AN IN VIVO MODEL OF HYPERACUTE REJECTION: CHARACTERIZATION AND EVALUATION OF THE EFFECT OF TRANSGENIC HUMAN COMPLEMENT INHIBITORS

Hyperacute rejection (HAR) occurring after transplantation within phylogenetically distant species is a severe reaction triggered by preexisting xenoreactive antibodies and complement activation, leading to the destruction of the donor organ. Expression of human complement inhibitors in transgenic pig organs prolongs the survival of xenograft in experimental models. Moreover, the extent of protection from hyperacute rejection is dependent on the level and site of expression of the transgenic molecules and, probably, on the combination of different molecules. In this regard a small animal model to test the efficacy of expression vectors and different human molecules could be very advantageous. A murine model developed in our laboratory was characterized by measurement of several parameters characteristic of HAR in the livers of control and transgenic mice expressing transgenic human DAF (CD55) or MCP (CD46) at the end of 2 h of perfusion with human plasma and after 1 day. The parameters studied were heamatological values of hepatic functions (GOT and GPT), induction of pro-inflammatory molecules and histopathological evaluation. Cytokines (IL-1 alpha, IL-1 beta, IL-6) induction and exposure of P-selectin on the endothelial cell surface, was only observed in control animals after 2 h of perfusion, as an early event. GOT and GPT values increase drammatically after 2 h perfusion and 1 day after the treatment according to the histopathological observation of liver damage. On the contrary, the livers of hDAF or hMCP transgenic mice, under the same treatment were significantly protected although the extent of this protection is dependent on the level of expression of transgenic human molecules

Multiway modeling and analysis in stem cell systems biology

<p>Abstract</p> <p>Background</p> <p>Systems biology refers to multidisciplinary approaches designed to uncover emergent properties of biological systems. Stem cells are an attractive target for this analysis, due to their broad therapeutic potential. A central theme of systems biology is the use of computational modeling to reconstruct complex systems from a wealth of reductionist, molecular data (e.g., gene/protein expression, signal transduction activity, metabolic activity, etc.). A number of deterministic, probabilistic, and statistical learning models are used to understand sophisticated cellular behaviors such as protein expression during cellular differentiation and the activity of signaling networks. However, many of these models are bimodal i.e., they only consider row-column relationships. In contrast, multiway modeling techniques (also known as tensor models) can analyze multimodal data, which capture much more information about complex behaviors such as cell differentiation. In particular, tensors can be very powerful tools for modeling the dynamic activity of biological networks over time. Here, we review the application of systems biology to stem cells and illustrate application of tensor analysis to model collagen-induced osteogenic differentiation of human mesenchymal stem cells.</p> <p>Results</p> <p>We applied Tucker1, Tucker3, and Parallel Factor Analysis (PARAFAC) models to identify protein/gene expression patterns during extracellular matrix-induced osteogenic differentiation of human mesenchymal stem cells. In one case, we organized our data into a tensor of type protein/gene locus link × gene ontology category × osteogenic stimulant, and found that our cells expressed two distinct, stimulus-dependent sets of functionally related genes as they underwent osteogenic differentiation. In a second case, we organized DNA microarray data in a three-way tensor of gene IDs × osteogenic stimulus × replicates, and found that application of tensile strain to a collagen I substrate accelerated the osteogenic differentiation induced by a static collagen I substrate.</p> <p>Conclusion</p> <p>Our results suggest gene- and protein-level models whereby stem cells undergo transdifferentiation to osteoblasts, and lay the foundation for mechanistic, hypothesis-driven studies. Our analysis methods are applicable to a wide range of stem cell differentiation models.</p

Mesenchymal stem cell as salvage treatment for refractory chronic GVHD

Refractory chronic GVHD (cGVHD) is an important complication after allogeneic hematopoietic SCT and is prognostic of poor outcome. MSCs are involved in tissue repair and modulating immune responses in vitro and in vivo. From April 2005 to October 2008, 19 patients with refractory cGVHD were treated with MSCs derived from the BM of volunteers. The median dose of MSCs was 0.6 × 106 cells per kg body weight. Fourteen of 19 patients (73.7%) responded well to MSCs, achieving a CR (n=4) or a PR (n=10). The immunosuppressive agent could be tapered to less than 50% of the starting dose in 5 of 14 surviving patients, and five patients could discontinue immunosuppressive agents. The median duration between MSC administration and immunosuppressive therapy discontinuation was 324 days (range, 200–550 days). No patients experienced adverse events during or immediately after MSC infusion. The 2-year survival rate was 77.7% in this study. Clinical improvement was accompanied by the increasing ratio of CD5+CD19+/CD5−CD19+ B cells and CD8+CD28−/CD8+CD28+ T cells. In conclusion, transfusion of MSCs expanded in vitro, irrespective of the donor, might be a safe and effective salvage therapy for patients with steroid-resistant, cGVHD

TARJETA POSTAL NAVIDEÑA [Material gráfico]

ITALIACopia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

The origin and differentiation of adrenocortical cells in rats with portacaval shunt. A structural and ultrastructural study

Tlie foi-mation of adreiiocortical cells in thc rat was st~idicd by light and elcctron inicroscopy in an csperinicntal modcl. namcly portacuval shunt (P.C.S.). in v.liicli .;trong hypcrpl~isia of the cells oí' the c¿ipsulairrgion occurs. The results of this study indicate that in physiological cunditions at the lcvel of thc adrenal glnnd cnpsulc sonic epithclial cells, morphologically distinguisliable as dark and clcnr cells, are found which can he interprctcd as precursors of adrenocortical cells. Fi-orn observations of intermediate forrns betwccn cupsular precursors arid mature adrcnocortical cells. wliich are found in high numbers following P.C.S.. it seellis that tlie dark prccursors give rise to cclls of thc zoiia glonicriilosa and the clcar precursors e\-olve into cclls of tlie zona intermedia, which are to he considercd as thc starting point for the formiition of cells «f thc zona fnsciculata

Ultrastructure of striated muscle fibers in the middle third of the human esophagus

Striated muscle fibers and .their spatial relationship to smooth muscle cells have been studied in the middle third of human esophagus. Biopsies were obtained from 3 patients during surgery. In both the circular and longitudinal layers, the muscle coat of this transition zone was composed of fascicles of uniform dimensioi~ (100-200 pm of diameter); some of these bundles were made up of striated muscle fibers, others were pure bundles of smooth muscle cells and some were of the mixed type. Striated muscle fibers represented three different types, which were considered as intermediate, with certain structural features characteristic of the fast fiber type. Of these, the most frequently-found fibers were most similar to the fast fiber type. Satellite cells were numerous; in mixed fascicles they were gradually replaced by smooth muscle cells. The gap between striated muscle fiber and smooth muscle cells was more than 200 nm wide. It contained the respective basal laminae and a delicate layer of amorphous conective tissue. No specialized junctions were formed between consecutive striated muscle fibers, or between striated muscle fibers and smooth muscle cells. Interstitial cells of Cajal were never situated as close to striated muscle fibers as to smooth muscle cells