Nephrotoxicity Assessment with Human Kidney Tubuloids using Spherical Nucleic Acid-Based mRNA Nanoflares.

Drug-induced nephrotoxicity represents an important cause of acute kidney injury with associated patient morbidity and mortality and is often responsible for termination of drug development, after extensive resource allocation. We have developed a human kidney tubuloid system that phenocopies, in 3D culture, kidney proximal tubules, a primary injury site of most nephrotoxicants. Traditional end point assays are often performed on 2D cultures of cells that have lost their differentiated phenotype. Herein, we pair a tubuloid system with Nanoflare (NF) mRNA nanosensors to achieve a facile, real-time assessment of drug nephrotoxicity. Using kidney injury molecule-1 (KIM-1) mRNA as a model injury biomarker, we verify NF specificity in engineered and adenovirus-transfected cells and confirm their efficacy to report tubular cell injury by aristolochic acid and cisplatin. The system also facilitates nephrotoxicity screening as demonstrated with 10 representative anticancer moieties. 5-Fluorouracil and paclitaxel induce acute tubular injury, as reflected by an NF signal increase.

Nanodelivery Systems for Topical Management of Skin Disorders.

Topical drug delivery has inherent advantages over other administration routes. However, the existence of stratum corneum limits the diffusion to small and lipophilic drugs. Fortunately, the advancement of nanotechnology brings along opportunities to address this challenge. Taking the unique features in size and surface chemistry, nanocarriers such as liposomes, polymeric nanoparticles, gold nanoparticles, and framework nucleic acids have been used to bring drugs across the skin barrier to epidermis and dermis layers. This article reviews the development of these formulations and focuses on their applications in the treatment of skin disorders such as acne, skin inflammation, skin infection, and wound healing. Existing hurdles and further developments are also discussed.

Functional Imaging with Nucleic-Acid-Based Sensors: Technology, Application and Future Healthcare Prospects.

Timely monitoring and assessment of human health plays a crucial role in maintaining the wellbeing of our advancing society. In addition to medical tools and devices, suitable probe agents are crucial to assist such monitoring, either in passive or active ways (i.e., sensors) through inducible signals. In this review we highlight recent developments in activatable optical sensors based on nucleic acids. Sensing mechanisms and bio-applications of these nucleic acid sensors in ex vivo assays, intracellular or in vivo settings are described. In addition, we discuss the limitations of these sensors and how nanotechnology can complement/enhance sensor properties to promote translation into clinical applications.

Real-Time Imaging of Dynamic Cell Reprogramming with Nanosensors.

Cellular reprogramming, the process by which somatic cells regain pluripotency, is relevant in many disease modeling, therapeutic, and drug discovery applications. Molecular evaluation of reprogramming (e.g., polymerase chain reaction, immunostaining) is typically disruptive, and only provides snapshots of phenotypic traits. Gene reporter constructs facilitate live-cell evaluation but is labor intensive and may risk insertional mutagenesis during viral transfection. Herein, the utilization of a non-integrative nanosensor is demonstrated to visualize key reprogramming events in situ within live cells. Principally based on sustained intracellular release of encapsulated molecular probes, nanosensors successfully monitored mesenchymal-epithelial transition, pluripotency acquisition, and transdifferentiation events. Tracking the dynamic expression of four pivotal biomarkers (i.e., THY1, E-CADHERIN, OCT4, and GATA4 mRNA), nanosensor signal showed great agreement with polymerase chain reaction and gene reporter imaging (R2 > 0.9). Overall, such facile, versatile nanosensor enables real-time monitoring of low-frequency reprogramming events, thereby useful for high-throughput assessment, optimization, and biomarker-specific cell enrichment.

Oligonucleotide Molecular Sprinkler for Intracellular Detection and Spontaneous Regulation of mRNA for Theranostics of Scar Fibroblasts.

