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Published on: August 24, 2021
Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis
Jiangtao Chu1, Vitali Koudriavtsev, Klas Hjort
1Department of Engineering Sciences, Uppsala University, Box 534, 751 21, Uppsala, Sweden.
Abstract:
When microdialysis (MD) membrane exceeds molecular weight cut-off (MWCO) of 100 kDa, the fluid mechanics are in the ultrafiltration regime. Consequently, fluidic mass transport of macromolecules in the perfusate over the membrane may reduce the biological relevance of the sampling and cause an inflammatory response in the test subject. Therefore, a method to investigate the molecular transport of high MWCO MD is presented. An in vitro test chamber was fabricated to facilitate the fluorescent imaging of the MD sampling process, using fluoresceinylisothiocyanate (FITC) dextran and fluorescence microscopy. Qualitative studies on dextran behavior inside and outside the membrane were performed. Semiquantitative results showed clear dextran leakage from both 40 and 250 kDa dextran when 100 kDa MWCO membranes were used. Dextran 40 kDa leaked out with an order of magnitude higher concentration and the leakage pattern resembled more of a convective flow pattern compared with dextran 250 kDa, where the leakage pattern was more diffusion based. No leakage was observed when dextran 500 kDa was used as a colloid osmotic agent. The results in this study suggest that fluorescence imaging could be used as a method for qualitative and semiquantitative molecular transport and fluid dynamics studies of MD membranes and other hollow fiber catheter membranes.
Insights
High molecular weight cut-off (MWCO) microdialysis (MD) membranes allow macromolecule leakage, impacting biological relevance. Fluorescence imaging effectively visualizes this molecular transport and fluid dynamics in MD and hollow fiber membranes.
Area of Science:
- Biomedical Engineering
- Biomaterials Science
- Analytical Chemistry
Background:
- Microdialysis (MD) membranes exceeding 100 kDa molecular weight cut-off (MWCO) operate in an ultrafiltration regime.
- This can lead to reduced biological relevance of sampling and potential inflammatory responses due to macromolecule transport.
Purpose of the Study:
- To present a novel method for investigating molecular transport in high MWCO MD membranes.
- To qualitatively and semiquantitatively assess dextran leakage and transport dynamics.
Main Methods:
- Fabrication of an in vitro test chamber for fluorescence imaging.
- Utilizing fluoresceinylisothiocyanate (FITC) dextran and fluorescence microscopy to study molecular transport.
- Testing membranes with varying MWCOs (100 kDa) and dextran sizes (40 kDa, 250 kDa, 500 kDa).
Main Results:
- Significant dextran leakage observed with 40 kDa and 250 kDa dextrans through 100 kDa MWCO membranes.
- 40 kDa dextran exhibited higher concentration leakage with a convective pattern, while 250 kDa showed diffusion-based leakage.
- No leakage was detected for 500 kDa dextran when used as a colloid osmotic agent.
Conclusions:
- Fluorescence imaging provides a viable method for qualitative and semiquantitative analysis of molecular transport in MD membranes.
- The study highlights potential issues with high MWCO MD membranes and offers insights into fluid dynamics.
- Findings are applicable to other hollow fiber catheter membrane systems.
