A Protective Extracellular Matrix-Based Gene Delivery Reservoir Fabricated by Electrostatic Charge Manipulation

Glucose-Responsive Gene Delivery at Physiological pH through Tertiary-Amine Stabilized Boronate-PVA Particles Synthesized by One-Pot Reaction

We report a physiologically stable and cytocompatible glucose-responsive nonviral gene delivery system made up of boronate functionalized polymeric material. Herein, we utilize boronate cis-diol interactions to develop a glucose-responsive submicron particle (SMP) system. The stability of the boronate interaction at a physiological pH was achieved by copolymerization of dimethyl aminoethyl methacrylate (DMAEMA) with acrylamidophenylboronic acid (AAPBA) and the formation of a complex with polyvinylalcohol (PVA) which is governed by cis-diol interactions. The shift in hydrodynamic diameter of SMPs was observed and correlated with increasing glucose concentrations at a physiological pH. Optimal transfection was observed for a 5 µg dose of the gaussia luciferase reporter gene in NIH3T3 cells without any adverse effect on cellular viability. The destabilization of the AAPBA–PVA complex by interacting with glucose allowed the release of encapsulated bovine serum albumin (BSA) in a glucose-responsive manner. In total, 95% of BSA was released from SMPs at a 50 mM glucose concentration after 72 h. A two-fold increase in transfection was observed in 50 mM glucose compared to that of 10 mM glucose.

A Review of Gene Therapy Delivery Systems for Intervertebral Disc Degeneration

Background: :

Intervertebral Disc (IVD) degeneration is a major public health concern, and gene therapy seems a promising approach to delay or even reverse IVD degeneration. However, the delivery system used to transfer exogenous genes into intervertebral disc cells remains a challenge.

Methods::

The MEDLINE, Web of Science, and Scopus databases were searched for English-language articles related to gene therapy for IVD degeneration articles from 1999 to May 2019. The keywords included “gene therapy” AND “intervertebral disc”. The history of the development of different delivery systems was analysed, and the latest developments in viral and non-viral vectors for IVD degeneration treatment were reviewed.

Results: :

Gene therapy delivery systems for IVD degeneration are divided into two broad categories: viral and non-viral vectors. The most commonly used viral vectors are adenovirus, adeno-associated virus (AAV), and lentivirus. Enthusiasm for the use of adenovirus vectors has gradually declined and has been replaced by a preference for lentivirus and AAV vectors. New technologies, such as RNAi and CRISPR, have further enhanced the advantage of viral vectors. Liposomes are the classic non-viral vector, and their successors, polyplex micelles and exosomes, have more potential for use in gene therapy for IVD degeneration.

Conclusion::

Lentivirus and AAV are the conventional viral vectors used in gene therapy for IVD degeneration, and the new technologies RNAi and CRISPR have further enhanced their advantages. Nonviral vectors, such as polyplex micelles and exosomes, are promising gene therapy vectors for IVD degeneration.

Mineral-Coated Microparticles Enhance mRNA-Based Transfection of Human Bone Marrow Cells

The regenerative potential of bone marrow cells could be harnessed for tissue engineering applications. Bone marrow can be easily collected from patients, providing a valuable autologous source of therapeutic cells. However, years of delivery of bone marrow cells have highlighted the need for their genetic manipulation to overcome heterogeneity and to confer specificity to the regenerative process. In this study, we optimized the use of condensed mRNA as a non-viral alternative. As a proof of concept, we used mRNA encoding for reporter proteins such as EGFP or Firefly luciferase, which was condensed by complexing agents and delivered to human bone marrow cells using mineral-coated microparticles. We demonstrated that human bone marrow cells could be transfected with complexed mRNA, and that this approach was more efficient than the delivery of complexed plasmid DNA. In addition, human bone marrow cells were vulnerable to the toxicity of mRNA complexing agents, but these deleterious effects were mitigated by using mineral-coated microparticles as a carrier of complexed mRNA. Microparticle-mediated delivery of complexed mRNA also enabled higher cell metabolic activity and higher transfection in multiple in vitro culture conditions, including suspension culture and three-dimensional culture.

