The effect of donor and recipient age on engraftment of tissue-engineered liver.

A novel treatment for end-stage liver disease using heterotopic hepatocyte transplantation on biodegradable polymers has been investigated. Survival and repopulation of adequate cell mass to replace hepatic function has been the principal difficulty of this method. Hence the authors have begun to investigate the role of donor and recipient age on the efficiency of hepatocyte transplantation.

Tissue-engineered heart valves. Autologous valve leaflet replacement study in a lamb model.

Background: We have previously reported the successful creation of tissue-engineered valve leaflets and the implantation of these autologous tissue leaflets in the pulmonary valve position. This study was designed to trace cultured cells that were seeded onto a biodegradable polymer with the use of a 1,1'-dioctadecyl-3,3,3' 3'-tetramethylindo-carbocyanine perchlorate (Di-1) cell-labeling method. We also examined the time-related biochemical, biomechanical, and histological characteristics and evolution of these tissue constructs.

Tissue engineering.

The loss or failure of an organ or tissue is one of the most frequent, devastating, and costly problems in health care. Current treatment modalities include transplantation of organs, surgical reconstruction, use of mechanical devices, or supplementation of metabolic products. Tissue engineering is the application of the principles and methods of engineering and the life sciences to the fundamental understanding of structure/function relationships in normal and pathological tissues and the development of biological substitutes to restore, maintain, or improve function.

Novel approach to fabricate porous sponges of poly(D,L-lactic-co-glycolic acid) without the use of organic solvents.

A novel method was developed to produce highly porous sponges for potential use in tissue engineering, without the use of organic solvents. Highly porous sponges of biodegradable polymers are frequently utilized in tissue engineering both to transplant cells or growth factors, and to serve as a template for tissue regeneration. The processes utilized to fabricate sponges typically use organic solvents, but organic residues remaining in the sponges may be harmful to adherent cells, protein growth factors or nearby tissues.

Outcome of subcutaneous islet transplantation improved by polymer device.

Syngeneic transplantation of rat islets into subcutaneous tissue failed to cure streptozocin diabetes. The reason is unknown, but poor vascularization may play a role. We hypothesize that if a well-vascularized subcutaneous site could be created, islet grafts would do well.

Tissue engineering lamb heart valve leaflets.

Tissue engineered lamb heart valve leaflets (N - 3) were constructed by repeatedly seeding a concentrated suspension of autologous myofibroblasts onto a biodegradable synthetic polymeric scaffold composed of fibers made from polyglycolic acid and polylactic acid. Over a 2-week period the cells attached to the polymer fibers, multiplied, and formed a tissue core in the shape of the matrix. The tissue core was seeded with autologous large-vessel endothelial cells that formed a monolayer which coated the outer surface of the leaflet.

Femoral shaft reconstruction using tissue-engineered growth of bone.

Tissue engineering is an interdisciplinary field that applies the principles and methods of engineering and the life sciences to the development of biologic substitutes. Bovine periosteum-derived cells were cultivated in vitro, put onto bioresorbable polymer fiber constructs, and allowed to grow until most of the fibers were coated with multiple layers of osteoblasts. Standardized 9-mm nonhealing defects were created in 24 male athymic rats femurs and bridged with titanium miniplates.

Localized delivery of epidermal growth factor improves the survival of transplanted hepatocytes.

Hepatocyte transplantation may provide a new approach for treating a variety of liver diseases if a sufficient number of the transplanted cells survive over an extended time period. In this report, we describe a technique to deliver growth factors to transplanted hepatocytes to improve their engraftment. Epidermal growth factor (EGF) was incorporated (0.

Segmental defect of the intestinal musculature of a newborn: evidence of acquired pathogenesis.

Two cases of premature newborns with a segmental defect of the intestinal musculature are presented. The clinical diagnoses were intestinal obstruction and perforation, respectively. Emergency laparotomy was performed.

Functional Viability of Chondrocytes Stored at 4 degrees C.

Little is known about the survival and function of chondrocytes when stored as a suspension at different temperatures. We compared the functional viability of chondrocytes stored in suspension at room temperature to those stored at 4 degrees C in either tissue culture medium or phosphate-buffered saline. Approximately half (47%) of the cells stored in culture media at 4 degrees C maintained viability after 4 weeks, while the cells stored at 4 degrees C in phosphate-buffered saline or in either suspension at room temperature for the same time demonstrated almost no viability.

Toward development of an implantable tissue engineered liver.

Hepatocyte transplantation on implantable devices is a tissue engineering approach to improve the treatment of liver disease and the efficacy of ex vivo gene therapy. Diverse physiological functions and high metabolic activity of the liver represent significant challenges to engineering implantable devices that provide long-term hepatic support. Liver tissue engineering research has explored alternatives to direct hepatocyte injection that include hepatocyte attachment to microcarriers, encapsulation and transplantation on biodegradable polymer scaffolds.

Liver transplantation and its long-term management in children.

Liver transplantation is an effective treatment for end-stage liver disease in the pediatric population. The 1-year survival rate in the United States is now approximately 80%, with some series showing a 90% 1-year survival rate. Most children who receive liver transplantation attain normal growth and development.

A regional experience with emergency liver transplantation.

Liver transplantation for patients requiring life-support results in the lowest survival and highest costs. A ten year (1983-1993) regional experience with liver transplantation for critically ill patients was undertaken to ascertain the fate of several subgroups of patients. Of the 828 liver transplants performed at six transplant centers within the region over this period, 168 (20%) were done in patients who met today's criteria for a United Network of Organ Sharing (UNOS) status 1 (emergency) liver transplant candidate.

Stabilized polyglycolic acid fibre-based tubes for tissue engineering.

Polyglycolic acid (PGA) fibre meshes are attractive candidates to transplant cells, but they are incapable of resisting significant compressional forces. To stabilize PGA meshes, atomized solutions of poly(L-lactic acid) (PLLA) and a 50/50 copolymer of poly(D,L-lactic-co-glycolic acid) (PLGA) dissolved in chloroform were sprayed over meshes formed into hollow tubes. The PLLA and PLGA coated the PGA fibres and physically bonded adjacent fibres.

De novo cartilage generation using calcium alginate-chondrocyte constructs.

These studies investigated the utility of calcium alginate as a biocompatible polymer matrix within which large numbers of chondrocytes could be held successfully in a three-dimensional structure and implanted. Further, the ability of chondrocyte-calcium alginate constructs to engraft and generate new cartilage was examined. Chondrocytes isolated from calf shoulders were mixed with a 1.

Tissue engineering heart valves: valve leaflet replacement study in a lamb model.

Background: Valve replacements using either bioprosthetic or mechanical valves have the disadvantage that these structures are unable to grow, repair, or remodel and are both thrombogenic and susceptible to infection. These characteristics have significantly limited their durability and longevity. In an attempt to begin to overcome these shortcomings, we have tested the feasibility of constructing heart valve leaflets in lambs by seeding a synthetic polyglycolic acid fiber matrix in vitro with fibroblasts and endothelial cells.

Injectable cartilage.

Slowly polymerizing calcium alginate gels were investigated as a means of delivering large numbers of isolated chondrocytes by means of injection to determine if these gels would promote engraftment and could provide three-dimensional templates for new cartilage growth. Chondrocytes isolated from the articular surface of calf forelimbs were added to a 1% sodium alginate dissolved in a 0.1 M potassium phosphate buffer solution (pH 7.