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Generation of Alginate Microspheres for Biomedical Applications
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Radiopaque alginate microcapsules for X-ray visualization and immunoprotection of cellular therapeutics
B P Barnett1, D L Kraitchman, C Lauzon
1Russell H Morgan Department of Radiology and Radiological Science and Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Molecular Pharmaceutics
|October 3, 2006
Summary
Researchers developed novel radiopaque microcapsules for X-ray guided delivery and imaging of cellular therapeutics. These barium or bismuth sulfate-containing capsules maintain cell viability and function, enabling non-invasive monitoring of cell transplants.
Area of Science:
- Biomaterials Science
- Regenerative Medicine
- Medical Imaging
Background:
- Alginate-poly-L-lysine-alginate (APA) microcapsules offer controlled drug release and immunoisolation for cell therapies.
- Non-invasive monitoring of microcapsule-delivered therapeutics is crucial for assessing transplantation site, delivery methods, and graft survival.
- Current APA microcapsules lack radiopacity, hindering X-ray based imaging and tracking.
Purpose of the Study:
- To develop novel radiopaque alginate-based microcapsules for X-ray guided delivery and imaging of cellular therapeutics.
- To evaluate the biocompatibility, permselectivity, and functionality of radiopaque microcapsules containing human islets.
Main Methods:
- Formulation of two radiopaque microcapsule types: barium sulfate (Ba X-Caps) and bismuth sulfate (Bi X-Caps).
- Assessment of cell viability and function (glucose-responsive insulin secretion) of encapsulated human islets.
- Evaluation of capsule permselectivity using lectins of varying molecular weights.
- In vitro and in vivo visualization of radiopaque microcapsules using fluoroscopy in mice and rabbits.
Main Results:
- Ba X-Caps and Bi X-Caps showed minimal impact (<5%) on encapsulated islet viability over 14 days.
- Capsules exhibited selective permeability, blocking antibodies (>120 kDa) while allowing nutrient and insulin diffusion (<75 kDa).
- Encapsulated islets maintained glucose-responsive insulin secretion, comparable to non-radiopaque controls.
- Both Ba X-Caps and Bi X-Caps were successfully visualized in vitro and in vivo for at least two weeks post-transplantation.
Conclusions:
- The developed radiopaque microcapsules are biocompatible and maintain the function of encapsulated cellular therapeutics.
- These novel capsules enable non-invasive X-ray imaging for tracking and monitoring cell delivery and survival.
- Radiopaque microcapsules hold significant potential for advancing cell-based therapies requiring image-guided delivery and assessment.
