The effects of pore architecture in silk fibroin scaffolds on the growth and differentiation of BMP7-expressing mesenchymal stem cells

Periodical: Acta Biomater ISBN: 1878-7568 (Electronic) 1742-7061 (Linking)  Date: 2010/03/02  Language: Eng

Authors:Zhang, Y., Fan, W., Ma, Z., Wu, C., Fang, W., Liu, G., Xiao, Y.

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Abstract
Pore architecture of scaffolds is known to play a critical role in tissue engineering as it provides the vital framework for the seeded cells to organize into a functioning tissue. In this report, we investigated the effects of different concentrations of silk fibroin protein on 3 dimensional (3D) scaffold pore microstructure. Four pore size ranges of silk fibroin scaffolds were made by freeze-dry technique, with the pore sizes ranging from 50 to 300 mum. The pore size of the scaffold decreases as the concentration of fibroin protein increases. Human bone marrow mesenchymal stromal cells (BMSCs) transfected with BMP7 gene were cultured in these scaffolds. Cell viability Colorimetric assay (MTS), alkaline phosphatase (ALP) assay and reverse transcription-polymerase chain reaction (RT-PCR) were performed to analyze the effect of the pore size on cell growth, the secretion of extracellular matrix (ECM), and osteogenic differentiation. Cell migration in 3D scaffolds was confirmed by confocal microscopy. Calvarial defects in SCID mice were used to determine the bone forming ability of the silk fibroin scaffolds incorporated with BMP7-expressing BMSCs. The results showed that BMP7 expressing BMSCs preferred a pore size between 100 and 300 mum of silk fibroin protein fabricated scaffolds, with better cell proliferation and ECM production. Furthermore, in vivo transplantation of the silk fibroin scaffolds combined with BMP7-expressing BMSCs induced new bone formation. This study identified that optimized pore architecture of silk fibroin scaffolds could modulate the bioactivities of BMP7 transfected BMSCs in bone formation.