Regulation of soybean stem growth habit:A ten-year progress report

Stem growth habit dictates plant architecture and influences flowering and podding(seed setting),making it an essential morphological and breeding agronomic trait of soybean(Glycine max).Stem growth habit in soybean is affected by photoperiod and environment and is determined by genetic variation at major genes.Classical genetic analysis identified two critical loci,designated Determinacy 1(Dt1)and Determinacy 2(Dt2).Dt1 is an ortholog of Arabidopsis thaliana TERMINAL FLOWER1(TFL1)and specifies an indeterminate stem growth habit,whereas Dt2 specifies a semi-determinate growth habit.MADS-box proteins,including Dt2,SUPPRESSOR OF OVEREXPRESSION OF CO1(GmSOC1)and MADS-box genes downregulated by E1(GmMDE),repress Dt1 expression.Photoreceptors encoded by the E3 and E4 loci regulate the expression of soybean FLOWERING LOCUS T(GmFT)orthologs via circadian clock genes and E1,and GmFTs compete with Dt1 to regulate stem growth habit.Study of the molecular mechanism underlying the regulation of stem growth habit in soybean has focused on the repression of Dt1 expression.Here we provide an overview of progress made in elucidating the genetic and molecular bases of stem growth habit in soybean,with emphasis on the molecular components responsible for integrating photoperiodic flowering and stem growth habit.

Intra-annual stem diameter growth of Tamarix ramosissima and association with hydroclimatic factors in the lower reaches of China's Heihe River

High-resolution observations of cambial phenology and intra-annual growth dynamics are useful approaches for understanding the response of tree growth to climate and environmental change. During the past two decades, rapid socioeconomic development has increased the demand for water resources in the oases of the middle reaches of the Heihe River in northwestern China, and the lower reaches of the Heihe River have changed from a perennial river to an ephemeral stream with a decreased and degraded riparian zone. Tamarisk（Tamarix ramosissima） is the dominant shrub species of the desert riparian forest. In this study, the daily and seasonal patterns of tamarisk stem diameter growth, including the main period of tree ring formation, were examined. Observations concerning the driving forces of growth changes, along with implications for the ecology of the dendrohydrological area and management of desert riparian forests in similar arid regions, are also presented. The diurnal-seasonal activity of stem diameter and the dynamics of growth ring formation were studied using a point dendrometer and micro-coring methods during the 2012 growing season in shrub tamarisk in a desert riparian forest stand in the lower reaches of the Heihe River in Ejin Banner, Inner Mongolia of northwestern China. Generally, the variation in diurnal diameter of tamarisk was characterized by an unstable multi-peak pattern, with the cumulative stem diameter growth over the growing season following an S-shaped curve. The period from late May to early August was the main period of stem diameter growth and growth-ring formation. Among all of the hydroclimatic factors considered in this study, only groundwater depth was significantly correlated with stem diameter increment during this period. Therefore, for the dendrochronological study, the annual rings of the tamarisk can be used to reconstruct processes that determine the regional water regime, such as river runoff and fluctuations in groundwater depth. For the management of desert riparian forests, suitable groundwater depths must be maintained in the spring and summer to sustain tree health and a suitable stand structure.

Making a tooth:growth factors,transcription factors,and stem cells

Mammalian tooth development is largely dependent on sequential and reciprocal epithelial-mesenchymal interactions. These processes involve a series of inductive and permissive interactions that result in the determination, differentiation, and organization of odontogenic tissues. Multiple signaling molecules, including BMPs, FGFs, Shh, and Wnt proteins, have been implicated in mediating these tissue interactions. Transcription factors participate in epithelial-mesenchymal interactions via linking the signaling loops between tissue layers by responding to inductive signals and regulating the expression of other signaling molecules. Adult stem cells are highly plastic and multipotent. These cells including dental pulp stem cells and bone marrow stromal cells could be reprogrammed into odontogenic fate and participated in tooth formation. Recent progress in the studies of molecular basis of tooth development, adult stem cell biology, and regene- ration will provide fundamental knowledge for the realization of human tooth regeneration in the near future.

