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Results for “Bioartificial Organs”

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At least 181 records · Page 10Linked to original sources
PubMed2002

In vitro and in vivo evaluation of alginate/sol-gel synthesized aminopropyl-silicate/alginate membrane for bioartificial pancreas.

Alginate/aminopropyl-silicate/alginate (Alg/AS/Alg) membrane was prepared on Ca-alginate gel beads by a sol-gel process. The membrane has identical to Si-O-Si identical to bonds as well as electrostatic bonds between amino groups of AS and carboxyl groups of alginate. Permeability and stability were investigated for the membrane. Furthermore, rat islets encapsulated in the membrane (499 +/- 32 microns in diameter, 1000 islets/recipient) were transplanted to the peritoneal cavities of the mice with streptozotocin-induced diabetes. Our data show that the membrane had the molecular weight cut-off point of between 70 and 150 kDa, and hardly inhibited the permeation of glucose and insulin. The Alg/AS/Alg microcapsule was more stable than the well-known Alg/poly-L-lysine (PLL)/Alg microcapsule. After 30 days of soaking in stimulated body fluid, the percentages of intact microcapsule were 98.4 +/- 0.5 (mean +/- SEM)% and 88.0 +/- 1.5% (p < 0.001) for the Alg/AS/Alg and Alg/PLL/Alg microcapsules, respectively. The maximum maintenance period of normoglycemia was 105 days without administration of immunosuppressive drugs.

Alginates↗
PubMed2003

Kinetic modelling of blood glucose variation in a bioartificial pancreas.

Methods are presented for assessing the performance of biomaterials for a bioartificial pancreas using a kinetic model of blood glucose variation. The model is composed of simultaneous differential equations that simulate variation of blood glucose concentration of rats outside the biomaterial and decrease of islet number inside the biomaterial. The resulting calculations agree well with the in vivo experimental data and indicate that the characteristics of bioartificial pancreas can be expressed as the actually working number of islets from the viewpoint of rats, regardless of the functioning of the bioartificial pancreas. The contributions of the capability of a biomaterial permeable to insulin and against immune rejection, and other factors that may induce cell death were involved in the actually working number of islets, i.e., the model used a lumped-parameter expression for assessment of the performance of biomaterials for a bioartificial pancreas. This model would be useful as a research tool for analysis of clinical investigation of bioartificial pancreas and physiological significance of blood glucose variation dynamics.

Animals↗
PubMed2003

Bioartificial grafts for transmural myocardial restoration: a new cardiovascular tissue culture concept.

OBJECTIVE: Survival of bioartificial grafts that are destined to restore cardiac function stands and falls with their nutrient supply. Engineering of myocardial tissue is limited because of lack of vascularization. We introduce a new concept to obtain bioartificial myocardial grafts in which perfusion by a macroscopic core vessel is simulated. METHODS: We have designed an experimental reactor with multiple chambers for the production of bioartificial tissue or tissue precursors. By introduction of in- and output lines of distinct diameter and insertion of a core vessel into each chamber, we established pulsatile, continuous flow through the embodied three-dimensional tissue culture. In the present study, collagen components served as the ground matrix wherein neonatal rat cardiomyocytes were inoculated. For the assessment of cellular viability and distribution in comparison to static, non-perfused culture, fluor-desoxy-glucose-positron-emission-tomography and life/dead assays were employed. RESULTS: We obtained 3D constructs of 8-mm thickness, which display high viability and metabolism (6.0+/-1.3(e-03) in the perfused vs. 4.0+/-0.3(e-03) in the unperfused chambers). The core vessel has the size of a human coronary and remained patent during the entire culture process. We observed centripetal migration of the embedded cardiomyocytes to the site of the core vessel. Cardiomyocytes partially resumed a spindle like form without additional stretch. CONCLUSIONS: The present dynamic tissue culture concept is highly effective in manufacturing thick, viable grafts for cardiac muscle restoration, which could be surgically anastomosable. The bioreactor may accommodate multiple types of cells and tissues for innumerable in vitro and in vivo applications.

Animals↗
PubMed2006

Quantitative assessment of olfactory receptors activity in immobilized nanosomes: a novel concept for bioelectronic nose.

We describe how mammalian olfactory receptors (ORs) could be used as sensing elements of highly specific and sensitive bioelectronic noses. An OR and an appropriate G(alpha) protein were co-expressed in Saccharomyces cerevisiae cells from which membrane nanosomes were prepared, and immobilized on a sensor chip. By Surface Plasmon Resonance, we were able to quantitatively evaluate OR stimulation by an odorant, and G protein activation. We demonstrate that ORs in nanosomes discriminate between odorant ligands and unrelated odorants, as in whole cells. This assay also provides the possibility for quantitative assessment of the coupling efficiency of the OR with different G(alpha) subunits, without the interference of the cellular transduction pathway. Our findings will be useful to develop a new generation of electronic noses for detection and discrimination of volatile compounds, particularly amenable to micro- and nano-sensor formats.

