Scaffold mediated gene knockdown for neuronal differentiation of human neural progenitor cells

Electrospun fiber-mediated delivery of neurotrophin-3 mRNA for neural tissue engineering applications

Aligned electrospun fibers provide topographical cues and local therapeutic delivery to facilitate robust peripheral nerve regeneration. mRNA delivery enables transient expression of desired proteins that promote axonal regeneration. However, no prior work delivers mRNA from electrospun fibers for peripheral nerve regeneration applications. Here, we developed the first aligned electrospun fibers to deliver pseudouridine-modified (Ψ) neurotrophin-3 (NT-3) mRNA (ΨNT-3mRNA) to primary Schwann cells and assessed NT-3 secretion and bioactivity. We first electrospun aligned poly(L-lactic acid) (PLLA) fibers and coated them with the anionic substrates dextran sulfate sodium salt (DSS) or poly(3,4-dihydroxy-L-phenylalanine) (pDOPA). Cationic lipoplexes containing ΨNT-3mRNA complexed to JetMESSENGER® were then immobilized to the fibers, resulting in detectable ΨNT-3mRNA release for 28 days from all fiber groups investigated (PLLA+mRNA, 0.5DSS4h+mRNA, and 2pDOPA4h+mRNA). The 2pDOPA4h+mRNA group significantly increased Schwann cell secretion of NT-3 for 21 days compared to control PLLA fibers (p < 0.001-0.05) and, on average, increased Schwann cell secretion of NT-3 by ≥ 2-fold compared to bolus mRNA delivery from the 1µgBolus+mRNA and 3µgBolus+mRNA groups. The 2pDOPA4h+mRNA fibers supported Schwann cell secretion of NT-3 at levels that significantly increased dorsal root ganglia (DRG) neurite extension by 44% (p < 0.0001) and neurite area by 64% (p < 0.001) compared to control PLLA fibers. The data show that the 2pDOPA4h+mRNA fibers enhance the ability of Schwann cells to promote neurite growth from DRG, demonstrating this platform's potential capability to improve peripheral nerve regeneration. STATEMENT OF SIGNIFICANCE: Aligned electrospun fibers enhance axonal regeneration by providing structural support and guidance cues, but further therapeutic stimulation is necessary to improve functional outcomes. mRNA delivery enables the transient expression of therapeutic proteins, yet achieving local, sustained delivery remains challenging. Previous work shows that genetic material delivery from electrospun fibers improves regeneration; however, mRNA delivery has not been explored. Here, we examine mRNA delivery from aligned electrospun fibers to enhance neurite outgrowth. We show that immobilization of NT-3mRNA/JetMESSENGER® lipoplexes to aligned electrospun fibers functionalized with pDOPA enables local, sustained NT-3mRNA delivery to Schwann cells, increasing Schwann cell secretion of NT-3 and enhancing DRG neurite outgrowth. This study displays the potential benefits of electrospun fiber-mediated mRNA delivery platforms for neural tissue engineering.

Designing electrospun fiber platforms for efficient delivery of genetic material and genome editing tools

Electrospun fibers are versatile biomaterial platforms with great potential to support regeneration. Electrospun fiber characteristics such as fiber diameter, degree of alignment, rate of degradation, and surface chemistry enable the creation of unique, tunable scaffolds for various drug or gene delivery applications. The delivery of genetic material and genome editing tools via viral and non-viral vectors are approaches to control cellular protein production. However, immunogenicity, off-target effects, and low delivery efficiencies slow the progression of gene delivery strategies to clinical settings. The delivery of genetic material from electrospun fibers overcomes such limitations by allowing for localized, tunable delivery of genetic material. However, the process of electrospinning is harsh, and care must be taken to retain genetic material bioactivity. This review presents an up-to-date summary of strategies to incorporate genetic material onto or within electrospun fiber platforms to improve delivery efficiency and enhance the regenerative potential of electrospun fibers for various tissue engineering applications.