Cloning of the Eukaryotic Expression Vector with Nerve Growth Factor in Rats and Its Effects on Proliferation and Differentiation of Mesencephal Neural Stem Cells of Fetal Rats

The eukaryotic expression vector containing full-length cDNA sequence of rate nerve growth factor （NGF） β subunit was constructed and its effects on proliferation and differentiation of neural stem cells were observed. By using PCR, full-length cDNA sequence of NGF β subunit in rats was cloned and ligated into the eukaryotic expression vector pEGFP-N1-NGF. The recombinant plasmid pEGFP-N1-NGF was transfected into the mesencephal neural stem cells of embryonic rats by Lipofectamin and transiently expressed. MTT method was used to determine the effects of NGF on proliferation of neural stem cells, and under phase-contrast microscopy, the effects of NGF on growth of nervous processes following differentiation of neural stem cells were observed. Sequence analysis indicated that the cloned full-length cDNA sequence of rat NGF β was identical to that of published sequence encoding NGF in gene GeneBank. The transfection of recombinant plasmid pEGFP-N1-NGF into mesencephal neural stem cells of embryonic rats could obviously promote proliferation of neural stem cells and faciliate the growth of neural stem cells-derived nerve cells. It was suggested that neural stem cells could be used as a vehicle of gene transfer, and the expression of NGF β subunit in the neural stem cells could promote the growth of nerve cells derived from neural stem cells.

Effects of Co-grafts Mesenchymal Stem Cells and Nerve Growth Factor Suspension in the Repair of Spinal Cord Injury

To investigate effect of the transplantation of mesenchymal stem cells （MSCs） in combination with nerve growth factor （NGF） on the repair of spinal cord injury （SCI） in adult rats, spinal cord of adult rats （n= 32） was injured by using the modified Allen＇ s method. One week after the injury, the injured cords were injected with Dubeeeo-modified Eagles medium （DMEM , Group Ⅰ ）, MSCs （Group Ⅱ ）, NGF （Group Ⅲ）, and MSCs plus NGF （Group Ⅳ）. One month and two months after the injury, rats were sacrificed and their injured cord tissues were sectioned for the identification of the transplanted cells. The axonal regeneration and the differentiation of MSCs were examined by immunoeytoehemieal staining. At the same time, rats were subjected to behavioral tests by using the open-field BBB scoring system. Immunoeytoehemieal staining showed that axonal regeneration and the transplanted cells partially expressed neuron-specific nuclear protein （NeuN） and glial fibrillary acidic protein （GFAP）. At the same time, significant improvement in BBB locomotor rating scale （P〈0. 05） were observed in the treatment group. More importantly, further functional improvement were noted in the combined treatment group. MSCs could differentiate into neurons and astroeytes. MSCs and NGF can promote axonal regeneration and improve functional recovery. There might exist a synergistic effect between MSCs and NGF.

Chondrogenesis of periodontal ligament stem cells by transforming growth factor-β3 and bone morphogenetic protein-6 in a normal healthy impacted third molar