Early diagnosis and timely intervention are key for the successful treatment of skin diseases like abnormal scars. This study introduces a nucleic-acid-based probe (i.e., molecular sprinkler) for the diagnosis and spontaneous regulation of the abnormal expression of fibrosis-related mRNA in scar-derived skin fibroblasts. Using mRNA encoding connective tissue growth factor (CTGF) as the model gene, a probe with three oligonucleotides is constructed, including a recognition sequence complementary to the CTGF mRNA, a siRNA against transforming growth factor receptor I (TGFßRI) as the CTGF mRNA suppressor, and a connecting sequence. The probe can detect CTGF mRNA with a limit of 10 × 10-9 m and distinguishes scar fibroblasts from normal ones in both 2D and 3D environments. Two days after transfection, the siRNA released from the probe reduces the expression of TGFßRI and, consequently, decreases the cellular expression of CTGF mRNA (up to 70%). This dual-role probe presents opportunities to monitor the TGF- ß signaling pathway, screen for drugs that target the CTGF pathway, and determine the role of inhibition of the CTGF pathway in therapeutic efficacy.

Near-Infrared Fluorescent Molecular Probe for Sensitive Imaging of Keloid.

Early detection of skin diseases is imperative for their effective treatment. However, fluorescence molecular probes that allow this are rare. The first activatable near-infrared (NIR) fluorescent molecular probe is reported for sensitive imaging of keloid cells, skin cells from abnormal scar fibrous lesions. As keloid cells have high expression levels of fibroblast activation protein-alpha (FAPα), the probe (FNP1) is designed to have a caged NIR dye and a FAPα-cleavable peptide substrate linked by a self-immolative segment. FNP1 can quickly and specifically turn on its fluorescence at 710 nm by 45-fold in the presence of FAPα, allowing it to effectively recognize keloid cells from normal skin cells. Integration of FNP1 with a simple microneedle-assisted topical application enables sensitive detection of keloid cells in metabolically-active human skin tissue with a theoretical limit of detection down to 20 000 cells.

Nanosensors for Continuous and Noninvasive Monitoring of Mesenchymal Stem Cell Osteogenic Differentiation.

Assessing mesenchymal stem cell (MSC) differentiation status is crucial to verify therapeutic efficacy and optimize treatment procedures. Currently, this involves destructive methods including antibody-based protein detection and polymerase chain reaction gene analysis, or laborious and technically challenging genetic reporters. Development of noninvasive methods for real-time differentiation status assessment can greatly benefit MSC-based therapies. This report introduces a nanoparticle-based sensing platform that encapsulates two molecular beacon (MB) probes within the same biodegradable polymeric nanoparticles. One MB targets housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal reference, while another detects alkaline phosphatase (ALP), a functional biomarker. Following internalization, MBs are gradually released as the nanoparticle degrades. GAPDH MBs provide a stable reference signal throughout the monitoring period (18 days) regardless of differentiation induction. Meanwhile, ALP mRNA undergoes well-defined dynamics with peak expression observed during early stages of osteogenic differentiation. By normalizing ALP-MB signal with GAPDH-MB, changes in ALP expression can be monitored, to noninvasively validate osteogenic differentiation. As proof-of-concept, a dual-colored nanosensor is applied to validate MSC osteogenesis on 2D culture and polycaprolactone films containing osteo-inductive tricalcium phospate.

Synergism of Water Shock and a Biocompatible Block Copolymer Potentiates the Antibacterial Activity of Graphene Oxide.

Graphene oxide (GO) is promising in the fight against pathogenic bacteria. However, the antibacterial activity of pristine GO is relatively low and concern over human cytotoxicity further limits its potential. This study demonstrates a general approach to address both issues. The developed approach synergistically combines the water shock treatment (i.e., a sudden decrease in environmental salinity) and the use of a biocompatible block copolymer (Pluronic F-127) as a synergist co-agent. Hypoosmotic stress induced by water shock makes gram-negative pathogens more susceptible to GO. Pluronic forms highly stable nanoassemblies with GO (Pluronic-GO) that can populate around bacterial envelopes favoring the interactions between GO and bacteria. The antibacterial activity of GO at a low concentration (50 µg mL(-1) ) increases from <30% to virtually complete killing (>99%) when complemented with water shock and Pluronic (5 mg mL(-1) ) at ≈2-2.5 h of exposure. Results suggest that the enhanced dispersion of GO and the osmotic pressure generated on bacterial envelopes by polymers together potentiate GO. Pluronic also significantly suppresses the toxicity of GO toward human fibroblast cells. Fundamentally, the results highlight the crucial role of physicochemical milieu in the antibacterial activity of GO. The demonstrated strategy has potentials for daily-life bacterial disinfection applications, as hypotonic Pluronic-GO mixture is both safe and effective.

