Transplantation of encapsulated pancreatic islets is a novel therapeutic approach for the treatment of Type 1 diabetes mellitus that has the potential to circumvent both a limited islet supply and immunosuppression. Current methods for scoring the biocompatibility of the alginate-based capsules that sequester Islets of Langerhans include fabrication and implantation into the peritoneal cavity of mice, incubation, retrieval via peritoneal lavage, and observation of the number of cells or cell layers surrounding the capsules. This method allows only one data point to be obtained per animal. We describe a method to measure biocompatibility real time and in situ. This method of monitoring immune response using bioluminescent technology and a nuclear factor-kappa beta (NF-kB) sensitive transgenic mouse model allows many data points to be acquired per animal, reduces the number of animals required to obtain statistically significant immune response data over time, and in turn reduces error associated with animal variability. NF-kB is a transcription factor that coordinates the inflammatory and wound healing cascades by initiating the transcription of cytokines, chemokines, adhesion molecules, and proinflammatory genes.
Inflammation after the transplantation of five types of capsules was monitored for 6 six weeks after transplantation into the dorsal-cervical fat pad.
Bioluminescence over 6-week time period: Capsule group 1.0±.00 normalized units2, Bead group 1.3±.26 normalized units2, No coat group .96±.48 normalized units2, Sham group .96±.00 normalized units2, Control group .17±.11 normalized units2.
This imaging modality was able to detect statistically significant differences in NF-kB activity between pre- and postoperative data points per mouse. It was also able to discern an unexpected increase in NF-kB activity due to capsule size instead of capsule wall composition over a 6-week time period.
1 Department of Biomedical Engineering, Vanderbilt University, Nashville, TN.
2 Diabetes, Endocrinology, and Metabolism Division, Vanderbilt University, Nashville, TN.
3 Department of Mechanical Engineering, Vanderbilt University, Nashville, TN.
This study was supported by the Juvenile Diabetes Foundation and the National Aeronautics and Space Administration.
4 Address correspondence to: David Roth, M.S., Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville TN, 37232. E-mail: email@example.com
Received 18 October 2005. Accepted 31 December 2005.