The periodontal ligament-derived mesenchymal stem cell is regarded as a source of adult stem cells due to its multipotency.However, the proof of chondrogenic potential of the cells is scarce.Therefore,we investigated the chondrogenic differentiation capacity of periodontal ligament derived mesenchymal stem cells induced by transforming growth factor(TGF)-p3 and bone morphogenetic protein(BMP)-6.After isolation of periodontal ligament stem cells(PDLSCs) from human periodontal ligament,the cells were cultured in Dulbecco’s modified Eagle’s medium(DMEM) with 20%fetal bovine serum(FBS).A mechanical force initiated chondrogenic differentiation of the cells.For chondrogenic differentiation,10μg·LTGF-β3 or 100μg·LBMP-6 and the combination treating group for synergistic effect of the growth factors.We analyzed the PDLSCs by fluorescence-activated cell sorting and chondrogenesis were evaluated by glycosaminoglycans assay,histology,immunohistochemistry and genetic analysis.PDLSCs showed mesenchymal stem cell properties proved by FACS analysis.Glycosaminoglycans contents were increased 217%by TGF-β3 and 220%by BMP-6. The synergetic effect of TGF-β3 and BMP-6 were shown up to 281%compared to control.The combination treatment increased Sox9, aggrecan and collagen II expression compared with not only controls,but also TGF-P3 or BMP-6 single treatment dramatically.The histological analysis also indicated the chondrogenic differentiation of PDLSCs in our conditions.The results of the present study demonstrate the potential of the dental stem cell as a valuable cell source for chondrogenesis,which may be applicable for regeneration of cartilage and bone fracture in the field of cell therapy.

Nerve growth factor promotes in vitro proliferation of neural stem cells from tree shrews

Neural stem cells promote neuronal regeneration and repair of brain tissue after injury,but have limited resources and proliferative ability in vivo.We hypothesized that nerve growth factor would promote in vitro proliferation of neural stem cells derived from the tree shrews,a primate-like mammal that has been proposed as an alternative to primates in biomedical translational research.We cultured neural stem cells from the hippocampus of tree shrews at embryonic day 38,and added nerve growth factor（100 μg/L） to the culture medium.Neural stem cells from the hippocampus of tree shrews cultured without nerve growth factor were used as controls.After 3 days,fluorescence microscopy after DAPI and nestin staining revealed that the number of neurospheres and DAPI/nestin-positive cells was markedly greater in the nerve growth factor-treated cells than in control cells.These findings demonstrate that nerve growth factor promotes the proliferation of neural stem cells derived from tree shrews.

Peripheral blood stem cell mobilization in multiple myeloma: Growth factors or chemotherapy?

High-dose therapy followed by autologous hematopoietic stem cell(HSC) transplant is considered standard of care for eligible patients with multiple myeloma. The optimal colection strategy should be effective in procuring sufficient HSC while maintaining a low toxicity profile. Currently available mobilization strategies include growth factors alone,growth factors in combination with chemotherapy,or growth factors in combination with chemokine receptor antagonists; however,the optimal strategy has yet to be elucidated. Herein,we review the risks and benefits of each approach.

Noggin versus basic fibroblast growth factor on the differentiation of human embryonic stem cells

The difference between Noggin and basic fibroblast growth factor for the neural precursor differen- tiation from human embryonic stem cells has not been studied. In this study, 100 tJg/L Noggin or 20 IJg/L basic fibroblast growth factor in serum-free neural induction medium was used to differen- tiate human embryonic stem cells H14 into neural precursors using monolayer differentiation. Two weeks after induction, significantly higher numbers of neural rosettes formed in the Noggin-induced group than the basic fibroblast growth factor-induced group, as detected by phase contrast micro- scope. Immunofluorescence staining revealed expression levels of Nestin, [3-111 Tubulin and Sox-1 were higher in the induced cells and reverse-transcription PCR showed induced cells expressed Nestin, Sox-1 and Neurofilament mRNA. Protein and mRNA expression in the Noggin-induced group was increased compared with the basic fibroblast growth factor-induced group. Noggin has a greater effect than basic fibroblast growth factor on the induction of human embryonic stem cell differentiation into neural precursors by monolayer differentiation, as Noggin accelerates and in- creases the differentiation of neural precursors.

