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Controlled Release of Bone Growth Factors from Injectable, Biodegradable Polymer Scaffolds for Bone Tissue Engineering

Published online by Cambridge University Press:  15 March 2011

Elizabeth L. Hedberg  and
Antonios G. Mikos
Elizabeth L. Hedberg
Affiliation:
Department of Bioengineering, Rice University Houston, TX 77005, U.S.A
Antonios G. Mikos
Affiliation:
Department of Bioengineering, Rice University Houston, TX 77005, U.S.A
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Abstract

The objective of this research is to fabricate injectable, polymeric composites that will act as scaffolds for bone ingrowth as well as carriers for the controlled release of bone growth factors. To that end, the injectable polyester poly(propylene fumarate) (PPF) was loaded with poly(DLlactic-co-glycolic acid) (PLGA) microparticles carrying the model drug FITC-dextran. This preparation was then crosslinked with N-vinyl pyrrolidinone in the presence of benzoyl peroxide as initiator and sodium chloride (NaCl) as leachable porogen. The encapsulation of growth factors in microparticles is necessary to minimize their denaturation during scaffold crosslinking. PLGA microparticles (0.04 g microparticles/g PPF) were incorporated into PPF composites having variable NaCl weight percents (50 and 70 wt% NaCl) and the effect on FITC-dextran release kinetics was determined in vitro for cylinders of diameter 6.5 mm and height 13.0 mm. The FITC-dextran loaded microparticles alone exhibited a large initial burst effect, while the composite materials displayed a smaller burst effect and a longer linear region of release. At day 3, 54.6±2.1%, 5.1±0.9%, and 12.5±0.3% of loaded FITC-dextran was released into pH 7.4 phosphate buffered saline from the microparticles, the 50 wt% NaCl, and the 70 wt% NaCl composites, respectively. By day 28, 90.9±6.9%, 12.7±1.7%, and 34.4±0.4% of loaded FITC-dextran was released. Our results demonstrate that PLGA microparticles can be incorporated into PPF composites and that the release kinetics of FITC-dextran can be systematically manipulated through alteration of the composite initial salt content.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 662: Symposia LL/MM/NN/OO – Biomaterials for Drug Delivery & Tissue Engineering , 2000 , NN3.7
Copyright
Copyright © Materials Research Society 2001

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References

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