Self-assembling Peptide Nanofiber Scaffolds Research Articles

Metal-Chelating Self-Assembling Peptide Nanofiber Scaffolds for Modulation of Neuronal Cell Behavior.

Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and characteristics of PA nanofiber scaffolds along with their interaction with Zn, Cu, and Mn essential microelements were studied. The effects of TM-activated PA scaffolds on mammalian cell behavior, reactive oxygen species (ROS), and glutathione levels were shown. The study reveals the ability of these scaffolds to modulate adhesion, proliferation, and morphological differentiation of neuronal PC-12 cells, suggesting a particular role of Mn(II) in cell-matrix interaction and neuritogenesis. The results provide a proof-of-concept for the development of histidine-functionalized peptide nanofiber scaffolds activated with ROS- and cell-modulating TMs to induce regenerative responses.

GDNF to the rescue: GDNF delivery effects on motor neurons and nerves, and muscle re-innervation after peripheral nerve injuries.

Peripheral nerve injuries commonly occur due to trauma, like a traffic accident. Peripheral nerves get severed, causing motor neuron death and potential muscle atrophy. The current golden standard to treat peripheral nerve lesions, especially lesions with large (≥ 3 cm) nerve gaps, is the use of a nerve autograft or reimplantation in cases where nerve root avulsions occur. If not tended early, degeneration of motor neurons and loss of axon regeneration can occur, leading to loss of function. Although surgical procedures exist, patients often do not fully recover, and quality of life deteriorates. Peripheral nerves have limited regeneration, and it is usually mediated by Schwann cells and neurotrophic factors, like glial cell line-derived neurotrophic factor, as seen in Wallerian degeneration. Glial cell line-derived neurotrophic factor is a neurotrophic factor known to promote motor neuron survival and neurite outgrowth. Glial cell line-derived neurotrophic factor is upregulated in different forms of nerve injuries like axotomy, sciatic nerve crush, and compression, thus creating great interest to explore this protein as a potential treatment for peripheral nerve injuries. Exogenous glial cell line-derived neurotrophic factor has shown positive effects in regeneration and functional recovery when applied in experimental models of peripheral nerve injuries. In this review, we discuss the mechanism of repair provided by Schwann cells and upregulation of glial cell line-derived neurotrophic factor, the latest findings on the effects of glial cell line-derived neurotrophic factor in different types of peripheral nerve injuries, delivery systems, and complementary treatments (electrical muscle stimulation and exercise). Understanding and overcoming the challenges of proper timing and glial cell line-derived neurotrophic factor delivery is paramount to creating novel treatments to tend to peripheral nerve injuries to improve patients’ quality of life.

Local Delivery of Taxol From FGL-Functionalized Self-Assembling Peptide Nanofiber Scaffold Promotes Recovery After Spinal Cord Injury.

Taxol has been clinically approved as an antitumor drug, and it exerts its antitumor effect through the excessive stabilization of microtubules in cancer cells. Recently, moderate microtubule stabilization by Taxol has been shown to efficiently promote neurite regeneration and functional recovery after spinal cord injury (SCI). However, the potential for the clinical translation of Taxol in treating SCI is limited by its side effects and low ability to cross the blood-spinal cord barrier (BSCB). Self-assembled peptide hydrogels have shown potential as drug carriers for the local delivery of therapeutic agents. We therefore hypothesized that the localized delivery of Taxol by a self-assembled peptide scaffold would promote axonal regeneration by stabilizing microtubules during the treatment of SCI. In the present study, the mechanistic functions of the Taxol-releasing system were clarified in vitro and in vivo using immunofluorescence labeling, histology and neurobehavioral analyses. Based on the findings from the in vitro study, Taxol released from a biological functionalized SAP nanofiber scaffold (FGLmx/Taxol) remained active and promoted neurite extension. In this study, we used a weight-drop contusion model to induce SCI at T9. The local delivery of Taxol from FGLmx/Taxol significantly decreased glial scarring and increased the number of nerve fibers compared with the use of FGLmx and 5% glucose. Furthermore, animals administered FGLmx/Taxol exhibited neurite preservation, smaller cavity dimensions, and decreased inflammation and demyelination. Thus, the local delivery of Taxol from FGLmx/Taxol was effective at promoting recovery after SCI and has potential as a new therapeutic strategy for SCI.

Peptide-Based Scaffolds for the Culture and Transplantation of Human Dopaminergic Neurons.