Hepatocyte Growth Factor Gene-modified Bone Marrow-derived Mesenchymal Stem Cells Transplantation Promotes Angiogenesis in a Rat Model of Hindlimb Ischemia

Summary： Angiogenic gene therapy and cell-based therapy for peripheral arterial disease （PAD） have been studied intensively currently. This study aimed to investigate whether combining mesenchymal stem cells （MSCs）transplantation with ex vivo human hepatocyte growth factor （HGF） gene transfer was more therapeutically efficient than the MSCs therapy alone in a rat model of hindlimb ischemia. One week after establishing hindlimb ischemia models, Sprague-Dawley （SD） rats were randomized to receive HGF gene-modified MSCs transplantation （HGF-MSC group）, untreated MSCs transplantation （MSC group）, or PBS injection （PBS group）, respectively. Three weeks after injection, angiogenesis was significantly induced by both MSCs and HGF-MSCs transplantation, and capillary density was the highest in the HGF-MSC group. The number of transplanted cell-derived endothelial cells was greater in HGF-MSC group than in MSC group after one week treatment. The expression of angiogenic cytokines such as HGF and VEGF in local ischemic muscles was more abundant in HGF-MSC group than in the other two groups. In vitro, the conditioned media obtained from HGF-MSCs cultures exerted proproliferative and promigratory effects on endothelial cells. It is concluded that HGF gene-modified MSCs transplantation therapy may induce more potent angiogenesis than the MSCs therapy alone. Engraftment of MSCs combined with angiogenic gene delivery may be a promising therapeutic strategy for the treatment of severe PAD.

Molecular Tissue Engineering: Applications for Modulation of Mesenchymal Stem Cells Proliferation by Transforming Growth Factor β_1 Gene Transfer

The effect of transforming growth factor β 1 (TGF β 1 ) gene transfection on the proliferation of bone marrow derived mesenchymal stem cells (MSC S ) and the mechanism was investigated to provide basis for accelerating articular cartilage repairing using molecular tissue engineering technology. TGF β 1 gene at different doses was transduced into the rat bone marrow derived MSCs to examine the effects of TGF β 1 gene transfection on MSCs DNA synthesis, cell cycle kinetics and the expression of proliferating cell nuclear antigen (PCNA). The results showed that 3 μl lipofectamine mediated 1 μg TGF β 1 gene transfection could effectively promote the proliferation of MSCs best; Under this condition (DNA/Lipofectamine=1μg/3μl), flow cytometry and immunohistochemical analyses revealed a significant increase in the 3 H incorporation, DNA content in S phase and the expression of PCNA. Transfection of gene encoding TGF β 1 could induce the cells at G0/G1 phase to S1 phase, modulate the replication of DNA through the enhancement of the PCNA expression, increase the content of DNA at S1 phase and promote the proliferation of MSCs. This new molecular tissue engineering approach could be of potential benefit to enhance the repair of damaged articular cartilage, especially those caused by degenerative joint diseases.

Effect of endogenous insulin-like growth factor and stem cell factor on diabetic colonic dysmotility

AIM: To investigate whether the reduction of stem cell factor (SCF) is mediated by decreased endogenous insulin-like growth factor (IGF)-1 in diabetic rat colon smooth muscle. METHODS: Sixteen Sprague-Dawley rats were randomly divided into two groups: control group and streptozotocin-induced diabetic group. After 8 wk of streptozotocin administration, colonic motility function and contractility of circular muscle strips were measured. The expression of endogenous IGF-1 and SCF was tested in colonic tissues. Colonic smooth muscle cells were cultured from normal adult rats. IGF-1 siRNA transfection was used to investigate whether SCF expression was affected by endogenous IGF-1 expression in smooth muscle cells, and IGF-1 induced SCF expression effects were studied. The effect of high glucose on the expression of endogenous IGF-1 and SCF was also investigated. RESULTS: Diabetic rats showed prolonged colonic transit time (252 ± 16 min vs 168 ± 9 min, P < 0.01) and weakness of circular muscle contraction (0.81 ± 0.09 g vs 2.48 ± 0.23 g, P < 0.01) compared with the control group. Endogenous IGF-1 and SCF protein expression was significantly reduced in the diabetic colonic muscle tissues. IGF-1 and SCF mRNA expression also showed a paralleled reduction in diabetic rats. In the IGF-1 siRNA transfected smooth muscle cells, SCF mRNA and protein expression was significantly decreased. IGF-1 could induce SCF expression in a concentration and time-dependent manner, mainly through the extracellular-signal-regulated kinase 1/2 signal pathway. High glucose inhibited endogenous IGF-1 and SCF expression and the addition of IGF-1 to the medium reversed the SCF expression. CONCLUSION: Myopathy may resolve in colonic motility dysfunction in diabetic rats. Deficiency of endogenous IGF-1 in colonic smooth muscle cells leads to reduction of SCF expression.

