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
. 2007;17(13):2085-2093.
doi: 10.1002/adfm.200700012.

Multifunctional hydrogels that promote osteogenic hMSC differentiation through stimulation and sequestering of BMP2

Danielle S W Benoit  1 , Stuart D Collins, Kristi S Anseth
Affiliations

Multifunctional hydrogels that promote osteogenic hMSC differentiation through stimulation and sequestering of BMP2

Danielle S W Benoit et al. Adv Funct Mater. 2007.

Abstract

The extracellular environment controls many cellular activities thereby linking external material cues to internal cell function. By better understanding these processes, synthetic extracellular material niches can be tailored to present cells with highly regulated physical and/or chemical cues that promote or suppress selected cell functions. Here, poly(ethylene glycol) (PEG) hydrogels were functionalized with fluvastatin-releasing grafts and growth factor binding heparin domains to enable the dynamic exchange of information between the material and cells from the outside-in and inside-out (i.e., bidirectional signaling). By incorporating a fluvastatin-releasing graft and carefully controlling the dose and temporal release, materials were designed to promote bone morphogenic protein (BMP2) and alkaline phosphatase (ALP) production by human mesenchymal stem cells (hMSCs). When the release of fluvastatin was controlled to occur over 2 weeks, BMP2 and ALP production was increased 2.2-fold and 1.7-fold, respectively, at day 28 compared to hMSCs cultured in the absence of fluvastatin. By introducing a heparin functionality into the gel to sequester and localize the hMSC-produced BMP2, the osteogenic differentiation of hMSCs was further augmented over fluvastatin delivery alone. Osteopontin and core binding factor α1 gene expression was 6-fold and 4-fold greater for hMSCs exposed to fluvastatin in the presence of the heparin functionalities, respectively. These results demonstrate how multifunctional gels that interact with cells in a bidirectional manner can efficiently promote selected cell functions, such as the osteogenic differentiation of hMSCs.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Cumulative fluvastatin release (Mt/M∞) as a function of time for hydrogels synthesized through the copolymerization of PEG526MMA-nLA-fluvastatin (n=2: ♦, n=4: ■, n=6: ▲) with a 10 wt% solution of PEG4600DM. Release profiles were measured in PBS at sink conditions. Gels (d=5 mm, t=2 mm) initially contained ~500 µg of statin. * and # - statistically different cumulative release values between n=4 and n=6 and n=2 and n=6, respectively, at particular times (p<0.05).
Figure 2
Figure 2
ALP and BMP2 production normalized to metabolic activity (AlamarBlue) of hMSCs encapsulated in RGDS-functionalized hydrogels in the absence of fluvastatin (–x–) or with releasing fluvastatin (--♦--), n=4 samples/condition. * p<0.05 of sample versus control (no delivered fluvastatin) at that time.
Figure 3
Figure 3
Native PAGE gel (A) and semi-quantitative analysis (B) demonstrated that BMP2 binding to heparin decreased with increasing extent of methacrylation (% methacrylation in parentheses). * p< 0.05 versus no methacrylation and # p<0.05 versus 6% methacrylation, n=3 samples/condition. Representative images showing that methacrylated heparin, labeled with Oregon green and copolymerized with PEG4600DM is uniformly distributed (C), and retained its ability to specifically bind to BMP2 (red) (D) as qualitatively shown by the merged image, where the colocalized fluorescence appears orange (E). Control PEG hydrogels showed no staining (not pictured), indicating no BMP2 sequestering, bar=200 µm.
Figure 4
Figure 4
BMP2 production normalized to levels of metabolic activity (AlamarBlue) of hMSCs encapsulated in RGDS-functionalized hydrogels in the absence of fluvastatin (--○--) or with releasing fluvastatin (–●–) or encapsulated in heparin-functionalized hydrogels in the absence of fluvastatin (--□--) or with releasing fluvastatin (–■–), n=4 samples/condition. * p<0.05 of sample versus control (same chemistry but no delivered fluvastatin) at that time.
Figure 5
Figure 5
hMSC OPN (A+B) and CBFA1 (C+D) gene expression normalized to levels of GAPDH. hMSCs were cultured in the presence (–■–) or absence (--●--) of fluvastatin in RGDS-functionalized hydrogels, in RGDS-functionalized, fluvastatin-releasing hydrogels, in heparin-functionalized hydrogels, or in heparin-functionalized, fluvastatin-releasing hydrogels. n = 4 samples/condition. * p<0.05 of sample versus control (same chemistry but no delivered fluvastatin) at that time.
Figure 6
Figure 6
Structures of PEG4600DM (A), PEG526MMA-nLA-fluvastatin (B), acrylated-PEG3400-RGDS (C), and methacrylated heparin (D) used for hydrogel fabrication.
Figure 7
Figure 7
Controlled delivery of fluvastatin, a small molecule that increases BMP2 production, combined with heparin functionalities (green) incorporated into a poly(ethylene glycol)-based hydrogel enables local sequestering of cell-produced BMP2 (red) to temporally and spatially regulate human mesenchymal stem cell osteogenesis.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Ramamurthy A, Vesely I. Biomaterials. 2005;26:999. - PubMed
    1. Burdick JA, Anseth KS. Biomaterials. 2002;23:4315. - PubMed
    1. Hoffman AS. Adv. Drug Del. Rev. 2002;43:3. - PubMed
    1. Lee KY, Mooney DJ. Chem. Rev. 2001;101:1869. - PubMed
    1. Babensee JE, McIntire LV, Mikos AG. Pharm. Res. 2000;17:497. - PubMed

LinkOut - more resources