1,721,340 research outputs found
Production of human hematopoietic progenitors in a clinical-scale stirred suspension bioreactor
No full textEx vivo expanded primitive hematopoietic cells can be utilized in bone marrow transplantation therapies to treat patients suffering from various cancers and hematopoietic malignancies. A high initial cell density (10(6) cells/mL) and the supplement of soluble factors secreted by stromal feeders in combination with growth-promoting (interleukin-3 and stem cell factor) and growth-inhibiting (macrophage-inflammatory protein-1 alpha) cytokines resulted in high, long-term expansions (17-fold over a 14-day culture period) of human hematopoietic progenitors in a stirred suspension bioreactor. This study demonstrated that a transplantable dosage of human hematopoietic progenitor cells (8.1 +/- 1.3 x 10(6) colony forming unit-granulocyte/macrophage) can be generated from approximately 10 mL of bone marrow aspirate in a 14-day culture using a 250 mL suspension bioreactor system.N
Engineering of human cartilage rods: Potential application for penile prostheses
No full textPurpose: Natural penile prostheses created from the patient's own cells may eliminate the biocompatibility risks associated with artificial prostheses. We previously demonstrated that autologous cartilaginous rods could be created in animal corpus cavernosum. as penile prostheses in situ by transplanting autologous chondrocytes on biodegradable polymer scaffolds. In the present study we investigated the possibility of engineering human cartilage rods for potential use as penile prostheses. Materials and Methods: Chondrocytes isolated from human ear were seeded on rod shaped biodegradable polymer scaffolds (1.2 cm. in diameter, 6.0 cm. long). The seeded scaffolds were maintained in stirred bioreactors for 1 month. Subsequently, the seeded scaffolds were implanted subcutaneously into athymic rats. The specimens were retrieved 2 months after implantation, and histological, structural and mechanical properties were analyzed. The mechanical properties of the engineered prostheses were compared to those of silicone prostheses. Results: Human chondrocytes seeded onto polymer scaffolds formed milk-white cartilaginous rods of the same size as the initial implants. Histological analyses using hematoxylin and eosin, toluidine blue and alcian blue showed mature and well-formed chrondrocytes in the retrieved implants. The engineered human cartilaginous rods were flexible, elastic and able to withstand high degrees of compressive forces. The mechanical properties were comparable to those of commercially available silicone prostheses. Conclusions: Transplantation of chrondrocytes isolated from human ear on polymer scaffolds resulted in the formation of human cartilage rods with the appropriate mechanical properties required for use as penile prostheses. This study demonstrates the feasibility of creating human cartilage rods with a large dimension. This technology may be useful for patients who need penile reconstruction.N
Production of poly(3-hydroxybutyrate) from starch by Azotobacter chroococcum
No full textProduction of poly(3-hydroxybutyrate) (PHB) from starch was investigated in flask, batch, and fed-batch cultures of Azotobacter chroococcum. In flask culture, PHB content increased up to 74% of dry cell wt with increasing culture volume. In batch culture, PHB content increased to 44% with O-2 limitation. In fed-batch culture, cell concentration of 71 g/l with 20% PHB was obtained without O-2 limitation, whereas cell concentration of 54 g/l with 46% PHB was obtained with O-2 limitation
Poly(lactic-co-glycolic acid) microspheres as a potential bulking agent for urological injection therapy: Preliminary results
No full textInjection of bulking substances has been introduced as a new therapy to treat urinary incontinence and vesicoureteral reflux. Currently available bulking substances for the injection therapies include liquid or particulated silicone, collagen gel, and polytetrafluoroethylene paste. However, these materials have shown shortcomings such as inflammation, rapid volume decrease, and particle migration to distant organs. In the present study, we evaluated poly(lactic-co-glycolic acid) (PLGA) microspheres as a potential injectable bulking agent for the injection therapies. PLGA microspheres (52 mum in average diameter) were injectable through various gauges of needles, as the injected microspheres showed no tendency to obstruct the needles and microsphere size exclusion was not observed upon injection through the needles. After injection of PLGA microspheres into the subcutaneous dorsum of mice, inflammation, new tissue volume change, and microsphere migration were examined. Host cells from the surrounding tissues migrated to the implanted microspheres and formed new hybrid tissue structures. The volume of the newly generated tissues was maintained approximately constant for 7 weeks. Histological analyses showed no evidence of migration of the implanted microspheres to the distant organs. In summary, PLGA microspheres were injectable and able to induce a new hybrid tissue formation without initial volume decrease or particle migration. These preliminary results suggest that this material may be a potentially useful bulking agent for urological injection therapies. (C) 2004 Wiley Periodicals, Inc.Y
Highly porous polymer matrices as a three-dimensional culture system for hepatocytes: Initial results
No full textCell transplantation as a therapy for end-stage liver disease is currently under investigation by a variety of research groups. We have used biodegradable porous sponges as hepatocyte transplantation vehicles in past studies and were able to demonstrate engraftment, proliferation, and metabolic function of the transplanted hepatocytes in vivo.2-4 These highly porous three-dimensional matrices may provide novel in vitro culture systems with possible applications in cell banking, cell transplantation, and tissue engineering. In this study, we investigated the suitability of these matrices for long-term hepatocyte culture.N
Suspension culture of hematopoietic stem cells in stirred bioreactors
No full textHematopoietic stem cells have applications in bone marrow transplantations for the treatment of hematopoietic disorders. When murine hematopoietic stem cells were cultured in 50 ml stirred bioreactors for 14 d, stem-cell-antigen-1 positive cells (hematopoietic primitive progenitor cells) and long-term culture-initiating cells (hematopoietic stem cells) grew by 5-fold and 4-fold, respectively. These results show the possibility of growing hematopoietic stem cells using a stirred bioreactor.N
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