REVIEW: "ISCHEMIC STROKE: From Fibrinolysis to Functional Recovery" Nanomedicine: Emerging Approaches to Treat Ischemic Stroke

Stroke is responsible for 11% of all deaths worldwide, the majority of which are caused by ischemic strokes, thus making the need to urgently find safe and effective therapies. Today, these can be cured either by mechanical thrombectomy when the thrombus is accessible, or by intravenous injection of fibrinolytics. However, the latter present several limitations, such as potential severe side effects, few eligible patients and low rate of partial and full recovery. To design safer and more effective treatments, nanomedicine appeared in this medical field a few decades ago. This review will explain why nanoparticle-based therapies and imaging techniques are relevant for ischemic stroke management. Then, it will present the different nanoparticle types that have been recently developed to treat this pathology. It will also study the various targeting strategies used to bring nanoparticles to the stroke site, thereby limiting side effects and improving the therapeutic efficacy. Finally, this review will present the few clinical studies testing nanomedicine on stroke and discuss potential causes for their scarcity.

Nanomedicines to treat rare neurological disorders: The case of Krabbe disease

The brain remains one of the most challenging therapeutic targets due to the low and selective permeability of the blood-brain barrier and complex architecture of the brain tissue. Nanomedicines, despite their relatively large size compared to small molecules and nucleic acids, are being heavily investigated as vehicles to delivery therapeutics into the brain. Here we elaborate on how nanomedicines may be used to treat rare neurodevelopmental disorders, using Krabbe disease (globoid cell leukodystrophy) to frame the discussion. As a monogenetic disorder and lysosomal storage disease affecting the nervous system, the lessons learned from examining nanoparticle delivery to the brain in the context of Krabbe disease can have a broader impact on the treatment of various other neurodevelopmental and neurodegenerative disorders. In this review, we introduce the epidemiology and genetic basis of Krabbe disease, discuss current in vitro and in vivo models of the disease, as well as current therapeutic approaches either approved or at different stage of clinical developments. We then elaborate on challenges in particle delivery to the brain, with a specific emphasis on methods to transport nanomedicines across the blood-brain barrier. We highlight nanoparticles for delivering therapeutics for the treatment of lysosomal storage diseases, classified by the therapeutic payload, including gene therapy, enzyme replacement therapy, and small molecule delivery. Finally, we provide some useful hints on the design of nanomedicines for the treatment of rare neurological disorders.

μMESH-Enabled Sustained Delivery of Molecular and Nanoformulated Drugs for Glioblastoma Treatment

Modest tissue penetrance, nonuniform distribution, and suboptimal release of drugs limit the potential of intracranial therapies against glioblastoma. Here, a conformable polymeric implant, μMESH, is realized by intercalating a micronetwork of 3 × 5 μm poly(lactic-co-glycolic acid) (PLGA) edges over arrays of 20 × 20 μm polyvinyl alcohol (PVA) pillars for the sustained delivery of potent chemotherapeutic molecules, docetaxel (DTXL) and paclitaxel (PTXL). Four different μMESH configurations were engineered by encapsulating DTXL or PTXL within the PLGA micronetwork and nanoformulated DTXL (nanoDTXL) or PTXL (nanoPTXL) within the PVA microlayer. All four μMESH configurations provided sustained drug release for at least 150 days. However, while a burst release of up to 80% of nanoPTXL/nanoDTXL was documented within the first 4 days, molecular DTXL and PTXL were released more slowly from μMESH. Upon incubation with U87-MG cell spheroids, DTXL-μMESH was associated with the lowest lethal drug dose, followed by nanoDTXL-μMESH, PTXL-μMESH, and nanoPTXL-μMESH. In orthotopic models of glioblastoma, μMESH was peritumorally deposited at 15 days post-cell inoculation and tumor proliferation was monitored via bioluminescence imaging. The overall animal survival increased from ∼30 days of the untreated controls to 75 days for nanoPTXL-μMESH and 90 days for PTXL-μMESH. For the DTXL groups, the overall survival could not be defined as 80% and 60% of the animals treated with DTXL-μMESH and nanoDTXL-μMESH were still alive at 90 days, respectively. These results suggest that the sustained delivery of potent drugs properly encapsulated in conformable polymeric implants could halt the proliferation of aggressive brain tumors.