Cell replacement therapy is a promising treatment strategy for Parkinson's disease (PD); however, the poor survival rate of transplanted neurons is a critical barrier to functional recovery. In this study, we used self-assembling peptide nanofiber scaffolds (SAPNS) based on the peptide RADA16-I to support the in vitro maturation and in vivo post-transplantation survival of encapsulated human dopaminergic (DA) neurons derived from induced pluripotent stem cells. Neurons encapsulated within the SAPNS expressed mature neuronal and midbrain DA markers and demonstrated in vitro functional activity similar to neurons cultured in two dimensions. A microfluidic droplet generation method was used to encapsulate cells within monodisperse SAPNS microspheres, which were subsequently used to transplant adherent, functional networks of DA neurons into the striatum of a 6-hydroxydopamine-lesioned PD mouse model. SAPNS microspheres significantly increased the in vivo survival of encapsulated neurons compared with neurons transplanted in suspension, and they enabled significant recovery in motor function compared with control lesioned mice using approximately an order of magnitude fewer neurons than have been previously needed to demonstrate behavioral recovery. These results indicate that such biomaterial scaffolds can be used as neuronal transplantation vehicles to successfully improve the outcome of cell replacement therapies for PD. Impact Statement Transplantation of dopaminergic (DA) neurons holds potential as a treatment for Parkinson's disease (PD), but low survival rates of transplanted neurons is a barrier to successfully improving motor function. In this study, we used hydrogel scaffolds to transplant DA neurons into PD model mice. The hydrogel scaffolds enhanced survival of the transplanted neurons compared with neurons that were transplanted in a conventional manner, and they also improved recovery of motor function by using significantly fewer neurons than have typically been transplanted to see functional benefits. This cell transplantation technology has the capability to improve the outcome of neuron transplantation therapies.

GDNF pretreatment overcomes Schwann cell phenotype mismatch to promote motor axon regeneration via sensory graft

In the clinic, severe motor nerve injury is commonly repaired by autologous sensory nerve bridging, but the ability of Schwann cells (SCs) in sensory nerves to support motor neuron axon growth is poor due to phenotype mismatch. In vitro experiments have demonstrated that sensory-derived SCs overcome phenotypic mismatch-induced growth inhibition after pretreatment with exogenous glial cell-derived neurotrophic factor (GDNF) and induce motor neuron axonal growth. Thus, we introduced a novel staging surgery: In the first stage of surgery, the denervated sensory nerve was pretreated with sustained-release GDNF, which was encapsulated into a self-assembling peptide nanofiber scaffold (SAPNS) RADA-16I in the donor area in vivo. In the second stage of surgery, the pretreated sensory grafts were transplanted to repair motor nerve injury. Motor axon regeneration and remyelination and muscle functional recovery after the second surgery was compared to those in the control groups. The expression of genes previously shown to be differently expressed in motor and sensory SCs was also analyzed in pretreated sensory grafts by qRT-PCR to explore possible changes after exogenous GDNF application. Exogenous GDNF acted directly on the denervated sensory nerve graft in vivo, increasing the expression of endogenous GDNF and sensory SC-derived marker brain-derived neurotrophic factor (BDNF). After transplantation to repair motor nerve injury, exogenous GDNF pretreatment promoted the regeneration and remyelination of proximal motor axons and the recovery of muscle function. Further research into how phenotype, gene expression and changes in neurotrophic factors in SCs are affected by GDNF will help us design more effective methods to treat peripheral nerve injury.

Promotion of neuronal regeneration by using self-polymerized dendritic polypeptide scaffold for spinal cord tissue engineering.

