A self-assembling peptide matrix used to control stiffness and binding site density supports the formation of microvascular networks in three dimensions

A three-dimensional (3-D) cell culture system that allows control of both substrate stiffness and integrin binding density was created and characterized. This system consisted of two self-assembling peptide (SAP) sequences that were mixed in different ratios to achieve the desired gel stiffness and...

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Bibliographic Details
Published in:	Acta biomaterialia Vol. 9; no. 8; pp. 7651 - 7661
Main Authors:	Stevenson, M.D., Piristine, H., Hogrebe, N.J., Nocera, T.M., Boehm, M.W., Reen, R.K., Koelling, K.W., Agarwal, G., Sarang-Sieminski, A.L., Gooch, K.J.
Format:	Journal Article
Language:	English
Published:	England Elsevier Ltd 01-08-2013
Subjects:	adhesion atomic force microscopy Binding site density Binding Sites Biomimetic Materials - chemistry cell adhesion cell culture cell growth Cells, Cultured Elastic Modulus endothelial cells Endothelial Cells - cytology Endothelial Cells - physiology Extracellular Matrix - chemistry gels Humans integrins Integrins - chemistry Materials Testing Mechanotransduction, Cellular - physiology Microvascular networks Microvessels - growth & development Neovascularization, Physiologic - physiology Oligopeptides - chemistry peptides Self-assembling peptide stem cells Stiffness storage modulus Three-dimensional cell culture Tissue Engineering - methods Self-assembling peptide Three-dimensional cell culture Stiffness Binding site density Microvascular networks
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Summary:	A three-dimensional (3-D) cell culture system that allows control of both substrate stiffness and integrin binding density was created and characterized. This system consisted of two self-assembling peptide (SAP) sequences that were mixed in different ratios to achieve the desired gel stiffness and adhesiveness. The specific peptides used were KFE ((acetyl)-FKFEFKFE-CONH2), which has previously been reported not to support cell adhesion or MVN formation, and KFE-RGD ((acetyl)-GRGDSP-GG-FKFEFKFE-CONH2), which is a similar sequence that incorporates the RGD integrin binding site. Storage modulus for these gels ranged from ∼60 to 6000Pa, depending on their composition and concentration. Atomic force microscopy revealed ECM-like fiber microarchitecture of gels consisting of both pure KFE and pure KFE-RGD as well as mixtures of the two peptides. This system was used to study the contributions of both matrix stiffness and adhesiveness on microvascular network (MVN) formation of endothelial cells and the morphology of human mesenchymal stem cells (hMSC). When endothelial cells were encapsulated within 3-D gel matrices without binding sites, little cell elongation and no network formation occurred, regardless of the stiffness. In contrast, matrices containing the RGD binding site facilitated robust MVN formation, and the extent of this MVN formation was inversely proportional to matrix stiffness. Compared with a matrix of the same stiffness with no binding sites, a matrix containing RGD-functionalized peptides resulted in a ∼2.5-fold increase in the average length of network structure, which was used as a quantitative measure of MVN formation. Matrices with hMSC facilitated an increased number and length of cellular projections at higher stiffness when RGD was present, but induced a round morphology at every stiffness when RGD was absent. Taken together, these results demonstrate the ability to control both substrate stiffness and binding site density within 3-D cell-populated gels and reveal an important role for both stiffness and adhesion on cellular behavior that is cell-type specific.
Bibliography:	http://dx.doi.org/10.1016/j.actbio.2013.04.002 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1742-7061 1878-7568
DOI:	10.1016/j.actbio.2013.04.002