| Property |
Value |
| Category |
Drug Delivery Technology |
| Target |
Brain tumors, Parkinson's, Alzheimer's, ALS |
| Mechanism |
Bulk flow infusion under pressure for distributed drug delivery |
| Status |
Clinical Trials (Phase I/II) |
Convection-Enhanced Delivery (CED) is an advanced technique for delivering therapeutic agents directly into brain tissue by applying hydrostatic pressure to create bulk flow. This method overcomes the limitations of diffusion-based delivery, enabling uniform distribution of large molecules, nanoparticles, and genes throughout targeted brain regions.
CED uses the following principle:
- Infusion catheter placed in target brain region
- Positive pressure applied via infusion pump (typically 0.5-10 μL/min)
- Bulk flow creates interstitial distribution
- Uniform coverage achieved beyond catheter tip
| Factor |
Convection-Enhanced |
Diffusion |
| Distribution |
Pressure-driven bulk flow |
Concentration gradient |
| Volume |
Predictable, scalable |
Limited, unpredictable |
| Molecular weight |
All sizes |
Limited to small molecules |
| Time |
Hours to days |
Days to weeks |
| Coverage |
1-10 cm³ per catheter |
Few millimeters |
| Application |
Agent |
Target |
Status |
| Neurotrophic factor delivery |
GDNF |
Putamen |
Phase I/II |
| Neurotrophic factor delivery |
AAV-GDNF |
Putamen |
Phase I |
| Gene therapy |
AAV-AADC |
Putamen |
Phase I/II |
- Anti-amyloid antibodies (e.g., aducanumab, lecanemab)
- Anti-tau therapies
- Neurotrophic factors (BDNF, NGF)
- Gene therapy vectors
- Antisense oligonucleotides
- Neurotrophic factors
- VEGF delivery
- Stem cells
- Chemotherapy agents (e.g., paclitaxel, topotecan)
- Immunotoxins
- Viral vectors
¶ Equipment and Technique
- Single-lumen catheters - Standard CED
- Dual-lumen catheters - Reflux prevention
- Multiple microcatheters - Extended coverage
- Smart catheters - Real-time pressure monitoring
- Pressure: 5-100 mmHg
- Rate: 0.5-10 μL/min (typically 1-5 μL/min)
- Volume: 0.5-10 mL per infusion
- Duration: 4-48 hours per treatment
- MRI - Real-time visualization with gadolinium
- CT - Anatomical planning
- PET - Target verification
- Bypasses BBB - Direct brain delivery
- Predictable distribution - Pressure-controlled
- Large molecule delivery - Proteins, antibodies, genes
- Reduced systemic toxicity - Local delivery
- Repeatable treatments - Implantable ports
- Targeted delivery - Specific brain regions
¶ Challenges and Limitations
- Reflux - Backflow along catheter track
- Infusion rate optimization - Balance of distribution vs. pressure
- Catheter placement accuracy - Requires precise targeting
- Distribution heterogeneity - Tissue variability
- Increased intracranial pressure - Large volumes
- Tissue damage - High pressure/flow rates
- Infection risk - Indwelling catheters
- Brain edema - Fluid extravasation
| Study |
Year |
Agent |
Patients |
Outcome |
| Gill et al. |
2003 |
GDNF |
10 |
Improved UPDRS |
| Lang et al. |
2006 |
GDNF |
58 |
Mixed results |
| Marks et al. |
2010 |
AAV-GAD |
66 |
Improved motor function |
- CED of AAV-GDNF for advanced PD
- CED of AADC gene therapy for PD
- CED of topotecan for gliomas
- Gene therapy - AAV, lentiviral vectors
- Combination therapy - Multiple agents
- Stem cell delivery - Neural progenitors
- RNAi/antisense - Gene silencing
- CAR-T cells - Immunotherapy
- Real-time MRI monitoring - Improved distribution
- Smart catheters - Pressure/reflux control
- Novel formulations - Enhanced convection
- Automated systems - Precision infusion
The study of Convection Enhanced Delivery For Neurodegeneration has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Bobo RH, et al. (1994). Convection-enhanced delivery of macromolecules in the brain. Proc Natl Acad Sci. 91(6):2076-2080. PMID:8134401
- Morrison PF, et al. (1994). Focal delivery during direct infusion to the brain: the role of diffusion, bulk flow, and stereotactic injection. Cancer Res. 54(12):3283-3291. PMID:8205544
- Gill SS, et al. (2003). Direct brain infusion of glial cell line-derived neurotrophic factor in Parkinson disease. Nat Med. 9(5):589-595. PMID:12669033
- Lonser RR, et al. (2015). Convection-enhanced delivery to the central nervous system. J Neurosurg. 122(3):697-706. PMID:25479570
- Mehta AM, et al. (2017). Convection-enhanced delivery: anatomical and clinical considerations. Neurosurgery. 81(2):277-288. PMID:28379661