RESUMEN
Addressing the aberrant interactions between immune cells and biomaterials represents an unmet need in biomaterial research. Although progress has been made in the development of bioinert coatings, identifying and targeting relevant cellular and molecular pathways can provide additional therapeutic strategies to address this major healthcare concern. To that end, we describe the immune inhibitory motif, receptor-ligand pairing of signal regulatory protein alpha and its cognate ligand CD47 as a potential signaling pathway to enhance biocompatibility. The goals of this article are to detail the known roles of CD47-signal regulatory protein alpha signal transduction pathway and to describe how immobilized CD47 can be used to mitigate the immune response to biomaterials. Current applications of CD47-modified biomaterials will also be discussed herein.
Asunto(s)
Materiales Biocompatibles/metabolismo , Materiales Biocompatibles/farmacología , Antígeno CD47/metabolismo , Factores Inmunológicos/metabolismo , Factores Inmunológicos/farmacología , Animales , Materiales Biocompatibles/química , Humanos , Factores Inmunológicos/química , Transducción de SeñalRESUMEN
The fate of nanoparticle (NP) formulations in the multifaceted biological environment is a key determinant of their biocompatibility and therapeutic performance. An understanding of the degradation patterns of different types of clinically used and experimental NP formulations is currently incomplete, posing an unmet need for novel analytical tools providing unbiased quantitative measurements of NP disassembly directly in the medium of interest and in conditions relevant to specific therapeutic/diagnostic applications. In the present study, this challenge was addressed with an approach enabling real-time in situ monitoring of the integrity status of NPs in cells and biomimetic media using Förster resonance energy transfer (FRET). Disassembly of polylactide-based magnetic NPs (MNPs) was investigated in a range of model biomimetic media and in cultured vascular cells using an experimentally established quantitative correlation between particle integrity and FRET efficiency controlled through adjustments in the spectral overlap between two custom-synthesized polylactide-fluorophore (boron dipyrromethene) conjugates incorporated in MNPs. The results suggest particle disassembly governed by diffusion-reaction processes with kinetics strongly dependent on conditions promoting release of oligomeric fragments from the particle matrix. Thus, incubation in gels simulating the extracellular environment and in protein-rich serum resulted in notably lower and higher MNP decomposition rates, respectively, compared with nonviscous liquid buffers. The diffusion-reaction mechanism also is consistent with a significant cell growth-dependent acceleration of MNP processing in dividing vs. contact-inhibited vascular cells. The FRET-based analytical strategy and experimental results reported herein may facilitate the development and inform optimization of biodegradable nanocarriers for cell and drug delivery applications.
Asunto(s)
Materiales Biomiméticos/análisis , Portadores de Fármacos/química , Nanopartículas de Magnetita/química , Ensayo de Materiales/métodos , Análisis de Varianza , Vasos Sanguíneos/citología , Sistemas de Computación , Transferencia Resonante de Energía de Fluorescencia , Nanopartículas de Magnetita/uso terapéuticoRESUMEN
Gene therapeutic strategies have shown promise in treating vascular disease. However, their translation into clinical use requires pharmaceutical carriers enabling effective, site-specific delivery as well as providing sustained transgene expression in blood vessels. While replication-deficient adenovirus (Ad) offers several important advantages as a vector for vascular gene therapy, its clinical applicability is limited by rapid inactivation, suboptimal transduction efficiency in vascular cells, and serious systemic adverse effects. We hypothesized that novel zinc oleate-based magnetic nanoparticles (MNPs) loaded with Ad would enable effective arterial cell transduction by shifting vector processing to an alternative pathway, protect Ad from inactivation by neutralizing factors, and allow site-specific gene transfer to arteries treated with stent angioplasty using a 2-source magnetic guidance strategy. Ad-loaded MNPs effectively transduced cultured endothelial and smooth muscle cells under magnetic conditions compared to controls and retained capacity for gene transfer after exposure to neutralizing antibodies and lithium iodide, a lytic agent causing disruption of free Ad. Localized arterial gene expression significantly stronger than in control animal groups was demonstrated after magnetically guided MNP delivery in a rat stenting model 2 and 9 d post-treatment, confirming feasibility of using Ad-loaded MNPs to achieve site-specific transduction in stented blood vessels. In conclusion, Ad-loaded MNPs formed by controlled precipitation of zinc oleate represent a novel delivery system, well-suited for efficient, magnetically targeted vascular gene transfer.