Nanotechnology-Assisted RNA Delivery: From Nucleic Acid Therapeutics to COVID-19 Vaccines

In recent years, the main quest of science has been the pioneering of the groundbreaking biomedical strategies needed for achieving a personalized medicine. Ribonucleic acids (RNAs) are outstanding bioactive macromolecules identified as pivotal actors in regulating a wide range of biochemical pathways. The ability to intimately control the cell fate and tissue activities makes RNA-based drugs the most fascinating family of bioactive agents. However, achieving a widespread application of RNA therapeutics in humans is still a challenging feat, due to both the instability of naked RNA and the presence of biological barriers aimed at hindering the entrance of RNA into cells. Recently, material scientists' enormous efforts have led to the development of various classes of nanostructured carriers customized to overcome these limitations. This work systematically reviews the current advances in developing the next generation of drugs based on nanotechnology-assisted RNA delivery. The features of the most used RNA molecules are presented, together with the development strategies and properties of nanostructured vehicles. Also provided is an in-depth overview of various therapeutic applications of the presented systems, including coronavirus disease vaccines and the newest trends in the field. Lastly, emerging challenges and future perspectives for nanotechnology-mediated RNA therapies are discussed.

Scaffold-mediated CRISPR-Cas9 delivery system for acute myeloid leukemia therapy

Leukemia stem cells (LSCs) sustain the disease and contribute to relapse in acute myeloid leukemia (AML). Therapies that ablate LSCs may increase the chance of eliminating this cancer in patients. To this end, we used a bioreducible lipidoid-encapsulated Cas9/single guide RNA (sgRNA) ribonucleoprotein [lipidoid nanoparticle (LNP)-Cas9 RNP] to target the critical gene interleukin-1 receptor accessory protein (IL1RAP) in human LSCs. To enhance LSC targeting, we loaded LNP-Cas9 RNP and the chemokine CXCL12α onto mesenchymal stem cell membrane-coated nanofibril (MSCM-NF) scaffolds mimicking the bone marrow microenvironment. In vitro, CXCL12α release induced migration of LSCs to the scaffolds, and LNP-Cas9 RNP induced efficient gene editing. IL1RAP knockout reduced LSC colony-forming capacity and leukemic burden. Scaffold-based delivery increased the retention time of LNP-Cas9 in the bone marrow cavity. Overall, sustained local delivery of Cas9/IL1RAP sgRNA via CXCL12α-loaded LNP/MSCM-NF scaffolds provides an effective strategy for attenuating LSC growth to improve AML therapy.

Electrospun Nanofibers for Cancer Therapy

Lately, a remarkable progress has been recorded in the field of electrospinning for the preparation of numerous types of nanofiber scaffolds. These scaffolds present some remarkable features including high loading capacity and encapsulation efficiency, superficial area and porosity, potential for modification, structure for the co-delivery of various therapies, and cost-effectiveness. Their present and future applications for cancer diagnosis and treatment are promising and pioneering. In this chapter we provide a comprehensive overview of electrospun nanofibers (ESNFs) applications in cancer diagnosis and treatment, covering diverse types of drug-loaded electrospun nanofibers.

Scaffold-Based Delivery of CRISPR/Cas9 Ribonucleoproteins for Genome Editing

The simple and versatile CRISPR/Cas9 system is a promising strategy for genome editing in mammalian cells. Generally, the genome editing components, namely Cas9 protein and single-guide RNA (sgRNA), are delivered in the format of plasmids, mRNA, or ribonucleoprotein (RNP) complexes. In particular, non-viral approaches are desirable as they overcome the safety concerns posed by viral vectors. To control cell fate for tissue regeneration, scaffold-based delivery of genome editing components will offer a route for local delivery and provide possible synergistic effects with other factors such as topographical cues that are co-delivered by the same scaffold. In this chapter, we detail a simple method of surface modification to functionalize electrospun nanofibers with CRISPR/Cas9 RNP complexes. The mussel-inspired bio-adhesive coating will be used as it is a simple and effective method to immobilize biomolecules on the surface. Nanofibers will provide a biomimicking microenvironment and topographical cues to seeded cells. For evaluation, a model cell line with single copies of enhanced green fluorescent protein (U2OS.EGFP) will be used to validate the efficiency of gene disruption.

Oriented and sustained protein expression on biomimicking electrospun fibers for evaluating functionality of cells

A proper protein orientation is often required in order to achieve specific protein-receptor interaction to elicit a desired biological response. Here, we present a Protein A-based biomimicking platform that is capable of efficiently orienting proteins for evaluating cellular behaviour. By absorbing Protein A onto aligned bio-mimicking polycaprolactone (PCL) fibers, we demonstrate that protein binding could be retained on these fibers for at least 7 days under physiologically relevant conditions. We further show that Protein A served as a molecular orientor to arrange the recombinant proteins in similar orientations. Such protein-orienting scaffolds were further verified to be biologically functional by using sensitive primary rat cortical neurons (CNs) and oligodendrocyte progenitor cells (OPCs), as model neural cells for a stringent proof of concept. Specifically, CNs that were seeded on fibers coated with Protein A and a known enhancer of neurite growth (L1 Cell Adhesion Molecular L1CAM) displayed the longest total neurite length (462.77 ± 100.79 μm, p < 0.001) as compared to the controls. Besides that, OPCs seeded on fibers coated with Protein A and Neuregulin-1 Type III (Nrg1 type III) (myelin enhancer) produced the longest myelin ensheathment length (19.8 ± 11.69 μm). These results demonstrate the efficacy of this platform for protein screening applications.

