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- Author or Editor: Russell Jamison x
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Abstract
Objectives—To compare combined vacuum and rotation with the spinner flask technique for seeding chondrocytes on chitosan versus polyglycolic acid matrices.
Sample Population—Porcine chondrocytes.
Procedure—A suspension containing 5 × 106 chondrocytes/ scaffold was used to evaluate 2 seeding techniques, including a spinner flask and a customdesigned vacuum chamber used for 2 hours prior to transfer to a bioreactor. For each seeding technique, prewetted scaffolds were composed of polyglycolic acid (PGA) mesh or macroporous chitosan sponge. Constructs were collected at 48 hours for DNA quantification, measurement of water and gycosaminoglycan (GAG) content, and scanning electron microscopy.
Results—Yield of both seeding techniques was similar for each type of scaffold. Percentage of cells contained in the center of PGA constructs was increased with seeding in the bioreactor (43% of total cell number), compared with the spinner flask (18%). The DNA content and cell number per construct were 10 times greater for PGA constructs, compared with chitosan constructs. Chitosan scaffolds seeded in the bioreactor yielded a significantly higher GAG:DNA ratio than did PGA scaffolds. Whereas chondrones formed on chitosan scaffolds, cell distribution was more uniform on PGA scaffolds.
Conclusions and Clinical Relevance—The vacuumbioreactor technique allowed seeded chondrocytes to attach to PGA scaffolds within 48 hours and improved uniformity of cell distribution, compared with the spinner technique. Although formation of extracellular matrix may be stimulated by seeding chitosan scaffolds in the bioreactor, further evaluations of the seeding technique and characteristics of chitosan scaffolds are warranted. (Am J Vet Res 2005;66:599–605)
Abstract
Objective—To determine whether sustained release of transforming growth factor (TGF)-β1 from a gelatin hydrogel would enhance bone regeneration in critical-sized long-bone defects and overcome inhibitory effects of preoperative irradiation.
Animals—24 adult New Zealand White rabbits.
Procedure—Rabbits were allocated to 2 groups. Twelve rabbits received localized megavoltage radiation to the right ulna by use of a cobalt 60 teletherapy unit, and 12 rabbits received no irradiation. Then, a 1.5-cm defect was aseptically created in the right ulna of each rabbit. Gelatin hydrogel that contained 5 µg of adsorbed recombinant-human (rh) TGF-β1 was placed in the defect of 12 rabbits (6 irradiated and 6 nonirradiated), and the other 12 rabbits received hydrogel without rhTGF-β1. Rabbits were euthanatized 10 weeks after surgery. New bone formation within the defect was analyzed by use of nondecalcified histomorphometric methods. A 1-way ANOVA was used to compare differences among groups.
Results—New bone formation within the defect was significantly greater in TGF-β1–treated rabbits than in rabbits treated with hydrogel carrier alone. Local delivery of rhTGF-β1 via a hydrogel carrier in irradiated defects resulted in amounts of bone formation similar to those for nonirradiated defects treated by use of rhTGF-β1.
Conclusions and Clinical Relevance—Local delivery of TGF-β1 by use of a hydrogel carrier appears to have therapeutic potential for enhancing bone formation in animals after radiation treatments.
Impact for Human Medicine—This technique may be of value for treating human patients at risk for delayed bone healing because of prior radiation therapy. (Am J Vet Res 2005;66:1039–1045)
