Delivery of cardiovascular progenitors with biomimetic microcarriers reduces adverse ventricular remodeling in a rat model of chronic myocardial infarction.

Despite tremendous progress in cell-based therapies for heart repair, many challenges still exist. To enhance the therapeutic potential of cell therapy one approach is the combination of cells with biomaterial delivery vehicles. Here, we developed a biomimetic and biodegradable micro-platform based on polymeric microparticles (MPs) capable of maximizing the therapeutic potential of cardiac progenitor cells (CPCs) and explored its efficacy in a rat model of chronic myocardial infarction. The transplantation of CPCs adhered to MPs within the infarcted myocardial microenvironment improved the long-term engraftment of transplanted cells for up to one month. Furthermore, the enhancement of cardiac cellular retention correlated with an increase in functional recovery. In consonance, better tissue remodeling and vasculogenesis were observed in the animals treated with cells attached to MPs, which presented smaller infarct size, thicker right ventricular free wall, fewer deposition of periostin and greater density of vessels than animals treated with CPCs alone. Finally, we were able to show that part of this beneficial effect was mediated by CPC-derived extracellular vesicles (EVs). Taken together, these findings indicate that the biomimetic microcarriers support stem cell survival and increase cardiac function in chronic myocardial infarction through modulation of cardiac remodeling, vasculogenesis and CPCs-EVs mediated therapeutic effects. The biomimetic microcarriers provide a solution for biomaterial-assisted CPC delivery to the heart. STATEMENT OF SIGNIFICANCE: In this study, we evaluate the possibility of using a biomimetic and biodegradable micro-platform to improve cardiovascular progenitor therapy. The strategy reported herein serves as an injectable scaffold for adherent cells due to their excellent injectability through cardiac catheters, capacity for biomimetic three-dimensional stem cell support and controllable biodegradability. In a rat model of chronic myocardial infarction, the biomimetic microcarriers improved cardiac function, reduced chronic cardiac remodeling and increased vasculogenesis through the paracrine signaling of CPCs. We have also shown that extracellular vesicles derived from CPCs cultured on biomimetic substrates display antifibrotic effects, playing an important role in the therapeutic effects of our tissue-engineered approach. Therefore, biomimetic microcarriers represent a promising and effective strategy for biomaterial-assisted CPC delivery to the heart.

NRG1 PLGA MP locally induce macrophage polarisation toward a regenerative phenotype in the heart after acute myocardial infarction.

Neuregulin-1 loaded poly(lactic-co-glycolic acid) (PLGA) microparticles hold great promise for treating acute myocardial infarction, as they have been proved to recover heart function and induce positive heart remodelling in preclinical studies. More recently, the inflammatory response of the heart after acute myocardial infarction (AMI) has been identified as one of the major mechanisms in cardiac tissue remodelling and repair. However, the connection between neuregulin-1 PLGA microparticles and inflammation is still not well characterised. In the present study we assessed this relationship in a mouse AMI model. First, in vitro evidence indicated that neuregulin-1 PLGA microparticles induced a macrophage polarisation toward a regenerative phenotype (CD206+ cells), preventing macrophages from evolving toward the inflammatory phenotype (B7-2+ cells). This correlated with in vivo experiments, where neuregulin-1 PLGA microparticles locally improved the CD206+/B7-2+ ratio. Moreover, neuregulin-1 PLGA microparticles were administered at different time points (15 min, 24, 72 and 168 h) after infarction induction without causing secondary inflammatory issues. The time of treatment administration did not alter the inflammatory response. Taken together, these results suggest that neuregulin-1 PLGA microparticles can be administered depending on the therapeutic window of the encapsulated drug and that they enhance the heart's reparative inflammatory response after acute myocardial infarction, helping cardiac tissue repair.

Development and characterization of polo-like kinase 2 loaded nanoparticles-A novel strategy for (serine-129) phosphorylation of alpha-synuclein.