A laser microdissection-based axotomy model incorporating the use of biomimicking fiber scaffolds reveals that microRNAs promote axon regeneration over long injury distances

The regeneration of injured neurons over long injury distances remains suboptimal. In order to successfully stimulate nerve regrowth, potent biomolecules are necessary. Furthermore, reproducible and translatable methods to test the potency of candidate drugs for enhancing nerve regeneration over long axotomy distances are also needed. To address these issues, we report a novel laser microdissection-based axotomy model that involves the use of biomimicking aligned fiber substrates to precisely control neuronal axotomy distances. Correspondingly, we demonstrate that in the absence of therapeutics, dorsal root ganglion (DRG) explants (consisting of neurons) axotomized within short distances from the main cell somas regenerated significantly longer than axons that were injured more distally (p < 0.05). However, when treated with a cocktail of microRNAs (miR-132/miR-222/miR-431), robust neurite outgrowth was observed (p < 0.05). Specifically, microRNA treatment promoted neurite outgrowth by ∼2.2-fold as compared to untreated cells and this enhancement was more significant under the less conducive regeneration condition of a long axotomy distance (i.e. 1000 μm from the cell soma). Besides that, we demonstrated that the treatment of miR-132/miR-222/miR-431 led to a longer length of nerve regeneration as well as a bigger nerve extension area after sciatic nerve transection injury. These results indicate that distance effects on axonal regrowth may be overcome by the effects of microRNAs and that these microRNAs may serve as promising therapeutics for nerve injury treatment.

Maneuvering the Migration and Differentiation of Stem Cells with Electrospun Nanofibers

Electrospun nanofibers have been extensively explored as a class of scaffolding materials for tissue regeneration, because of their unique capability to mimic some features and functions of the extracellular matrix, including the fibrous morphology and mechanical properties, and to a certain extent the chemical/biological cues. This work reviews recent progress in applying electrospun nanofibers to direct the migration of stem cells and control their differentiation into specific phenotypes. First, the physicochemical properties that make electrospun nanofibers well-suited as a supporting material to expand stem cells by controlling their migration and differentiation are introduced. Then various systems are analyzed in conjunction with mesenchymal, neuronal, and embryonic stem cells, as well as induced pluripotent stem cells. Finally, some perspectives on the challenges and future opportunities in combining electrospun nanofibers with stem cells are offered to address clinical issues.

RNA interference in glial cells for nerve injury treatment

Drivers of RNA interference are potent for manipulating gene and protein levels, which enable the restoration of dysregulated mRNA expression that is commonly associated with injuries and diseases. This review summarizes the potential of targeting neuroglial cells, using RNA interference, to treat nerve injuries sustained in the central nervous system. In addition, the various methods of delivering these RNA interference effectors will be discussed.

Electrospinning Nanofibers for Therapeutics Delivery

The limitations of conventional therapeutic drugs necessitate the importance of developing novel therapeutics to treat diverse diseases. Conventional drugs have poor blood circulation time and are not stable or compatible with the biological system. Nanomaterials, with their exceptional structural properties, have gained significance as promising materials for the development of novel therapeutics. Nanofibers with unique physiochemical and biological properties have gained significant attention in the field of health care and biomedical research. The choice of a wide variety of materials for nanofiber fabrication, along with the release of therapeutic payload in sustained and controlled release patterns, make nanofibers an ideal material for drug delivery research. Electrospinning is the conventional method for fabricating nanofibers with different morphologies and is often used for the mass production of nanofibers. This review highlights the recent advancements in the use of nanofibers for the delivery of therapeutic drugs, nucleic acids and growth factors. A detailed mechanism for fabricating different types of nanofiber produced from electrospinning, and factors influencing nanofiber generation, are discussed. The insights from this review can provide a thorough understanding of the precise selection of materials used for fabricating nanofibers for specific therapeutic applications and also the importance of nanofibers for drug delivery applications.