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We report a novel strategy for achieving low-to-high hierarchical structure transformation through the cooperative self-assembly of naphthyl-capped tripeptides with reverse sequences.

Current bone defect treatment strategies are associated with several risks and have major limitations. Therefore, it is necessary to develop an inexpensive growth factor delivery system that can be easily produced in large quantities and can promote long-term bone regeneration. An osteogenic growth peptide (OGP) is a 14 amino acid peptide with a short peptide sequence active fragment. In this study, we developed two OGP-based self-assembling supramolecular hydrogels (F- and G-sequence hydrogels) and investigated the

Background and purpose Targeting macrophage but not hepatocyte liver X receptors (LXRs) can reduce atherosclerosis without effect on hepatic lipogenesis. In this study, we encapsulated LXR ligands with D-Nap-GFFY to form a nanofibre hydrogel (D-Nap-GFFY-T0901317 or GFFY-T0901317) and determined its effect on atherosclerosis, hepatic lipogenesis and the underlying mechanisms involved. Experimental approach D-Nap-GFFY-T0901317 was subcutaneously injected to proatherogenic diet-fed apoE-deficient (Apoe-/- ) mice, followed by determination of the development of atherosclerosis, liver steatosis and the involved mechanisms, with comparison of T0901317 oral administration. Key results Subcutaneous injection of D-Nap-GFFY-T0901317 to Apoe-/- mice inhibited atherosclerosis at a comparable level as T0901317 oral administration without effect on hepatic lipogenesis. More importantly, D-Nap-GFFY-T0901317 regressed the advanced lesions. In arterial wall, D-Nap-GFFY-T0901317 reduced macrophage/foam cells, necrotic cores and calcification and increased collagen content. It activated expression of ABCA1/G1 and smooth muscle α-actin, while inhibiting expression of intracellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1). D-Nap-GFFY-T0901317 also reduced serum pro-inflammatory cytokines and facilitated Kupffer cell M2 polarization. Mechanistically, D-Nap-GFFY-T0901317 was selectively taken up by macrophages but not hepatocytes, resulting in activation of macrophage ABCA1/G1 expression, while having no effect on lipogenic genes in hepatocytes. Moreover, the selective uptake of D-Nap-GFFY-T0901317 by macrophages was mainly completed in a scavenger receptor class A-dependent manner. Conclusion and implications Our study demonstrates that D-Nap-GFFY-T0901317 reduces atherosclerosis without effect on hepatic lipogenesis by targeting macrophage LXRs selectively, indicating its potential application for atherosclerosis treatment.

Cell-targeted peptides are recommended for precision cancer treatment due to their comparable targeting properties, small molecular size, and good biocompatibility. However, unpredictable bioactivity, low penetration rate and poor stability greatly limit its efficacy. Supramolecular self-assembly based on synthetic peptide has great potential to solve related problems and achieve better therapeutic effects. Herein, we report and compare the effects of two different assembly pathway, heating-cooling, and enzyme instruction, on the penetrability of SKBR-3 cell targeted peptides. It was found that enzyme-instructed self-assembly (EISA) resulted in hydrogels composed of uniform supramolecular nanofibers, whereas heating-cooling resulted in solutions and precipitations composed of slightly different nanoparticles. The nanofibers formed by EISA showed enhanced cellular uptake (2.54 μM), which was significantly higher than the 1.06 μM of the nanoparticles formed by temperature regulation. Thus, EISA is a promising strategy to improve the cell penetration rate of targeted peptides and could provide a better solution for precision cancer treatment.