The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries. First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided. The advances and shortfalls of various collagen preparations (e.g., mammalian/marine extracted collagen, cell-produced collagens, recombinant collagens, and collagen-like peptides) and crosslinking technologies (e.g., chemical, physical, and biological) are then critically discussed. Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures. Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (e.g., tissue grafts, biomaterials, cell-assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules. Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice.

Responsive triggering systems for delivery in chronic wound healing

Non-communicable diseases including cancer, cardiovascular disease, diabetes, and neuropathy are chronic in nature. Treatment of these diseases with traditional delivery systems is limited due to lack of site-specificity, non-spatiotemporal release and insufficient doses. Numerous responsive delivery systems which respond to both physiological and external stimuli have been reported in the literature. However, effective strategies incorporating a multifactorial approach are required to control these complex wounds. This can be achieved by fabricating spatiotemporal release systems, multimodal systems or dual/multi-stimuli responsive delivery systems loaded with one or more bioactive components. Critically, these next generation stimuli responsive delivery systems that are at present not feasible are required to treat chronic wounds. This review provides a critical assessment of recent developments in the field of responsive delivery systems, highlighting their limitations and providing a perspective on how these challenges can be overcome.

Recent advances in smart biotechnology: Hydrogels and nanocarriers for tailored bioactive molecules depot

Over the past ten years, the global biopharmaceutical market has remarkably grown, with ten over the top twenty worldwide high performance medical treatment sales being biologics. Thus, biotech R&D (research and development) sector is becoming a key leading branch, with expanding revenues. Biotechnology offers considerable advantages compared to traditional therapeutic approaches, such as reducing side effects, specific treatments, higher patient compliance and therefore more effective treatments leading to lower healthcare costs. Within this sector, smart nanotechnology and colloidal self-assembling systems represent pivotal tools able to modulate the delivery of therapeutics. A comprehensive understanding of the processes involved in the self-assembly of the colloidal structures discussed therein is essential for the development of relevant biomedical applications. In this review we report the most promising and best performing platforms for specific classes of bioactive molecules and related target, spanning from siRNAs, gene/plasmids, proteins/growth factors, small synthetic therapeutics and bioimaging probes.

Synthetic/ECM-inspired hybrid platform for hollow microcarriers with ROS-triggered nanoporation hallmarks

Reactive oxygen species (ROS) are key pathological signals expressed in inflammatory diseases such as cancer, ischemic conditions and atherosclerosis. An ideal drug delivery system should not only be responsive to these signals but also should not elicit an unfavourable host response. This study presents an innovative platform for drug delivery where a natural/synthetic composite system composed of collagen type I and a synthesized polythioether, ensures a dual stimuli-responsive behaviour. Collagen type I is an extracellular matrix constituent protein, responsive to matrix metalloproteinases (MMP) cleavage per se. Polythioethers are stable synthetic polymers characterized by the presence of sulphur, which undergoes a ROS-responsive swelling switch. A polythioether was synthesised, functionalized and tested for cytotoxicity. Optimal conditions to fabricate a composite natural/synthetic hollow sphere construct were optimised by a template-based method. Collagen-polythioether hollow spheres were fabricated, revealing uniform size and ROS-triggered nanoporation features. Cellular metabolic activity of H9C2 cardiomyoblasts remained unaffected upon exposure to the spheres. Our natural/synthetic hollow microspheres exhibit the potential for use as a pathological stimuli-responsive reservoir system for applications in inflammatory diseases.

