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Ex vivo cadaveric human temporal bone study. (A): Schematized midmodiolar cross-section of a mammalian cochlea, showing injection needle approaching the modiolus. (B-C): Photomicrograph of the basal turn of the left cochlea in a cadaveric temporal bone (B) and in humans (C). Black arrows indicate direction of injection with IKVAV-PA gels. Note the direction of the fine needle for injection of IKVAV gel containing hESCs. A blue-dotted line shows the cochleostomy site. A white dotted line: round window. (D and E): Endoscopic IKVAV-PA gel injection into human modiolus. View of cochleostomy site using a 16-mm 0˚rigid 0˚rigid endoscope. A black dashed line marks cochleostomy boundary. A white dashed line indicates presumed plane of the scala vestibuli. (F): Artist's rendition of the superior view of the human skull base, with black arrow showing the direction of injection of IKVAV gels with hESCs and anatomical landmarks. Black square corresponds to sectioned area in subsequent figures. (G-L): IKVAV-PA gels with hESCs in the IAC in two sets of human cadaveric temporal bones. (G and J): Middle cranial fossa view of the human cadaveric temporal bone before the hESC injection. TAMRA-tagged IKVAV gels (H) and corresponding autofluorescence measurement observed in normal temporal bone tissue abutting the IAC (I). TRA-1-81 tagged hESCs with magnified inset (K) and corresponding autofluorescence measurement (L). Abbreviations: RW: round window; C: cochleostomy site; ST: scala tympani; SV: scala vestibule; M: modiolus; N: spinal needle; ACF: anterior cranial fossa; MCF: middle cranial fossa; PCF: posterior cranial fossa. Cranial nerves are denoted by Roman numerals. https://doi.org/10.1371/journal.pone.0190150.g006
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The use of human embryonic stem cells (hESCs) for regeneration of the spiral ganglion will require techniques for promoting otic neuronal progenitor (ONP) differentiation, anchoring of cells to anatomically appropriate and specific niches, and long-term cell survival after transplantation. In this study, we used self-assembling peptide amphiphile (...
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... Additionally, IKVAV-PA gels (peptide based hydrogels) were injected into the temporal bone of a human cadaver and showed promising results for the delivery of SC in a clinical setting. Therefore, it is recommended to combine injectable self-assembled PA gels with ESC transplantation to provide the ideal microenvironment for inner ear regeneration [144] (Figure 2). ...
Hydrogels are networks of three-dimensional cross-linked polymers, which possess the capacity to absorb and retain water. Hydrogels have proven to be adaptable and versatile, making them useful in various biomedical applications such as tissue engineering and regenerative medicine. Among the various types of hydrogels, peptide-based hydrogels are most suited for biological applications due to their special features, which include biodegradability, mechanical stability, biocompatibility, capacity to retain more water, injectability, and elasticity like that of tissues. In this review, we will present the recent advancements that have occurred in the field of peptide-based hydrogels concerning its biomedical applications especially delivery of targeted delivery, wound healing, tissue engineering, stem cell therapy, etc.
... Moreover, the elasticity modulus provided by Matrigel is insufficient to provide adequate support for cells (Soofi et al., 2009). To address these problems, hydrogels with defined components and improved mechanical properties have been investigated for their biological effects on inner ear regeneration (Rajasingh et al., 2017;Pouraghaei et al., 2020;Shi et al., 2023). One study demonstrated that Matrigel mixed with a certain ratio of alginate induced better differentiation of human gingival mesenchymal stem cells into auditory progenitor cells than Matrigel alone (Pouraghaei et al., 2020). ...
... Moreover, alginate modified by the Arg-Gly-Asp (RGD) sequence, a common cell adhesion peptide mainly derived from fibronectin, could also provide bioactive sites for cell-hydrogel interaction (Chikar et al., 2012). A single-component hydrogel crosslinked by self-assembling peptide amphiphiles with an Ile-Lys-Val-Ala-Val (IKVAV) epitope, another signal peptide epitope from laminin, has also been shown to promote the differentiation of hESCs into otic neural progenitors, as well as cell survival and localization after transplantation (Rajasingh et al., 2017). Interestingly, bacterial cellulose can also be fabricated into hydrogels for the differentiation and functional maintenance of SGNs (Shi et al., 2023). ...
... Multidirectional ECM-cytoskeleton binding has been verified to be conducive to the formation of cellular actin-rich extension (Langevin et al., 2005), which may contribute to neurite growth. Hydrogels with modified cell adhesion-related signaling peptide epitopes, such as RGD (Chikar et al., 2012) or IKVAV (Frick et al., 2017;Rajasingh et al., 2017), have been reported to promote cellhydrogel interactions and neuronal differentiation, which further demonstrated the importance of cell adhesion for inner ear cell regeneration. ...