Sarcopenia is a common disease in older people due to aging, and it can also occur in midlife because of diseases including cancer. Sarcopenia, characterized by rapid loss of muscle mass and accelerated loss of function, can lead to adverse outcomes such as frailty, falls, and even mortality. The development of pharmacological and therapeutic approaches to treat sarcopenia remains challenging. The growth status and quantity of myoblasts are the key factors directly affecting muscle formation. Therefore, enhancing the function of myoblasts is crucial for the treatment of sarcopenia. In our study, we introduced an insulin-like growth factor-I (IGF-1) mimicking supramolecular nanofibers/hydrogel formed by Nap-FFGSSSR that effectively promoted proliferation and significantly reduced dexamethasone-induced apoptosis of myoblasts, assisted myoblasts to differentiate into myotubes, and prevented the fibrosis of muscle tissue and the deposition of collagen, ultimately achieving outstanding effects in the treatment of sarcopenia. The RNA-sequencing results revealed that our nanofibers possessed similar bioactivity to the growth factor IGF-1, which increased the phosphorylation of Akt by activating the insulin signaling pathway. We prepared novel supramolecular nanomaterials to reverse glucocorticoid-induced myoblast dysfunction, which was promising for the treatment of muscular atrophy. In addition, we envisioned the generation of biofunctional nanomaterials by molecular self-assembly for the treatment of chronic diseases in middle-aged and older people.

Purpose By providing a stem cell microenvironment with particular bioactive constituents in vivo, synthetic biomaterials have been progressively successful in stem cell-based tissue regeneration by enhancing the engraftment and survival of transplanted cells. Designs with bioactive motifs to influence cell behavior and with D-form amino acids to modulate scaffold stability may be critical for the development and optimization of self-assembling biomimetic hydrogel scaffolds for stem cell therapy. Materials and methods In this study, we linked naphthalene (Nap) covalently to a short D-form peptide (Nap-DFDFG) and the C domain of insulin-like growth factor-1 (IGF-1C) as a functional hydrogel-based scaffolds, and we hypothesized that this hydrogel could enhance the therapeutic efficiency of human placenta-derived mesenchymal stem cells (hP-MSCs) in a murine acute kidney injury (AKI) model. Results The self-assembling peptide was constrained into a classical β-sheet structure and showed hydrogel properties. Our results revealed that this hydrogel exhibited increased affinity for IGF-1 receptor. Furthermore, cotransplantation of the β-IGF-1C hydrogel and hP-MSCs contributed to endogenous regeneration post-injury and boosted angiogenesis in a murine AKI model, leading to recovery of renal function. Conclusion This hydrogel could provide a favorable niche for hP-MSCs and thereby rescue renal function in an AKI model by promoting cell survival and angiogenesis. In conclusion, by covalently linking the desired functional groups to D-form peptides to create functional hydrogels, self-assembling β-sheet peptide hydrogels may serve as a promising platform for tissue-engineering and stem cell therapy.

Purpose By providing a stem cell microenvironment with particular bioactive constituents in vivo, synthetic biomaterials have been progressively successful in stem cell-based tissue regeneration by enhancing the engraftment and survival of transplanted cells. Designs with bioactive motifs to influence cell behavior and with D-form amino acids to modulate scaffold stability may be critical for the development and optimization of self-assembling biomimetic hydrogel scaffolds for stem cell therapy. Materials and Methods In this study, we linked naphthalene (Nap) covalently to a short D-form peptide (Nap-DFDFG) and the C domain of insulin-like growth factor-1 (IGF-1C) as a functional hydrogel-based scaffolds, and we hypothesized that this hydrogel could enhance the therapeutic efficiency of human placenta-derived mesenchymal stem cells (hP-MSCs) in a murine acute kidney injury (AKI) model. Results The self-assembling peptide was constrained into a classical β-sheet structure and showed hydrogel properties. Our results revealed that this hydrogel exhibited increased affinity for IGF-1 receptor. Furthermore, cotransplantation of the β-IGF-1C hydrogel and hP-MSCs contributed to endogenous regeneration post-injury and boosted angiogenesis in a murine AKI model, leading to recovery of renal function. Conclusion This hydrogel could provide a favorable niche for hP-MSCs and thereby rescue renal function in an AKI model by promoting cell survival and angiogenesis. In conclusion, by covalently linking the desired functional groups to D-form peptides to create functional hydrogels, self-assembling β-sheet peptide hydrogels may serve as a promising platform for tissue-engineering and stem cell therapy., Video abstract Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use: https://youtu.be/ZIksZ7GICP4

