Biomimetic Adhesive Micropatterned Hydrogel Patches for Drug Release.

The optimized physical adhesion between bees' leg hairs and pollen grains-whereby the latter's diameter aligns with the spacing between the hairs-has previously inspired the development of a biomimetic drug dressing. Combining this optimized process with the improved natural mussels' adhesion in wet environments in a dual biomimetic process, it is herein proposed the fabrication of a natural-derived micropatterned hydrogel patch of methacrylated laminarin (LAM-MET), with enriched drug content and improved adhesiveness, suitable for applications like wound healing. Enhanced adhesion is accomplished by modifying LAM-MET with hydroxypyridinone groups, following the patch microfabrication by soft lithography and UV/vis-irradiation, resulting in a membrane with micropillars with a high aspect ratio. Following the biomimetics rational, a drug patch is engineered by combining the microfabricated dressing with drug particles milled to fit the spaces between pillars. Controlled drug release is achieved, together with inherent antibacterial activity against Escherichia coli and Pseudomonas aeruginosa, and enhanced biocompatibility using the bare micropatterned patches. This new class of biomimetic dressings overcomes the challenges of current patches, like poor mechanical properties and biocompatibility, limited adhesiveness and drug dosage, and lack of prolonged antimicrobial activity, opening new insights for the development of high drug-loaded dressings with improved patient compliance.

Self-glucose feeding hydrogels by enzyme empowered degradation for 3D cell culture.

Hydrogels have been used in combination with cells for several biomedical and biotechnological applications. Nevertheless, the use of bulk hydrogels has exhibited severe limitations in diffusion of oxygen, nutrients, and metabolites. Here, a support for cell culture is reported where glucose is generated in situ by the own hydrogel degradation, allowing cell survival and function while promoting tissue growth. For this purpose, laminaran (or laminarin)-based hydrogels were fabricated, immobilizing the adequate enzymes to obtain structural platforms for 3D cell culture and providing glucose feeding for metabolic activity of cells through polysaccharide degradation. We demonstrate that tumor A549 cells and human mesenchymal stem cells (hMSCs) can use the glucose resultant from the hydrogel degradation to survive and grow in non-added glucose cell culture medium. Additionally, in vivo biocompatibility and biodegradability of laminaran-based hydrogels were explored for the first time. The self-feeding hydrogels exhibited high potential in cell survival compared to native cell-laden laminaran hydrogels over two weeks of sub-cutaneous implantation. Such bioscaffolds with enzyme-empowered degradation capacity can be applied in diverse biotechnological contexts such as tissue regeneration devices, biofactories, disease models, and cell delivery systems.

Rational design of multistage drug delivery vehicles for pulmonary RNA interference therapy.

Small interfering RNA (siRNA) therapy has significant potential for the treatment of myriad diseases, including cancer. While intravenous routes of delivery have been found to be effective for efficient targeting to the liver, achieving high accumulations selectively in other organs, including lung tissues, can be a challenge. We demonstrate the rational design and engineering of a layer-by-layer (LbL) nanoparticle-containing aerosol that is able to achieve efficient, multistage delivery of siRNA in vitro. For the purpose, LbL nanoparticles were, for the first time, encapsulated in composite porous micro scale particles using a supercritical CO2-assisted spray drying (SASD) apparatus using chitosan as an excipient. Such particles exhibited aerodynamic properties highly favorable for pulmonary administration, and effective silencing of mutant KRAS in lung cancer cells derived from tumors of a non-small cell lung cancer (NSCLC) autochthonous model. Furthermore, efficient alveolar accumulation following inhalation in healthy mice was also observed, corroborating in vitro aerodynamic results, and opening new perspectives for further studies of effective lung therapies These results show that multistage aerosols assembled by supercritical CO2-assisted spray drying can enable efficient RNA interference therapy of pulmonary diseases including lung cancer.

Physical immobilization of particles inspired by pollination.

Biomimetic systems often exhibit striking designs well adapted to specific functions that have been inspiring the development of new technologies. Herein, we explored the remarkable ability of honey bees to catch and release large quantities of pollen grains. Hair spacing and height on bees are crucial for their ability to mechanically fix pollen grains. Inspired by this, we proposed the concept of a micropatterned surface for microparticle entrapment, featuring high-aspect-ratio elastic micropillars spaced to mimic the hairy surface of bees. The hypothesis was validated by investigating the ability of polydimethylsiloxane microfabricated patches to fix microparticles. The geometrical arrangement, spacing, height, and flexibility of the fabricated micropillars, and the diameter of the microparticles, were investigated. Higher entrapment capability was found through the match between particle size and pillar spacing, being consistent with the observations that the diameter of pollen grains is similar to the spacing between hairs on bees' legs. Taller pillars permitted immobilization of higher quantities of particles, consistent with the high aspect ratio of bees' hairs. Our biomimetic surfaces were explored for their ability to fix solid microparticles for drug-release applications, using tetracycline hydrochloride as a model antibiotic. These surfaces allowed fixation of more than 20 mg/cm2 of antibiotic, about five times higher dose than commercialized patches (5.1 mg/cm2). Such bioinspired hairy surfaces could find applications in a variety of fields where dry fixation of high quantities of micrometer-sized objects are needed, including biomedicine, agriculture, biotechnology/chemical industry, and cleaning utensils.

