OBJECTIVETo further investigate the osteogenic potential of rabbit marrow stromal stem cells cultured in vitro.

METHODSRabbit marrow stromal stem cells were isolated by density gradient centrifugation method and amplified in the flasks, using the osteogenic inducing conditions (OGC) as the culture media. The osteogenic potential of marrow stromal stem cells were investigated by means of bone-seeking fluorescence (tetracycline) labelling, Alizarin red S (ARS) staining, Alcian blue-Sirius red (AS) staining, and scanning electron microscope.

RESULTSAfter being passaged, the marrow stromal stem cells increased in number, became confluent and formed multi-layer structure. The stromal stem cells excreted innumerable tiny granules, heaping up on the cell body and merging gradually into foggy substances. These foggy substances kept on enlarging and formed round, oval, or flake-like nodules. These nodules revealed bright golden yellow fluorescence under fluorescence microscope when labelled with tetracycline. Histochemical study with specific new bone staining with ARS revealed positive calcium reaction, both denoting that they were newly formed bone tissues. After they were stained with AS, collagen and acid mucopolysaccharide were shown. Under scanning electron microscope, three types of cells with different configurations were found. They were globular cells, spindle-shaped cells and polygonal or polygonal cells. Granules were excreted from the cells and heaped up on the cell body. Needle-shaped and irregularly rectangular crystals also appeared and agglomerated with the granules to form nodules and trabecula-like or flake-like structures.

CONCLUSIONSSequence of events of bone formation by rabbit marrow stromal stem cells cultured in vitro is fully depicted and confirmed, which provides the foundation for further investigating the mechanisms of osteoblast differentiation from marrow stromal stem cells and the possible application in orthopaedics.

Animals ; Bone Marrow Cells ; pathology ; ultrastructure ; Cells, Cultured ; Immunohistochemistry ; In Vitro Techniques ; Male ; Microscopy, Electron, Scanning ; Models, Animal ; Osteogenesis ; physiology ; Rabbits ; Sensitivity and Specificity ; Stromal Cells ; physiology ; ultrastructure

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal tract (GIT). Although interstitial cells of Cajal has been suggested as origin of this tumor, the cytological and ultrastructural features of GISTs are heterogeneous and unclear. A total 10 cases of normal gastrointestinal tissue (control), 13 GISTs of the stomach (8), small intestine (3), mesocolon (1) and liver (1), and 2 gastrointestinal autonomic nervous tumor (GANT) of small intestine were ultrastructurally studied. Normal interstitial cells of Cajal (ICC) were abundantly present around the myenteric plexuses or individually scattered through the wall of GIT. ICC was characterized by slender cytoplasmic processes, well-developed endoplasmic reticulum (ER), mitochondria, Golgi apparatus, caveolae and intermediate filaments. The GISTs and GANTs had overlapping ultrastructures. The most common and important ultrastructural features of GISTs were rich villous cytoplasmic processes, dispersed intermediate filaments and abundant SER, and those of GANTs were neurosecretory granules and skenoid fibers. Compared with ICC, the GISTs and GANTs had remarkably reduced caveolae and gap junctions. Our study suggested that ultrastructural analysis gives much information to investigate lineage differentiation of neoplastic cells and make a differential diagnosis of these tumors from other mesenchymal tumors and between GISTs and GANTs.
Adult ; Aged ; Autonomic Nervous System/*pathology/ultrastructure ; Comparative Study ; Cytoplasm/pathology/ultrastructure ; Female ; Gastrointestinal Neoplasms/*pathology/ultrastructure ; Human ; Immunohistochemistry ; Male ; Microscopy, Electron ; Middle Aged ; Peripheral Nervous System Neoplasms/*pathology/ultrastructure ; Stromal Cells/*pathology/ultrastructure ; Support, Non-U.S. Gov't ; Tumor Markers, Biological ; Vacuoles/pathology/ultrastructure

OBJECTIVETo explore the histogenesis and neural differentiation of gastrointestinal stromal tumor (GIST).

METHODSThe ultrastructural morphology and neural differentiated antigen expression were studied in 20 cases of GIST using electron microscopy and immunohistochemistry.

RESULTSAll of the 20 cases mentioned were positive for c-kit expression. The ultrastructural features of neural differentiation were observed in 7 cases, while no neural or myogenic differentiation seen in 12 cases. Myogenic differentiation to smooth muscle was observed in one case. The ultrastructural features of neural differentiation included scattered or cluster distribution of dense core granules in cytoplasm and cytoplasmic processes; formation of synaptic construction of cell processes; and neurogenic-like processes. In some cases pinocytotic vesicles under the cell membrane and skenoid fibers were seen. Neural differentiation with dense core granules was seen in one case in benign, one case in borderline and five cases in malignant group. The positive reactivity of neural differentiated antigen NSE, CD99, S-100p and CD56 in cases of the neural differentiation group appeared in seven, seven, five and four cases respectively, which were significantly higher than that of the undifferentiated group.