Tissue engineering technology is applicable for study of nerve regeneration after spinal cord injury. Many natural and artificial scaffold are not applicable because of poor mechanical properties and cell compatibility. Polypeptides with fine three-dimensional structure and cell compatibility and are widely used in tissue engineering research. The purpose of this study was to verify the neuronal differentiation of neural stem cells by using self-polymerize dendritic polypeptide for spinal cord tissue engineering. Neural stem cells were isolated from cerebral cortex of neonatal SD rats.Conventional media was triggered the 1wt% nano peptide solution self polymerizated to formed a nano gel. The gel was tested by scanning electron microscope and transmission electron microscope. Neural stem cells were inoculated onto gel or on Polylysine-coated slides with fetal bovine serum or not. SD rats were randomized divided into four groups. neural stem cells and self-polymerized peptide were transplanted into spinal cord injury models. Then we test the Density of NF-positive axons in the spinal cord injury area at 8 weeks after surgery and MS score of the locomotive function of hind limbs among mice of four groups. Neural stem cells were showed anti Nestin (+), anti NSE (+), anti GFAP (+). The gel tested by scanning electron microscope was showed thick wall structure, another one tested by transmission electron microscope was showed self-polymerized dendritic nanofibers, which contains several spacings. The cells in serum group were differentiate into neurons, but non serum group were not. These results suggest that the self-assembling peptide nanofiber scaffold(SAPNS) were cytocompatible to neural stem cells which were differentiated into neurons. A large number of axonal regeneration and recovery of joint function of hind limb were appeared. The self-polymerized Peptide maybe used as practical tissue engineering materials as future.

Using primate neural stem cells cultured in self-assembling peptide nanofiber scaffolds to repair injured spinal cords in rats.

This corrects the article DOI: 10.1038/sc.2016.36.

Self-Assembling Peptide Nanofiber Scaffolds for 3-D Reprogramming and Transplantation of Human Pluripotent Stem Cell-Derived Neurons.

While cell transplantation presents a potential strategy to treat the functional deficits of neurodegenerative diseases or central nervous system injuries, the poor survival rate of grafted cells in vivo is a major barrier to effective therapeutic treatment. In this study, we investigated the role of a peptide-based nanofibrous scaffold composed of the self-assembling peptide RADA16-I to support the reprogramming and maturation of human neurons in vitro and to transplant these neurons in vivo. The induced human neurons were generated via the single transcriptional factor transduction of induced pluripotent stem cells (iPSCs), which are a promising cell source for regenerative therapies. These neurons encapsulated within RADA16-I scaffolds displayed robust neurite outgrowth and demonstrated high levels of functional activity in vitro compared to that of 2-D controls, as determined by live cell calcium imaging. When evaluated in vivo as a transplantation vehicle for adherent, functional networks of neurons, monodisperse RADA16-I microspheres significantly increased survival (over 100-fold greater) compared to the conventional transplantation of unsupported neurons in suspension. The scaffold-encapsulated neurons integrated well in vivo within the injection site, extending neurites several hundred microns long into the host brain tissue. Overall, these results suggest that this biomaterial platform can be used to successfully improve the outcome of cell transplantation and neuro-regenerative therapies.

Functionalized d-form self-assembling peptide hydrogels for bone regeneration.

Bone defects are very common in orthopedics, and there is great need to develop suitable bone grafts for transplantation in vivo. However, current bone grafts still encounter some limitations, including limited availability, immune rejection, poor osteoinduction and osteoconduction, poor biocompatibility and degradation properties, etc. Self-assembling peptide nanofiber scaffolds have emerged as an important substrate for cell culture and bone regeneration. We report on the structural features (eg, Congo red staining, circular dichroism spectroscopy, transmission electron microscopy, and rheometry assays) and osteogenic ability of d-RADA16-RGD peptide hydrogels (with or without basic fibroblast growth factor) due to the better stability of peptide bonds formed by these peptides compared with those formed by l-form peptides, and use them to fill the femoral condyle defect of Sprague Dawley rat model. The bone morphology change, two-dimensional reconstructions using microcomputed tomography, quantification of the microcomputed tomography analyses as well as histological analyses have demonstrated that RGD-modified d-form peptide scaffolds are able to enhance extensive bone regeneration.

Using primate neural stem cells cultured in self-assembling peptide nanofiber scaffolds to repair injured spinal cords in rats.

