- Email:
Blood-Brain Barrier Model
Overview of Blood-Brain Barrier Model
The blood-brain barrier (BBB) is unique because it has selective permeability (which also changes in some diseased conditions). The BBB is a complex system made up of a structurally distinct, continuous endothelial cell layer separating the blood from the extracellular fluid of the brain. The luminal plasma membrane of the endothelial cells is directed towards the blood, while the abluminal plasma membrane faces the brain. The presence of adhesion molecules and tight junctions between endothelial cells and the low density of pinocytes are some of the key structural features that make the BBB selectively permeable.
Fig.1 The multicellular structure of the blood-brain barrier (BBB)/neurovascular unit (NVU). (Daneman, 2015)
BBB and Drug Delivery in CNS
The BBB is responsible for physiologically protecting the brain from exposure to toxins and ill effects. However, this physiological protective function of the BBB presents a key challenge to the pharmaceutical fraternity, with a need to circumvent it to deliver drugs to the brain in various CNS disorders. While actual or potential routes across the BBB are under rigorous control to maintain the homeostatic functions of the barrier, many of them are altered or disturbed in pathology. Hence therapeutic delivery strategies need to consider both the possible routes for the transendothelial movement of therapeutics and how these routes are modified pathologies. CNS drugs should possess specific physicochemical properties, which allow them to penetrate the blood-brain barrier.
Functions of the blood-brain barrier:
- Controls molecular traffic, keeps out toxins (minimizes neuronal cell death, preserves neural connectivity).
- Contributes to ion homeostasis for optimal neural signaling.
- Maintains low protein environment in CNS, limits proliferation, preserves neural connectivity.
- Separates central and peripheral neurotransmitter pools, reduces cross-talk allows non-synaptic signaling in CNS.
- Allows immune surveillance and response with minimal inflammation and cell damage.
In Vitro Models of BBB
- Cell-based In Vitro BBB Models
- ECM In Vitro BBB Models
- Microfluidic-based In Vitro BBB Models
- 3D Printing-based In Vitro BBB Models
Endothelial cells plated on synthetic materials have long been crafted for simulation of the BBB. Simple in vitro models have utilized endothelial cells plated in a monolayer to evaluate junctional integrity. Yet more sophisticated studies have utilized neurons, stem cells, microglia, lymphocytes, astrocytes, and/or pericytes, in addition to endothelial cells, to enhance paracellular BBB integrity for various analysis platforms.
Co-cultured cells in extracellular matrix (ECM) protein solutions, such as collagen I, laminin, fibronectin, and/or matrigel have assisted in evaluating the complexity of BBB architecture for three-dimensional modeling. While the brain consists mainly of neurons and glial cells, 10 to 25% of the total volume is ECM, which includes hyaluronic acid, proteoglycans, tenascins, link proteins, and laminin. The combination of these ECM components allows for ample support of neurons, glia, and endothelial-pericytes among a loose meshwork of soft material that is suitable for growth, migration, and extension. The use of these rich EC matrices enables observations of the adjacent interaction among BBB cells pre- and post-therapy in a three-dimensional culture setting, often with the formation of capillary-like tubes formed by adjacent endothelial cells.
Dynamic microfluidic systems, such as BBB-on-a-chip, enhance the co-culture models mentioned above by incorporating realistic geometries and physiological fluid flow. Like normal physiologic state, these dynamic systems allow for intraluminal pressure and shear stress to produce capillary-like models with low permeability, high TEER, and expression of relevant transporters and efflux proteins. These microfluidic models consist of a cylindrical chamber made of a porous cell culture substrate with a micropump, which allows media to flow through and around the chamber(s). Endothelial cells are seeded on the luminal surface and other neurovascular unit cells can be seeded on the abluminal surface.
In recent years, three-dimensional printing has emerged as an alternative manufacturing process. The 3D printing approach allows faster and cheaper fabrication, built-in assay technology, and greater flexibility in design. These microfluidic devices enable dynamic evaluation of BBB integrity, permeability, and cell invasion through real-time measurements of TEER, dye permeability, and fluorescent cell imaging. These real-time readouts are advantageous for studying drug permeability across the BBB, dye extravasation in response to drug screening, and cell invasion by immune cells or tumor cells. When coupled with the co-culture of iPSC-derived endothelial cells, pericytes, astrocytes, and neurons, these microfluidic devices closely resemble physiologic BBB.
