and Flk-1 in transplanted BMCs and recipient endogenous cardiomyocytes that enhanced angiogenesis.

Animals↗