Inner ear cell regeneration from stem/progenitor cells provides potential therapeutic strategies for the restoration of sensorineural hearing loss (SNHL), however, the efficiency of regeneration is low and the functions of differentiated cells are not yet mature. Biomaterials have been used in inner ear cell regeneration to construct a more physiologically relevant 3D culture system which mimics the stem cell microenvironment and facilitates cellular interactions. Currently, these biomaterials include hydrogel, conductive materials, magneto-responsive materials, photo-responsive materials, etc. We analyzed the characteristics and described the advantages and limitations of these materials. Furthermore, we reviewed the mechanisms by which biomaterials with different physicochemical properties act on the inner ear cell regeneration and depicted the current status of the material selection based on their characteristics to achieve the reconstruction of the auditory circuits. The application of biomaterials in inner ear cell regeneration offers promising opportunities for the reconstruction of the auditory circuits and the restoration of hearing, yet biomaterials should be strategically explored and combined according to the obstacles to be solved in the inner ear cell regeneration research.
... Additionally, IKVAV-PA gels were successfully injected into the human cadaveric temporal bone and revealed positive effects for SC delivery in the clinic. So, the combination of ESC transplantation with injectable PA gels is suggested to create an appropriate microenvironment for inner ear regeneration [281]. ...
Self-assembly is a growth mechanism in nature to apply local interactions forming a minimum energy structure. Currently, self-assembled materials are considered for biomedical applications due to their pleasant features, including scalability, versatility, simplicity, and inex-pensiveness. Self-assembled peptides can be applied to design and fabricate different structures, such as micelles, hydrogels, and vesicles, by diverse physical interactions between specific building blocks. Among them, bioactivity, biocompatibility, and biodegradability of peptide hydrogels have introduced them as versatile platforms in biomedical applications, such as drug delivery, tissue engineering, biosensing, and treating different diseases. Moreover, peptides are capable of mimicking the microenvironment of natural tissues and responding to internal and external stimuli for triggered drug release. In the current review, the unique characteristics of peptide hydrogels and recent advances in their design, fabrication, as well as chemical, physical, and biological properties are presented. Additionally, recent developments of these biomaterials are discussed with a particular focus on their biomedical applications in targeted drug delivery and gene delivery, stem cell therapy, cancer therapy and immune regulation, bioimaging, and regenerative medicine.
... Peptide amphiphiles (PAs), which self-assemble in water into nanofibers and form hydrogels under physiological conditions, are peptides that have hydrophobic groups linked to their termini or at particular positions along the sequence, such as lipid tails, and have been demonstrated as highly bioactive molecules that emulate the native ECM [116][117][118]. In 2017, Matsuoka et al. designed a suitable niche for enhanced in vitro neuronal differentiation and survival of the hESC-derived optic neuronal progenitor (ONP), which is based on self-assembling PA molecules that present an IKVAV epitope (IKVAV-PA) [119]. The capacity of IKVAVPA-gel to form organized nanofibers is attributed to direct neuronal differentiation. ...
Peptides, short protein fragments, can emulate the functions of their full-length native counterparts. Peptides are considered potent recombinant protein alternatives due to their specificity, high stability, low production cost, and ability to be easily tailored and immobilized. Stem cell proliferation and differentiation processes are orchestrated by an intricate interaction between numerous growth factors and proteins and their target receptors and ligands. Various growth factors, functional proteins, and cellular matrix-derived peptides efficiently enhance stem cell adhesion, proliferation, and directed differentiation. For that, peptides can be immobilized on a culture plate or conjugated to scaffolds, such as hydrogels or synthetic matrices. In this review, we assess the applications of a variety of peptides in stem cell adhesion, culture, organoid assembly, proliferation, and differentiation, describing the shortcomings of recombinant proteins and their full-length counterparts. Furthermore, we discuss the challenges of peptide applications in stem cell culture and materials design, as well as provide a brief outlook on future directions to advance peptide applications in boosting stem cell quality and scalability for clinical applications in tissue regeneration.
... PA-based hydrogels with incorporated IKVAV sequences were successfully used to create a niche in mice inner ear to increase the survival and support the differentiation of neuron progenitors to regenerate the spiral ganglion [79]. While in all other previous cases the differentiation of stem cells was externally induced, and only supported and enhanced by IKVAV, a recent work reported the successful differentiation of BMSCs induced only by this peptide sequence contained in a PA-based hydrogel [80]. ...
Proteins are functional building blocks of living organisms that exert a wide variety of functions, but their synthesis and industrial production can be cumbersome and expensive. By contrast, short peptides are very convenient to prepare at a low cost on a large scale, and their self-assembly into nanostructures and gels is a popular avenue for protein biomimicry. In this Review, we will analyze the last 5-year progress on the incorporation of bioactive motifs into self-assembling peptides to mimic functional proteins of the extracellular matrix (ECM) and guide cell fate inside hydrogel scaffolds.