Polo like kinase 2 (PLK2), a serine/threonine serum inducible kinase, has been proposed to be the major factor responsible for phosphorylating alpha-synuclein (α-syn) at Serine-129 (Ser-129) in Parkinson's disease (PD). A suitable strategy to gain insights into PLK2's biological effects might be to increase PLK2 intracellular levels with the aim of reproducing the slow progressive neuronal changes that occur in PD. The goal of this study was to develop and characterize a novel drug delivery system (DDS) for PLK2 cytosolic delivery using Total recirculating one machine system (TROMS), a technique capable of encapsulating fragile molecules while maintaining their native properties. A protocol for nanoparticle (NP) preparation using TROMS was set up. NPs showed a mean diameter of 257±15.61nm and zeta potential of -16±2mV, suitable for cell internalization. TEM and SEM images showed individual, spherical, dispersed NPs. The drug entrapment efficacy was 61.86±3.9%. PLK2-NPs were able to enter SH-SY5Y cells and phosphorylate α-syn at Ser-129, demonstrating that the enzyme retained its activity after the NP manufacturing process. This is the first study to develop a DDS for continuous intracellular delivery of PLK2. These promising results indicate that this novel nanotechnology approach could be used to elucidate the biological effects of PLK2 on dopaminergic neurons.

Brain aging and Parkinson's disease: New therapeutic approaches using drug delivery systems.

The etiology and pathogenesis of Parkinson's disease (PD) is unknown, aging being the strongest risk factor for brain degeneration. Understanding PD pathogenesis and how aging increases the risk of disease would aid the development of therapies able to slow or prevent the progression of this neurodegenerative disorder. In this review we provide an overview of the most promising therapeutic targets and strategies to delay the loss of dopaminergic neurons observed both in PD and aging. Among them, handling alpha-synuclein toxicity, enhancing proteasome and lysosome clearance, ameliorating mitochondrial disruptions and modifying the glial environment are so far the most promising candidates. These new and conventional drugs may present problems related to their labile nature and to the difficulties in reaching the brain. Thus, we highlight the latest types of drug delivery system (DDS)-based strategies for PD treatment, including DDS for local and systemic drug delivery. Finally, the ongoing challenges for the discovery of new targets and the opportunities for DDS-based therapies to improve and efficacious PD therapy will be discussed.

Tracking the in vivo release of bioactive NRG from PLGA and PEG-PLGA microparticles in infarcted hearts.

The growth factor neuregulin (NRG) is one of the most promising candidates in protein therapy as potential treatment for myocardial infarction (MI). In the last few years, biomaterial based delivery systems, such as polymeric microparticles (MPs) made of poly(lactic co glycolic acid) and polyethylene glycol (PLGA and PEG-PLGA MPs), have improved the efficacy of protein therapy in preclinical studies. However, no cardiac treatment based on MPs has yet been commercialized since this is a relatively new field and total characterization of polymeric MPs remains mandatory before they reach the clinical arena. Therefore, the objective of this study was to characterize the in vivo release, bioactivity and biodegradation of PLGA and PEG-PLGA MPs loaded with biotinylated NRG in a rat model of MI. The effect of PEGylation in the clearance of the particles from the cardiac tissue was also evaluated. Interestingly, MPs were detected in the cardiac tissue for up to 12 weeks after administration. In vivo release analysis showed that bNRG was released in a controlled manner throughout the twelve week study. Moreover, the biological cardiomyocyte receptor (ErbB4) for NRG was detected in its activated form only in those animals treated with bNRG loaded MPs. On the other hand, the PEGylation strategy was effective in diminishing phagocytosis of these MPs compared to noncoated MPs in the long term (12 weeks after injection). Taking all this together, we report new evidence in favor of the use of polymeric PLGA and PEG-PLGA MPs as delivery systems for treating MI, which could be soon included in clinical trials.

Heart regeneration after myocardial infarction using synthetic biomaterials.

Myocardial infarction causes almost 7.3 million deaths each year worldwide. However, current treatments are more palliative than curative. Presently, cell and protein therapies are considered the most promising alternative treatments. Clinical trials performed until now have demonstrated that these therapies are limited by protein short half-life and by low transplanted cell survival rate, prompting the development of novel cell and protein delivery systems able to overcome such limitations. In this review we discuss the advances made in the last 10years in the emerging field of cardiac repair using biomaterial-based delivery systems with focus on the progress made on preclinical in vivo studies. Then, we focus in cardiac tissue engineering approaches, and how the incorporation of both cells and proteins together into biomaterials has opened new horizons in the myocardial infarction treatment. Finally, the ongoing challenges and the perspectives for future work in cardiac tissue engineering will also be discussed.

Modeling nigrostriatal degeneration in organotypic cultures, a new ex vivo model of Parkinson's disease.

