Porous silk fibroin 3-D scaffolds for delivery of bone morphogenetic protein-2 in vitro and in vivo

Vassilis Karageorgiou, Michael Tomkins, Robert Fajardo, Lorenz Meinel, Brian Snyder, Katherine Wade, Jake Chen, Gordana Vunjak-Novakovic, David L. Kaplan

Research output: Contribution to journalArticlepeer-review

185 Scopus citations


Bone morphogenetic protein-2 (BMP-2) plays a key role in osteogenesis. Biomaterials used for the sustained delivery of BMP-2 in vivo have shown therapeutic benefits. In the present study, BMP-2 was loaded in porous silk fibroin scaffolds derived from silkworm cocoons (2.4 ± 0.14 μg per scaffold). The release profile of BMP-2 under dynamic culture conditions (spinner flasks) showed that after 1 week in culture 25% of the initial BMP-2 was retained adsorbed to the scaffold; up to 4 weeks no additional BMP-2 was released. BMP-2 induced human bone marrow stromal cells (hMSCs) to undergo osteogenic differentiation when the seeded scaffolds were cultured in medium supplemented with osteogenic stimulants for 4 weeks, based on elevated alkaline phosphatase activity, calcium deposition, and transcript levels for bone sialoprotein, osteopontin, osteocalcin, BMP-2, and cbfa-1. Micro-computed tomography revealed densely deposited mineral at the center of the scaffolds. In contrast, hMSCs cultured in control scaffolds (no BMP-2) exhibited limited osteogenesis. When implanted in critical sized cranial defects in mice, scaffolds loaded with BMP-2 and seeded with hMSCs resulted in significant bone ingrowth. These results were qualitatively similar to scaffolds loaded with BMP-2 but no hMSCs or with BMP-2 and hMSCs but not pregrown into bone-like tissue. Bone-related outcomes were improved when compared with the scaffold controls implanted without BMP-2. These studies illustrate the potential use of slow degrading silk fibroin 3-D scaffolds loaded with BMP-2, in combination with hMSCs, in osteogenesis studies in vitro and in vivo, and provide a new range of material properties for these applications.

Original languageEnglish (US)
Pages (from-to)324-334
Number of pages11
JournalJournal of Biomedical Materials Research - Part A
Issue number2
StatePublished - Aug 2006


  • BMP-2
  • Bone
  • Silk
  • Stem cells

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Biomedical Engineering
  • Metals and Alloys


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