Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Oct;35(32):8951-9.
doi: 10.1016/j.biomaterials.2014.07.012. Epub 2014 Jul 30.

The combined effects of matrix stiffness and growth factor immobilization on the bioactivity and differentiation capabilities of adipose-derived stem cells

Jessica M Banks  1 , Laura C Mozdzen  2 , Brendan A C Harley  3 , Ryan C Bailey  4
Affiliations

The combined effects of matrix stiffness and growth factor immobilization on the bioactivity and differentiation capabilities of adipose-derived stem cells

Jessica M Banks et al. Biomaterials. 2014 Oct.

Abstract

Biomaterial designs are increasingly incorporating multiple instructive signals to induce a desired cell response. However, many approaches do not allow orthogonal manipulation of immobilized growth factor signals and matrix stiffness. Further, few methods support patterning of biomolecular signals across a biomaterial in a spatially-selective manner. Here, we report a sequential approach employing carbodiimide crosslinking and benzophenone photoimmobilization chemistries to orthogonally modify the stiffness and immobilized growth factor content of a model collagen-GAG (CG) biomaterial. We subsequently examined the singular and combined effects of bone morphogenetic protein (BMP-2), platelet derived growth factor (PDGF-BB), and CG membrane stiffness on the bioactivity and osteogenic/adipogenic lineage-specific gene expression of adipose derived stem cells, an increasingly popular cell source for regenerative medicine studies. We found that the stiffest substrates direct osteogenic lineage commitment of ASCs regardless of the presence or absence of growth factors, while softer substrates require biochemical cues to direct cell fate. We subsequently describe the use of this approach to create overlapping patterns of growth factors across a single substrate. These results highlight the need for versatile approaches to selectively manipulate the biomaterial microenvironment to identify synergies between biochemical and mechanical cues for a range of regenerative medicine applications.

Keywords: Growth factors; Mechanical properties; Mesenchymal stem cell; Osteogenesis; Photolithography; Surface modification.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
(A) Representative image of photoimmobilized PDGF (stripe) and BMP-2 (square) on CG membranes. Scale bar: 500 µm. (B) Immobilization of PDGF-BB as a function of UV exposure time (1, 5 min) normalized versus non-irradiated control. (C) Immobilization of BMP-2 as a function of UV exposure time (1, 5 min) normalized versus non-irradiated control.*: significant increase versus non-irradiated control.
Fig. 2
Fig. 2
Elastic modulus of crosslinked CG membranes as a function of EDC:NHS crosslinking intensity. *: significant difference between groups.
Fig. 3
Fig. 3
Orthogonal control of biomolecular patterning and CG membrane stiffness. (A) Elastic modulus of CG membranes as a function of UV exposure. (B) Mean fluorescence intensity of photoimmobilized PDGF (UV: 5 min) as a function of EDC crosslinking intensity. Results reported as mean ± standard deviation.
Fig. 4
Fig. 4
(A) ASC metabolic bioactivity and (B) overall cell number at day 7 on CG membranes as a function of substrate stiffness and photoimmobilized PDGF. †: significant increase compared to non-PDGF functionalized substrate of identical stiffness. Individual comparisons (substrate stiffness, PDGF immobilization) between all groups are shown in Supplementary Fig. 2.
Fig. 5
Fig. 5
Gene expression profiles of (A) collagen 1 (COL1A1), (B) alkaline phosphatase (ALP), and (C) osteocalcin (OCN) for ASCs cultured on CG substrates as a function of stiffness and photoimmobilized PDGF. *: significant increase compared to softest substrate with identical immobilized protein concentration. †: significant downregulation compared to non-PDGF functionalized substrate of identical stiffness. Individual comparisons (substrate stiffness, PDGF immobilization) between all groups are shown in Supplementary Fig. 3.
Fig. 6
Fig. 6
(A) ASC metabolic bioactivity and (B) overall cell number at day 7 on CG membranes as a function of substrate stiffness and photoimmobilized BMP-2. †: significant difference compared to substrate of equal stiffness but without BMP-2. Individual comparisons (substrate stiffness, BMP-2 immobilization) between all groups are shown in Supplementary Fig. 4.
Fig. 7
Fig. 7
Gene expression profiles of ASCs cultured on CG substrates as a function of stiffness and photoimmobilized BMP-2. (A) Alkaline phosphatase (ALP) expression is upregulated with substrate stiffness. *: significant decrease relative to stiffest membrane with no protein. (B) Adipogenic peroxisome proliferator-activated receptor gamma (PPARG) expression decreases with increasing substrate stiffness. Individual comparisons (substrate stiffness, BMP-2 immobilization) between all groups are shown in Supplementary Fig. 5.
Fig. 8
Fig. 8
(A) Schematic of 4-quadrant overlapping pattern of PDGF and BMP-2 generated on CG membranes. (B) Gene expression levels of collagen 1 (COL1A1) normalized versus ASCs on control substrates (−/−).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Borselli C, Storrie H, Benesch-Lee F, Shvartsman D, Cezar C, Lichtman JW, et al. Functional muscle regeneration with combined delivery of angiogenesis and myogenesis factors. Proc Natl Acad Sci U S A. 2010;107:3287–3292. - PMC - PubMed
    1. Buket Basmanav F, Kose GT, Hasirci V. Sequential growth factor delivery from complexed microspheres for bone tissue engineering. Biomaterials. 2008;29:4195–4204. - PubMed
    1. Caliari SR, Harley BAC. The effect of anisotropic collagen-GAG scaffolds and growth factor supplementation on tendon cell recruitment, alignment, and metabolic activity. Biomaterials. 2011;32:5330–5340. - PMC - PubMed
    1. Hagerty P, Lee A, Calve S, Lee CA, Vidal M, Baar K. The effect of growth factors on both collagen synthesis and tensile strength of engineered human ligaments. Biomaterials. 2012;33:6355–6361. - PubMed
    1. Becerra-Bayona S, Guiza-Arguello V, Qu X, Munoz-Pinto DJ, Hahn MS. Influence of select extracellular matrix proteins on mesenchymal stem cell osteogenic commitment in three-dimensional contexts. Acta Biomater. 2012;8:4397–4404. - PMC - PubMed

Publication types

LinkOut - more resources