Parkinson's disease (PD) is the second most frequent neurodegenerative disorder afflicting 2% of the population older than 65 years worldwide. Recently, brain organotypic slices have been used to model neurodegenerative disorders, including PD. They conserve brain three-dimensional architecture, synaptic connectivity and its microenvironment. This model has allowed researchers a simple and rapid method to observe cellular interactions and mechanisms. In the present study, we developed an organotypic PD model from rat brains that includes all the areas involved in the nigrostriatal pathway in a single slice preparation, without using neurotoxins to induce the dopaminergic lesion. The mechanical transection of the nigrostriatal pathway obtained during slice preparation induced PD-like histopathology. Progressive nigrostriatal degeneration was monitored combining innovative approaches, such as diffusion tensor magnetic resonance imaging (DT-RMI) to follow fiber degeneration and mass spectrometry to quantify striatal dopamine content, together with bright-field and fluorescence microscopy imaging. A substantia nigra dopaminergic cell number decrease was observed by immunohistochemistry against rat tyrosine hydroxylase (TH) reaching 80% after 2 days in culture associated with a 30% decrease of striatal TH-positive fiber density, a 15% loss of striatal dopamine content quantified by mass spectrometry and a 70% reduction of nigrostriatal fiber fractional anisotropy quantified by DT-RMI. In addition, a significant decline of medium spiny neuron density was observed from days 7 to 16. These sagittal organotypic slices could be used to study the early stage of PD, namely dopaminergic degeneration, and the late stage of the pathology with dopaminergic and GABAergic neuron loss. This novel model might improve the understanding of PD and may represent a promising tool to refine the evaluation of new therapeutic approaches.

Adipose-derived stem cells combined with neuregulin-1 delivery systems for heart tissue engineering.

Myocardial infarction (MI) is the leading cause of death worldwide, and extensive research has therefore been performed to find a cure. Neuregulin-1 (NRG) is a growth factor involved in cardiac repair after MI. We previously described how biocompatible and biodegradable microparticles, which are able to release NRG in a sustained manner, represent a valuable approach to avoid problems related to the short half-life after systemic administration of proteins. The effectiveness of this strategy could be improved by combining NRG with several cytokines involved in cardiac regeneration. The present study investigates the potential feasibility of using NRG-releasing particle scaffold combined with adipose-derived stem cells (ADSC) as a multiple growth factor delivery-based tissue engineering strategy for implantation in the infarcted myocardium. NRG-releasing particle scaffolds with a suitable size for intramyocardial implantation were prepared by TROMS. Next, ADSC were adhered to particle scaffolds and their potential for heart administration was assessed in a MI rat model. NRG was successfully encapsulated reaching encapsulation efficiencies of 92.58 ± 3.84%. NRG maintained its biological activity after the microencapsulation process. ADSCs adhered efficiently to particle scaffolds within a few hours. The ADSC-cytokine delivery system developed proved to be compatible with intramyocardial administration in terms of injectability through a 23-gauge needle and tissue response. Interestingly, ADSC-scaffolds were present in the peri-infarted tissue 2 weeks after implantation. This proof of concept study provides important evidence required for future effectiveness studies and for the translation of this approach.

Drug development in Parkinson's disease: from emerging molecules to innovative drug delivery systems.

Current treatments for Parkinson's disease (PD) are aimed at addressing motor symptoms but there is no therapy focused on modifying the course of the disease. Successful treatment strategies have been so far limited and brain drug delivery remains a major challenge that restricts its treatment. This review provides an overview of the most promising emerging agents in the field of PD drug discovery, discussing improvements that have been made in brain drug delivery for PD. It will be shown that new approaches able to extend the length of the treatment, to release the drug in a continuous manner or to cross the blood-brain barrier and target a specific region are still needed. Overall, the results reviewed here show that there is an urgent need to develop both symptomatic and disease-modifying treatments, giving priority to neuroprotective treatments. Promising perspectives are being provided in this field by rasagiline and by neurotrophic factors like glial cell line-derived neurotrophic factor. The identification of disease-relevant genes has also encouraged the search for disease-modifying therapies that function by identifying molecularly targeted drugs. The advent of new molecular and cellular targets like α-synuclein, leucine-rich repeat serine/threonine protein kinase 2 or parkin, among others, will require innovative delivery therapies. In this regard, drug delivery systems (DDS) have shown great potential for improving the efficacy of conventional and new PD therapy and reducing its side effects. The new DDS discussed here, which include microparticles, nanoparticles and hydrogels among others, will probably open up possibilities that extend beyond symptomatic relief. However, further work needs to be done before DDS become a therapeutic option for PD patients.