Boosting the Potential of Chemotherapy in Advanced Breast Cancer Lung Metastasis via Micro-Combinatorial Hydrogel Particles

Breast cancer cell colonization of the lungs is associated with a dismal prognosis as the distributed nature of the disease and poor permeability of the metastatic foci challenge the therapeutic efficacy of small molecules, antibodies, and nanomedicines. Taking advantage of the unique physiology of the pulmonary circulation, here, micro-combinatorial hydrogel particles (µCGP) are realized via soft lithographic techniques to enhance the specific delivery of a cocktail of cytotoxic nanoparticles to metastatic foci. By cross-linking short poly(ethylene glycol) (PEG) chains with erodible linkers within a shape-defining template, a deformable and biodegradable polymeric skeleton is realized and loaded with a variety of therapeutic and imaging agents, including docetaxel-nanoparticles. In a model of advanced breast cancer lung metastasis, µCGP amplified the colocalization of docetaxel-nanoparticles with pulmonary metastatic foci, prolonged the retention of chemotoxic molecules at the diseased site, suppressed lesion growth, and boosted survival beyond 20 weeks post nodule engraftment. The flexible design and modular architecture of µCGP would allow the efficient deployment of complex combination therapies in other vascular districts too, possibly addressing metastatic diseases of different origins.

Shape-specific microfabricated particles for biomedical applications: a review

The storied history of controlled the release systems has evolved over time; from degradable drug-loaded sutures to monolithic zero-ordered release devices and nano-sized drug delivery formulations. Scientists have tuned the physico-chemical properties of these drug carriers to optimize their performance in biomedical/pharmaceutical applications. In particular, particle drug delivery systems at the micron size regime have been used since the 1980s. Recent advances in micro and nanofabrication techniques have enabled precise control of particle size and geometry-here we review the utility of microplates and discoidal polymeric particles for a range of pharmaceutical applications. Microplates are defined as micrometer scale polymeric local depot devices in cuboid form, while discoidal polymeric nanoconstructs are disk-shaped polymeric particles having a cross-sectional diameter in the micrometer range and a thickness in the hundreds of nanometer range. These versatile particles can be used to treat several pathologies such as cancer, inflammatory diseases and vascular diseases, by leveraging their size, shape, physical properties (e.g., stiffness), and component materials, to tune their functionality. This review highlights design and fabrication strategies for these particles, discusses their applications, and elaborates on emerging trends for their use in formulations.

Sub-Lethal Concentrations of Graphene Oxide Trigger Acute-Phase Response and Impairment of Phase-I Xenobiotic Metabolism in Upcyte® Hepatocytes

The impact of graphene oxide on hepatic functional cells represents a crucial evaluation step for its potential application in nanomedicine. Primary human hepatocytes are the gold standard for studying drug toxicity and metabolism; however, current technical limitations may slow down the large-scale diffusion of this cellular tool for in vitro investigations. To assess the potential hepatotoxicity of graphene oxide, we propose an alternative cell model, the second-generation upcyte^® hepatocytes, which show metabolic and functional profiles akin to primary human hepatocytes. Cells were acutely exposed to sub-lethal concentrations of graphene oxide (≤80 μg/ml) for 24 h and stress-related cell responses (such as apoptosis, oxidative stress, and inflammatory response) were evaluated, along with a broad investigation of graphene oxide impact on specialized hepatic functions. Results show a mild activation of early apoptosis but not oxidative stress or inflammatory response in our cell model. Notably, while graphene oxide clearly impacted phase-I drug-metabolism enzymes (e.g., CYP3A4, CYP2C9) through the inhibition of gene expression and metabolic activity, conversely, no effect was observed for phase-II enzyme GST and phase-III efflux transporter ABCG2. The GO-induced impairment of CYP3A4 occurs concomitantly with the activation of an early acute-phase response, characterized by altered levels of gene expression and protein production of relevant acute-phase proteins (i.e., CRP, Albumin, TFR, TTR). These data suggest that graphene oxide induces an acute phase response, which is in line with recent in vivo findings. In conclusion, upcyte^® hepatocytes appear a reliable in vitro model for assessing nanomaterial-induced hepatotoxicity, specifically showing that sub-lethal doses of graphene oxide have a negative impact on the specialized hepatic functions of these cells. The impairment of the cytochrome P450 system, along with the activation of an acute-phase response, may suggest potential detrimental consequences for human health, as altered detoxification from xenobiotics and drugs.