... Therefore, stem cells, for example embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are an important tool for studying the molecular mechanisms underlying the innerear pathology as well as for generating cells for replacement therapies. Several groups have reported that mouse and human ESCs/iPSCs can be differentiated into inner-ear cells, including hair cells, supporting cells, progenitor cells and sensory neurons by in vitro differentiation in adherent culture and/or floating aggregation culture (21)(22)(23)(24)(25)(26)(27)(28). Previously, we described the generation of CX26 gap junction-forming cells from iPSCs (induced CX26 gap junction-forming cells; hereafter, iCX26GJC) derived from mice by using a floating culture (serumfree culture of embryoid body-like aggregates with quick aggregation culture; hereafter, SFEBq culture) and adherent culture systems. ...
There are >120 forms of non-syndromic deafness associated with identified genetic loci. In particular, mutation of the gap junction beta 2 gene (GJB2), which encodes connexin (CX)26 protein, is the most frequent cause of hereditary deafness worldwide. We previously described an induction method to develop functional CX26 gap junction-forming cells from mouse-induced pluripotent stem cells (iPSCs) and generated in vitro models for GJB2-related deafness. However, functional CX26 gap junction-forming cells derived from human iPSCs or embryonic stem cells (ESCs) have not yet been reported. In this study, we generated human iPSC-derived functional CX26 gap junction-forming cells (iCX26GJCs), which have the characteristics of cochlear supporting cells. These iCX26GJCs had gap junction plaque-like formations at cell–cell borders and co-expressed several markers that are expressed in cochlear supporting cells. Furthermore, we generated iCX26GJCs derived from iPSCs from two patients with the most common GJB2 mutation in Asia, and these cells reproduced the pathology of GJB2-related deafness. These in vitro models may be useful for establishing optimal therapies and drug screening for various mutations in GJB2-related deafness.
... Among them, one of the most explored class is peptide amphiphiles (PAs), which are short peptide sequences attached to a hydrophobic tail. 88,[177][178][179][180][181][182][183][184][185] The key structure of most designed peptide amphiphiles comprises of 4-8 amino acid β-sheet forming peptide sequence attached to an alkyl tail. The final structure of the peptide amphiphile is completed by the addition of charged residues to aid in solubility and gelation. ...
... The final structure of the peptide amphiphile is completed by the addition of charged residues to aid in solubility and gelation. 177,178,182,184 Additionally, in order to impart bioactivity to these peptide amphiphiles, various bioactive sequences can be attached covalently after the charged residues. 88,177,178,184 Under aqueous conditions, the hydrophobic interactions among the alkyl tails and subsequent β-sheet formation triggers the self-assembly of PAs to form high aspect ratio cylindrical nanofibers. ...
... 177,178,182,184 Additionally, in order to impart bioactivity to these peptide amphiphiles, various bioactive sequences can be attached covalently after the charged residues. 88,177,178,184 Under aqueous conditions, the hydrophobic interactions among the alkyl tails and subsequent β-sheet formation triggers the self-assembly of PAs to form high aspect ratio cylindrical nanofibers. 177 In self-assembled systems based on peptide amphiphiles, the core of the fiber is composed of packed alkyl tails thus exposing the peptide motifs towards the aqueous environment. ...
Neural tissue engineering holds great potential in addressing current challenges faced by medical therapies employed for the functional recovery of the brain. In this context, self-assembling peptides have gained considerable interest owing to their diverse physicochemical properties, which enable them to closely mimic the biophysical characteristics of the native ECM. Additionally, in contrast to synthetic polymers, which lack inherent biological signaling, peptide-based nanomaterials could be easily designed to present essential biological cues to the cells to promote cellular adhesion. Moreover, injectability of these biomaterials further widens their scope in biomedicine. In this context, hydrogels obtained from short bioactive peptide sequences are of particular interest owing to their facile synthesis and highly tunable properties. In spite of their well-known advantages, the exploration of short peptides for neural tissue engineering is still in its infancy and thus detailed discussion is required to evoke interest in this direction. This review provides a general overview of various bioactive hydrogels derived from short peptide sequences explored for neural tissue engineering. The review also discusses the current challenges in translating the benefits of these hydrogels to clinical practices and presents future perspectives regarding the utilization of these hydrogels for advanced biomedical applications.
... ONPs enhanced neural survival and differentiation after transplantation into X-SCID rat cochlea. 70 The same group used 3D-spheroid system, ECM (ie, nanofibrillar cellulose hydrogel), and a neurotrophic factor delivery to artificially create a stem cell niche that allowed hESC-derived ONP engraftment as well as neuronal differentiation. 71 Despite the recent progress in cell transplantation to the inner ear, the optimization of this regenerative strategy is a phenomenal task, since there are multiple variables to consider in each experimental paradigm. ...