Transplanted primates' neural stem cells (NSCs) tissue engineering complex into spinal cord injury (SCI) model rats, analyze and evaluate the long-term effects of repairing. Primate NSCs were cultured in self-assembling peptide nanofiber scaffolds to repair SCI. Sun Yat-sen Memorial Hospital, Guangzhou, China. Primate NSCs were isolated and cultured in self-assembling peptide nanofiber scaffolds. T10 SCI model was established; the rats were randomly divided into four groups: NSC plus self-assembling peptide scaffold group; NSC group; self-assembling peptide scaffold group; and control group. Immunohistochemical staining and electronic microscope were used to investigate the growth and differentiation of transplanted NSCs. The motor function of the hind limbs of rats was evaluated (P<0.05 was considered as statistically significant). NSCs and NSCs cultured in self-assembling peptide nanofiber scaffolds could be induced to differentiation into neurons, glial cells and oligodendrocytes in vitro. The primate NSC culture was established in self-assembling peptide scaffolds. No significant difference was seen in the differentiation rate between primate NSCs cultured in self-assembling peptide nanofiber scaffolds and primate NSCs cultured in regular medium. The motor function of the hind limbs in the NSC plus self-assembling peptide scaffold group was significantly better than that of the other three groups. In addition, the NSCs of the NSC group mainly differentiated into astrocytes. Transplantation of primate NSCs cultured in self-assembling peptide scaffolds is efficient for repairing the injured spinal cord and for improving the motor function of spinal cord in rats. The National Natural Science Foundation of China; Science and Technology Office of Guangdong Province.

PLGA nanofibers blended with designer self-assembling peptides for peripheral neural regeneration

Electrospun nanofibers are attractive candidates for neural regeneration due to similarity to the extracellular matrix. Several synthetic polymers have been used but they lack in providing the essential biorecognition motifs on their surfaces. Self-assembling peptide nanofiber scaffolds (SAPNFs) like RADA16 and recently, designer SAPs with functional motifs RADA16-I-BMHP1 areexamples, which showed successful spinal cord regeneration. But these peptide nanofiber scaffolds have poor mechanical properties and faster degradation rates that limit their use for larger nerve defects. Hence, we have developed a novel hybrid nanofiber scaffold of polymer poly(l-lactide-co-glycolide) (PLGA) and RADA16-I-BMHP1. The scaffolds were characterized for the presence of peptides both qualitatively and quantitatively using several techniques like SEM, EDX, FTIR, CHN analysis, Circular Dichroism analysis, Confocal and thermal analysis. Peptide self-assembly was retained post-electrospinning and formed rod-like nanostructures on PLGA nanofibers. In vitro cell compatibility was studied using rat Schwann cells and their adhesion, proliferation and gene expression levels on the designed scaffolds were evaluated. Our results have revealed the significant effects of the peptide blended scaffolds on promoting Schwann cell adhesion, extension and phenotypic expression. Neural development markers (SEM3F, NRP2 & PLX1) gene expression levels were significantly upregulated in peptide blended scaffolds compared to the PLGA scaffolds. Thus the hybrid blended novel designer scaffolds seem to be promising candidates for successful and functional regeneration of the peripheral nerve.

Self-Assembling Peptide Nanofiber Scaffolds for Bone Tissue Engineering

Self-Assembling Peptide Nanofiber Scaffolds for Bone Tissue Engineering

FGL-functionalized self-assembling nanofiber hydrogel as a scaffold for spinal cord-derived neural stem cells.

A class of designed self-assembling peptide nanofiber scaffolds has been shown to be a good biomimetic material in tissue engineering. Here, we specifically made a new peptide hydrogel scaffold FGLmx by mixing the pure RADA16 and designer functional peptide RADA16-FGL solution, and we analyzed the physiochemical properties of each peptide with atomic force microscopy (AFM) and circular dichroism (CD). In addition, we examined the biocompatibility and bioactivity of FGLmx as well as RADA16 scaffold on spinal cord-derived neural stem cells (SC-NSCs) isolated from neonatal rats. Our results showed that RADA16-FGL displayed a weaker β-sheet structure and FGLmx could self-assemble into nanofibrous morphology. Moreover, we found that FGLmx was not only noncytotoxic to SC-NSCs but also promoted SC-NSC proliferation and migration into the three-dimensional (3-D) scaffold, meanwhile, the adhesion and lineage differentiation of SC-NSCs on FGLmx were similar to that on RADA16. Our results indicated that the FGL-functionalized peptide scaffold might be very beneficial for tissue engineering and suggested its further application for spinal cord injury (SCI) repair.

