Ting Yu Li

Vitamin A deficiency impairs postnatal cognitive function via inhibition of neuronal calcium excitability in hippocampus.

J. Neurochem. (2012) 121, 932–943.

Plasticity of rat bone marrow-derived 5-hydroxytryptamine-sensitive neurons: dedifferentiation and redifferentiation

Inducing cellular dedifferentiation has been proposed as a potential method for enhancing endogenous regeneration in mammals. Here we demonstrate that phenotypic and functional neurons derived from adult rat bone marrow stromal stem cells (MSCs) can be induced to undergo dedifferentiation, then proliferation and redifferentiation. In addition to morphological changes and expression of neuronal markers, neuron‐specific enolase and neurofilament H, functional differentiation was monitored by intracellular Ca2+ mobilization in response to a ubiquitous neurotransmitter, 5‐hydroxytryptamine (5‐HT) at different stages. The neurons derived from rMSCs were found to have increased 5‐HT response. This 5‐HT sensitivity could be reversed to basal level similar to that found in rMSCs when neurons, up to 3 days after neuronal induction, were induced to undergo dedifferentiation. Increase in 5‐HT‐induced Ca2+ mobilization was again observed when rMSCs derived from dedifferentiated neurons were induced to redifferentiate into neurons again. Variation in 5‐HT1A receptor immunoreactivity was observed in stem cells, differentiated neurons, dedifferentiated neurons and redifferentiation neurons, consistent with their respective 5‐HT sensitivity. These results suggest that adult bone marrow‐derived 5‐HT sensitive neurons are capable of dedifferentiation, then proliferation and redifferentiation, indicating their plasticity and potential use in treatment of neural degenerative diseases.

Differentiation of adult rat bone marrow stem cells into epithelial progenitor cells in culture

We have previously obtained monoclonal bone marrow stem cells from adult rats (rMSCs) and induced them into phenotypic neurons. In the present study, we aimed to induce rMSCs into epithelial cells by culturing them onto compartmentalized permeable supports, which have been used for growing a variety of polarized epithelia in culture. Hematoxylin staining showed that after 4 days grown on permeable supports, rMSCs formed an epithelial‐like monolayer. Immunofluorescence of the permeably‐supported monolayers, but not the rMSCs grown in culture flasks, showed positive signals for epithelial markers, cytokeratin 5 & 8. RT‐PCR results also showed the mRNA expression of epithelial sodium channel (ENaC) and cystic fibrosis transmembrane conductance regulator (CFTR) as well as tight junction protein ZO‐1 in the rMSC‐derived monolayers grown on permeable supports but absent from those grown in culture flasks. However, western blot only detected protein expression of ZO‐1 but not ENaC nor CFTR. The short‐circuit current measurements showed that the rMSC‐derived monolayers grown on permeable supports exhibited a trans‐monolayer resistance of 30–50 Ω cm2; however, the monolayers did not respond to activators or blockers of CFTR or ENaC. The results suggest that compartmentalized or polarized culture conditions provide a suitable environment for rMSCs to differentiate into epithelial progenitor cells with tight junction formation; however, this condition is not sufficient for functional expression of epithelial ion channels associated with well‐differentiated epithelia.

Altered expression of inflammatory cytokine receptors in response to LPS challenge through interaction between intestinal epithelial cells and lymphocytes of Peyer's patch

The intense innate immunological activities occurring at the enteric mucosal surface involve interactions between intestinal epithelial cells and immune cells. Our previous studies have indicated that Peyers patch lymphocytes may modulate intestinal epithelial barrier and ion transport function in homeostasis and host defense via cell–cell contact as well as cytokine signaling. The present study was undertaken using the established co‐culture system of Caco‐2 epithelial cells with lymphocytes of Peyers patch to investigate the expression of IL‐8 and IL‐6 cytokines and cytokine receptors in the co‐culture system after challenge with Shigella F2a‐12 lipopolysaccharide (LPS). The human colonic epithelial cell line Caco‐2 was co‐cultured with freshly isolated lymphocytes from the murine Peyers patch either in the mixed or separated (isolated but permeable compartments) co‐culture configuration, and was challenged with Shigella F2a‐12 LPS for 8 h. The level of mRNA expressions of human interleukin‐8 (hIL‐8), human interleukin‐8 receptor (hIL‐8R), mouse interleukin‐8 receptor (mIL‐8R), mouse interleukin‐6 (mIL‐6), mouse interleukin‐6 receptor (mIL‐6R) and human interleukin‐6 receptor (hIL‐6R) was examined by semi‐quantitative PCR. In both co‐culture groups, hIL‐8 expression of Caco‐2 cells was decreased, and hIL‐8R expression was increased compared to the Caco‐2 alone group. Upon LPS challenge, hIL‐8 expression from the Caco‐2 cells of both co‐culture groups was higher than in the Caco‐2 control group. The increased hIL‐8 expression of Caco‐2 cells in the separated co‐culture group is correlated with a decreased hIL‐8R expression and an increased mIL‐8R expression. In the mixed co‐culture group, the increased expression of hIL‐8 was associated with the upregulated hIL‐8R expression on Caco‐2 cells and downregulated mIL‐8R on murine Peyers patch lymphocytes (PPL). mIL‐6 expression from mouse PPL was also upregulated by LPS in mixed co‐culture. However, upon the treatment with LPS, hIL‐6R expression of Caco‐2 cells was decreased in the mixed co‐culture, but increased in separated co‐culture. The data suggest that release of hIL‐8 from epithelial cells may act on lymphocytes through a paracrine pathway, but it may also act on the epithelial cells themselves via an autocrine pathway. The data also suggest that the release of mIL‐6 from Peyers patch lymphocytes affects epithelial cells in a paracrine fashion.