The sense of hearing depends on a specialized sensory organ in the inner ear, called the cochlea, which contains the auditory hair cells (HCs). Noise trauma, infections, genetic factors, side effects of ototoxic drugs (ie, some antibiotics and chemotherapeutics), or simply aging lead to the loss of HCs and their associated primary neurons. This results in irreversible sensorineural hearing loss (SNHL) as in mammals, including humans; the inner ear lacks the capacity to regenerate HCs and spiral ganglion neurons. SNHL is a major global health problem affecting millions of people worldwide and provides a growing concern in the aging population. To date, treatment options are limited to hearing aids and cochlear implants. A major bottleneck for development of new therapies for SNHL is associated to the lack of human otic cell bioassays. Human induced pluripotent stem cells (hiPSCs) can be induced in two-dimensional and three-dimensional otic cells in vitro models that can generate inner ear progenitors and sensory HCs and could be a promising preclinical platform from which to work toward restoring SNHL. We review the potential applications of hiPSCs in the various biological approaches, including disease modeling, bioengineering, drug testing, and autologous stem cell based-cell therapy, that offer opportunities to understand the pathogenic mechanisms of SNHL and identify novel therapeutic strategies.
... For example, scaffolds such as the self-assembling peptide amphiphiles (Sato et al., 2018) developed in recent years is an example of how these scaffolds can be specifically designed to suit regeneration of different tissues such as muscle (Sleep et al., 2017) and nerves (Cheng et al., 2013;Matsuoka et al., 2017). In these studies, peptides mimicking various ECM proteins, such as collagen (Gore et al., 2001;Luo and Tong, 2011), laminin (Cheng et al., 2013), heparin (Mammadov et al., 2011), and TNC (Sever et al., 2014), were incorporated into peptide amphiphiles. ...
Cellular plasticity refers to the ability of cell fates to be reprogrammed given the proper signals, allowing for dedifferentiation or transdifferentiation into different cell fates. In vitro, this can be induced through direct activation of gene expression, however this process does not naturally occur in vivo. Instead, the microenvironment consisting of the extracellular matrix (ECM) and signaling factors, directs the signals presented to cells. Often the ECM is involved in regulating both biochemical and mechanical signals. In stem cell populations, this niche is necessary for maintenance and proper function of the stem cell pool. However, recent studies have demonstrated that differentiated or lineage restricted cells can exit their current state and transform into another state under different situations during development and regeneration. This may be achieved through (1) cells responding to a changing niche; (2) cells migrating and encountering a new niche; and (3) formation of a transitional niche followed by restoration of the homeostatic niche to sequentially guide cells along the regenerative process. This review focuses on examples in musculoskeletal biology, with the concept of ECM regulating cells and stem cells in development and regeneration, extending beyond the conventional concept of small population of progenitor cells, but under the right circumstances even “lineage-restricted” or differentiated cells can be reprogrammed to enter into a different fate.
... Hydrogels based on other peptide amphiphiles with bioactive domains as IKVAV, or with a tenascin-C-mimetic configuration, showed potential as cell encapsulation and regeneration matrices for inner ear and neural repair. [367][368][369][370] Native tissues can display different degrees of anisotropy and spatially varying stiffness, that are key players in guiding cell migration, organization, and function. [340] Beyond their flexibility for designing self-assembled hydrogels with tunable Adv. ...
Bottom‐up tissue engineering is a promising approach for designing modular biomimetic structures that aim to recapitulate the intricate hierarchy and biofunctionality of native human tissues. In recent years, this field has seen exciting progress driven by an increasing knowledge of biological systems and their rational deconstruction into key core components. Relevant advances in the bottom‐up assembly of unitary living blocks toward the creation of higher order bioarchitectures based on multicellular‐rich structures or multicomponent cell–biomaterial synergies are described. An up‐to‐date critical overview of long‐term existing and rapidly emerging technologies for integrative bottom‐up tissue engineering is provided, including discussion of their practical challenges and required advances. It is envisioned that a combination of cell–biomaterial constructs with bioadaptable features and biospecific 3D designs will contribute to the development of more robust and functional humanized tissues for therapies and disease models, as well as tools for fundamental biological studies. The recapitulation of native tissue hierarchy and biofunctionality remains a remarkable challenge. Bottom‐up tissue engineering has arisen as the most promising approach for designing modular biomimetic 3D microtissues that can better display the biofunctionality and biospecific design of living architectures. The most recent advances in integrative bottom‐up engineering of functional microtissues are discussed.
