Functional nanoarrays for investigating stem cell fate and function

Biomaterials-Based Technologies in Skeletal Muscle Tissue Engineering

For many clinically prevalent severe injuries, the inherent regenerative capacity of skeletal muscle remains inadequate. Skeletal muscle tissue engineering (SMTE) seeks to meet this clinical demand. With continuous progress in biomedicine and related technologies including micro/nanotechnology and 3D printing, numerous studies have uncovered various intrinsic mechanisms regulating skeletal muscle regeneration and developed tailored biomaterial systems based on these understandings. Here, the skeletal muscle structure and regeneration process are discussed and the diverse biomaterial systems derived from various technologies are explored in detail. Biomaterials serve not merely as local niches for cell growth, but also as scaffolds endowed with structural or physicochemical properties that provide tissue regenerative cues such as topographical, electrical, and mechanical signals. They can also act as delivery systems for stem cells and bioactive molecules that have been shown as key participants in endogenous repair cascades. To achieve bench-to-bedside translation, the typical effect enabled by biomaterial systems and the potential underlying molecular mechanisms are also summarized. Insights into the roles of biomaterials in SMTE from cellular and molecular perspectives are provided. Finally, perspectives on the advancement of SMTE are provided, for which gene therapy, exosomes, and hybrid biomaterials may hold promise to make important contributions.

Self-Supporting Metal-Organic Framework-Based Nanoarrays for Electrocatalysis

The replacement of powdery catalysts with self-supporting alternatives for catalyzing various electrochemical reactions is extremely important for the large-scale commercial application of renewable energy storage and conversion technologies. Metal-organic framework (MOF)-based nanoarrays possess tunable compositions, well-defined structure, abundant active sites, effective mass and electron transport, etc., which enable them to exhibit superior electrocatalytic performance in multiple electrochemical reactions. This review presents the latest research progress in developing MOF-based nanoarrays for electrocatalysis. We first highlight the structural features and electrocatalytic advantages of MOF-based nanoarrays, followed by a detailed summary of the design and synthesis strategies of MOF-based nanoarrays, and then describe the recent progress of their application in various electrocatalytic reactions. Finally, the challenges and perspectives are discussed, where further exploration into MOF-based nanoarrays will facilitate the development of electrochemical energy conversion technologies.

Silicon Nanoneedle-Induced Nuclear Deformation: Implications for Human Somatic and Stem Cell Nuclear Mechanics

Cell nuclear size and shape are strictly regulated, with aberrations often leading to or being indicative of disease. Nuclear mechanics are critically responsible for intracellular responses to extracellular cues, such as the nanotopography of the external environment. Silicon nanoneedle (SiNN) arrays are tunable, engineered cell culture substrates that permit precise, nanoscale modifications to a cell's external environment to probe mechanotransduction and intracellular signaling. We use a library of four different SiNN arrays to investigate the immediate and downstream effects of controlled geometries of nanotopographical cues on the nuclear integrity/dynamics of human immortalized somatic and renewing stem cell types. We quantify the significant, albeit different, nuclear shape changes that both cell types undergo, which suggest that cellular responses to SiNN arrays are more comparable to three-dimensional (3D) environments than traditional flat cultureware. We show that nanotopography-induced effects on nuclear envelope integrity, protein localization, and focal adhesion complex formation are cell-dependent. Migration is shown to be dramatically impeded for human neural progenitor cells (hNPCs) on nanotopographies compared to flat substrates but not for somatic cells. Our results indicate an additional layer of complexity in cellular mechanotransduction, which warrants closer attention in the context of engineered substrates and scaffolds for clinical applications.

Modulated nanowire scaffold for highly efficient differentiation of mesenchymal stem cells

Background

Nanotopographical cues play a critical role as drivers of mesenchymal stem cell differentiation. Nanowire scaffolds, in this regard, provide unique and adaptable nanostructured surfaces with focal points for adhesion and with elastic properties determined by nanowire stiffness.

Results

We show that a scaffold of nanowires, which are remotely actuated by a magnetic field, mechanically stimulates mesenchymal stem cells. Osteopontin, a marker of osteogenesis onset, was expressed after cells were cultured for 1 week on top of the scaffold. Applying a magnetic field significantly boosted differentiation due to mechanical stimulation of the cells by the active deflection of the nanowire tips. The onset of differentiation was reduced to 2 days of culture based on the upregulation of several osteogenesis markers. Moreover, this was observed in the absence of any external differentiation factors.

Conclusions

The magneto-mechanically modulated nanosurface enhanced the osteogenic differentiation capabilities of mesenchymal stem cells, and it provides a customizable tool for stem cell research and tissue engineering.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01488-5.