Delivery of Wnt inhibitor WIF1 via engineered polymeric microspheres promotes nerve regeneration after sciatic nerve crush.

Injuries within the peripheral nervous system (PNS) lead to sensory and motor deficits, as well as neuropathic pain, which strongly impair the life quality of patients. Although most current PNS injury treatment approaches focus on using growth factors/small molecules to stimulate the regrowth of the injured nerves, these methods neglect another important factor that strongly hinders axon regeneration-the presence of axonal inhibitory molecules. Therefore, this work sought to explore the potential of pathway inhibition in promoting sciatic nerve regeneration. Additionally, the therapeutic window for using pathway inhibitors was uncovered so as to achieve the desired regeneration outcomes. Specifically, we explored the role of Wnt signaling inhibition on PNS regeneration by delivering Wnt inhibitors, sFRP2 and WIF1, after sciatic nerve transection and sciatic nerve crush injuries. Our results demonstrate that WIF1 promoted nerve regeneration (p < 0.05) after sciatic nerve crush injury. More importantly, we revealed the therapeutic window for the treatment of Wnt inhibitors, which is 1 week post sciatic nerve crush when the non-canonical receptor tyrosine kinase (Ryk) is significantly upregulated.

Monitoring Wound Healing with Topically Applied Optical NanoFlare mRNA Nanosensors.

An effective wound management strategy needs accurate assessment of wound status throughout the whole healing process. This can be achieved by examining molecular biomarkers including proteins, DNAs, and RNAs. However, existing methods for quantifying these biomarkers such as immunohistochemistry and quantitative polymerase chain reaction are usually laborious, resource-intensive, and disruptive. This article reports the development and utilization of mRNA nanosensors (i.e., NanoFlare) that are topically applied on cutaneous wounds to reveal the healing status through targeted and semi-quantitative examination of the mRNA biomarkers in skin cells. In 2D and 3D in vitro models, the efficacy and efficiency of these nanosensors are demonstrated in revealing the dynamic changes of mRNA biomarkers for different stages of wound development. In mouse models, this platform permits the tracking and identification of wound healing stages and a normal and diabetic wound healing process by wound healing index in real time.

Transdermal delivery of Chinese herbal medicine extract using dissolvable microneedles for hypertrophic scar treatment.

Hypertrophic scars are unfavorable skin diseases characterized by excessive collagen deposition. Although systemic treatments exist in clinic to manage hypertrophic scars, they pose significant side effects and tend to lose efficacy over prolonged applications. Traditional Chinese medicine (TCM) offers as a promising candidate to treat pathological scars. A large number of TCMs have been studied to show anti-scarring effect, however, the natural barrier of the skin impedes their penetration, lowering its therapeutic efficacy. Herein, we reported the use of dissolvable hyaluronic acid (HA) microneedles (MNs) as a vehicle to aid the transdermal delivery of therapeutic agent, a model TCM called shikonin for the treatment of hypertrophic scars. Here, shikonin was mixed with HA to make MNs with adequate mechanical strength for skin penetration, making its dosage controllable during the fabrication process. The therapeutic effect of the shikonin HA MNs was studied in vitro using HSFs and then further verified with quantitative reverse transcriptase polymerase chain reaction. Our data suggest that the shikonin HA MNs significantly reduce the viability and proliferation of the HSFs and downregulate the fibrotic-related genes (i.e., TGFß1, FAP-α and COL1A1). Furthermore, we observed a localized therapeutic effect of the shikonin HA MNs that is beneficial for site-specific treatment.