Drug-eluting biodegradable ureteral stent: New approach for urothelial tumors of upper urinary tract cancer

Upper urinary tract urothelial carcinoma (UTUC) accounts for 5-10% of urothelial carcinomas and is a disease that has not been widely studied as carcinoma of the bladder. To avoid the problems of conventional therapies, such as the need for frequent drug instillation due to poor drug retention, we developed a biodegradable ureteral stent (BUS) impregnated by supercritical fluid CO₂ (scCO₂) with the most commonly used anti-cancer drugs, namely paclitaxel, epirubicin, doxorubicin, and gemcitabine. The release kinetics of anti-cancer therapeutics from drug-eluting stents was measured in artificial urine solution (AUS). The in vitro release showed a faster release in the first 72h for the four anti-cancer drugs, after this time a plateau was achieved and finally the stent degraded after 9days. Regarding the amount of impregnated drugs by scCO₂, gemcitabine showed the highest amount of loading (19.57μg _drug/mg _polymer: 2% loaded), while the lowest amount was obtained for paclitaxel (0.067μg _drug/mg _polymer: 0.01% loaded). A cancer cell line (T24) was exposed to graded concentrations (0.01-2000ng/ml) of each drugs for 4 and 72h to determine the sensitivities of the cells to each drug (IC₅₀). The direct and indirect contact study of the anti-cancer biodegradable ureteral stents with the T24 and HUVEC cell lines confirmed the anti-tumoral effect of the BUS impregnated with the four anti-cancer drugs tested, reducing around 75% of the viability of the T24 cell line after 72h and demonstrating minimal cytotoxic effect on HUVECs.

Co-transfection of decorin and interleukin-10 modulates pro-fibrotic extracellular matrix gene expression in human tenocyte culture

Extracellular matrix synthesis and remodelling are driven by increased activity of transforming growth factor beta 1 (TGF-β1). In tendon tissue repair, increased activity of TGF-β1 leads to progressive fibrosis. Decorin (DCN) and interleukin 10 (IL-10) antagonise pathological collagen synthesis by exerting a neutralising effect via downregulation of TGF-β1. Herein, we report that the delivery of DCN and IL-10 transgenes from a collagen hydrogel system supresses the constitutive expression of TGF-β1 and a range of pro-fibrotic extracellular matrix genes.

Fibrin-genipin annulus fibrosus sealant as a delivery system for anti-TNFα drug

BACKGROUND CONTEXT

Intervertebral discs (IVDs) are attractive targets for local drug delivery because they are avascular structures with limited transport. Painful IVDs are in a chronic inflammatory state. Although anti-inflammatories show poor performance in clinical trials, their efficacy treating IVD cells suggests that sustained, local drug delivery directly to painful IVDs may be beneficial.

PURPOSE

The purpose of this study was to determine if genipin cross-linked fibrin (FibGen) with collagen Type I hollow spheres (CHS) can serve as a drug-delivery carrier for infliximab, the anti-tumor necrosis factor α (TNFα) drug. Infliximab was chosen as a model drug because of the known role of TNFα in increasing downstream production of several pro-inflammatory cytokines and pain mediators. Genipin cross-linked fibrin was used as drug carrier because it is adhesive, injectable, and slowly degrading hydrogel with the potential to seal annulus fibrosus (AF) defects. CHS allow simple and nondamaging drug loading and could act as a drug reservoir to improve sustained delivery.

STUDY DESIGN/SETTING

This is a study of biomaterials and human AF cell culture to determine drug release kinetics and efficacy.

METHODS

Infliximab was delivered at low and high concentrations using FibGen with and without CHS. Gels were analyzed for structure, drug release kinetics, and efficacy treating human AF cells after release.

RESULTS

Fibrin showed rapid infliximab drug release but degraded quickly. CHS alone showed a sustained release profile, but the small spheres may not remain in a degenerated IVD with fissures. Genipin cross-linked fibrin showed steady and low levels of infliximab release that was increased when loaded with higher drug concentrations. Infliximab was bound in CHS when delivered within FibGen and was only released after enzymatic degradation. The infliximab released over 20 days retained its bioactivity as confirmed by the sustained reduction of interleukin (IL)-1β, IL-6, IL-8, and TNFα concentrations produced by AF cells.