Gelatin-based electrospun and lyophilized scaffolds with nano scale feature for bone tissue engineering application: review

The rebuilding of the normal functioning of the damaged human body bone tissue is one of the main objectives of bone tissue engineering (BTE). Fabricated scaffolds are mostly treated as artificial supports and as materials for regeneration of neo bone tissues and must closely biomimetic the native extracellular matrix of bone. The materials used for developing scaffolds should be biodegradable, nontoxic, and biocompatible. For the resurrection of bone disorder, specifically natural and synthetic polymers such as chitosan, PCL, gelatin, PGA, PLA, PLGA, etc. meet the requirements for serving their functions as artificial bone substitute materials. Gelatin is one of the potential candidates which could be blended with other polymers or composites to improve its physicochemical, mechanical, and biological performances as a bone graft. Scaffolds are produced by several methods including electrospinning, self-assembly, freeze-drying, phase separation, fiber drawing, template synthesis, etc. Among them, freeze-drying and electrospinning are among the popular, simplest, versatile, and cost-effective techniques. The design and preparation of freeze-dried and electrospun scaffolds are of intense research over the last two decades. Freeze-dried and electrospun scaffolds offer a distinctive architecture at the micro to nano range with desired porosity and pore interconnectivity for selective movement of small biomolecules and play its role as an appropriate matrix very similar to the natural bone extracellular matrix. This review focuses on the properties and functionalization of gelatin-based polymer and its composite in the form of bone scaffolds fabricated primarily using lyophilization and electrospinning technique and their applications in BTE.

A polymer-based chemical tongue for the non-invasive monitoring of osteogenic stem-cell differentiation by pattern recognition of serum-supplemented spent media

The development of non-invasive techniques to characterize cultured cells is invaluable not only to ensure the reproducibility of cell research, but also for quality assurance of industrial cell products for...

Nano-sized graphene oxide coated nanopillars on microgroove polymer arrays that enhance skeletal muscle cell differentiation

The degeneration or loss of skeletal muscles, which can be caused by traumatic injury or disease, impacts most aspects of human activity. Among various techniques reported to regenerate skeletal muscle tissue, controlling the external cellular environment has been proven effective in guiding muscle differentiation. In this study, we report a nano-sized graphene oxide (sGO)-modified nanopillars on microgroove hybrid polymer array (NMPA) that effectively controls skeletal muscle cell differentiation. sGO-coated NMPA (sG-NMPA) were first fabricated by sequential laser interference lithography and microcontact printing methods. To compensate for the low adhesion property of polydimethylsiloxane (PDMS) used in this study, graphene oxide (GO), a proven cytophilic nanomaterial, was further modified. Among various sizes of GO, sGO (< 10 nm) was found to be the most effective not only for coating the surface of the NM structure but also for enhancing the cell adhesion and spreading on the fabricated substrates. Remarkably, owing to the micro-sized line patterns that guide cellular morphology to an elongated shape and because of the presence of sGO-modified nanostructures, mouse myoblast cells (C2C12) were efficiently differentiated into skeletal muscle cells on the hybrid patterns, based on the myosin heavy chain expression levels. Therefore, the developed sGO coated polymeric hybrid pattern arrays can serve as a potential platform for rapid and highly efficient in vitro muscle cell generation.

Advanced Optogenetic-Based Biosensing and Related Biomaterials

The ability to stimulate mammalian cells with light, brought along by optogenetic control, has significantly broadened our understanding of electrically excitable tissues. Backed by advanced (bio)materials, it has recently paved the way towards novel biosensing concepts supporting bio-analytics applications transversal to the main biomedical stream. The advancements concerning enabling biomaterials and related novel biosensing concepts involving optogenetics are reviewed with particular focus on the use of engineered cells for cell-based sensing platforms and the available toolbox (from mere actuators and reporters to novel multifunctional opto-chemogenetic tools) for optogenetic-enabled real-time cellular diagnostics and biosensor development. The key advantages of these modified cell-based biosensors concern both significantly faster (minutes instead of hours) and higher sensitivity detection of low concentrations of bioactive/toxic analytes (below the threshold concentrations in classical cellular sensors) as well as improved standardization as warranted by unified analytic platforms. These novel multimodal functional electro-optical label-free assays are reviewed among the key elements for optogenetic-based biosensing standardization. This focused review is a potential guide for materials researchers interested in biosensing based on light-responsive biomaterials and related analytic tools.

Electrochemical Cell Chips Based on Functionalized Nanometals

The electrochemical technique is one of the most accurate, rapid, and sensitive analytical assays, which becomes promising techniques for biological assays at a single-cell scale. Nanometals have been widely used for modification of the traditional electrodes to develop highly sensitive electrochemical cell chips. The electrochemical cell chips based on the nanostructured surface have been used as label-free, simple, and non-destructive techniques for in vitro monitoring of the effects of different anticancer drugs at the cellular level. Here, we will provide the recent progress in fabrication of nanopatterned surface and cell-based nanoarray, and discuss their applications based on electrochemical techniques such as detection of cellular states and chemicals, and non-destructive monitoring of stem cell differentiation.