Biodegradation and heart retention of polymeric microparticles in a rat model of myocardial ischemia.

Poly-lactide-co-glycolide (PLGA) microparticles emerged as one of the most promising strategies to achieve site-specific drug delivery. Although these microparticles have been demonstrated to be effective in several wound healing models, their potential in cardiac regeneration has not yet been fully assessed. The present work sought to explore PLGA microparticles as cardiac drug delivery systems. PLGA microparticles were prepared by Total Recirculation One-Machine System (TROMS) after the formation of a multiple emulsion. Microparticles of different size were prepared and characterized to select the most suitable size for intramyocardial administration. Next, the potential of PLGA microparticles for administration in the heart was assessed in a MI rat model. Particle biodegradation over time and myocardial tissue reaction were studied by routine staining and confocal microscopy. Results showed that microparticles with a diameter of 5 µm were the most compatible with intramyocardial administration in terms of injectability through a 29-gauge needle and tissue response. Particles were present in the heart tissue for up to 3 months post-implantation and no particle migration toward other solid organs was observed, demonstrating good myocardial retention. CD68 immunolabeling revealed 31%, 47% and below 4% microparticle uptake by macrophages 1 week, 1 month, and 3 months after injection, respectively (P<0.001). Taken together, these findings support the feasibility of the developed PLGA microparticles as vehicles for delivering growth factors in the infarcted myocardium.

Brain drug delivery systems for neurodegenerative disorders.

Neurodegenerative disorders (NDs) are rapidly increasing as population ages. However, successful treatments for NDs have so far been limited and drug delivery to the brain remains one of the major challenges to overcome. There has recently been growing interest in the development of drug delivery systems (DDS) for local or systemic brain administration. DDS are able to improve the pharmacological and therapeutic properties of conventional drugs and reduce their side effects. The present review provides a concise overview of the recent advances made in the field of brain drug delivery for treating neurodegenerative disorders. Examples include polymeric micro and nanoparticles, lipidic nanoparticles, pegylated liposomes, microemulsions and nanogels that have been tested in experimental models of Parkinson's, Alzheimer's and Huntington's disease. Overall, the results reviewed here show that DDS have great potential for NDs treatment.

Effective GDNF brain delivery using microspheres--a promising strategy for Parkinson's disease.

Glial cell line-derived neurotrophic factor (GDNF) has shown promise in the treatment of neurodegenerative disorders of basal ganglia origin such us Parkinson's disease (PD). In this study, we investigated the neurorestorative effect of controlled GDNF delivery using biodegradable microspheres in an animal model with partial dopaminergic lesion. Microspheres were loaded with N-glycosylated recombinant GDNF and prepared using the Total Recirculation One-Machine System (TROMS). GDNF-loaded microparticles were unilaterally injected into the rat striatum by stereotaxic surgery two weeks after a unilateral partial 6-OHDA nigrostriatal lesion. Animals were tested for amphetamine-induced rotational asymmetry at different times and were sacrificed two months after microsphere implantation for immunohistochemical analysis. The putative presence of serum IgG antibodies against rat glycosylated GDNF was analyzed for addressing safety issues. The results demonstrated that GDNF-loaded microspheres, improved the rotational behavior induced by amphetamine of the GDNF-treated animals together with an increase in the density of TH positive fibers at the striatal level. The developed GDNF-loaded microparticles proved to be suitable to release biologically active GDNF over up to 5 weeks in vivo. Furthermore, none of the animals developed antibodies against GDNF demonstrating the safety of glycosylated GDNF use.

Sustained release of bioactive glycosylated glial cell-line derived neurotrophic factor from biodegradable polymeric microspheres.

Glial cell-line derived neurotrophic factor (GDNF), a potent neurotrophic factor for dopaminergic neurons, appeared as a promising candidate for treating Parkinson's disease. GDNF microencapsulation could ensure protection against degradation due to the fragile nature of the protein. Poly(lactide-co-glycolide) (PLGA) microparticles loaded with recombinant glycosylated GDNF obtained in a mammalian cell line were prepared by TROMS, a semi-industrial technique capable of encapsulating fragile molecules maintaining their native properties. The effects of several parameters as PLGA copolymer type, PEG 400 quantity co-encapsulated with GDNF or drug loading, on the properties of the particles were investigated. Microparticles showed a mean diameter between 8 and 30 microm, compatible with their stereotaxic implantation. The drug entrapment efficiency ranged from 50.6% to 100% depending on the microsphere composition. GDNF was better encapsulated using hydrophilic polymers with high molecular weight such as RG 503H. In vitro drug release was influenced by the polymer type as well as by the amount of PEG 400 co-encapsulated with GDNF. Microparticles prepared using PLGA RG 503H released 67% of the total protein content within 40 days. Moreover, very low concentrations of poly(vinyl alcohol) were detected after microparticles washing and freeze-drying. Finally, a PC-12 bioassay demonstrated that the in vitro GDNF released was bioactive.