Rationale: Nanomaterials capable of specifically interacting with proteins are very important for protein storage and vaccine delivery. Supramolecular hydrogels based on peptides have emerged as promising vaccine adjuvants because of their good compatibility, ease of antigen incorporation and display, and efficiency in activating immune responses. Methods: We synthesized a self-assembling peptide (Fbp-GDFDFDYDK(γE)2-NH2, Comp. 1 ) serving as a supramolecular protein chaperone for protein antigen delivery. The gelation was triggered by simply mixing Comp. 1 and proteins. The vaccine adjuvant potential of Comp. 1 was demonstrated by using two protein antigens, ovalbumin (OVA) and hepatitis B surface antigen (HBsAg). Results: The peptide derivative Comp. 1 exhibited high protein binding capacity. Upon contacting proteins, Comp. 1 rapidly formed coassembled nanofibers/hydrogels with the proteins, which greatly delayed the release of protein antigens. Our supramolecular protein chaperone significantly stimulated specific antibody titers by assisting protein delivery to antigen-presenting cells, promoting dendritic cell (DC) maturation, prolonging antigen accumulation and retention in the lymph nodes, and eliciting the secretion of cytokines. Most importantly, our supramolecular protein chaperone strongly stimulated the cellular immune response and significantly retarded tumor growth. Conclusion: Our study demonstrated the great potential of the supramolecular protein chaperone in protein storage and delivery, vaccine production and tumor immunotherapy.

We have developed a co-assembled nanosystem based on fenofibrate and ketoprofen by tactfully utilizing their simultaneous benzophenone interaction, which greatly enhances the bioavailability of fenofibrate and plays a role in the dual-targeted treatment of NAFLD by reducing hepatic lipid accumulation and inflammatory responses.

The substitution of a single amino acid with its enantiomer may lead to variations in self-assembled nanostructures and biological functions. In this study, we reported three novel heterochiral peptide hydrogels, Nap-GDFFY (gel-1), Nap-GFDFY (gel-2) and Nap-GFFDY (gel-3), from Nap-GFFY via the substitution of a single amino acid with its enantiomer. We found that the resulting hydrogels possessed diverse self-assembly behaviors and adjuvant activities. Compared to the homochiral L-gel formed from Nap-GFFY, gel-1 was basically similar, gel-2 exhibited a medium improvement in immunocompetence tuning ability, and gel-3 showed the better self-assembly of nanofibers with superior mechanical properties and the ability for slow antigen release. Moreover, the adjuvant effect of gel-3 was prominent, promoting both specific antibody titers and the production of cytokines. Besides, this regulation was more remarkable with respect to enhancing cellular immune responses. Hence, we came to the conclusion in this study that the substitution of a single amino acid with its enantiomer further away from rather than closer to the end-capping group could be important and effective for biofunction regulation. Our study provides a useful strategy for tuning the properties of self-assembling peptides for different biological applications.

Background and Purpose: Atherosclerosis is an underlying cause of coronary heart disease. Foam cell, a hallmark of atherosclerosis, is prominently derived from monocyte-differentiated macrophage, and vascular smooth muscle cells (VSMCs) through unlimitedly phagocytizing oxidized low-density lipoprotein (oxLDL). Therefore, the inhibition of monocyte adhesion to endothelium and uptake of oxLDL might be a breakthrough point for retarding atherosclerosis. Formononetin, an isoflavone extracted from Astragalus membranaceus, has exhibited multiple inhibitory effects on proatherogenic factors, such as obesity, dyslipidemia, and inflammation in different animal models. However, its effect on atherosclerosis remains unknown. In this study, we determined if formononetin can inhibit atherosclerosis and elucidated the underlying molecular mechanisms. Methods: ApoE deficient mice were treated with formononetin contained in high-fat diet for 16 weeks. After treatment, mouse aorta, macrophage and serum samples were collected to determine lesions, immune cell profile, lipid profile and expression of related molecules. Concurrently, we investigated the effect of formononetin on monocyte adhesion, foam cell formation, endothelial activation, and macrophage polarization in vitro and in vivo. Results: Formononetin reduced en face and aortic root sinus lesions size. Formononetin enhanced lesion stability by changing the composition of plaque. VSMC- and macrophage-derived foam cell formation and its accumulation in arterial wall were attenuated by formononetin, which might be attributed to decreased SRA expression and reduced monocyte adhesion. Formononetin inhibited atherogenic monocyte adhesion and inflammation. KLF4 negatively regulated the expression of SRA at transcriptional and translational level. Conclusions: Our study demonstrate that formononetin can substantially attenuate the development of atherosclerosis via regulation of interplay between KLF4 and SRA, which suggests the formononetin might be a novel therapeutic approach for inhibition of atherosclerosis.

