Biomedical subjects

Eduardo Mitrani

Publications and source records attributed to Eduardo Mitrani.

6 recordsLinked to original sources

PubMed2006

Skin-derived micro-organs induce angiogenesis in rabbits.

We have recently reported an alternative cell therapy approach to induce angiogenesis. The approach is based on small organ fragments--micro-organs (MOs)--whose geometry allows preservation of the natural epithelial/mesenchymal interactions and ensures appropriate diffusion of nutrients and gases to all cells. We have shown that lung-derived MOs, when implanted into hosts, transcribe a wide spectrum array of angiogenic factors and can induce an angiogenic response that can rescue experimentally induced ischemic regions in mice. From a clinical perspective, skin-derived MOs are particularly appealing as they could readily be obtained from a skin biopsy taken from the same target patient. In the present work we have investigated the angiogenesis-inducing capacity of rabbit and human skin-derived micro-organs in vitro and in vivo. Rabbit skin MOs were implanted into homologous adult rabbits and human skin MOs were encapsulated and implanted into xenogenic mice. Skin-derived MOs, as lung-derived MOs, were found to secrete a whole array of angiogenic factors and to induce a powerful angiogenic response when implanted back into animals. We believe the approach presented suggests a novel, efficacious and simple approach for therapeutic angiogenesis.

Adult↗

PubMed2005

Epithelial-mesenchymal interactions allow for epidermal cells to display an in vivo-like phenotype in vitro.

We here report that preservation of the basic epithelial-mesenchymal interactions allows for highly complex ex vivo function of epidermal cells. The approach taken is based on the preparation of organ fragments that preserve the basic epithelial/mesenchymal interactions but also ensure appropriate diffusion of nutrients and gases to all cells. Human and mice keratinocytes in such organ fragments, remain viable, proliferate and express epidermal-specific gene products when cultured in serum-free medium without added growth factors, for several weeks in vitro. When implanted into syngeneic animals they remain viable, become vascularized and continue to function and transcribe tissue-specific gene products for several months. Such fragments allow primary cells ex vivo to preserve most of the functional attributes of the in vivo system. Clearly, the effect of the extracellular matrix is critical in this system in order for the cells to proliferate and differentiate ex vivo. We are not aware of any other system which allows for localized expression of epidermal-specific genes ex vivo for significant periods in culture in defined serum-free medium.

Base Sequence↗

PubMed2004

A cell-based multifactorial approach to angiogenesis.

We here propose an alternative cell therapy approach to induce angiogenesis. We prepared small organ fragments whose geometry allows preservation of the natural epithelial/mesenchymal interactions and ensures appropriate diffusion of nutrients and gases to all cells. Fragments derived from lung are shown to behave as fairly independent units, to undergo a marked upregulation of angiogenic factors and to continue to function for several weeks in vitro in serum-free media. When implanted into hosts, they transcribe a similar array of angiogenic factors that specifically induce the formation of a potent vascular network. The angiogenic induction capacity of these fragments was also tested in a mouse and rat model of limb ischemia. We report that such fragments, when implanted in the vicinity of the ischaemic area, induce an angiogenic response which can rescue the ischaemia-induced damage. The approach presented differs from single factor application, gene therapy and other cell therapy methods in that it exploits the complex behaviour of autologous cells in their near to normal environment in order to achieve secretion of a whole range of angiogenic stimuli continuously and in an apparently coordinated fashion.

Animals↗

PubMed2004

Development of a scaled up liver device incorporating cryo-preserved pig liver micro-organs.