Hepatogenic differentiation of mesenchymal stem cells induced by insulin like growth factor-Ⅰ

AIM:To improve hepatic differentiation of human mesenchymal stem cell(MSC)using insulin growth factor 1(IGF-Ⅰ),which has important role in liver development,hepatocyte differentiation and function.METHODS:Bone marrow of healthy donors was aspirated from the iliac crest.The adherent cells expanded rapidly and were maintained with periodic passages until a relatively homogeneous population was established.The identification of these cells was carried out by immunophenotype analysis and differentiation potential into osteocytes and adipocytes.To effectively induce hepatic differentiation,we designed a protocol based on a combination of IGF-Ⅰ and liver specificfactors(hepatocyte growth factor,oncostatin M and dexamethasone).Morphological features,hepatic functions and cytological staining were assessed to evaluate transdifferentiation of human marrow-derived MSCs.RESULTS:Flow cytometric analysis and the differentiation potential into osteoblasts and adipocytes showed that more than 90% of human MSCs which were isolated and expanded were positive by specif ic markers and functional tests.Morphological assessment and evaluation of glycogen storage,albumin and α-feto protein expression,as well as albumin and urea secretion revealed a statistically signif icant difference between the experimental groups and control.CONCLUSION:In vitro differentiated MSCs using IGF-Ⅰwere able to display advanced liver metabolic functions,supporting the possibility of developing them as potential alternatives to primary hepatocytes.

LRP6 in mesenchymal stem cells is required for bone formation during bone growth and bone remodeling

Lipoprotein receptor-related protein 6 （LRP6） plays a critical role in skeletal development and homeostasis in adults. However, the role of LRP6 in mesenchymal stem cells （MSCs）, skeletal stem cells that give rise to osteoblastic lineage, is unknown. In this study, we generated mice lacking LRP6 expression specifically in nestin＋ MSCs by crossing nestin-Cre mice with LRP6 flox mice and investigated the functional changes of bone marrow MSCs and skeletal alterations. Mice with LRP6 deletion in nestin＋ cells demonstrated reductions in body weight and body length at I and 3 months of age. Bone architecture measured by microCT （uCT） showed a significant reduction in bone mass in both trabecular and cortical bone of homozygous and heterozygous LRP6 mutant mice. A dramatic reduction in the numbers of osteoblasts but much less significant reduction in the numbers of osteoclasts was observed in the mutant mice. Osterix＋ osteoprogenitors and osteocalcin＋ osteoblasts significantly reduced at the secondary spongiosa area, but only moderately decreased at the primary spongiosa area in mutant mice. Bone marrow MSCs from the mutant mice showed decreased colony forming, cell viability and cell proliferation. Thus, LRP6 in bone marrow MSCs is essential for their survival and proliferation, and therefore, is a key positive regulator for bone formation during skeletal growth and remodeling.

Keratinocyte Growth Factor-2 on the Proliferation of Corneal Epithelial Stem Cells in Rabbit Alkali Burned Cornea