Conformable hierarchically engineered polymeric micromeshes enabling combinatorial therapies in brain tumours

The poor transport of molecular and nanoscale agents through the blood-brain barrier together with tumour heterogeneity contribute to the dismal prognosis in patients with glioblastoma multiforme. Here, a biodegradable implant (μMESH) is engineered in the form of a micrometre-sized poly(lactic-co-glycolic acid) mesh laid over a water-soluble poly(vinyl alcohol) layer. Upon poly(vinyl alcohol) dissolution, the flexible poly(lactic-co-glycolic acid) mesh conforms to the resected tumour cavity as docetaxel-loaded nanomedicines and diclofenac molecules are continuously and directly released into the adjacent tumour bed. In orthotopic brain cancer models, generated with a conventional, reference cell line and patient-derived cells, a single μMESH application, carrying 0.75 mg kg^-1 of docetaxel and diclofenac, abrogates disease recurrence up to eight months after tumour resection, with no appreciable adverse effects. Without tumour resection, the μMESH increases the median overall survival (∼30 d) as compared with the one-time intracranial deposition of docetaxel-loaded nanomedicines (15 d) or 10 cycles of systemically administered temozolomide (12 d). The μMESH modular structure, for the independent coloading of different molecules and nanomedicines, together with its mechanical flexibility, can be exploited to treat a variety of cancers, realizing patient-specific dosing and interventions.

Platelet-rich plasma-based bioactive membrane as a new advanced wound care tool

Chronic skin ulcers, consequence of diabetes and other pathological conditions, heavily compromise the patient life quality and represent a high and constantly growing cost for National Health Services. Autologous platelet-rich plasma (PRP), has been proposed to treat these lesions. The absence of guidelines for the PRP production and the need of a fresh preparation for each treatment lead us to develop a protocol for the production of an allogenic PRP-based bioactive membrane (BAM), standardized for platelet concentration and growth factor release. This work compares BAMs obtained starting from two different platelet concentrations. There was no direct correlation between the amount of growth factors released by BAM in vitro and the initial platelet count. However, different release kinetics were noticed for different growth factors, suggesting that they were differently retained by the two BAMs. The angiogenic potential of both BAMs was determined by Luminex Angiogenesis Assay. The biological activity of the factors released by the two BAMs was confirmed by cell proliferation and migration. A diabetic mouse chronic ulcer model was used to define the best PRP therapeutic dose in vivo. Both BAMs induced wound healing by increasing the thickness of the regenerated epidermis and the vessel number. However, a too high platelet concentration resulted in a slowdown of the membrane resorption that interfered with the skin healing. Overall, the results indicate that the BAMs could represent a natural and effective wound healing tool for the treatment of skin ulcers. Copyright © 2016 John Wiley & Sons, Ltd.

Characterization of mouse spinal cord vascular network by means of synchrotron radiation X-ray phase contrast tomography

High resolution Synchrotron-based X-ray Phase Contrast Tomography (XPCT) allows the simultaneous detection of three dimensional neuronal and vascular networks without using contrast agents or invasive casting preparation. We show and discuss the different features observed in reconstructed XPCT volumes of the ex vivo mouse spinal cord in the lumbo-sacral region, including motor neurons and blood vessels. We report the application of an intensity-based segmentation method to detect and quantitatively characterize the modification in the vascular networks in terms of reduction in experimental visibility. In particular, we apply our approach to the case of the experimental autoimmune encephalomyelitis (EAE), i.e. human multiple sclerosis animal model.