Ocular Delivery of Predatory Bacteria with Cryomicroneedles Against Eye Infection.

The development of potent antibiotic alternatives with rapid bactericidal properties is of great importance in addressing the current antibiotic crisis. One representative example is the topical delivery of predatory bacteria to treat ocular bacterial infections. However, there is a lack of suitable methods for the delivery of predatory bacteria into ocular tissue. This work introduces cryomicroneedles (cryoMN) for the ocular delivery of predatory Bdellovibrio bacteriovorus (B. bacteriovorus) bacteria. The cryoMN patches are prepared by freezing B. bacteriovorus containing a cryoprotectant medium in a microneedle template. The viability of B. bacteriovorus in cryoMNs remains above 80% as found in long-term storage studies, and they successfully impede the growth of gram-negative bacteria in vitro or in a rodent eye infection model. The infection is significantly relieved by nearly six times through 2.5 days of treatment without substantial effects on the cornea thickness and morphology. This approach represents the safe and efficient delivery of new class of antimicrobial armamentarium to otherwise impermeable ocular surface and opens up new avenues for the treatment of ocular surface disorders.

Cryomicroneedles for transdermal cell delivery.

Cell therapies for the treatment of skin disorders could benefit from simple, safe and efficient technology for the transdermal delivery of therapeutic cells. Conventional cell delivery by hypodermic-needle injection is associated with poor patient compliance, requires trained personnel, generates waste and has non-negligible risks of injury and infection. Here, we report the design and proof-of-concept application of cryogenic microneedle patches for the transdermal delivery of living cells. The microneedles are fabricated by stepwise cryogenic micromoulding of cryogenic medium with pre-suspended cells, and can be easily inserted into porcine skin and dissolve after deployment of the cells. In mice, cells delivered by the cryomicroneedles retained their viability and proliferative capability. In mice with subcutaneous melanoma tumours, the delivery of ovalbumin-pulsed dendritic cells via the cryomicroneedles elicited higher antigen-specific immune responses and led to slower tumour growth than intravenous and subcutaneous injections of the cells. Biocompatible cryomicroneedles may facilitate minimally invasive cell delivery for a range of cell therapies.

A Double-Layered Microneedle Platform Fabricated through Frozen Spray-Coating.

This work reports a frozen spray-coating method for the fabrication of double-layered microneedles (MNs). Taking swellable methacrylated hyaluronic acid (MeHA)-derived MNs as the model, both hydrophobic molecules (Nile red, Cy5) and hydrophilic ones (FITC, FITC-Dextran, Insulin) can be homogeneously coated without impacting the mechanical properties of the original MeHA MNs. The prepared double-layered MNs can execute multiple roles. It is demonstrated that insulin-coated MeHA double-layered MNs allow the effective delivery of the insulin into circulation of mice for controlling the blood glucose level while they also permit the extraction of skin interstitial fluid for the timely analysis of the biomarker (glucose).

Reprogramming of macrophages with macrophage cell membrane-derived nanoghosts.

Macrophages can be polarized to M1 or M2 type with pro-inflammatory or anti-inflammatory properties. Nanoparticles have recently been found to be a promising platform to polarize macrophages to desired phenotypes. This article explores the usage of cell membrane-derived nanoparticles (nanoghosts) for reprogramming macrophages. The efficacy and efficiency of this technology are examined via cytokine analysis and immunostaining of the nanoghost-treated cells. We find that several cytokines/chemokines are highly expressed on nanoghosts. In addition, a 2D wound healing model is deployed to reveal their potential application in clinical settings.

Unraveling Framework Nucleic Acid-Skin Cell Interactions with a Co-Culture System.