Purpose: To determine whether the topical application of keratinocyte growth factor-2 (KGF-2) can enhance corneal epithelial healing in rabbit alkali burned cornea. In addition, the distribution and proliferation of corneal epithelial stem cells in KGF-2-treated and control corneas were investigated to explain their mechanisms of effects on the epithelium. Methods: Twenty-four New Zealand eyes were divided into four groups, treated with KGF-2 solution (1, 50, 100 μg/ml) and PBS solution. Eighth millimeter filter paper discs, produced by standard paper punch, were soaked for 15 sec in 0.5N NaOH solution. The alkali-soaked discs were applied to the central cornea, centered on the pupil and held gently in position with forceps for 1 min. The cornea was finally irrigated over 1 min with 100 ml balanced salt solution (BSS). Keratinocyte growth factor-2 was then applied topically three times a day. The phosphate-buffered saline (PBS) group was served as a control. Each corneal epithelial defect was subsequently photographed every 24 hours with a slit lamp and was measured by computer-assisted digitizer. In each group, two rabbits were sacrificed for light microscopic examination after the interval of 7, 14 and 21 days. Meanwhile, the cornea epithelium was examined by immunohistochemistry for P63, AE5, EGFR. Results: Topical application of 10 μg/ml to 100 μg/ml KGF-2 significantly accelerated corneal epithelial wound healing when compared with controls. After 24 hours, epithelial healing rate of the 100 μg/ml KGF-2 group and the PBS treated group was (74±6)% and (40±8)% (P < 0.05). After 48 hours, the rate of the C group was (94±6)%, whereas in the control group it was (73±12)% (P < 0.05). Epithelial defects were often recurrent, which happened only two times in the 100 μg/ml KGF-2-treated group, but many times in the control group. In the corneal epithelial stem cell analysis, the number of the P63 positive cells was higher in the KGF-2-treated corneal epithelium than in the controls. The P63 positive cells in the alkali burned epithelium were found not only in the limbal area but also in the central cornea. In addition, the number of stem cells in each group came to the maximum on the 14th day. For example, on the 7th day after alkali injury, it was 40.3±2.1 NPC in the non-limbal area of 50 μg/ml KGF-2-treated group; whereas, it was 84.8±2.7 NPC on the 14th day(P = 0.000). Conclusions: From the daily evaluation of the corneal surface as well as the microscopic examinations at the end of the three periods of observation, we concluded that KGF-2 provided a beneficial effect in the treatment of alkali burns of the cornea. Furthermore, the results of epithelial stem cell analysis demonstrated that KGF-2 accelerated the corneal epithelial healing by markedly stimulating epithelial stem cells proliferation and making them migrate to the central cornea.

Response of the sensorimotor cortex of cerebral palsy rats receiving transplantation of vascular endothelial growth factor 165-transfected neural stem cells

Neural stem cells are characterized by the ability to differentiate and stably express exogenous ge- nes. Vascular endothelial growth factor plays a role in protecting local blood vessels and neurons of newborn rats with hypoxic-ischemic encephalopathy. Transplantation of vascular endothelial growth factor-transfected neural stem cells may be neuroprotective in rats with cerebral palsy. In this study, 7-day-old Sprague-Dawley rats were divided into five groups： （1） sham operation （control）, （2） cerebral palsy model alone or with （3） phosphate-buffered saline, （4） vascular en- dothelial growth factor 165 ＋ neural stem cells, or （5） neural stem cells alone. The cerebral palsy model was established by ligating the left common carotid artery followed by exposure to hypox- ia. Phosphate-buffered saline, vascular endothelial growth factor ＋ neural stem cells, and neural stem cells alone were administered into the sensorimotor cortex using the stereotaxic instrument and microsyringe. After transplantation, the radial-arm water maze test and holding test were performed. Immunohistochemistry for vascular endothelial growth factor and histology using hematoxylin-eosin were performed on cerebral cortex. Results revealed that the number of vas- cular endothelial growth factor-positive cells in cerebral palsy rats transplanted with vascular endothelial growth factor-transfected neural stem cells was increased, the time for finding water and the finding repetitions were reduced, the holding time was prolonged, and the degree of cell degeneration or necrosis was reduced. These findings indicate that the transplantation of vascu- lar endothelial growth factor-transfected neural stem cells alleviates brain damage and cognitive deficits, and is neuroprotective in neonatal rats with hypoxia ischemic-mediated cerebral palsy.