Fumarate-loaded electrospun nanofibers with anti-inflammatory activity for fast recovery of mild skin burns

In the biomedical sector the availability of engineered scaffolds and dressings that control and reduce inflammatory states is highly desired, particularly for the management of burn wounds. In this work, we demonstrate for the first time, to the best of our knowledge, that electrospun fibrous dressings of poly(octyl cyanoacrylate) (POCA) combined with polypropylene fumarate (PPF) possess anti-inflammatory activity and promote the fast and effective healing of mild skin burns in an animal model. The fibers produced had an average diameter of (0.8  ±  0.1) µm and they were able to provide a conformal coverage of the injured tissue. The application of the fibrous mats on the burned tissue effectively reduced around 80% of the levels of pro-inflammatory cytokines in the first 48 h in comparison with un-treated animals, and enhanced skin epithelialization. From histological analysis, the skin thickness of the animals treated with POCA : PPF dressings appeared similar to that of one of the naïve animals: (13.7  ±  1.4) µm and (14.3  ±  2.5) µm for naïve and treated animals, respectively. The density of dermal cells was comparable as well: (1100  ±  112) cells mm(-2) and (1358  ±  255) cells mm(-2) for naïve and treated mice, respectively. The results demonstrate the suitability of the electrospun dressings in accelerating and effectively promoting the burn healing process.

Combined platelet and plasma derivatives enhance proliferation of stem/progenitor cells maintaining their differentiation potential

BACKGROUND AIMS

Platelet derivatives have been proposed as alternatives to animal sera given that for cell therapy applications, the use of fetal bovine/calf serum (FBS/FCS) is subjected to severe limitations for safety and ethical concerns. We developed a cell culture medium additive obtained by the combination of two blood-derived standardized components.

METHODS

A platelet lysate (PL) and a platelet-poor plasma (PPP) were produced in a lyophilized form. Each component was characterized for its growth factor content (platelet-derived growth factor-BB/vascular endothelial growth factor). PL and PPP were used as single components or in combination in different ratio at cumulative 5% final concentration in the culture medium.

RESULTS

The single components were less effective than the component combination. In primary cell cultures (bone marrow stromal cells, adipose derived adult stem cells, osteoblasts, chondrocytes, umbilical cord-derived mesenchymal stromal cells, lymphocytes), the PL/PPP supplement promoted an increased cell proliferation in respect to the standard FCS culture in a dose-dependent manner, maintaining the cell functionality, clonogenicity, phenotype and differentiative properties throughout the culture. At a different component ratio, the supplement was also used to support proliferation of a cell line (U-937).

CONCLUSIONS

The PL/PPP supplement is an efficient cell culture medium additive that can replace FCS to promote cell proliferation. It can outdo FCS, especially when adopted in primary cultures from tissue biopsies. Moreover, the dual component nature of the supplement allows the researcher to determine the more appropriate ratio of the two components for the nutritional and functional requirements of the cell type of interest.

High-Resolution X-Ray Techniques as New Tool to Investigate the 3D Vascularization of Engineered-Bone Tissue

The understanding of structure–function relationships in normal and pathologic mammalian tissues is at the basis of a tissue engineering (TE) approach for the development of biological substitutes to restore or improve tissue function. In this framework, it is interesting to investigate engineered bone tissue, formed when porous ceramic constructs are loaded with bone marrow stromal cells (BMSC) and implanted in vivo. To monitor the relation between bone formation and vascularization, it is important to achieve a detailed imaging and a quantitative description of the complete three-dimensional vascular network in such constructs. Here, we used synchrotron X-ray phase-contrast micro-tomography to visualize and analyze the three-dimensional micro-vascular networks in bone-engineered constructs, in an ectopic bone formation mouse-model. We compared samples seeded and not seeded with BMSC, as well as samples differently stained or unstained. Thanks to the high quality of the images, we investigated the 3D distribution of both vessels and collagen matrix and we obtained quantitative information for all different samples. We propose our approach as a tool for quantitative studies of angiogenesis in TE and for any pre-clinical investigation where a quantitative analysis of the vascular network is required.