BACKGROUND/AIMS: Currently there is no effective therapy for most patients with fulminant or end stage liver disease. METHODS: Pig liver micro-organs (LMOs), which preserve liver micro-architecture and ensure a maximal 150-200mum distance from a source of nutrients and gases have been prepared and a method to cryo-preserve them has been developed. A new scaled-up extra-corporeal liver device termed aLIVE-H in which LMOs are exposed to liver-like hemodynamic conditions has also been developed. The purpose of this work is to test the safety and function of cryo-preserved LMOs and how the hemodynamic properties of the scaled up aLIVE device affect their function. RESULTS: Pig LMOs in aLIVE-H, transcribe albumin and Factor V at similar levels, irrespective of their position within the bioreactor, indicating that the hemodynamic features of the aLIVE-H device allow for homogeneous plasma distribution and proper function at different locations. Cryo-preserved LMOs transcribe albumin and Factor V at levels comparable to those transcribed by a normal pig liver. Connecting the aLIVE-H bioreactor to normal pigs did not affect key blood components and biochemical parameters. CONCLUSIONS: An extra-corporeal liver device aLIVE-H which imitates the hemodynamic and functional properties of the normal liver and incorporates cryo-preserved LMOs has been developed and characterized. aLIVE-H was found to perform key synthetic liver functions.

Albumins↗

PubMed2003

Liver micro-organs transcribe albumin and clotting factors and increase survival of 92% hepatectomized rats.

BACKGROUND/AIMS: Currently there is no effective non-surgical therapy for most patients with fulminant or end stage chronic liver disease. METHODS: We have prepared rat liver micro-organs (LMOs), which preserve the liver micro-architecture and ensure that no cell is more than 150 microm away from a source of nutrients and gases. The function of LMOs has been evaluated in vitro and in a new extra-corporeal liver device termed aLIVE in which LMOs are exposed to liver-like hemodynamic conditions. RESULTS: In vitro LMOs maintain normal physiological and biochemical functions including oxygen consumption, glucose metabolism, conversion of ammonia to urea, secretion of albumin and de novo transcription of genes coding for albumin and clotting factors. Inside the aLIVE bioreactor, LMOs also display sustained oxygen consumption, glucose metabolism and transcription of albumin and clotting factors IX and X, when connected both to normal and to 92% hepatectomized rats. Survival of 92% hepatectomized rats was 40% longer following a single 4-h treatment with aLIVE, compared to untreated animals. CONCLUSIONS: An extra-corporeal liver device, aLIVE, which provides key liver functions, has been developed. When tested in 92% hepatectomized rats, aLIVE improved the clinical condition and significantly increased survival time of the treated rats.

Albumins↗

PubMed2002

Cell surface expression and secretion of heparanase markedly promote tumor angiogenesis and metastasis.

The present study emphasizes the importance of cell surface expression and secretion of heparanase (endo-beta-D-glucuronidase) in tumor angiogenesis and metastasis. For this purpose, nonmetastatic Eb mouse lymphoma cells were transfected with the predominantly intracellular human heparanase or with a readily secreted chimeric construct composed of the human enzyme and the chicken heparanase signal peptide. Eb cells overexpressing the secreted heparanase invaded a reconstituted basement membrane to a much higher extent than cells overexpressing the intracellular enzyme. Cell invasion was inhibited in the presence of laminaran sulfate, a potent inhibitor of heparanase activity and experimental metastasis. The increased invasiveness in vitro was reflected in vivo by rapid and massive liver colonization and accelerated mortality. In fact, mice inoculated with cells expressing the secreted enzyme succumb because of liver metastasis and dysfunction, as early as 10 days after s.c. inoculation of the cells, when their tumor burden did not exceed 1% of body weight. Cell surface localization and secretion of heparanase markedly stimulated tumor angiogenesis, as demonstrated by a 4-6-fold increase in vessel density and functionality evaluated by MRI of tumors produced by cells expressing the secreted vs. the nonsecreted heparanase, consistent with actual counting of blood vessels. Altogether, our results indicate that the potent proangoigenic and prometastatic properties of heparanase are tightly regulated by its cellular localization and secretion. The increased potency of the secreted enzyme makes it a promising target for anticancer drug development.

Animals↗