Müller glia and phagocytosis of cell debris in retinal tissue

Müller cells are the predominant glial cell type in the retina of vertebrates. They play a wide variety of roles in both the developing and the mature retina that have been widely reported in the literature. However, less attention has been paid to their role in phagocytosis of cell debris under physiological, pathological or experimental conditions. Müller glia have been shown to phagocytose apoptotic cell bodies originated during development of the visual system. They also engulf foreign molecules that are injected into the eye, cone outer segments and injured photoreceptors. Phagocytosis of photoreceptor cell debris in the light‐damaged teleost retina is primarily carried out by Müller cells. Once the microglial cells become activated and migrate to the photoreceptor cell layer, the phagocytic activity of Müller cells progressively decreases, suggesting a possible mechanism of communication between Müller cells and neighbouring microglia and photoreceptors. Additionally, it has been shown that phagocytic Müller cells acquire proliferating activity in the damaged teleost retina, suggesting that engulfment of apoptotic photoreceptor debris might stimulate the Müller glia to proliferate during the regenerative response. These findings highlight Müller glia phagocytosis as an underlying mechanism contributing to degeneration and regeneration under pathological conditions.     

Do Myoepithelial Cells Hold the Key for Breast Tumor Progression?

Mammary myoepithelial cells have been a neglected facet of breast cancer biology, largely ignored since they have been considered to be less important for tumorigenesis than luminal epithelial cells from which most of breast carcinomas are thought to arise. In recent years as our knowledge of stem cell biology and the cellular microenvironment has been increasing, myoepithelial cells are slowly starting to gain more attention. Emerging data raise the hypothesis whether myoepithelial cells play a key role in breast tumor progression by regulating the in situ to invasive carcinoma transition and that myoepithelial cells are part of the mammary stem cell niche. Paracrine interactions between myoepithelial and luminal epithelial cells are known to be important for regulation of cell cycle progression, establishing epithelial cell polarity, and inhibiting cell migration and invasion. Based on these functions, normal mammary myoepithelial cells have been called “natural tumor suppressors.” However, during tumor progression myoepithelial cells seem to loose these properties, and eventually this cell population diminishes as tumors become invasive. Better understanding of myoepithelial cell function and their role in tumor progression may lead to their exploitation for cancer therapeutic and preventative measures.     

骨髓间充质干细胞旁分泌HGF体外调控肝星状细胞

目的 探讨大鼠骨髓间充质干细胞（BMSCs）与肝星状细胞（HSCs）体外共培养体系中,BMSCs旁分泌肝细 胞生长因子（HGF）对 HSCs 增殖、凋亡、活化的影响。方法 全骨髓贴壁法分离、培养、纯化大鼠 BMSCs,另培养 HSCs。6 孔板半透膜建立上下两层细胞非直接接触共培养体系,实验设 H 组（HSCs 单独培养）、H-H 组（HSCs 与 HSCs共培养）、M-H组（BMSCs与HSCs共培养）、M-H-C组（BMSCs与HSCs共培养并加c-met抑制剂）,各组细胞培 养48 h后,流式细胞仪鉴定BMSCs,检测HSCs凋亡率,MTT法检测HSCs的增殖,免疫荧光共聚焦定量检测HSCs中 α-肌动蛋白（α-SMA）的表达量,ELISA法检测共培养体系上清液中HGF的浓度。结果 MSCs高表达阳性表面分子 CD29、CD90,低表达造血细胞表面标记CD45;BMSCs能明显抑制HSCs的增殖、活化并促进其凋亡,且M-H组上清液 中HGF的浓度明显高于其他组。结论 BMSCs与HSCs共培养过程中,BMSCs通过旁分泌HGF促进HSCs的凋亡,抑 制HSCs的增殖、活化。     

IGF Ligand and Receptor Regulation of Mammary Development

The insulin-like growth factors, IGF-I and IGF-II, have endocrine as well as autocrine-paracrine actions on tissue growth. Both IGF ligands are expressed within developing mammary tissue throughout postnatal stages with specific sites of expression in the epithelial and stromal compartments. The elucidation of circulating versus local actions and of epithelial versus stromal actions of IGFs in stimulating mammary epithelial development has been the focus of several laboratories. The recent studies addressing IGF ligand function provide support for the hypotheses that (1) the diverse sites of IGF expression may mediate different cellular outcomes, and (2) IGF-I and IGF-II are distinctly regulated and have diverse functions in mammary development. The mechanisms for IGF function likely are mediated, in part, through diverse IGF signaling receptors. The local actions of the IGF ligands and receptors as revealed through recent publications are the focus of this review. Grant Support: National Institute of Diabetes and Digestive and Kidney Diseases DK60612 and National Cancer Institute CA120850 to TLW     