CONCLUSIONS

Direct mixing of infliximab into FibGen was the simplest drug-loading protocol capable of sustained release. Results show feasibility of using drug-loaded FibGen for delivery of infliximab and, in the context with the literature, show potential to seal AF defects and partially restore IVD biomechanics. Future investigations are required to determine if drug-loaded FibGen can effectively deliver drugs, seal AF defects, and promote IVD repair or prevent further IVD degeneration in vivo.

Biomaterial-mediated modification of the local inflammatory environment

Inflammation plays a major role in the rejection of biomaterial implants. In addition, despite playing an important role in the early stages of wound healing, dysregulated inflammation has a negative impact on the wound healing processes. Thus, strategies to modulate excessive inflammation are needed. Through the use of biomaterials to control the release of anti-inflammatory therapeutics, increased control over inflammation is possible in a range of pathological conditions. However, the choice of biomaterial (natural or synthetic), and the form it takes (solid, hydrogel, or micro/nanoparticle) is dependent on both the cause and tissue location of inflammation. These considerations also influence the nature of the anti-inflammatory therapeutic that is incorporated into the biomaterial to be delivered. In this report, the range of biomaterials and anti-inflammatory therapeutics that have been combined will be discussed, as well as the functional benefit observed. Furthermore, we point toward future strategies in the field that will bring more efficacious anti-inflammatory therapeutics closer to realization.

Glucosamine loaded injectable silk-in-silk integrated system modulate mechanical properties in bovine ex-vivo degenerated intervertebral disc model

Injectable hydrogels offer a tremendous potential for treatment of degenerated intervertebral disc due to their ability to withstand complex loading, conforming precisely to the defect spaces and eliminating the need for invasive surgical procedures. We have developed an injectable hydrogel platform of N-acetyl-glucosamine (GlcNAc) loaded silk hollow spheres embedded in silk hydrogel for in situ therapeutic release and enhanced mechanical strength. The assembled silk hydrogel provided adequate structural support to the ex vivo degenerated disc model in a cyclic compression test at par with the native tissue. Spatiotemporal release of GlcNAc in a controlled manner from the silk hollow microspheres trigger enhanced proteoglycan production from ADSCs embedded in the composite system. Role of MAPK and SMAD pathways in increasing proteoglycan production have been explored by immunohistological analysis as a result of the action of GlcNAc on the cells, elucidating the potential of injectable silk microsphere-in-silk hydrogel for the regeneration of degenerated disc tissue.

Biomimetic approaches in bone tissue engineering: Integrating biological and physicomechanical strategies

The development of responsive biomaterials capable of demonstrating modulated function in response to dynamic physiological and mechanical changes in vivo remains an important challenge in bone tissue engineering. To achieve long-term repair and good clinical outcomes, biologically responsive approaches that focus on repair and reconstitution of tissue structure and function through drug release, receptor recognition, environmental responsiveness and tuned biodegradability are required. Traditional orthopedic materials lack biomimicry, and mismatches in tissue morphology, or chemical and mechanical properties ultimately accelerate device failure. Multiple stimuli have been proposed as principal contributors or mediators of cell activity and bone tissue formation, including physical (substrate topography, stiffness, shear stress and electrical forces) and biochemical factors (growth factors, genes or proteins). However, optimal solutions to bone regeneration remain elusive. This review will focus on biological and physicomechanical considerations currently being explored in bone tissue engineering.

