@article{fe347572247547ff8217d0d1f012c4c7,
title = "Transforming Growth Factor β-1 Binding by Peptide Amphiphile Hydrogels",
abstract = "Supramolecular biomaterials are promising systems to bind or deliver therapeutic growth factors given their great structural versatility and tunability of properties by simply mixing molecules. In this work, we have investigated this approach for the growth factor cytokine TGFβ-1, which is potentially important in the regeneration of damaged cartilage or in the prevention of fibrinogenesis of organs and the progression of tumors. Our previous work identified a peptide sequence capable of binding TGFβ-1 and supramolecular peptide amphiphile (PA) nanofiber hydrogels that displayed the sequence were found to enhance regeneration of cartilage in a rabbit model. In this work, we have synthesized novel PA molecules motivated by the tendency of the original bioactive peptide to undergo deamidation during purification procedures, thus interfering with synthesis of molecularly well-defined structures. We report here on novel PA nanofibers that can be purified without deamidation to establish if the chemical reaction affects chondrogenesis. Interestingly, we found that gels formed from nanofibers displaying a fully deamidated sequence by introducing an asparagine to aspartic acid mutation retain 25% more growth factor relative to those displaying the original bioactive peptide even though the individual peptides have similar affinity for the cytokine. We attribute this difference in growth factor retention to bundling of nanofibers displaying the original asparagine-containing sequence, thus masking the growth factor-binding structure. Improved retention of the growth factor resulted in chondrogenesis of cells encapsulated in the gels as indicated by a more than 50% increase in Sox 9 expressing cells at 3 days and a 100% increase in glycosaminoglycan production at 21 days. We have therefore been able to design a more effective bioactive supramolecular biomaterial to bind TGFβ-1, and also demonstrated how bioactive peptide sequences in supramolecular biomaterials can have impact on their structure at larger length scales that change their biological functions. ",
keywords = "TGFβ-1, cartilage regeneration, peptide amphiphiles, self-assembly, supramolecular biomaterials",
author = "Lewis, {Jacob A.} and Ronit Freeman and Carrow, {James K.} and Clemons, {Tristan D.} and Palmer, {Liam C.} and Stupp, {Samuel I.}",
note = "Funding Information: This research was supported by a gift from Mike and Mary Sue Shannon to the Simpson Querrey Institute at Northwestern University for research on musculoskeletal regeneration. Additional support was provided by the Center for Regenerative Nanomedicine at the Simpson Querrey Institute. J.A.L. acknowledges financial support from an NSF Graduate Research Fellowship (grant DGE-1324585). The authors thank Mark Karver of the Peptide Synthesis Core Facility of the Simpson Querrey Institute at Northwestern University for his guidance in synthesizing and characterizing peptides, and Arabela Grigorescu of the Keck Biophysics Facility for help designing binding affinity experiments. Work was performed using the Peptide Synthesis Core Facility (peptide synthesis) and the Analytical BioNanoTechnology Core (chemical and biological analysis) at the Simpson Querrey Institute at Northwestern University. The Simpson Querrey Institute, Northwestern University Office for Research, U.S. Army Research Office, and the U.S. Army Medical Research and Materiel Command have provided funding to develop both of these facilities and ongoing support is being received from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS–1542205). This work also utilized the Northwestern University Keck Biophysics Facility, supported partially by a Cancer Center Support Grant (NCI CA060553). The authors made use of the EPIC facility and BioCryo facility of the Northwestern NUANCE center, which has received support from ShyNE Resource (NSF ECCS – 1542205); the MRSEC program (NSF DMR – 1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. Imaging was performed at the Center for Advanced Microscopy (CAM) at Northwestern University, which is supported by NCI CCSG P30 CA060553 awarded to the Robert H. Lurie Comprehensive Cancer Center. X-ray experiments were carried out at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, E.I. DuPont de Nemours & Co., and The Dow Chemical Company. Use of APS, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.",
year = "2020",
month = aug,
day = "10",
doi = "10.1021/acsbiomaterials.0c00679",
language = "English",
volume = "6",
pages = "4551--4560",
journal = "ACS Biomaterials Science and Engineering",
issn = "2373-9878",
publisher = "American Chemical Society",
number = "8",
}