13.2 Single and Multi-organ Chip Systems

Organ-on-a-chip systems are revolutionizing drug testing and disease modeling. Single-organ chips focus on specific organs, while multi-organ chips integrate multiple organs to better mimic whole-body physiology. These systems offer exciting possibilities for more accurate and efficient drug development.

Examples include liver-on-a-chip for toxicity studies and heart-on-a-chip for cardiotoxicity screening. Multi-organ chips face challenges in maintaining different cell types and scaling organ models, but they provide valuable insights into complex physiological processes and organ-organ interactions.

Single-Organ Chip Systems

Single-organ vs multi-organ chips

• Single-organ chip systems replicate specific organ function, feature simpler design and fabrication, allow easier control and analysis but limit systemic interaction representation (liver-on-a-chip)
• Multi-organ chip systems integrate multiple organ models on one platform, involve more complex design and fabrication, better represent organ-organ interactions, and mimic whole-body physiology more closely (body-on-a-chip)

Examples of organ-specific chips

• Liver-on-a-chip cultures hepatocytes in microfluidic channels mimicking liver sinusoids and lobular structure used for drug metabolism and toxicity studies
• Kidney-on-a-chip cultures renal tubular epithelial cells on a membrane simulating kidney filtration and reabsorption processes applied in nephrotoxicity testing
• Heart-on-a-chip cultures cardiomyocytes on flexible substrates mimicking cardiac tissue contraction and electrical activity used for cardiotoxicity screening and drug discovery
• Lung-on-a-chip recreates alveolar-capillary interface for studying respiratory diseases and drug delivery
• Brain-on-a-chip models blood-brain barrier and neural networks for neurotoxicity and neurological disorder research

Multi-Organ Chip Systems

Organ-organ interactions in chips

• Organ-organ interactions involve communication via signaling molecules, metabolic interplay, substance exchange, and systemic responses to stimuli
• Significance in multi-organ chips:
  1. Accurately represent in vivo conditions
  2. Enable complex physiological process studies
  3. Improve drug efficacy and toxicity predictions
  4. Allow investigation of multi-organ disease progression
• Examples: liver-kidney interaction for drug metabolism and elimination, gut-brain axis for studying neurological disorders

Challenges of multi-organ chips

• Technical challenges involve maintaining different cell types, scaling organ models to physiological ratios, and integrating modules while preserving individual functionalities
• Biological limitations include incomplete organ functionality in simplified models, absence of immune system components, and limited long-term effect representation
• Analytical challenges encompass real-time monitoring of multiple organs and complex data interpretation due to interconnected responses
• Standardization issues arise from lack of uniform protocols and variability in cell sources and culture conditions
• Validation and regulatory hurdles require extensive in vivo data comparison and overcoming adoption barriers for drug testing