Supramolecular Nanofibers with Superior Bioactivity to Insulin-Like Growth Factor-I

Abstract

Bioactive peptides derived from proteins generally need to be folded into secondary structures to activate downstream signaling pathways. However, synthetic peptides typically form random-coils, thus losing their bioactivities. Here, we show that by introducing a self-assembling peptide motif and using different preparation pathways, a peptide from insulin-like growth factor-I (IGF-1) can be folded into an α-helix and β-sheet. The β-sheet one exhibits a low dissociation constant to the IGF-1 receptor (IGF-1R, 11.5 nM), which is only about 3 times higher than that of IGF-1 (4.3 nM). However, the α-helical one and the peptide without selfassembling motif show weak affinities to IGF-1R (K D = 179.1 and 321.6 nM, respectively). At 10 nM, the β-sheet one efficiently activates the IGF-1 downstream pathway, significantly enhancing HUVEC proliferation and preventing cell apoptosis. The β-sheet peptide shows superior performance to IGF-1 in vivo, and it improves ischemic hind-limb salvage by significantly reducing muscle degradation and enhancing limb vascularization. Our study provides a useful strategy to constrain peptides into different conformations, which may lead to the development of supramolecular nanomaterials mimicking biofunctional proteins.

<p>Delivery of MSCs with a Hybrid β-Sheet Peptide Hydrogel Consisting IGF-1C Domain and D-Form Peptide for Acute Kidney Injury Therapy</p>

“…All peptides were prepared by standard solid phase peptide synthesis (SPPS) by using 2-chlorotrityl chloride resin and the corresponding N-Fmoc (9-fluorenylmethyl carbamates) protected amino acids with the side chains properly protected. 11,12 First, the C-terminus of the first amino acid was conjugated on the resin. Anhydrous N, N'dimethyl formamide (DMF) containing 20% piperidine was used to remove the Fmoc protection group.…”

“…Preparation of the hydrogel followed the heating-cooling protocol described previously. 11 In brief, 2.5mg of lyophilized self-assembling IGF-1C was dissolved in 496 μL of phosphate buffered solution (PBS), and 4μL of 1M sodium carbonate was added to adjust the pH to 7.4. The mixture was heated with an alcohol lamp until completely dissolved, and then cooled to room temperature to form a hydrogel.…”

“…SPR was performed using a BIAcore 2000 system (Biacore Inc., Piscataway, NJ). 11,33 Soluble recombinant human IGF-1 receptor (rhIGF-1R) was immobilized on research grade CM5 chips (Biacore Inc., Piscataway, NJ) before chip activation with 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). To obtain kinetic data, different concentrations of analytes in HBSEP buffer (0.01 M HEPES, pH 7.4, 0.15 M NaCl, 3 mM EDTA, 0.005% Tween 20 v/v) were injected over the sensor chip at a flow rate of 50 mL/ min.…”

“…4,7 To develop specific cell-scaffolds for tissue regeneration, biologically active motifs for cell attachment can be chemically conjugated to create functional hydrogels through selfassembly. 3,[10][11][12][13] As bulky proteins have disadvantages in terms of immunogenicity and sudden loss of bioactivity, accumulating evidence supports the use of bioactivitymimicking peptides such as RGD, QK and QHREDGS, as surrogates for fibronectin, vessel endothelial growth factor (VEGF), and angiopoietin-1, respectively, to increase the bioactivity of engineered matrices. [14][15][16] The 12-peptide sequence GYGSSSRRAPQT, known as the C domain of insulin-like growth factor-1 (IGF-1C), has been identified as the active region of the IGF-1 protein, which can increase stem cell survival and substantially improve renal function in acute kidney injury (AKI) 17,18 .…”

The substitution of a single amino acid with its enantiomer for control over the adjuvant activity of self-assembling peptides

“…[1][2][3][4] Among these, peptide-based supramolecular hydrogels have attracted extensive research interest over the last few decades because of their inherent advantages, such as their ease of design, good biocompatibility, and biodegradability. 5 More and more smart supramolecular hydrogels have been developed, and they have shown excellent results in nanomedicine, [6][7][8][9] tissue engineering, 10,11 vaccine adjuvants, [12][13][14] and disease detection. [15][16][17] The self-assembly properties of peptides are sequence-dependent 18,19 and they are also inuenced by further ne-tuning of the chemical structure; [20][21][22][23][24] this leads to further variations of self-assembled nanostructures and biofunctions.…”