CONCLUSIONSIt's rather difficult to differentiate GIST accompanying with neural differentiation from gastrointestinal autonomic nerve tumor if depending only on its histology and immunophenotype appearance, since many features were overlapping in both tumors. Examination of the neural ultrastructures and neural differentiated antigen in GIST might be helpful to clarify the neural differentiation and potential behavior of GIST.

12E7 Antigen ; Adolescent ; Adult ; Aged ; Antigens, CD ; metabolism ; Autonomic Nervous System Diseases ; metabolism ; pathology ; Biomarkers, Tumor ; metabolism ; CD56 Antigen ; metabolism ; Calcium-Binding Proteins ; metabolism ; Cell Adhesion Molecules ; metabolism ; Cell Differentiation ; Child ; Diagnosis, Differential ; Female ; Gastrointestinal Stromal Tumors ; metabolism ; ultrastructure ; Humans ; Immunohistochemistry ; Male ; Middle Aged ; Neoplasm Proteins ; metabolism ; Proto-Oncogene Proteins c-kit ; metabolism ; Stromal Cells ; ultrastructure ; Synapses ; ultrastructure

Stem cells are known to maintain stemness at least in part through secreted factors that promote stem-like phenotypes in resident cells. Accumulating evidence has clarified that stem cells release nano-vesicles, known as exosomes, which may serve as mediators of cell-to-cell communication and may potentially transmit stem cell phenotypes to recipient cells, facilitating stem cell maintenance, differentiation, self-renewal, and repair. It has become apparent that stem cell-derived exosomes mediate interactions among stromal elements, promote genetic instability in recipient cells, and induce malignant transformation. This review will therefore discuss the potential of stem cell-derived exosomes in the context of stromal remodeling and their ability to generate cancer-initiating cells in a tumor niche by inducing morphologic and functional differentiation of fibroblasts into tumor-initiating fibroblasts. In addition, the immunosuppressive potential of stem cell-derived exosomes in cancer immunotherapy and their prospective applications in cell-free therapies in future translational medicine is discussed.
Apoptosis ; Cell Communication ; Cell Transformation, Neoplastic ; Disease Progression ; Exosomes ; physiology ; Humans ; Immunotherapy ; methods ; Mesenchymal Stromal Cells ; physiology ; Neoplasms ; blood supply ; pathology ; therapy ; Neoplastic Stem Cells ; ultrastructure ; Neovascularization, Pathologic ; pathology ; Organelle Biogenesis ; Tumor Microenvironment

OBJECTIVETo investigate the effects of GM1 on inducing adult rat bone marrow stromal cells (MSCs) to form neural progenitor cells and their differentiation.

METHODSPurified MSCs were induced by different components of basic fibroblast growth factor (bFGF) alone, GM1 alone or combination of bFGF with GM1. After 3 days' incubation, fibronectin and collagen I were detected with immunocytochemistry, and nestin was detected with immunofluorescence. Neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP) and galactose cerebroside (GalC) were detected with immunocytochemistry after 7 days' incubation.

RESULTSAfter induction with bFGF alone or combination of bFGF and GM1, some MSCs exhibited the phenotypes of neural progenitor cells, and then neurons and astrocytes. In these two groups, the positive cells for fibronectin and collagen I decreased markedly after 3 days' induction. At the same time, the positive cells for nestin increased markedly. After 7 days' induction, NSE and GFAP-positive cells increased significantly. Furthermore, the addition of bFGF and GM1 caused the maximal variation. However, addition of GM1 alone had no inductive effects.

CONCLUSIONSCombination of bFGF with GM1 may synergistically promote the transformation of MSCs and differentiation into neurons and astrocyte-like cells. The results suggest a promising route for the application of MSCs.

Analysis of Variance ; Animals ; Bone Marrow Cells ; Cell Differentiation ; drug effects ; physiology ; Cells, Cultured ; Drug Synergism ; Fibroblast Growth Factor 2 ; pharmacology ; Fluorescent Antibody Technique ; G(M1) Ganglioside ; pharmacology ; Immunohistochemistry ; Probability ; Rats ; Rats, Wistar ; Sensitivity and Specificity ; Stem Cells ; pathology ; physiology ; Stromal Cells ; drug effects ; physiology ; ultrastructure