Asunto(s)
Adenoviridae/genética , Arterias , Técnicas de Transferencia de Gen , Vectores Genéticos/administración & dosificación , Nanopartículas de Magnetita , Stents , Angioplastia , Animales , Arterias/metabolismo , Bovinos , Línea Celular , Terapia Genética , Masculino , Ácido Oléico , Ratas , Ratas Sprague-Dawley , ZincRESUMEN
PURPOSE: Cells modified with magnetically responsive nanoparticles (MNP) can provide the basis for novel targeted therapeutic strategies. However, improvements are required in the MNP design and cell treatment protocols to provide adequate magnetic properties in balance with acceptable cell viability and function. This study focused on select variables controlling the uptake and cell compatibility of biodegradable polymer-based MNP in cultured endothelial cells. METHODS: Fluorescent-labeled MNP were formed using magnetite and polylactide as structural components. Their magnetically driven sedimentation and uptake were studied fluorimetrically relative to cell viability in comparison to non-magnetic control conditions. The utility of surface-activated MNP forming affinity complexes with replication-deficient adenovirus (Ad) for transduction achieved concomitantly with magnetic cell loading was examined using the green fluorescent protein reporter. RESULTS: A high-gradient magnetic field was essential for sedimentation and cell binding of albumin-stabilized MNP, the latter being rate-limiting in the MNP loading process. Cell loading up to 160 pg iron oxide per cell was achievable with cell viability >90%. Magnetically driven uptake of MNP-Ad complexes can provide high levels of transgene expression potentially useful for a combined cell/gene therapy. CONCLUSIONS: Magnetically responsive endothelial cells for targeted delivery applications can be obtained rapidly and efficiently using composite biodegradable MNP.
Asunto(s)
Sistemas de Liberación de Medicamentos , Células Endoteliales/metabolismo , Magnetismo , Nanopartículas , Implantes Absorbibles , Animales , Bovinos , Supervivencia Celular , Células Cultivadas , Química Farmacéutica , Estabilidad de Medicamentos , Óxido Ferrosoférrico/química , Colorantes Fluorescentes/química , Técnicas de Transferencia de Gen , Cinética , Estructura Molecular , Tamaño de la Partícula , Poliésteres/química , Tensoactivos/químicaRESUMEN
The application of porous hollow fibers has recently been extended to the controlled release of biologics such as protein growth factors and lipid angiogenesis promoters. Release of these materials tends to occur more rapidly than would be predicted by conventional diffusion-based models of controlled release. Analysis of other modalities of transport as well as structural analysis of the controlled release system itself was performed to provide insight into the observed controlled release behavior from such systems. Specifically, it was discovered that osmotic-driven processes play a significant role in controlled release of proteins including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). It was also found that the fiber pore microstructure and (more importantly) macrostructure influences release behavior. Model-guided design was implemented to adjust the physical properties of the fiber wall, leading to a release system that is better able to sustain the delivery of VEGF. This model may be used to more easily achieve a desired complex release behavior when used in combination with external regulation of the reservoir.
Asunto(s)
Productos Biológicos/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Microscopía Electrónica de Rastreo , Modelos Teóricos , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
An externally regulated delivery model that permits temporal separation of multiple angiogenic factors was used for the delivery of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF). While bFGF plays a significant role in the sprouting of new capillaries, PDGF plays a role in the recruitment of mural cells, which stabilize neovessels. However, these two factors have been shown to inhibit each other, when presented together. Using the externally regulated model, sequential delivery of bFGF and PDGF led to not only increased endothelial cell migration, but also endothelial cell and vascular pericyte colocalization. More importantly, this delivery strategy was able to induce red blood cell-filled neovessels, suggesting integration of angiogenesis with the existing vasculature.
Asunto(s)
Movimiento Celular/efectos de los fármacos , Células Endoteliales/metabolismo , Factor 2 de Crecimiento de Fibroblastos/farmacología , Neovascularización Fisiológica/efectos de los fármacos , Pericitos/metabolismo , Factor de Crecimiento Derivado de Plaquetas/farmacología , Animales , Células Endoteliales/citología , Ratones , Neovascularización Fisiológica/fisiología , Pericitos/citologíaRESUMEN
Angiogenesis is an organized series of events, beginning with vessel destabilization, followed by endothelial cell re-organization, and ending with vessel maturation. Vascular endothelial growth factor (VEGF) aids in vascular permeability and endothelial cell recruitment while sphingosine 1-phosphate (S1P) stimulates vascular stability. Accordingly, VEGF may inhibit vessel stabilization while S1P may inhibit endothelial cell recruitment. For this reason, we created a new externally-regulated delivery model that not only permits sustained release of bioactive factors, but also temporal separation of the delivery of growth factors. Using this model, sequential delivery of factors was first confirmed in vitro with associated endothelial cells responding in a dose dependent manner. Furthermore, using a modified murine Matrigel plug model, it is apparent that delivery strategies where VEGF presentation is temporally separated from S1P presentation not only led to greater recruitment of endothelial cells, but also higher maturation index of associated vessels.