Effect of microencapsulation on oxygen distribution in islets organs

Area of Science:

• Physiology
• Biomedical Engineering

Background:

• Oxygen supply is a critical factor limiting graft function in islet transplantation, especially with encapsulated tissues.
• Understanding oxygen distribution within isolated islet organs is essential for improving transplantation outcomes.

Purpose of the Study:

• To measure oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami.
• To investigate the effects of fluid convection and microencapsulation on oxygen distribution within these tissues.

Main Methods:

• PO2 measurements were conducted using microelectrodes in a controlled chamber at 37°C.
• Studies involved two groups: one examining fluid convection (n=12) and another microencapsulation (n=12).
• Sigmoidal PO2 profiles were analyzed to identify oxygen-depleted zones, oxygen-consuming rims, and central necrotic areas.

Main Results:

• Sigmoidal PO2 profiles were observed, indicating distinct oxygen gradients from the surface to the center.
• Stopping fluid convection significantly decreased PO2 levels, both at the surface and in the tissue center.
• Microencapsulation, compared to non-encapsulated tissue, resulted in lower surface and center PO2 values and a thicker oxygen-depleted zone.

Conclusions:

• Barium alginate encapsulation appears to worsen islet tissue oxygenation, primarily by increasing the unstirred water layer.
• Fluid convection plays a vital role in maintaining adequate oxygen supply to isolated islet tissues.
• These findings highlight the importance of optimizing oxygenation strategies for successful islet transplantation.