Stem cells based in vitro models: trends and prospects in biomaterials cytotoxicity studies

Advanced biomaterials are increasingly used for numerous medical applications from the delivery of cancer-targeted therapeutics to the treatment of cardiovascular diseases. The issues of foreign body reactions induced by biomaterials must be controlled for preventing treatment failure. Therefore, it is important to assess the biocompatibility and cytotoxicity of biomaterials on cell culture systems before proceeding to in vivo studies in animal models and subsequent clinical trials. Direct use of biomaterials on animals create technical challenges and ethical issues and therefore, the use of non-animal models such as stem cell cultures could be useful for determination of their safety. However, failure to recapitulate the complex in vivo microenvironment have largely restricted stem cell cultures for testing the cytotoxicity of biomaterials. Nevertheless, properties of stem cells such as their self-renewal and ability to differentiate into various cell lineages make them an ideal candidate for in vitro screening studies. Furthermore, the application of stem cells in biomaterials screening studies may overcome the challenges associated with the inability to develop a complex heterogeneous tissue using primary cells. Currently, embryonic stem cells, adult stem cells, and induced pluripotent stem cells are being used as in vitro preliminary biomaterials testing models with demonstrated advantages over mature primary cell or cell line based in vitro models. This review discusses the status and future directions of in vitro stem cell-based cultures and their derivatives such as spheroids and organoids for the screening of their safety before their application to animal models and human in translational research.

The Effect of Physical Cues of Biomaterial Scaffolds on Stem Cell Behavior

Stem cells have been sought as a promising cell source in the tissue engineering field due to their proliferative capacity as well as differentiation potential. Biomaterials have been utilized to facilitate the delivery of stem cells in order to improve their engraftment and long-term viability upon implantation. Biomaterials also have been developed as scaffolds to promote stem cell induced tissue regeneration. This review focuses on the latter where the biomaterial scaffold is designed to provide physical cues to stem cells in order to promote their behavior for tissue formation. Recent work that explores the effect of scaffold physical properties, topography, mechanical properties and electrical properties, is discussed. Although still being elucidated, the biological mechanisms, including cell shape, focal adhesion distribution, and nuclear shape, are presented. This review also discusses emerging areas and challenges in clinical translation.

Topographical regulation of stem cell differentiation by plant-derived micro/nanostructures

This study examines the osteogenic differentiation promotion effect of micro/nanostructures of raffia on human adipose-derived stem cells to confirm the potential application of plant-derived micro/nanotopographies in tissue regeneration. The results confirm that the nanorod array on the front surface and the honeycomb-like microstructure on the back surface of raffia can not only regulate the adhesion, spreading, and migration of stem cells but also promote the osteogenic differentiation of the stem cells at a subsequent stage of cell culture. The osteocalcin expressions by the 21-day cultured cells on the front and back surfaces of raffia were 55-fold and 36-fold higher compared to the expression on a tissue culture plate. This indicates that plant-derived micro/nanotopographies can significantly promote stem cell differentiation. Furthermore, a general strategy for the application of plant-derived materials to stem-cell differentiation and bone-tissue engineering is suggested.

Remote Control of Neural Stem Cell Fate Using NIR-Responsive Photoswitching Upconversion Nanoparticle Constructs

Light-mediated remote control of stem cell fate, such as proliferation, differentiation, and migration, can bring a significant impact on stem cell biology and regenerative medicine. Current UV/vis-mediated control approaches are limited in terms of nonspecific absorption, poor tissue penetration, and phototoxicity. Upconversion nanoparticle (UCNP)-based near-infrared (NIR)-mediated control systems have gained increasing attention for vast applications with minimal nonspecific absorption, good penetration depth, and minimal phototoxicity from NIR excitations. Specifically, 808 nm NIR-responsive upconversion nanomaterials have shown clear advantages for biomedical applications owing to diminished heating effects and better tissue penetration. Herein, a novel 808 nm NIR-mediated control method for stem cell differentiation has been developed using multishell UCNPs, which are optimized for upconverting 808 nm NIR light to UV emission. The locally generated UV emissions further toggle photoswitching polymer capping ligands to achieve spatiotemporally controlled small-molecule release. More specifically, with 808 nm NIR excitation, stem cell differentiation factors can be released to guide neural stem cell (NSC) differentiation in a highly controlled manner. Given the challenges in stem cell behavior control, the developed 808 nm NIR-responsive UCNP-based approach to control stem cell differentiation can represent a new tool for studying single-molecule roles in stem cell and developmental biology.