Animals↗
PubMed2003

Development of bioartificial kidneys.

Bioartificial kidneys, which consist of continuous haemofiltration and bioartificial tubules using tubular epithelial cells, have been studied since 1987. The bioartificial tubules consist of hollow fibre modules and tubular epithelial cells grown on the hollow fibre membranes after coating with extracellular matrices. The kinds of tubular epithelial cells, extracellular matrices and artificial membranes therefore have been investigated and then the most appropriate cell and materials have been selected on the basis of the development of bioartificial kidneys. Successful seeding to form confluent monolayers on the surfaces of hollow fibers is not easy, but this method has already been established. Renal assist devices using human renal proximal tubular epithelial cells have been used in the treatment of acute renal failure patients with endotoxemia by Humes et al., and successful treatment of acute renal failure patients with these devices was reported in 2001 and 2002, in which the improved mortality rate of those patients was shown. A bioartificial kidney, in which cDNA of multidrug resistance protein-1 was transfected into tubular epithelial cells that were then grown on the outer surfaces of hollow fibers, was used in the experimental treatment of digoxin-intoxicated dogs. Rapidly reduced digoxin levels were noted in the plasma of the dogs after treatment. Bioartificial kidneys, however, have never been used in the long-term treatment of a maintenance dialysis patient, although patients need those kidneys. In order to establish long-term treatment with a bioartificial kidney, each haemofilter has to function for more than one week without systemic anticoagulation and a bioartificial tubule must function for 3-4 weeks.

Acute Kidney Injury↗
PubMed2002

Combination of a new composite biocampatible skin graft on the neodermis of artificial skin in an animal model.

INTRODUCTION: There have been very limited and inconsistent attempts at combining the cultured epidermal autograft (CEA) with the neodermis of artificial skin (Integra). The reasons for this remain unknown. The basement membrane proteins of conventional CEA sheets are easily damaged by the dispase treatment during the harvesting of the CEA from the culture flask. The damage of the basement membrane proteins may affect the anchorage of CEA onto the neodermis of Integra. A new Composite Biocompatible Skin Graft (CBSG) was recently developed. METHODS: Composite biocompatible skin graft consists of autologous keratinocytes cultivated on a pliable hyaluronate-derived membrane (Laserskin)which has been pre-seeded with allogenic dermal fibroblasts. Basement membrane proteins of CBSG are protected from the dispase treatment because the keratinocytes are directly seeded onto Laserskin. The engraftment of CBSG was evaluated on 20 wounds of 10 rats. Integrawas grafted on two freshly excised full-thickness wounds (3cm in diameter) in the dorsum of each animal. A polypropylene ring was applied to each wound to prevent the migration of epithelium from the edges. Composite Biocompatible Skin Graft was used to cover the neodermis of Integra after the silicone membrane was removed 14-21 days postgrafting. RESULTS: Fourteen (70%) of 20 skin biopsies taken at day 21 from the centre of the grafted wounds revealed regenerated epithelium. CONCLUSION: A feasible delivery system of cultured keratinocytes onto theneodermis of Integra is demonstrated in this animal -experiment.

Animals↗
PubMed2002

The bioartificial kidney in the treatment of acute renal failure.

The application of cell therapy to the successful substitution process of hemofiltration may improve the poor prognosis of patients with acute renal failure (ARF) in the intensive care unit. An extracorporeal bioartificial kidney consisting of a conventional hemofilter followed in series with a renal tubule assist device (RAD) has been developed. The RAD is a hemofiltration cartridge containing 109 human renal tubule cells grown as monolayers along the inner surface of the hollow fibers. The fibers provide a porous scaffold that is immunoprotective. The ultrafiltrate from the hemofilter is delivered to the luminal compartment of the RAD, and the postfiltered blood is delivered to the extracapillary space of the RAD. The RAD has been shown to possess multiple differentiated transport, metabolic, and endocrinologic activities of renal epithelium. These activities have been demonstrated to occur when the RAD is placed in the extracorporeal circuit of the bioartificial kidney in uremic animals. This approach may improve the current therapies used to treat patients with ARF because of the RAD's ability to restore lost metabolic renal function and cytokine balance in these desperately ill patients. In this regard, the RAD was able to ameliorate endotoxin and bacteremic shock in uremic animals by altering cytokine levels, improve mean arterial blood pressure, and maintain better cardiac output. With these supportive preclinical data, an FDA-approved phase I/II clinical trial has been initiated and early results are encouraging.

Acute Kidney Injury↗