Background and Purpose: Atherosclerosis is vascular disease of chronic inflammation and lipid disorder, which is a major cause of coronary heart disease. Foam cell formation is key progress during the atherosclerosis development. Insulin-like growth factor (IGF)-1 is a growth hormone that plays a crucial role in growth, metabolism, and homeostasis. Previous studies have demonstrated that increase in circulating IGF-1 can reduce atherosclerotic burden. However, active IGF-1 is characterized with poor tissue retention and is at a very low level in circulation system. Therefore, supplementation of exogenous IGF-1 to restore the physiological level is a promising approach to inhibit atherosclerosis. In this study, we develop a self-assembling, anti-inflammatory drug-modified peptide derived from IGF-1 to mimic IGF-1 bioactivity and simultaneously with an anti-inflammatory property for the treatment of atherosclerosis. Methods: ApoE-/- mice were subcutaneously (s.c.) injected with the different hydrogels or natural IGF-1 protein solution per week and simultaneously fed a high-fat diet for 16 weeks. Atherosclerotic lesion formation and stability were assessed after treatment. Moreover, peritoneal macrophage and serum samples were collected to determine lipid profile and inflammatory cytokines. Concurrently, we determined the effect of bifunctional supramolecular nanofibers/hydrogel on cholesterol efflux, foam cell formation, phenotypic transformation of VSMC to macrophage-like cells, and macrophage polarization in vitro or in vivo. Results: Bifunctional supramolecular nanofibers/hydrogel for the treatment of atherosclerosis was formed by a short peptide consisting of a tetrapeptide SSSR from C-region of growth factor IGF-1, an anti-inflammatory drug naproxen (Npx), and a powerful self-assembling D-peptide DFDF. The resulting hydrogel of Npx-DFDFGSSSR (Hydrogel 1, H1) possessed both the anti-inflammatory and IGF-1 mimicking properties, and it efficiently promoted the expression of ABCA1 and ABCG1, thereby significantly reducing cholesterol accumulation in macrophages and preventing foam cell formation. Moreover, H1 markedly inhibited the transformation of vascular smooth muscle cells (VSMCs) into macrophage-like cells which also contributed to foam cell formation. In addition, H1 significantly reduced the inflammatory response in vitro and in vivo. Most importantly, the IGF-1 mimetic peptide showed comparable performance to IGF-1 in vivo and inhibited atherosclerosis by markedly reducing lesion area and enhancing plaque stability. Conclusions: Our study provides a novel supramolecular nanomaterial to inhibit pathological progress of atherosclerosis through regulating cholesterol efflux and inflammation, which may contribute to the development of a promising nanomedicine for the treatment of atherosclerosis in the clinic.

The shortage of donor kidneys is an important factor restricting kidney transplantation for patients with end-stage renal disease. To overcome this problem, we used decellularized kidney scaffolds and nephron progenitor cells (NPCs) as seed cells to construct bioengineered kidneys (BEKs). To reduce the effect of extracellular matrix (ECM) loss during the decellularization process on the cell growth microenvironment, we used dextrose to minimize collagen loss in decellularized kidney scaffolds. At the same time, to further improve the growth microenvironment of seed cells in the decellularized scaffolds, we modified the decellularized scaffolds with the self-assembling polypeptide Naphthalenephenylalanine-phenylalanine-glycine-arginine-glycine-aspartic (Nap-FFGRGD) to promote the adhesion and proliferation of seed cells in the scaffolds. NPCs were perfused into the decellularized kidney scaffolds and then the BEKs were cultured in vitro and transplanted in vivo. Markers of podocytes and renal tubules expressed in the glomeruli and renal tubules of the BEKs were detected by immunofluorescence staining, respectively were, suggesting that NPCs can continue to differentiate into renal cells and achieve nephron segment-specific re-population through self-assembly. These results indicate that by relying on the microenvironment provided by Nap-FFGRGD modified decellularized scaffolds, NPCs can be used to construct BEKs for transplantation in the future due to the self-assembly properties of organoids.