Simultaneous submicrometric 3D imaging of the micro-vascular network and the neuronal system in a mouse spinal cord

Faults in vascular (VN) and neuronal networks of spinal cord are responsible for serious neurodegenerative pathologies. Because of inadequate investigation tools, the lacking knowledge of the complete fine structure of VN and neuronal system represents a crucial problem. Conventional 2D imaging yields incomplete spatial coverage leading to possible data misinterpretation, whereas standard 3D computed tomography imaging achieves insufficient resolution and contrast. We show that X-ray high-resolution phase-contrast tomography allows the simultaneous visualization of three-dimensional VN and neuronal systems of ex-vivo mouse spinal cord at scales spanning from millimeters to hundreds of nanometers, with nor contrast agent nor sectioning and neither destructive sample-preparation. We image both the 3D distribution of micro-capillary network and the micrometric nerve fibers, axon-bundles and neuron soma. Our approach is very suitable for pre-clinical investigation of neurodegenerative pathologies and spinal-cord-injuries, in particular to resolve the entangled relationship between VN and neuronal system.

Altered bone development and turnover in transgenic mice over-expressing lipocalin-2 in bone

Lipocalin-2 (LCN2) is a protein largely expressed in many tissues, associated with different biological phenomena such as cellular differentiation, inflammation and cancer acting as a survival/apoptotic signal. We found that LCN2 was expressed during osteoblast differentiation and we generated transgenic (Tg) mice over-expressing LCN2 in bone. Tg mice were smaller and presented bone microarchitectural changes in both endochondral and intramembranous bones. In particular, Tg bones displayed a thinner layer of cortical bone and a decreased trabecular number. Osteoblast bone matrix deposition was reduced and osteoblast differentiation was slowed-down. Differences were also observed in the growth plate of young transgenic mice where chondrocyte displayed a more immature phenotype and a lower proliferation rate. In bone marrow cell cultures from transgenic mice, the number of osteoclast progenitors was increased whereas in vivo it was increased the number of mature osteoclasts expressing tartrate-resistant acid phosphatase (TRAP). Finally, while osteoprotegerin (OPG) levels remained unchanged, the expression of the conventional receptor activator of nuclear factor-κB ligand (RANKL) and of the IL-6 was enhanced in Tg mice. In conclusion, we found that LCN2 plays a role in bone development and turnover having both a negative effect on bone formation, by affecting growth plate development and interfering with osteoblast differentiation, and a positive effect on bone resorption by enhancing osteoclast compartment.

Biological activity of a standardized freeze-dried platelet derivative to be used as cell culture medium supplement

Serum of animal origin and in particular fetal bovine serum is the most commonly utilized cell culture medium additive for in vitro cell growth and differentiation. However, several major concerns have been raised by the scientific community regarding the use of animal sera for human cell-based culture applications. Among the possible alternatives to the animal serum, platelet-derived compounds have been proposed since more than 10 years. Nevertheless, the high degree of variability between the different platelet preparations, and the lack of standardized manufacturing and quality control procedures, made difficult to reach a consensus on the applicability of this novel cell culture medium supplement. In this study, we describe the preparation of a standardized platelet-rich plasma (PRP) derivative obtained starting from human-certified buffy coat samples with a defined platelet concentration and following protocols including also freeze-drying, gamma irradiation and biological activity testing prior the product release as cell culture medium additive. Biological activity testing of the different preparations was done by determining the capability of the different PRP preparations to sustain human bone marrow mesenchymal stem cell (MSC) clone formation and proliferation. Taking advantage of a developed MSC in vitro clonogenicity test, we also determined biological activity and stability of the freeze-dried gamma-sterilized PRP preparations after their storage for different times and at different temperatures. The PRP effects on cell proliferation were determined both on primary cell cultures established from different tissues and on a cell line. Results were compared with those obtained in "traditional" parallel control cultures performed in the presence of bovine serum [10% fetal calf serum (FCS)]. Compared to FCS, the PRP addition to the culture medium increased the MSC colony number and average size. In primary cell cultures and in cell line cultures, the PRP promoted cell proliferation also in conditions where the FCS had not a proliferation stimulating effect due to either the nature of the cells and the tissue of origin (such as human articular chondrocytes from elderly patients) or to the critical low density cell seeding (such as for HeLa cells). In summary, the standardized PRP formulation would provide an "off-the-shelf" product to be used for the selection and expansion of several cell types also in critical cell culture conditions.