Effects of marginal vitamin A deficiency on rat's lung maturation and the expression of retinoic acid receptors from prenatal to adult stage

EFFECTS OF MARGINAL VITAMIN A DEFICIENCY ON RAT’S LUNG MATURATION AND THE EXPRESSION OF RETINOIC ACID RECEPTORS FROM PRENATAL TO ADULT STAGE Ting Yu Li, Hua Wei, Hong Mei Huang, You Xue Liu, Ping Qu Children’s Hospital, Chongqing Medical University, 136 Second Zhongshan Road, Chongqing 400014, China Lung morphogenesis is a highly regulated process that could be impaired by nutrition deficiency and recent research suggests that disturbed early lung development may pave the way for later illness and accelerated senescence. Vitamin A (retinol) and their derivatives (retinoic acids, RA) are known key developmental regulators that bind and activate retinoic acid receptors (RARs). To evaluate whether marginal vitamin A deficiency (MVAD) begun from pregnancy alters the lung structure and extracellular matrix, we monitored lung morphology, collagen and elastin fiber at postnatal day 1, week 2 and adulthood (week 8) on MVAD and control group. In addition to morphological change, lung RA receptor (RARa, ß, and g) expression was analyzed by immunofluorescence, whereas mRNA levels were measured using RT-PCR. We demonstrate that MVAD begun from pregnancy resulted in lower lung weight, reduced numbers of alveoli and total alveolar surface area, in addition to increased alveoli septa thickness till to adulthood. Exposure to MVAD also resulted in increased collagen deposits and decreasing elastin fiber at postnatal week 2 and 8 in an unorganized manner. Over the normal course of development, total protein and mRNA levels for the RARs declined, but immunofluorescence and RT-PCR demonstrate that exposure to MVAD during the pregnancy period resulted in an immediate and durative increase in RARs levels from postnatal day 1 to adulthood, especially at postnatal week 2. In summary, this study demonstrates that developing lungs are sensitive to MVAD and this effect is permanent throughout the life of the animal and may be mediated in part through augmentation of transcriptional signals in the retinoid pathway. Thus, we hypothesize that durative pregnancy MVAD could impact lung development and result in the permanent impairment which may underlie at least some susceptibility to adult-onset chronic lung disease.

Behavioral improvement induced by bone marrow mesenchymal stem cells in neonatal rats after hypoxic‐ischemic brain damage

BEHAVIORAL IMPROVEMENT INDUCED BY BONE MARROW MESENCHYMAL STEM CELLS IN NEONATAL RATS AFTER HYPOXIC-ISCHEMIC BRAIN DAMAGE Yang Liu , Ting Yu Li , Xiao Hu Zhang , Yiu Wa Chung , Hsiao Chang Chan 1 1 Epithelial Cell Biology Research Center, Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong 2 Children’s Hospital, Chongqing University of Medical Sciences, Chongqing, China Neonatal hypoxic-ischemic brain damage (HIBD) harms the lives and health of newborn infants and children severely. Studies have shown bone marrow mesenchymal stem cells (rMSCs) have therapeutic potential in nervous system disease. Here we demonstrate behavioral improvement of different rMSCs treatment in neonatal HIBD rats by shuttle box test. HIBD models were successfully established in 7-day-postnatal SD rats. At 5 days after hypoxiaischemia, the rats were randomly divided into 4 groups and respectively transplanted with PBS, CM-DiI marked rMSCs (1e2 10), RA-induced rMSCs (1e2 10) or dedifferentiated rMSCs (1e2 10) into their lateral cerebral ventricle. At 2 months after MSCs administration, shuttle box test was performed to evaluate the condition of learning and memory in 6 continuous sessions for 6 days. And the 7 session was followed one month later. The learning curves of three rMSCs treatment groups were respectively steeper than PBS control group. Rats with transplantation of rMSCs exhibited higher number of active avoidance and lower number of passive escape, showing significant improvement on shuttle box test (P< 0.05). The numbers of change in explore time and inter-trial-interval were also higher in every rMSCs treatment group than control group (P< 0.05). But there was no noticeable difference between rMSCs treatment groups in the 6 preceding sessions. Dedifferentiated rMSCs group showed highest number of active avoidance in the 7 sessions. These results suggest that rMSCs treatment in neonatal rats after HIBD can bring out behavioral improvement, indicating rMSCs can enhance ability of learning and memory and dedifferentiated rMSCs may especially have important influence on the longer-term functional recovery.