Proteins possess many biological functions. However, they can easily degrade or aggregate, thus losing their bioactivity. Therefore, it is very important to develop materials capable of interacting with proteins and forming nanostructures for protein storage and delivery. In this study, we serendipitously found a novel peptide-based supramolecular protein glue (Nap-GFFYK(γE)2-NH2, compound 1 ) that could co-assemble with proteins into nanofibers and hydrogels. We found that compound 1 rapidly folded into a β-sheet conformation upon contact with many proteins but not with polymers. Total internal reflection fluorescence microscopy (TIRFM) images clearly show the formation of co-assembled nanofibers by proteins and the peptide. The supramolecular protein glue could improve the dispersion of enzymes (lipase and lysozyme) and therefore enhance their catalytic activity, especially at high temperatures. More importantly, the supramolecular protein glue could co-assemble with two enzymes, glucose oxidase/horseradish peroxidase (GOx/HRP) and GOx/cytochrome c (cyt c), to form nanofibers that significantly enhanced the catalytic activity of tandem enzymatic reactions. We envisioned the great potential of our supramolecular protein glue for protein storage, delivery, and bioactivity manipulation.

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 self-assembling motif show weak affinities to IGF-1R (KD = 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...

Supramolecular peptide hydrogel has shown promising potential in vaccine development largely because of its ability to function both as antigen depot and immune adjuvant. Nap‐GdFdFdY, a tetrapeptide hydrogel that has been previously reported to exhibit adjuvant effect, is inadvertently found to contain conserved peptide sequence for insulin, proinsulin, and glutamic acid decarboxylase, 3 major autoantigens for the autoimmune type 1 diabetes (T1D). At present, despite being managed clinically with insulin replacement therapy, T1D remains a major health threat with rapidly increasing incidences, especially in children and young adults, and antigen‐specific immune tolerance induction has been proposed as a feasible approach to prevent or delay T1D progression at an early stage. Here, it is reported that innoculation of Nap‐GdFdFdY leads to complete protection of nonobese diabetic (NOD) mice from T1D development till the age of 36 weeks. Better maintenance of pancreatic islet morphology with minimal immune cell infiltration is also observed from mice exposed to Nap‐GdFdFdY. This beneficial impact is mainly due to its facilitative role on enhancing peripheral T regulatory cell (Treg) population, shown as increased splenic Treg percentage, and function, demonstrated by maintenance of circulating TGF‐β1 level. Serum cytokine microarray data further implicate a “buffering” role of Nap‐GdFdFdY on systemic inflammatory tone in NOD mice. Thus, with its versatility, applicability, and excellent potency, Nap‐GdFdFdY is posited as a novel therapeutic intervention for T1D., A hydrogel of Nap‐GdFdFdY containing conserved sequence of autoantigens including insulin, proinsulin, and glutamic acid decarboxylase as a novel therapeutic intervention for the autoimmune type 1 diabetes. Better pancreatic islet morphology with minimal immune cell infiltration is observed from mice with hydrogel because of enhancing peripheral T regulatory cell population and maintenance of circulating TGF‐β1 level.

