Xenotransplantation of cells using biodegradable microcapsules

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Immunology

Background:

• Immunoisolation protects transplanted cells from host immune rejection, crucial for treating diseases like diabetes.
• Cellular therapies often require periodic cell replenishment due to limited functional longevity.
• Existing methods may necessitate surgical intervention for implant removal.

Purpose of the Study:

• To develop and characterize a hydrogel-based microcapsule system with tunable degradation rates.
• To assess the immunoprotective and biodegradable properties of these microcapsules for cell transplantation.
• To enable non-surgical replenishment of encapsulated cells.

Main Methods:

• Fabrication of composite microcapsules using alginate and poly(L-lysine) (PLL).
• Immobilization of xenogeneic islets (porcine and bovine) within the microcapsules.
• In vivo implantation into diabetic rat models and in vitro biodegradability studies using tritosomes.

Main Results:

• Xenogeneic islets encapsulated in composite microcapsules demonstrated long-term viability (>40 weeks) in non-immunosuppressed rats.
• Microcapsule degradation rates were controllable by adjusting alginate concentration, ranging from weeks to over a year.
• Uncoated alginate spheres showed poor islet survival, highlighting the necessity of the composite structure.

Conclusions:

• A microcapsule system with controllable biodegradability was successfully designed, allowing for natural absorption of implants.
• This technology facilitates cell replenishment without surgery, enhancing the practicality of cellular therapies.
• The cross-species compatibility of these biodegradable microcapsules broadens their potential application in treating a wider range of diseases.