Purification of bioactive glycosylated recombinant glial cell line-derived neurotrophic factor.

Glial cell line-derived neurotrophic factor (GDNF) neuroprotective effect on dopaminergic neurons has been described in vitro and in vivo, turning up as a promising drug for the treatment of Parkinson's disease. Unglycosylated bacteria-obtained GDNF has already been successfully delivered for a long period of time through an infusion pump directly to the putamen of Parkinsonian patients. Nevertheless, improved distribution and safety issues need to be solved and alternative strategies to long-term delivery seem necessary. The use of glycosylated GDNF could eliminate some safety concerns regarding the presence of antibodies against exogenous unglycosylated GDNF used for the treatment. Therefore, we have chosen a mammalian expression system as a source of glycosylated GDNF. In the present work, we describe the purification of recombinant rat GDNF from the culture media of baby hamster kidney (BHK) cells through several purification steps. Highly pure N-glycosylated recombinant GDNF has been obtained similar to the endogenous protein. Furthermore, the purified protein is biologically active when tested its ability to induce PC12 neurite outgrowth.

Terapias neuroprotectoras y neurorestauradoras en el tratamiento de la enfermedad de Parkinson / Neuroprotective and neurorestorative therapies for the treatment of Parkinson’s disease

La enfermedad de Parkinson es la segunda enfermedad neurodegenerativa más común después del Alzheimer. Actualmente se dispone únicamente de terapias sintomáticas que, aunque son muy eficaces en las primeras etapas de la enfermedad poseen a largo plazo considerables efectos secundarios. La terapia ideal sería aquella que permitiese frenar o detener la progresión de la enfermedad. Este es el caso de las terapias neuroprotectoras y neurorestauradoras. De entre todas ellas, la terapia celular y la terapia con factores tróficos tipo GDNF son las que mayores expectativas han generado en la comunidad científica. Aunque ya se ha planteado el uso de GDNF para el tratamiento de la enfermedad de Parkinson, es necesario buscar nuevas estrategias que permitan administrar dicho factor neurotrófico en las zonas concretas del cerebro donde vaya a ejercer su acción. Aquí se discute el uso de micropartículas como el sistema más apropiado para la administración de dicho factor neurotrófico

Parkinson´s disease is the second most common neurodegenerative disorder after Alzheimer´s disease. Current therapies are symptomatic and, although these therapies are efficacious during the early stages of the disease, they present important side effects when they are used for a long time. The ideal therapy would be the one that would slow down or stop the progression of the disease. This can be achieved, for instance, with neuroprotective and neurorestorative therapies. Among them, cell therapy and therapy with trophic factors such as glial cell line derived neurotrophic factor (GDNF) are the most challenging and promising ones for the scientific community. Although the use of GDNF as a treatment for Parkinson ´s disease was proposed several years ago, it is necessary to develop alternative strategies to deliver GDNF appropriately to concrete areas of the brain. Here, the use of microspheres as the most suitable tool for the administration of this neurotrophic factor is discussed

[Neuroprotective and neurorestorative therapies for the treatment of Parkinson's disease]. / Terapias neuroprotectoras y neurorestauradoras en el tratamiento de la enfermedad de Parkinson.

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease. Current therapies are symptomatic and, although these therapies are efficacious during the early stages of the disease, they present important side effects when they are used for a long time. The ideal therapy would be the one that would slow down or stop the progression of the disease. This can be achieved, for instance, with neuroprotective and neurorestorative therapies. Among them, cell therapy and therapy with trophic factors such as glial cell line derived neurotrophic factor (GDNF) are the most challenging and promising ones for the scientific community. Although the use of GDNF as a treatment for Parkinson s disease was proposed several years ago, it is necessary to develop alternative strategies to deliver GDNF appropriately to concrete areas of the brain. Here, the use of microspheres as the most suitable tool for the administration of this neurotrophic factor is discussed.