| BBB model | Model subtype | Applications/ biological relevance | Advantages | Limitations |
|---|---|---|---|---|
|
2-D transwell
|
Polycarbonate or polyethylene terephthalate membrane, varied pore size and pore density | Cell permeability/extravasation assays, junctional protein fluorescence expression, TEER | Short time assay for permeability assay, low-cost, co-cultured cells, high-throughput screening | Static system, lack of luminal shear stress, poor endothelial cell differentiation, and adaptation to microenvironmental cells |
|
3-D co-culture
|
Matrigel, hyaluronic acid, laminin, collagen I, fibronectin, scaffold matrix | Evaluation of close interactions between cells, cross-signaling, angiogenesis, gene expression | Low cost, co-cultured cells | Static system, unable to perfuse vasculature, unable to utilize for high-throughput screening, contains major cell-derived matrices but lacks minor ECM proteins/factors |
|
BBB-on-a-chip
|
Microfluidic devices | Physiologic representation of cell invasion, dye extravasation, drug sensitivity, cell growth, drug permeability, gene expression | Dynamic model of cell-cell interaction, high TEER values, co-cultured cells, cell imaging, and permeability evaluable in real-time, shear stress | Prolonged time for assay development and permeability assessment, expensive, time-consuming, technical expertise necessary, not suitable for high-throughput screens |
Services at Creative Biolabs
With rich experience in neuroscience ex vivo models, Creative Biolabs has established a great industrial reputation. We have successfully satisfied hundreds of customers' demands on neuroscience researches during the last ten years. Strong foundations and excellent expert teams are powerful guarantees of the quality of our services. If you are interested in custom blood-brain barrier models services, or any other services about neuroscience, please feel free to contact us for more information.
Our services are cutting-edge scientific services focused around creating and utilizing personalized blood-brain barrier models.
| Services | Descriptions |
|---|---|
| Custom BBB Model | Our service begins with creating a custom, personalized BBB model using client-specified factors. This can be from a variety of cell types, including induced pluripotent stem cells (iPSCs), primary cells, or immortalized cell lines. These personalized models mimic the human BBB's tight-junctional complex, in a superior manner, provide a more accurate prediction of a drug's BBB permeability. |
| Comprehensive Platform | We provide a comprehensive service platform aiding in areas such as drug penetration studies, neurotoxicity assessment, disease modelling, and drug efficiency testing. |
This service can help find solutions to some of the biggest challenges in neuroscience drug development, providing a critical tool in the advancement of treatments for various neurological disorders. We provide cutting-edge solutions tailored to meet the specific needs of our clients in drug development, neurobiology research, and neuropharmacology. Here are some features of our service:
- Advanced Cell Culture Techniques - Our BBB models utilize advanced cell culture techniques to ensure the fidelity and reliability of the in vitro system. We employ primary brain endothelial cells, co-culture systems with astrocytes and pericytes, or engineered cell lines to accurately replicate the BBB microenvironment.
- Barrier Integrity Assessment - We perform comprehensive assessments of barrier integrity using techniques such as transendothelial electrical resistance (TEER), permeability assays, and immunostaining. These evaluations ensure that the BBB model maintains its barrier properties over time and accurately reflects physiological conditions.
- Transport Studies - We can assess the ability of drugs or molecules to cross the barrier via passive diffusion, carrier-mediated transport, or receptor-mediated transcytosis, providing valuable insights into CNS drug delivery and pharmacokinetics.
- Experienced Team
- Quality Control
- Global Service
- Timely Delivery
Our services offer a comprehensive platform for studying BBB physiology, drug transport, and CNS drug development, empowering our clients to advance their research and therapeutic goals in the field of neuroscience.
Applications
Our services find application in several pivotal areas of the biology, medicine, and pharmaceutical sectors.
- Drug Development: with our customized BBB models, pharmaceutical companies can test and screen their drug candidates' ability to cross the BBB efficiently.
- Disease Modelling: our BBB models can help in creating specific disease models, including neurodegenerative diseases like Alzheimer's, Parkinson's, and Multiple Sclerosis.
- Nanoparticle Testing: BBB models can be pivotal in testing how well nanoparticles for drug delivery to the brain can traverse the barrier.
- Studying the Interactions: understanding the complex interaction between the brain and its barrier can help create better methods to temporarily open the BBB for drug delivery.
FAQs
-
Q: Can you accommodate specific requests for incorporating disease-related factors or stimuli into your blood-brain barrier models?
A: Yes, we can incorporate disease-relevant factors, such as inflammation mediators or neurotoxic agents, into our blood-brain barrier models to simulate pathological conditions accurately. This customization allows researchers to investigate disease mechanisms and evaluate potential therapeutic interventions in a controlled experimental setting. -
Q: What is the turnaround time for this service?
A: The turnaround time for our service greatly depends on the complexity of the custom-made model. However, the average time is often around 4-6 weeks. We strive to ensure that you receive your tailored model promptly and in optimal condition. -
Q: How do you ensure the quality and accuracy of your models?
A: We verify the integrity of our BBB models using permeability assays and expression analysis of BBB marker genes, ensuring that they accurately represent the human blood-brain barrier. Additionally, all our processes are performed following strict scientific guidelines to maintain high standards of quality and accuracy. -
Q: What if the model created does not meet my specific requirements?
A: We aim for client satisfaction, so if the model does not meet your specific requirements, we will redo the work. Our team will communicate with you closely throughout the project to ensure that we understand your needs and expectations, helping to minimize potential issues.
Scientific Resources
Reference
- Daneman, R. and Prat, A. The blood-brain barrier. Cold Spring Harb Perspect Biol. 2015, 7(1): a020412.
For Research Use Only. Not For Clinical Use.