Framework nucleic acid (FNA) is an emerging drug carrier platform, with its biodegradability and uniform, tunable structures. Recently, its applicability in transdermal drug delivery has been demonstrated, extending the range of applications that are predominantly based on intravenous injection. However, FNA's interaction and impact toward the skin cells are yet to be elucidated. This study employs an optically clear keratinocyte/fibroblast co-culture system to visualize the FNA-skin cell interactions. FNA's influence on these cells is evaluated through polymerase chain reaction analyses and metabolism assays. A size-dependent interaction and cellular internalization on both keratinocytes and fibroblasts is observed, with no adverse effects on cell viability and functions.

A self-adhesive microneedle patch with drug loading capability through swelling effect.

Microneedles (MNs) offer a rapid method of transdermal drug delivery through penetration of the stratum corneum. However, commercial translation has been limited by fabrication techniques unique to each drug. Herein, a broadly applicable platform is explored by drug-loading via swelling effect of a hydrogel MN patch. A range of small molecule hydrophilic, hydrophobic, and biomacromolecule therapeutics demonstrate successful loading and burst release from hydrogel MNs fabricated from methacrylated hyaluronic acid (MeHA). The post-fabrication drug loading process allows MeHA MN patches with drug loadings of 10 µg cm-2. Additional post-fabrication processes are explored with dendrimer bioadhesives that increase work of adhesion, ensuring stable fixation on skin, and allow for additional drug loading strategies.

Temporal pressure enhanced topical drug delivery through micropore formation.

Transdermal drug delivery uses chemical, physical, or biochemical enhancers to cross the skin barrier. However, existing platforms require high doses of chemical enhancers or sophisticated equipment, use fragile biomolecules, or are limited to a certain type of drug. Here, we report an innovative methodology based on temporal pressure to enhance the penetration of all kinds of drugs, from small molecules to proteins and nanoparticles (up to 500 nm). The creation of micropores (~3 µm2) on the epidermal layer through a temporal pressure treatment results in the elevated expression of gap junctions, and reduced expression of occludin tight junctions. A 1 min treatment of 0.28-MPa allows nanoparticles (up to 500 nm) and macromolecules (up to 20 kDa) to reach a depth of 430-µm into the dermal layer. Using, as an example, the delivery of insulin through topical application after the pressure treatment yields up to 80% drop in blood glucose in diabetic mice.

Upconversion Nanoparticle Powered Microneedle Patches for Transdermal Delivery of siRNA.

Microneedles (MNs) permit the delivery of nucleic acids like small interfering RNA (siRNA) through the stratum corneum and subsequently into the skin tissue. However, skin penetration is only the first step in successful implementation of siRNA therapy. These delivered siRNAs need to be resistant to enzymatic degradation, enter target cells, and escape the endosome-lysosome degradation axis. To address this challenge, this article introduces a nanoparticle-embedding MN system that contains a dissolvable hyaluronic acid (HA) matrix and mesoporous silica-coated upconversion nanoparticles (UCNPs@mSiO2 ). The mesoporous silica (mSiO2 ) shell is used to load and protect siRNA while the upconversion nanoparticle (UCNP) core allows the tracking of MN skin penetration and NP diffusion through upconversion luminescence imaging or optical coherence tomography (OCT) imaging. Once inserted into the skin, the HA matrix dissolves and UCNPs@mSiO2 diffuse in the skin tissue before entering the cells for delivering the loaded genes. As a proof of concept, this system is used to deliver molecular beacons (MBs) and siRNA targeting transforming growth factor-beta type I receptor (TGF-ßRI) that is potentially used for abnormal scar treatment.

Framework Nucleic Acids: A Paradigm Shift in Transdermal Drug Delivery.

Transdermal drug delivery (TDD) provides a direct drug administration route bypassing gastrointestinal and liver metabolism. Until now, topical nanocarriers responsible for efficient TDD are predominantly polymeric or lipid based. The size-dependent skin penetration ability of framework nucleic acids (FNAs) has recently been reported, along with their efficacy in delivering doxorubicin for skin melanoma therapy. This commentary is to highlight the paradigm shift of nucleic acid delivery from being a cargo moiety to serving as a drug carrier instead. Further development directions to maximize the potential of FNAs for TDD are also discussed.