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  • 1
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bone formation was investigated in vitro by culturing stromal osteoblasts in three-dimensional (3-D), biodegradable poly(DL-lactic-co-glycolic acid) foams. Three polymer foam pore sizes, ranging from 150-300, 300-500, and 500-710 μm, and two different cell seeding densities, 6.83 × 105 cells/cm2 and 22.1 × 105 cells/cm2, were examined over a 56-day culture period. The polymer foams supported the proliferation of seeded osteoblasts as well as their differentiated function, as demonstrated by high alkaline phosphatase activity and deposition of a mineralized matrix by the cells. Cell number, alkaline phosphatase activity, and mineral deposition increased significantly over time for all the polymer foams. Osteoblast foam constructs created by seeding 6.83 × 105 cells/cm2 on foams with 300-500 μm pores resulted in a cell density of 4.63 × 105 cells/cm2 after 1 day in culture; they had alkaline phosphatase activities of 4.28 × 10-7 and 2.91 × 10-6 μmol/cell/min on Days 7 and 28, respectively; and they had a cell density that increased to 18.7 × 105 cells/cm2 by Day 56. For the same constructs, the mineralized matrix reached a maximum penetration depth of 240 μm from the top surface of the foam and a value of 0.083 mm for mineralized tissue volume per unit of cross sectional area. Seeding density was an important parameter for the constructs, but pore size over the range tested did not affect cell proliferation or function. This study suggests the feasibility of using poly(α-hydroxy ester) foams as scaffolding materials for the transplantation of autogenous osteoblasts to regenerate bone tissue. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 2
    ISSN: 0021-9304
    Keywords: poly(α-hydroxy esters) ; biodegradable polymer scaffolds ; osteoblast transplantation ; boye tissue engineering ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous biodegradable poly(DL-lactic-co-glycolic acid) foams were seeded with rat marrow stromal cells and implanted into the rat mesentery to investigate in vivo bone formation at an ectopic site. Cells were seeded at a density of 6.83 × 105 cells/cm2 onto polymer foams having pore sizes ranging from either 150 to 300 or 500 to 710 μm and cultured for 7 days in vitro prior to implantation. The polymer/cell constructs were harvested after 1, 7, 28, or 49 days in vivo and processed for histology and gel permeation chromatography. Visual observation of hematoxylin and eosin-stained sections and von Kossa-stained sections revealed the formation of mineralized bonelike tissue in the constructs within 7 days postimplantation. Ingrowth of vascular tissue was also found adjacent to the islands of bone, supplying the necessary metabolic requirements to the newly formed tissue. Mineralization and bone tissue formation were investigated by histomorphometry. The average penetration depth of mineralized tissue in the construct ranged from 190 ± 50 μm for foams with 500-710-μm pores to 370 ± 160 μm for foams with 150-300-μm pores after 49 days in vivo. The mineralized bone volume per surface area and total bone volume per surface area had maximal values of 0.028 ± 0.021 mm (500-710-μm pore size, day 28) and 0.038 ± 0.024 mm (150-300-μm, day 28), respectively. As much as 11% of the foam volume penetrated by bone tissue was filled with mineralized tissue. No significant trends over time were observed for any of the measured values (penetration depth, bone volume/surface area, or percent mineralized bone volume). These results suggest the feasibility of bone formation by osteoblast transplantation in an orthotopic site where not only bone formation from transplanted cells but also ingrowth from adjacent bone may occur. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 1-8 1997.
    Additional Material: 8 Ill.
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