Differentiation of embryonic versus adult rat neural stem cells into dopaminergic neurons in vitro

BACKGROUND：It has been reported that the conversion of neural stem cells into dopaminergic neurons in vitro can be increased through specific cytokine combinations. Such neural stem cell-derived dopaminergic neurons could be used for the treatment of Parkinson’s disease. However, little is known about the differences in dopaminergic differentiation between neural stem cells derived from adult and embryonic rats. OBJECTIVE： To study the ability of rat adult and embryonic-derived neural stem cells to differentiate into dopaminergic neurons in vitro. DESIGN： Randomized grouping design. SETTING： Department of Neurosurgery in the First Affiliated Hospital of Sun Yat-sen University. MATERIALS： This experiment was performed at the Surgical Laboratory in the First Affiliated Hospital of Sun Yat-sen University （Guangzhou, Guangdong, China） from June to December 2007. Eight, adult, male, Sprague Dawley rats and eight, pregnant, Sprague Dawley rats （embryonic day 14 or 15） were provided by the Experimental Animal Center of Sun Yat-sen University. METHODS： Neural stem cells derived from adult and embryonic rats were respectively cultivated in serum-free culture medium containing epidermal growth factor and basic fibroblast growth factor. After passaging, neural stem cells were differentiated in medium containing interleukin-1α, interleukin-11, human leukemia inhibition factor, and glial cell line-derived neurotrophic factor. Six days later, cells were analyzed by immunocytochemistry and flow cytometry. MAIN OUTCOME MEASURES： Alterations in cellular morphology after differentiation of neural stem cells derived from adult and embryonic rats; and percentage of tyrosine hydroxylase-positive neurons in the differentiated cells. RESULTS： Neural stem cells derived from adult and embryonic rats were cultivated in differentiation medium. Six days later, differentiated cells were immunoreactive for tyrosine hydroxylase. The percentage of tyrosine hydroxylase positive neurons was （5.6 ± 2.8）% and （17.8 ± 4.2）% for adult and embryonic cells, respectively, with a significant difference between the groups （P 〈 0.01）. CONCLUSION： Neural stem cells from embryonic rats have a higher capacity to differentiate into dopaminergic neurons than neural stem cells derived from adult rats.

Identification and expression analysis of chlorogenic acid biosynthesis key gene PpHCT in peach

Shikimic acid/quinic acid hydroxy cinnamyl transferase(HCT)is one of the key enzymes in the phenylpropanoid pathway.However,the role of the HCT gene in chlorogenic acid(CGA)biosynthesis in peach fruit remains unclear.For this,we identified the accumulation pattern of CGA in four peach cultivars,cloned and characterized 11 PpHCT gene members,and further analyzed the expression patterns of these PpHCT genes during fruit development.The contents of CGAs in the four peach cultivars all exhibited a trend of increasing and then decreasing during the fruit growth and development.Moreover,the contents of CGAs in the peel and flesh were tissue-specific.Gene structure analysis indicated that the PpHCT genes were highly conserved,containing two exons and one intron.The protein structure analysis demonstrated that the PpHCT proteins contained two conserved motifs(HXXXD,DFGWG)and a transferase domain(PF02458),which belonged to the BAHD acyltransferase family.The cis-acting element analysis suggested that the promoters of PpHCT genes contained many light-related,hormone-related,stress-related,tissue-specific,and circadian-related elements,and they could participate in a variety of biological processes.Phylogenetic analysis showed that the HCT proteins of peach were closely related to the HCT proteins of plum and had a close evolutionary relationship.The qRT-PCR analysis indicated that the expression levels of PpHCT1 and PpHCT2 showed an opposite trend to the accumulation of CGA,whereas the expression levels of PpHCT4,PpHCT5,PpHCT7,PpHCT8,and PpHCT11 demonstrated the same trend as CGA accumulation.It was worth noting that only PpHCT4 and PpHCT5 were highly expressed in the two high-CGA cultivars but showed low levels of expression in the two low-CGA cultivars.Therefore,it was hypothesized that these two genes might be key genes to the synthesis of CGA in peach fruit.Those findings provide a theoretical basis for further study on the biological functions of the HCT gene and help to reveal the molecular mechanism of CGA.

Mesoporous radiosensitized nanoprobe for enhanced NIR-Ⅱ photoacoustic imaging-guided accurate radio-chemotherapy

Oxygen deficiency is a major obstacle to hypoxic-related cancer theranostics,and developing the oxygen production nanoplatforms received the widespread attention.However,it is remaining a challenge to structure a nanoplatform with hypoxia alleviation effect and imaging-guided cancer radiotherapy.Herein,we present a novel theranostics nanoplatform(Au NPs/UCNPs/WO_(3)@C)comprising of tungsten trioxide(WO3)that loaded gold nanoparticles(Au NPs)and up-conversion nanoparticles(UCNPs)for improved photoacoustic(PA)imaging performance in the second near infrared window(NIR-Ⅱ,900-1,700 nm).Au NPs/UCNPs/WO_(3)@C exhibited superior oxygen-generation effect and doxorubicin loading capacity,thus serving as an efficient radiosensitizer for radio-chemo anti-cancer therapy.Importantly,the accumulated Au NPs/UCNPs/WO_(3)@C in the tumor region led to the increased NIR-Ⅱ PA imaging signal and the blood oxygen saturation signal,which could enhance radiation sensitivity and accurately guiding cancer radiotherapy to reduce side effects on normal tissues.This study with proof-of-concept confirmed the multifaceted characteristics and encouraging potential of biomimetic Au NPs/UCNPs/WO_(3)@C for NIR-Ⅱ PA imaging-guided tumor therapeutics.