Current trends in biologics delivery to restore intervertebral disc anabolism

Low back pain is generally attributed to intervertebral disc (IVD) degeneration. This is a multifactorial disease induced by genetic and environmental factors and that progresses with aging. Disc degeneration is characterized by a limited ability of IVD cells to produce functional matrix while producing abnormal amounts of matrix-degrading enzymes. The prolonged imbalance between anabolism and catabolism in degenerative discs alters their composition and hydration. In turn, this results in increased angiogenesis and the loss of the disc's ability to maintain its aneural condition. Inflammation in the IVD, in particular the presence of pro-inflammatory cytokines, was found to favor innervation and also sensitization of the nociceptive pathways, thereby exacerbating degenerative symptoms. In this review, we discuss anti-inflammatory approaches to encounter disc catabolism, potential treatments to lower discogenic pain and pro-anabolic approaches in the form of protein delivery, gene therapy and cell delivery, to trigger regeneration in the IVD.

Fibrin-based microsphere reservoirs for delivery of neurotrophic factors to the brain

Aim: The in vivo therapeutic potential of neurotrophic factors to modify neuronal dysfunctions is limited by their short half-life. A biomaterials-based intervention, which protects these factors and allows a controlled release, is required. Materials & methods: Hollow fibrin microspheres were fabricated by charge manipulation using polystyrene templates and were loaded with NGF. Bioactivity of released NGF was demonstrated by neuronal outgrowth assay in PC-12 cells followed by in vivo assessment for NGF release and host response. Results: Fibrin-based hollow spheres showed high loading efficiency (>80%). Neurotrophin encapsulation into the microspheres did not alter its bioactivity and controlled release of NGF was observed in the in vivo study. Conclusion: Fibrin hollow microspheres act as a suitable delivery platform for neurotrophic factors with tunable loading efficiency and maintaining their bioactive form after release in vivo.

Flexible cyclic siloxane core enhances the transfection efficiency of polyethylenimine-based non-viral gene vectors

cD₄^H–AGE–PEI conjugates, with a favorable balance between hydrophilic and hydrophobic moieties, are promising carriers for gene delivery.

Microgel microenvironment primes adipose-derived stem cells towards an NP cells-like phenotype

Cell therapy of the degenerated intervertebral disc is limited by the lack of appropriate cell sources, thus new strategies for the differentiation of stem cells towards a nucleus pulposus (NP)-like phenotype need investigation. In the current study, it is hypothesized that spherical niche-like structures composed of type II collagen and hyaluronan (HA) mimic the NP microenvironment and promote the differentiation of adipose-derived stem cells (ADSCs) towards an NP-like phenotype. ADSCs are embedded in microgels of different concentrations of collagen II/HA. Cells' response to the different environments is studied by characterizing differences in cells' viability, morphology, and gene expression. After 21 days of culture, ADSCs maintain ± 80% viability in all the conditions tested. Moreover, microgels with higher concentration of collagen are stable and maintain cells in a rounder shape. In presence of differentiation media, cells are able to differentiate in all the conditions tested, but in a more pronounced manner in the microgel with a higher concentration of collagen. By tuning microgels' properties, it is possible to influence ADSCs' phenotype and ability to differentiate. Indeed, when cultured in high concentrations of collagen, ADSCs expresses high levels of collagen II, aggrecan, SOX9, and low levels of collagen I.

Multi-modal delivery of therapeutics using biomaterial scaffolds

Functionalisation of biomaterials with therapeutic moieties (proteins, drugs, genes) is a pre-requisite to tissue regeneration and restoration of function following injury or disease.

Assembly of protein-based hollow spheres encapsulating a therapeutic factor

Neurotrophins, as important regulators of neural development, function, and survival, have a therapeutic potential to repair damaged neurons. However, a controlled delivery of therapeutic molecules to injured tissue remains one of the greatest challenges facing the translation of novel drug therapeutics field. This study presents the development of an innovative protein-protein delivery technology of nerve growth factor (NGF) by an electrostatically assembled protein-based (collagen) reservoir system that can be directly injected into the injury site and provide long-term release of the therapeutic. A protein-based biomimetic hollow reservoir system was fabricated using a template method. The capability of neurotrophins to localize in these reservoir systems was confirmed by confocal images of fluorescently labeled collagen and NGF. In addition, high loading efficiency of the reservoir system was proven using ELISA. By comparing release profile from microspheres with varying cross-linking, highly cross-linked collagen spheres were chosen as they have the slowest release rate. Finally, biological activity of released NGF was assessed using rat pheochromocytoma (PC12) cell line and primary rat dorsal root ganglion (DRG) cell bioassay where cell treatment with NGF-loaded reservoirs induced significant neuronal outgrowth, similar to that seen in NGF treated controls. Data presented here highlights the potential of a high capacity reservoir-growth factor technology as a promising therapeutic treatment for neuroregenerative applications and other neurodegenerative diseases.