A self-assembling nanomaterial reduces acute brain injury and enhances functional recovery in a rat model of intracerebral hemorrhage

There is no effective treatment for intracerebral hemorrhage (ICH). Intracerebral delivery of nanomaterials into the hemorrhagic lesion may be a new therapeutic strategy. In a rat model of ICH plus ultra-early hematoma aspiration, we found that locally delivered self-assembling peptide nanofiber scaffold (SAPNS) replaced the hematoma, reduced acute brain injury and brain cavity formation, and improved sensorimotor functional recovery. SAPNS serves as biocompatible material in the hemorrhagic brain cavity. Local delivery of this nanomaterial may facilitate the repair of ICH related brain injury and functional recovery. From the Clinical EditorIn a rat model of intracranial hemorrhage, these authors demonstrate that following ultra-early hematoma aspiration, local delivery of a self-assembling peptide nanofiber scaffold replaces the hematoma, reduces brain cavity formation, and improves sensorimotor functional recovery. Similar approaches would be welcome additions to the clinical treatment of this often devastating condition.

A Self-assembling Nanomaterial Reduces Acute Brain Injury and Enhances Functional Recovery in a Rat Model of Hypertensive Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) carries a high morbidity and mortality rate. High systolic blood pressure promotes hematoma growth. A self-assembling peptide (SAP) can achieve immediate hemostasis via formation of a SAP nanofiber scaffold (SAPNS). A minimally invasive aspiration of hematoma plus local delivery of SAPNS may lead to decompression of brain tissue and prevent hematoma growth. In a rat model of renovascular hypertension, experimental ICH was induced by a local injection of bacterial collagenase IV into the left basal ganglia. At 3.5 hours after induction of ICH, stereotactic clot aspiration or sham aspiration was performed manually. Following hematoma aspiration, an intrastriatal injection of 1% SAP, saline or sham injection was performed. Hematoma volume and brain swelling were quantified at 24 hours after ICH. Brain sections were immuno histochemically processed for myeloperoxidase and CD68 to detect the inflammatory infiltration in the perihematomal area. Perihematomal apoptotic cell death was determined using TUNEL staining. Functional recovery was assessed using neurological severity score and modified limb placement test at 1, 3, 7, 10 days after ICH. The combined treatment with hematoma removal and locally delivered SAPNS decreased hematoma volume, hematoma growth, brain edema, perihematomal inflammatory cell infiltration and apoptosis, as well as improved sensorimotor functional recovery. Locally delivered SAPNS after hematoma aspiration may prevent hematoma growth, facilitate the repair of ICHrelated brain injury and promote functional recovery. Such combined treatment may be effective in patients with hypertensive ICH.

A novel artificial nerve graft for repairing long-distance sciatic nerve defects: a self-assembling peptide nanofiber scaffold-containing poly(lactic-co-glycolic acid) conduit.

In this study, we developed a novel artificial nerve graft termed self-assembling peptide nanofiber scaffold (SAPNS)-containing poly(lactic-co-glycolic acid) (PLGA) conduit (SPC) and used it to bridge a 10-mm-long sciatic nerve defect in the rat. Retrograde tracing, behavioral testing and histomorphometric analyses showed that compared with the empty PLGA conduit implantation group, the SPC implantation group had a larger number of growing and extending axons, a markedly increased diameter of regenerated axons and a greater thickness of the myelin sheath in the conduit. Furthermore, there was an increase in the size of the neuromuscular junction and myofiber diameter in the target muscle. These findings suggest that the novel artificial SPC nerve graft can promote axonal regeneration and remyelination in the transected peripheral nerve and can be used for repairing peripheral nerve injury.

Designer self-assembling peptide nanofiber scaffolds containing link protein N-terminal peptide induce chondrogenesis of rabbit bone marrow stem cells.

Designer self-assembling peptide nanofiber hydrogel scaffolds have been considered as promising biomaterials for tissue engineering because of their excellent biocompatibility and biofunctionality. Our previous studies have shown that a novel designer functionalized self-assembling peptide nanofiber hydrogel scaffold (RLN/RADA16, LN-NS) containing N-terminal peptide sequence of link protein (link N) can promote nucleus pulposus cells (NPCs) adhesion and three-dimensional (3D) migration and stimulate biosynthesis of type II collagen and aggrecan by NPCs in vitro. The present study has extended these investigations to determine the effects of this functionalized LN-NS on bone marrow stem cells (BMSCs), a potential cell source for NP regeneration. Although the functionalized LN-NS cannot promote BMSCs proliferation, it significantly promotes BMSCs adhesion compared with that of the pure RADA16 hydrogel scaffold. Moreover, the functionalized LN-NS remarkably stimulates biosynthesis and deposition of type II collagen and aggrecan. These data demonstrate that the functionalized peptide nanofiber hydrogel scaffold containing link N peptide as a potential matrix substrate will be very useful in the NP tissue regeneration.