Tuneable spheroidal hydrogel particles for cell and drug encapsulation.

The need to better mimic native tissues has accompanied research in tissue engineering and controlled drug delivery. The development of new platforms for cell and drug encapsulation followed the same trend, and studying the influence of the delivery material system's geometry has been gaining momentum. Aiming to investigate how an increase in surface area and varying particle shape could impact drug release and cell viability, a novel method was developed to produce spheroidal hydrogel particles with adjustable circularity, aiming to tune drug delivery. For this purpose, droplets of hydrogel precursor were squeezed between two superamphiphobic surfaces separated with spacers with different height, and then photo-crosslinked to maintain the acquired shape after "de-sandwiching". Numerical modelling studies were performed to study the polymeric droplet geometry deformation process, which were consistent with experimentally obtained results. The spheroidal particles were produced under mild conditions using methacrylated chitosan, capable of encapsulating proteins or cells. Likely due to their higher surface area to volume-ratio, compared to spherical-shaped ones, spheroids presented an improved viability of encapsulated cells due to enhanced nutrient diffusion to the core, and led to a significantly faster drug release rate from the polymer network. These results were also assessed numerically, in which the drug release rate was computed for different spheroidal-like geometries. Hence, the described method can be used to manufacture spheroidal particles with tailored geometry that can be broadly applied in the biomedical field, including for drug delivery or as cell encapsulation platforms.

Biomaterials for drug delivery patches.

The limited efficiency of conventional drugs has been instigated the development of new and more effective drug delivery systems (DDS). Transdermal DDS, are associated with numerous advantages such its painless application and less frequent replacement and greater flexibility of dosing, features that triggered the research and development of such devices. Such systems have been produced using either biopolymer; or synthetic polymers. Although the first ones are safer, biocompatible and present a controlled degradation by human enzymes or water, the second ones are the most currently available in the market due to their greater mechanical resistance and flexibility, and non-degradation over time. This review highlights the most recent advances (mainly in the last five years) of patches aimed for transdermal drug delivery, focusing on the different materials (natural, synthetic and blends) and latest designs for the development of such devices, emphasizing also their combination with drug carriers that enable enhanced drug solubility and a more controlled release of the drug over the time. The benefits and limitations of different patches formulations are considered with reference to their appliance to transdermal drug delivery. Furthermore, a record of the currently available patches on the market is given, featuring their most relevant characteristics. Finally, a list of most recent/ongoing clinical trials regarding the use of patches for skin disorders is detailed and critical insights on the current state of patches for transdermal drug delivery are also provided.

Aerosolizable gold nano-in-micro dry powder formulations for theragnosis and lung delivery.

Functionalized gold nanoparticles (AuNPs) have been widely investigated as promising multifunctional nanosystems for the theragnosis of lung cancer, the most common and prominent cause of cancer death worldwide. Nevertheless, nanoparticles are not in appropriate sizes for an accurate deep lung delivery and the lack of locally and effective delivery of therapeutic biomolecules to the deep lungs is, in fact, the major cause of low therapeutic outcome. Herein we incorporate, for the first time, AuNPs into respirable microparticles. AuNPs were functionalized with biocompatible oligo(2-oxazoline)-based optically stable fluorescent coatings, and conjugated with a laminin peptide (YIGSR) for targeted lung cancer delivery. These POxylated AuNPs were then incorporated into a chitosan matrix by a clean process, supercritical CO2-assisted spray drying (SASD), yielding nano-in-micro clean ultrafine dry powder formulations. The engineered formulations present the adequate morphology and flowability to reach the deep lung, with aerodynamic sizes ranging 3.2-3.8µm, and excellent fine particle fraction (FPF) (FPF of 47% for CHT-bearing targeted AuNPs). The optimal biodegradation and release profiles enabled a sustained and controlled release of the embedded nanoparticles, with enhanced cellular uptake, opening new prospects for future lung theragnosis.

An analysis and validation pipeline for large-scale RNAi-based screens.

Large-scale RNAi-based screens are a major technology, but require adequate prioritization and validation of candidate genes from the primary screen. In this work, we performed a large-scale pooled shRNA screen in mouse embryonic stem cells (ESCs) to discover genes associated with oxidative stress resistance and found several candidates. We then developed a bioinformatics pipeline to prioritize these candidates incorporating effect sizes, functional enrichment analysis, interaction networks and gene expression information. To validate candidates, we mixed normal cells with cells expressing the shRNA coupled to a fluorescent protein, which allows control cells to be used as an internal standard, and thus we could detect shRNAs with subtle effects. Although we did not identify genes associated with oxidative stress resistance, as a proof-of-concept of our pipeline we demonstrate a detrimental role of Edd1 silencing in ESC growth. Our methods may be useful for candidate gene prioritization of large-scale RNAi-based screens.