Effects of basic fibroblast growth factor on beta-catenin protein and mRNA expression during the proliferation of endogenous neural stem cells following focal cerebral ischemia

BACKGROUND： The Wnt/β-catenin signaling pathway plays an important role in neural development. ,β-catenin is an important component of the Wnt/β-catenin signaling pathway. The Wnt signaling pathway has been shown to regulate the interaction of neural stem cells with the extracellular matrix. OBJECTIVE： To investigate the effects of basic fibroblast growth factor （bFGF） on β-catenin protein and mRNA expression, and on hippocampal neural stem cell proliferation in a rat model of cerebral ischemia/reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, neurobiology experiment was performed in Shenyang Medical College between August 2006 and August 2008. MATERIALS： A total of 72 healthy male Wistar rats, aged 3 months, were used in this study. bFGF was provided by Beijing SL Pharmaceutical Co.,Ltd., China. METHODS： Rats were randomly divided into 3 groups： sham-operated, ischemia/reperfusion, and bFGF-treated （n = 24 per group）. Focal cerebral ischemia/reperfusion was induced in rats from the ischemia/reperfusion group and the bFGF-treated group by 2 hour right middle cerebral artery occlusion and 2 hour restoration of blood flow using the suture method. The ischemia/reperfusion and bFGF-treated groups were intraperitoneally administered 500 IU/mL of bFGF, or the same volume of physiological saline, once a day at postoperative days 1 3, and once every 3 days thereafter. Simultaneously, the sham-operated group underwent experimental procedures identical to the ischemia/reperfusion and bFGF-treated groups, with the exception of ischemia/reperfusion induction and drug administration. At 2 hours, 2, 6, 13, and 20 days after ischemiaJreperfusion induction, 50 mg/kg bromodeoxyuridine （BrdU） was administered to each group, twice daily, to label proliferating neural stem cells. MAIN OUTCOME MEASURES： The effects of bFGF on BrdU labeling, and ,8 -catenin mRNA and protein expression, in neural stem cells were examined by immunohistochemistry, Western blot, RT-PCR, and in situ hybridization techniques. RESULTS： In the sham-operated group, only a few BrdU-immunoreactive neural stem cells were found. In the ischemia/reperfusion group, BrdU-immunoreactive cells began to increase from 3 days after ischemia/reperfusion induction, reached a peak level at 7 days, and gradually reduced from 21 days. At 3, 7, 14, and 21 days after ischemia/reperfusion induction, the numbers of BrdU-immunoreactive cells were significantly greater in the bFGF-treated group than in the ischemia/reperfusion group. The sham-operated group exhibited slight expression of β-catenin and β-catenin mRNA. In the ischemia/reperfusion group, the expression of β-catenin and β-catenin mRNA gradually increased with reperfusion time, peaked at 14 days after reperfusion, and gradually decreased thereafter; by 21 days, the expression was markedly lower. Following bFGF injection, the expression of hippocampal BrdU, β-catenin, and β-catenin mRNA had apparently increased in each group. CONCLUSION： bFGF promotes neural stem cell proliferation, and the expression of β-catenin and β-catenin mRNA in the ischemic brain tissue. These findings indicate that bFGF promotion of neural stem cell proliferation may be mediated by Wnt/β-catenin signaling pathway.

Human insulin-like growth factor 1-transfected umbilical cord blood neural stem cell transplantation improves hypoxic-ischemic brain injury

Human insulin-like growth factor 1-transfected umbilical cord blood neural stem cells were transplanted into a hypoxic-ischemic neonatal rat model via the tail vein. BrdU-positive cells at day 7 post-transplantation, as well as nestin- and neuron specific enolase-positive cells at day 14 were increased compared with those of the single neural stem cell transplantation group. In addition, the proportion of neuronal differentiation was enhanced. The genetically modified cell-transplanted rats exhibited enhanced performance in correctly crossing a Y-maze and climbing an angled slope compared with those of the single neural stem cell transplantation group. These results showed that human insulin-like growth factor 1-transfected neural stem cell transplantation promotes the recovery of the leaming, memory and motor functions in hypoxic-ischemic rats.