Background: Atherosclerosis is a major pathogenic factor in cardiovascular diseases during the aging process. Foam cell formation and endothelial dysfunction play a key role in the initiation and development of atherosclerosis, which are affected by lipid disorder and inflammation. Therefore, the drug for inhibition of endothelial dysfunction and the subsequent foam cell formation is a therapeutic approach for atherosclerosis treatment. Total flavone of Astragalus membranaceus (TFA) is extracted from Astragalus membranaceus that has protective effect on cardiovascular disease. However, the effect of TFA on atherosclerosis and the underlying mechanism remains unknown. Methods: In this study, we determined whether TFA could inhibit atherosclerosis; and uncovered the underlying molecular mechanisms. In vivo, apoE deficient mice were treated with TFA contained in high-fat diet for 16 weeks. After treatment, aorta, macrophage and serum samples were collected to determine atherosclerotic lesions, lipid metabolism, and expression of associated genes. Concurrently, we investigated the effect of TFA on monocyte adhesion, foam cell formation, endothelial activation, and macrophage polarization in vitro and in vivo. Results: TFA reduced atherosclerotic plaque size; and enhanced lesion stability by changing the composition of plaque. Moreover, foam cell formation and its accumulation in arterial wall were attenuated by TFA, which might be attributed to improved lipid disorder, reduced inflammation, and decreased monocyte adhesion to endothelial cells. Mechanistically, TFA reduced the expression of scavenger receptor, such as CD36 and SRA; promoted the expression of ATP-binding cassette transporter A1 and G1 (ABCA1/G1). More importantly, TFA reduced the expression of miR-33, a negative regulator of cholesterol efflux as well as positive mediator on inflammation; and concurrently reduced NFkB activity, by which de-repressed ABCA1/G1 activity and inhibited the inflammation. Conclusions: This study demonstrates that TFA can attenuate atherosclerosis via dual inactivation of miR-33 and NFkB signaling pathway and inhibition of scavenger receptors (CD36 and SRA), which suggests that TFA might be a novel therapeutic approach for inhibition of atherosclerosis.

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC-EVs) have been recognized as a promising cell-free therapy for acute kidney injury (AKI), which avoids safety concerns associated with direct cell engraftment. However, low stability and retention of MSC-EVs have limited their therapeutic efficacy. RGD (Arg-Gly-Asp) peptide binds strongly to integrins, which have been identified on the surface of MSC-EV membranes; yet RGD has not been applied to EV scaffolds to enhance and prolong bioavailability. Here, we developed RGD hydrogels, which we hypothesized could augment MSC-EV efficacy in the treatment of AKI models. In vivo tracking of the labeled EVs revealed that RGD hydrogels increased retention and stability of EVs. Integrin gene knockdown experiments confirmed that EV-hydrogel interaction was mediated by RGD-integrin binding. Upon intrarenal injection into mouse AKI models, EV-RGD hydrogels provided superior rescuing effects to renal function, attenuated histopathological damage, decreased tubular injury, and promoted cell proliferation in early phases of AKI. RGD hydrogels also augmented antifibrotic effects of MSC-EVs in chronic stages. Further analysis revealed that the presence of microRNA let-7a-5p in MSC-EVs served as the mechanism contributing to the reduced cell apoptosis and elevated cell autophagy in AKI. In conclusion, RGD hydrogels facilitated MSC-derived let-7a-5p-containing EVs, improving reparative potential against AKI. This study developed an RGD scaffold to increase the EV integrin-mediated loading and in turn improved therapeutic efficacy in renal repair; therefore this strategy shed light on MSC-EV application as a cell-free treatment for potentiated efficiency.