Self-Assembling Peptide Nanofiber Scaffolds Enhance Dopaminergic Differentiation of Mouse Pluripotent Stem Cells in 3-Dimensional Culture

Dopaminergic differentiation of embryonic stem cells (ESCs) gains more and more attention worldwide owing to its potential use for neurorestorative therapy for the treatment of Parkinson’s disease. The conventional 2D cell culture on petri dishes with various animal derived substrata such as collagen gels, laminin, and Matrigel is widely used to induce dopaminergic differentiation and it may limit the efficiency in the generation of dopaminergic neurons from ESCs and prevent their application for human therapies. Here, we reported that a self-assembling peptide made from natural amino acids has a property to generate a true 3D environment for dopaminergic differentiation. Mouse ESCs (R1) and mouse iPSCs (TTF-1) embedded in RADA16-I peptide-derived nanofiber scaffolds led to a marked increase in dopaminergic differentiation compared to the laminin-coated 2D culture or Matrigel-encapsulated 3D culture. These differentiated neurons expressed specific dopaminergic markers and produced appropriate patterns of action potential firing. Consistent with the increase in the number of dopaminergic neurons differentiated from R1 or TTF-1 in the self-assembling peptide nanofiber scaffold (SAPNS), both the expression levels of genes that involve in dopaminergic differentiation and maturation and the dopamine release in SAPNS culture were significantly elevated. The results of the study suggest that SAPNS provides a promising 3D culture system for dopaminergic differentiation.

Designer D-form self-assembling peptide nanofiber scaffolds for 3-dimensional cell cultures

Traditional 2-D cell cultures have many limitations because they do not truly mimic the natural environment. In order to fully understand the in vivo 3-D environment, it is crucial to develop a biomimetic 3-D culture system. Recently progress toward 3-D tissue cell cultures has been gradually made by addressing many critical issues including the microenvironment, gradient diffusion and apoptosis. Here we report a D-form self-assembly peptide system that provides insight into the relationships between nanofiber scaffolds and cell behaviors in 3-D cell cultures. We observed the peptide secondary structures response to ions and confirmed that their participation increases mechanical force rapidly. We also showed the enzymes attachment to nanofibers, investigated scaffolds to form 3-D microenvironment and described a modified protocol for 3-D cell culture D-form self-assembly peptide. Using this protocol, we showed cell behavior in the D-form peptide with high cell viability and low-level cell apoptosis for weeks. Furthermore, we proposed a plausible model for chiral self-assembly peptides in 3-D culture. Our research may further stimulate others to design novel biological materials at single chiral amino acid level, and may broaden the applications of designer D-form self-assembling peptides in clinical and medical nanobiotechnology.

Functionalized self-assembling peptide nanofiber hydrogels mimic stem cell niche to control human adipose stem cell behavior in vitro

A class of designer functionalized self-assembling peptide nanofiber scaffolds developed from self-assembling peptide RADA16-I (AcN-RADARADARADARADA-CONH2) has become increasingly attractive not only for studying spatial behaviors of cells, but also for developing approaches for a wide range of medical applications including regenerative medicine, rapid hemostasis and cell therapy. In this study, we report three functionalized self-assembling peptide hydrogels that serve as a three-dimensional (3-D) artificial microenvironment to control human adipose stem cell (hASC) behavior in vitro. Short peptide motifs SKPPGTSS (bone marrow homing motif), FHRRIKA (heparin-binding motif) and PRGDSGYRGDS (two-unit RGD cell adhesion motif) were used to extend the C-terminus of RADA16-I to obtain functionalized peptides. Atomic force microscopy confirmed the formation of self-assembling nanofibers in the mixture of RADA16-I peptide and functionalized peptides. The behaviors of hASCs cultured in 3-D peptide hydrogels, including migration, proliferation and growth factor-secretion ability, were studied. Our results showed that the functionalized peptide hydrogels were suitable 3-D scaffolds for hASC growth with higher cell proliferation, migration and the secretion of angiogenic growth factors compared with tissue culture plates and pure RADA16-I scaffolds. The present study suggests that these functionalized designer peptide hydrogels not only have promising applications for diverse tissue engineering and regenerative medicine applications as stem cell delivery vehicles, but also could be a biomimetic 3-D system to study nanobiomaterial–stem cell interactions and to direct stem cell behaviors.