Adipose-derived stem cells enhance myogenic differentiation in the mdx mouse model of muscular dystrophyvia paracrine signaling

Adipose-derived stem cells have been shown to promote peripheral nerve regeneration through the paracrine secretion of neurotrophic factors. However, it is unclear whether these cells can promote myogenic differentiation in muscular dystrophy. Adipose-derived stem cells(6 × 10~6) were injected into the gastrocnemius muscle of mdx mice at various sites. Dystrophin expression was found in the muscle fibers. Phosphorylation levels of Akt, mammalian target of rapamycin(mT OR), e IF-4E binding protein 1 and S6 kinase 1 were increased, and the Akt/mT OR pathway was activated. Simultaneously, myogenin levels were increased, whereas cleaved caspase 3 and vimentin levels were decreased. Necrosis and fibrosis were reduced in the muscle fibers. These findings suggest that adipose-derived stem cells promote the regeneration and survival of muscle cells by inhibiting apoptosis and fibrosis, thereby alleviating muscle damage in muscular dystrophy.     

Alginate microencapsulation of human mesenchymal stem cells as a strategy to enhance paracrine‐mediated vascular recovery after hindlimb ischaemia

Stem cell‐based therapies hold great promise as a clinically viable approach for vascular regeneration. Preclinical studies have been very encouraging and early clinical trials have suggested favourable outcomes. However, significant challenges remain in terms of optimizing cell retention and maintenance of the paracrine effects of implanted cells. To address these issues, we have proposed the use of a cellular encapsulation approach to enhance vascular regeneration. We contained human mesenchymal stem cells (hMSCs) in biocompatible alginate microcapsules for therapeutic treatment in the setting of murine hindlimb ischaemia. This approach supported the paracrine pro‐angiogenic activity of hMSCs, prevented incorporation of hMSCs into the host tissue and markedly enhanced their therapeutic effect. While injection of non‐encapsulated hMSCs resulted in a 22 ± 10% increase in vascular density and no increase in perfusion, treatment with encapsulated hMSCs resulted in a 70 ± 8% increase in vascular density and 21 ± 7% increase in perfusion. The described cellular encapsulation strategy may help to better define the mechanisms responsible for the beneficial effects of cell‐based therapies and provide a therapeutic strategy for inducing vascular growth in the adult. As hMSCs are relatively easy to isolate from patients, and alginate is biocompatible and already used in clinical applications, therapeutic cell encapsulation for vascular repair represents a highly translatable platform for cell‐based therapy in humans. Copyright © 2012 John Wiley & Sons, Ltd.     

Paracrine effects of uterine leucocytes on gene expression of human uterine stromal fibroblasts

The endometrium contains a distinct population of immune cellsthat undergo cyclic changes during the menstrual cycle and implantation.The majority of these leucocytes are uterine NK (uNK) cells,however how these cells interact with uterine stromal fibroblastsremains unclear. We therefore investigated the paracrine effectof medium conditioned by uterine decidual leucocytes (whichare enriched for uNK cells) on the gene expression profile ofendometrial stromal fibroblasts in vitro using a cDNA microarray.Our results, verified by real-time PCR, ELISA and FACS analysis,reveal that soluble factors from uterine leucocytes substantiallyalter endometrial stromal fibroblast gene expression. The largestgroup of up-regulated genes found was chemokines and cytokines.These include IL-8, CCL8 and CXCL1, which have also been shownto be stimulated by contact of stromal fibroblasts with trophoblast,suggesting that uNK cells work synergistically to support trophoblastmigration during implantation. The decidual leucocytes alsoup-regulated IL-15 and IL-15R in stromal fibroblasts which couldproduce a niche for uNK cells allowing proliferation withinand recruitment into the uterus, as seen in bone marrow. Overallthis study demonstrates, for the first time, the paracrine communicationbetween uterine leucocytes and uterine stromal fibroblasts,and adds to the understanding of how the uterine immune systemcontributes to the changes seen within the cycling endometrium.