The utilization of nanotechnology to deliver vaccines and modulate immunity has shown great potential in cancer therapy. Peptide-based supramolecular hydrogels as novel vaccine adjuvants have been found to effectively improve the immune response and tumor curative effect. In this study, we designed a set of reduction-responsive self-assembled peptide precursors (Fbp-GDFDFDYD(E, S, or K)-ss-ERGD), which can be reduced by glutathione (GSH) into Fbp-GDFDFDYD(E, S or K)-SH for forming of hydrogel with different surface properties (E-gel, S-gel, and K-gel, respectively). Using the same method, co-assembled hydrogel vaccines (E-vac, S-vac, and K-vac, respectively) can also be prepared by mixing different precursors with antigens before GSH reduction. Through TEM observation of the nanostructure, we found that all the co-assembled hydrogels, especially K-vac, possessed much denser and more unified nanofiber networks as compared with antigen-free hydrogels, which were very suitable for antigen storage and vaccine delivery. Although the three peptides adopted similar β-sheet secondary structures, the mechanical properties of their resulted co-assembled hydrogel vaccines were obviously different. Compared to E-vac, S-vac had a much weaker mechanical property, while K-vac had a much higher. In vivo experiments, co-assembled hydrogel vaccines, especially K-vac, also promoted antibody production and anti-tumor immune responses more significantly than the other two vaccines. Our results demonstrated that co-assembled hydrogels formed by peptides and antigens co-assembly could act as effective vaccine delivery systems for boosting antibody production, and different immune effects can be acquired by tuning the surface properties of the involved self-assembling peptides.

Stem cell therapy has obtained extensive consensus to be an effective method for post myocardial infarction (MI) intervention. Induced pluripotent stem (iPS) cells, which are able to differentiate into multiple cell types, have the potential to generate cardiovascular lineage cells for myocardial repair after ischemic damage, but their poor retention rate significantly hinders the therapeutic efficacy. In the present study, we developed a supramolecular hydrogel which is formed by the self-assembly of folic acid (FA)-modified peptide via a biocompatible method (glutathione reduction) and suitable for cell encapsulation and transplantation. The iPS cells labeled with CM-Dil were transplanted into the MI hearts of mice with or without FA hydrogel encapsulation. The results corroborated that the FA hydrogel significantly improved the retention and survival of iPS cells in MI hearts post injection, leading to augmentation of the therapeutic efficacy of iPS cells including better cardiac function and much less adverse heart remodeling, by subsequent differentiation toward cardiac cells and stimulation of neovascularization. This study reported a novel supramolecular hydrogel based on FA-peptides capable of improving the therapeutic capacity of iPS cells, which held big potential in the treatment of MI.

An ideal periosteum substitute should be able to mimic the periosteum microenvironment that continuously provides growth factors, recruits osteoblasts, and subsequent extracellular matrix (ECM) mineralization to accelerate bone regeneration. Here, a calcium-binding peptide-loaded poly(ε-caprolactone) (PCL) electrospun membrane modified by the shish-kebab structure that can mimic the periosteum microenvironment was developed as a bionic periosteum. The calcium-binding peptide formed by the negatively charged heptaglutamate domain (E7) in the E7-BMP-2 with calcium ion in the tricalcium phosphate sol (TCP sol) through electrostatic chelation not only extended the release cycle of E7-BMP-2 but also promoted the biomineralization of the bionic periosteum. Cell experiments showed that the bionic periosteum could significantly improve the osteogenic differentiation of the rat-bone marrow-derived mesenchymal stem cells (rBMSCs) through both chemical composition and physical structure. The in vivo evaluation of the bionic periosteum confirmed the inherent osteogenesis of this periosteum microenvironment, which could promote the regeneration of vascularized bone tissue. Therefore, the hierarchical nanostructured electrospun membrane with periosteum-mimic microenvironment is a promising periosteum substitute for the treatment of bone defects.

A macroscopic silk-like fiber can be drawn directly from a hydrogel self-assembled from peptides, which offers an easy and versatile method for generating materials with hierarchically ordered structures over different scales and extends the utility of peptide hydrogels.

By providing a stem cell microenvironment with particular bioactive constituents in vivo, synthetic biomaterials have been progressively successful in stem cell-based tissue regeneration by enhancing the engraftment and survival of transplanted cells. Designs with bioactive motifs to influence cell behavior and with D-form amino acids to modulate scaffold stability may be critical for the development and optimization of self-assembling biomimetic hydrogel scaffolds for stem cell therapy.In this study, we linked naphthalene (Nap) covalently to a short D-form peptide (Nap-The self-assembling peptide was constrained into a classical β-sheet structure and showed hydrogel properties. Our results revealed that this hydrogel exhibited increased affinity for IGF-1 receptor. Furthermore, cotransplantation of the β-IGF-1C hydrogel and hP-MSCs contributed to endogenous regeneration post-injury and boosted angiogenesis in a murine AKI model, leading to recovery of renal function.This hydrogel could provide a favorable niche for hP-MSCs and thereby rescue renal function in an AKI model by promoting cell survival and angiogenesis. In conclusion, by covalently linking the desired functional groups to D-form peptides to create functional hydrogels, self-assembling β-sheet peptide hydrogels may serve as a promising platform for tissue-engineering and stem cell therapy.