Construction of hepatocyte growth factor gene recombinant adenovirus vector and its expression in rat bone marrow mesenchymal stem cells

Objective：To construct the adenoviral expression vector system containing human hepatocyte growth factor （hHGF） cDNA, and to further study the transduction efficiency and the expression of HGF in mesenchymal stem cells （MSCs）. Methods：The HGF cDNA was amplificated from the expression plasmid pCMV-HGF, and was subcloned into the adenovirus shuttle plasmid pDC316-IRESEGFP vector containing a green fluorescence protein （GFP） reporter gene. Virus Ad-HGF was produced by homologous recombination in HEK293 package cells. Bone marrow derived MSCs were harvested and cultured, and then were transduced with Ad-HGF. The efficiency of Ad-HGF transduction was assessed by FACS analysis using GFP gene expression. And HGF/MSCs were generated. The HGF concentrations in supernatants of HGF/MSCs were determined by ELISA using anti-human HGF monoclonal antibody. Results： The recombinant, named pDC316-HGF-IRES-eGFP, was digested with restriction enzyme, and the DNA sequencing of HGF was identical to the report in Genebank and did not reveal any mutation. GFP expression could be observed on the second day after packing of the linearized pAd-HGF in HEK293 cells and 7.15 × 10^10pfu/ml titer of Ad-HGF was obtained. Forty-eight hours after transduction, 96.89% of HGF/MSCs were GFP positive. Peak concentration levels of hHGF（103ng/mL） in the cultured supernatants were detected on day 2 post-transduction, and the adenovirus-mediated expression of HGF by MSCs was maintained for at least 2 weeks in vivo. Conclusion：Our data demonstrated that the adenovirus expression＇vector system pDC316-HGF-IRES-EGFP has been constructed successfully, and their effective expressions also have been obtained in MSCs. This will provide material basis for the next study on liver regeneration after small-for-size liver transplantation.

Stem cell factor-mediated wild-type KIT receptor activation is critical for gastrointestinal stromal tumor cell growth

AIM: To clarify the biological role of stem cell factor (SCF)-mediated wild-type KIT receptor activation in gastrointestinal stromal tumor (GIST) growth. METHODS: The co-expression of wild-type KIT receptor and SCF was evaluated in 51 GIST samples using mutation analysis and immunohistochemistry, and the results were correlated with clinicopathological param- eters, including the mitotic count, proliferative index (Ki-67 immunohistochemical staining), mitotic index (phospho-histone H3 immunohistochemical staining) and apoptotic index (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling). Using primary cultured GIST cells, the effect of SCF-mediated wild-type KIT receptor activation was determined by western blotting, methyl thiazolyl tetrazolium (MTT), and apoptosis assays. RESULTS: We found that wild-type KIT receptor and SCF protein were expressed in 100% and 76.5% of the 51 GIST samples, respectively, and the co-expression of wild-type KIT receptor and SCF was associated with known indicators of poor prognosis, including larger tumor size (P = 0.0118), higher mitotic count (P = 0.0058), higher proliferative index (P = 0.0012), higher mitotic index (P = 0.0282), lower apoptosis index (P = 0.0484), and increased National Institutes of Health risk level (P = 0.0012). We also found that the introduction of exogenous SCF potently increased KIT kinase activity, stimulated cell proliferation (P < 0.01) and inhibited apoptosis (P < 0.01) induced by serum starvation, while a KIT immunoblocking antibody suppressed proliferation (P = 0.01) and promoted apoptosis (P < 0.01) in cultured GIST cells. CONCLUSION: SCF-mediated wild-type KIT receptor activation plays an important role in GIST cell growth. The inhibition of SCF-mediated wild-type KIT receptor activation may prove to be particularly important for GIST therapy.