Biomaterial constructs for delivery of multiple therapeutic genes: a spatiotemporal evaluation of efficacy using molecular beacons

Gene therapy is emerging as a potential therapeutic approach for cardiovascular pathogenesis. An appropriate therapy may require multiple genes to enhance therapeutic outcome by modulating inflammatory response and angiogenesis in a controlled and time-dependent manner. Thus, the aim of this research was to assess the spatiotemporal efficacy of a dual-gene therapy model based on 3D collagen scaffolds loaded with the therapeutic genes interleukin 10 (IL-10), a potent anti-inflammatory cytokine, and endothelial nitric oxide synthase (eNOS), a promoter of angiogenesis. A collagen-based scaffold loaded with plasmid IL-10 polyplexes and plasmid eNOS polyplexes encapsulated into microspheres was used to transfect HUVECs and HMSCs cells.The therapeutic efficacy of the system was monitored at 2, 7 and 14 days for eNOS and IL-10 mRNA expression using RT-PCR and live cell imaging molecular beacon technology. The dual gene releasing collagen-based scaffold provided both sustained and delayed release of functional polyplexes in vitro over a 14 day period which was corroborated with variation in expression levels seen using RT-PCR and MB imaging. Maximum fold increases in IL-10 mRNA and eNOS mRNA expression levels occurred at day 7 in HMSCs and HUVECs. However, IL-10 mRNA expression levels seemed dependent on frequency of media changes and/or ease of transfection of the cell type. It was demonstrated that molecular beacons are able to monitor changes in mRNA levels at various time points, in the presence of a 3D scaffolding gene carrier system and the results complemented those of RT-PCR.

The neurotoxicity of gene vectors and its amelioration by packaging with collagen hollow spheres

Over the last twenty years there have been several reports on the use of nonviral vectors to facilitate gene transfer in the mammalian brain. Whilst a large emphasis has been placed on vector transfection efficiency, the study of the adverse effects upon the brain, caused by the vectors themselves, remains completely overshadowed. To this end, a study was undertaken to study the tissue response to three commercially available transfection agents in the brain of adult Sprague Dawley rats. The response to these transfection agents was compared to adeno-associated viral vector (AAV), PBS and naked DNA. Furthermore, the use of a collagen hollow sphere (CHS) sustained delivery system was analysed for its ability to reduce striatal toxicity of the most predominantly studied polymer vector, polyethyleneimine (PEI). The size of the gross tissue loss at the injection site was analysed after immunohistochemical staining and was used as an indication of acute toxicity. Polymeric vectors showed similar levels of acute brain toxicity as seen with AAV, and CHS were able to significantly reduce the toxicity of the PEI vector. In addition; the host response to the vectors was measured in terms of reactive astrocytes and microglial cell recruitment. To understand whether this gross tissue loss was caused by the direct toxicity of the vectors themselves an in vitro study on primary astrocytes was conducted. All vectors reduced the viability of the cells which is brought about by direct necrosis and apoptosis. The CHS delivery system reduced cell necrosis in the early stages of post administration. In conclusion, whilst polymeric gene vectors cause acute necrosis, administration in the brain causes adverse effects no worse than that of an AAV vector. Furthermore, packaging the PEI vector with CHS reduces surface charge and direct toxicity without elevating the host response.