Supramolecular hydrogels of self-assembling peptides and thermogels are very promising for biomedical applications. However, there were no thermogels of self-assembling peptides. In this study, we reported on a novel and versatile strategy to prepare thermogels of self-assembling peptides by enzyme-instructed peptide folding and self-assembly. We synthesized two phosphorylated peptides from insulin growth factor (IGF) and the second mitochondria-derived activator of caspases (Smac) (Nap-FFGGpYGSSSRRAPQT and NBD-GFFpYGAVPIAQK, respectively), which could be converted to possible hydrogelators by enzyme-instructed self-assembly (EISA). We found that EISA using phosphatase at 4 °C resulted in peptides with a random coil conformation, which would self-assemble into worm-like micelles or very short fibers in clear solutions. At a physiological temperature of 37 °C, the peptides would undergo fast transitions from random coil to β-sheet- or α-helix-like conformations, resulting in solution-to-gel transformations. This novel thermogel system was very useful for three-dimensional (3D) cell culture due to the biocompatibility and bioactivity of peptides. Our study provides a novel strategy to prepare a novel thermogel system for biomedical applications.

Platelet-derived growth factors (PDGFs) play crucial roles in regulating cell proliferation, apoptosis, and migration and have been recommended for injury repair in clinical practice. However, the low stability, poor biological barrier penetration ability, and high cost of protein drugs hinders their wide application. The development of small molecules or nanomaterials capable of simulating the bioactivity of PDGFs may overcome the shortcomings of PDGF proteins and expand their application. Herein, we report the first supramolecular nanofiber of the self-assembling peptide Nap-FFGVRKKP (Compound 1) with superior bioactivity over the PDGF protein. The peptide derivative Nap-FFG formed a β-sheet conformation, which mimicks the four-β-sheet peptide in PDGF, and the pentapeptide VRKKP from loop 3 in PDGF that is crucial for binding with the PDGF receptor. Therefore, the nanofibers possessed the multivalent loop 3 peptide on the surface that might assist oligomerization and activation of the PDGF receptor. The results indicated that our nanomaterials efficiently activated the PDGF signaling pathway and promoted NIH 3T3 cell proliferation and migration. Moreover, they significantly reduced the apoptosis rate caused by 10 Gy X-ray radiation from 33.60% to 5.83% and showed a good therapeutic effect on the ionizing radiation-induced injury repair by reducing the inflammatory response and enhancing skin regeneration. Our study offers a versatile strategy to construct nanomaterials with enhanced biological activity through multivalent interactions, and the development of PDGF mimics may overcome the limitation of PDGFs for their applications in injury repair, cell culture, cosmetics, and regenerative medicine.

We designed and synthesized three phosphorylated peptides as precursors of the same peptide Nap-YYY. We found that different precursors led to different materials with almost identical chemical compositions at the final stages. Only Nap-YpYY could form very uniform nanofibers in a stable supramolecular hydrogel by enzyme-instructed self-assembly (EISA) at the physiological temperature (37 °C). In contrast, de-phosphorylation of the other two precursors (Nap-pYYY and Nap-YYpY) resulted in diverse nanostructures in metastable hydrogels with precipitates. The formation of uniform nanomaterials in the stable hydrogels was due to the preorganization property of the precursor Nap-YpYY, which facilitated rapid folding and accelerated the kinetics of hydrogelation of the resulting peptide Nap-YYY generated by the EISA process. Our study demonstrated the importance of the precursor for the self-assembly of nanomaterials and provided a useful strategy to manipulate them.