Novel methodology based on biomimetic superhydrophobic substrates to immobilize cells and proteins in hydrogel spheres for applications in bone regeneration.

Cell-based therapies for regenerative medicine have been characterized by the low retention and integration of injected cells into host structures. Cell immobilization in hydrogels for target cell delivery has been developed to circumvent this issue. In this work mesenchymal stem cells isolated from Wistar rats bone marrow (rMSCs) were immobilized in alginate beads fabricated using an innovative approach involving the gellification of the liquid precursor droplets onto biomimetic superhydrophobic surfaces without the need of any precipitation bath. The process occurred in mild conditions preventing the loss of cell viability. Furthermore, fibronectin (FN) was also immobilized inside alginate beads with high efficiency in order to mimic the composition of the extracellular matrix. This process occurred in a very fast way (around 5 min), at room temperature, without aggressive mechanical strengths or particle aggregation. The methodology employed allowed the production of alginate beads exhibiting a homogenous rMSCs and FN distribution. Encapsulated rMSCs remained viable and were released from the alginate for more than 20 days. In vivo assays were also performed, by implanting these particles in a calvarial bone defect to evaluate their potential for bone tissue regeneration. Microcomputed tomography and histological analysis results showed that this hybrid system accelerated bone regeneration process. The methodology employed had a dual role by preventing cell and FN loss and avoiding any contamination of the beads or exchange of molecules with the surrounding environment. In principle, the method used for cell encapsulation could be extended to other systems aimed to be used in tissue regeneration strategies.

Gathering insights on disease etiology from gene expression profiles of healthy tissues.

MOTIVATION: Gene expression profiles have been widely used to study disease states. It may be possible, however, to gather insights into human diseases by comparing gene expression profiles of healthy organs with different disease incidence or severity. We tested this hypothesis and developed an approach to identify candidate genes associated with disease development by focusing on cancer incidence since it varies greatly across human organs. RESULTS: We normalized organ-specific cancer incidence by organ weight and found that reproductive organs tend to have a higher mass-normalized cancer incidence, which could be due to evolutionary trade-offs. Next, we performed a genome-wide scan to identify genes whose expression across healthy organs correlates with organ-specific cancer incidence. We identified a large number of genes, including genes previously associated with tumorigenesis and new candidate genes. Most genes exhibiting a positive correlation with cancer incidence were related to ribosomal and transcriptional activity, translation and protein synthesis. Organs with enhanced transcriptional and translational activation may have higher cell proliferation and therefore be more likely to develop cancer. Furthermore, we found that organs with lower cancer incidence tend to express lower levels of known cancer-associated genes. Overall, these results demonstrate how genes and processes that predispose organs to specific diseases can be identified using gene expression profiles from healthy tissues. Our approach can be applied to other diseases and serve as foundation for further oncogenomic analyses. CONTACT: jp@senescence.info SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Facomatosis pigmentovascularis: revisión y nueva clasificación / Phacomatosis pigmentovascularis: review and new classification

La facomatosis pigmentovascularis es un síndrome infrecuente caracterizado por la asociación de un nevus vascular con un nevus pigmentario. Su etiología es desconocida. Se ha propuesto un modelo genético de didimosis o manchas gemelas. La clasificación previa establece cinco categorías, que a su vez se subdividen en a) cuando existe compromiso cutáneo y b) cuando existe compromiso cutáneo y sistémico. Se ha propuesto una nueva clasificación, más simple, que resume las 10 categorías previas en tres tipos definidos: facomatosis cesioflammea, facomatosis spilorosea y facomatosis cesiomarmorata. Además, agrega un cuarto tipo de FPV no clasificables. Se han descrito asociaciones con otras alteraciones de la piel, oculares, vasculares, neurológicas, inmunológicas y malformaciones, por lo cual es recomendable realizar un examen físico extenso y derivación a especialidades para descartar patologías asociadas. Presentamos el caso de una mujer de 27 años que presenta lesiones correspondientes a una facomatosis cesioflammea en la nueva clasificación.

Phacomatosis pigmentovascularis is an uncommon syndrome characterized by the association of a widespread vascular nevus with a pigmentary nevus. Its etiology is unknown. A twin spotting or didymosis genetic model has been proposed. The previous classification established five categories, further subdivided into a) when cutaneous involvement was present or b) when cutaneous and systemic involvement was present. A new, more straightforward classification has been proposed, which summarizes the ten previous categories into three distinct types: phacomatosis cesioflammea, phacomatosis spilorosea and phacomatosis cesiomarmorata. Furthermore, a fourth category of unclassifiable phacomatosis pigmentovascularis was added. Diverse associations of phacomatosis pigmentovascularis with other skin lesions, malformations, and ocular, vascular, neurological and immunological abnormalities have been described, hence the importance of an extensive physical examination and consultations to discard associated pathologies. We present the case of a 27 year old woman, diagnosed with phacomatosis cesioflammea, based on the new classification.