Calcium phosphate cement chamber as an immunoisolative device for bioartificial pancreas: in vitro and preliminary in vivo study

Insulin-loaded hydroxyapatite combined with macrophage activity to deliver insulin for diabetes mellitus

InsHAP is engulfed by macrophages and the lysosome/endosome hybrid is broken down by osmosis, which facilitates delivery of insulin into the bloodstream.

Comparison of bioartificial pancreas performance in the bone marrow cavity and intramuscular space

BACKGROUND AND AIMS

Bone marrow with a widely distributed and well-vascularized microenvironment that is capable of sustaining grafts is a potential site for islet transplantation. The femur bone marrow cavity offers sufficient space that may also receive the implantation of bioartificial pancreas (BAP).

METHODS

Mouse insulinoma cells encapsulating in agarose gel were further enclosed in a calcium phosphate cement chamber to create a BAP. BAPs implanted into the femur bone marrow cavity of diabetics were compared with those implanted in the intramuscular space. Blood glucose level and C-peptide were determined perioperatively.

RESULTS

The blood glucose level of the diabetics receiving BAPs in the intramuscular space decreased from 413 +/- 24 to 285 +/- 47 mg/dL at 1 day post-surgery. However, the blood glucose level returned to 398 +/- 35 mg/dL with undetectable serum C-peptide at 2 weeks postoperatively that reveals implant failure. The blood glucose level of diabetics receiving BAPs into the femur bone marrow cavity decreased from 422 +/- 32 to 247 +/- 52 mg/dL and maintained in the range of 288 +/- 47 mg/dL during the experimental period with an increase in C-peptide level from 6.1 +/- 2.8 to 104.7 +/- 16.4 pmol/L.

CONCLUSIONS

This preliminary study indicates that the effectiveness of BAPs transplanted into the femur bone marrow cavity is superior to that implanted in the intramuscular space, which reveals the bone marrow may be a potential receptor site for the BAP transplantation.

Enhancing clinical islet transplantation through tissue engineering strategies

Clinical islet transplantation (CIT), the infusion of allogeneic islets within the liver, has the potential to provide precise and sustainable control of blood glucose levels for the treatment of type 1 diabetes. The success and long-term outcomes of CIT, however, are limited by obstacles such as a nonoptimal transplantation site and severe inflammatory and immunological responses to the transplant. Tissue engineering strategies are poised to combat these challenges. In this review, emerging methods for engineering an optimal islet transplantation site, as well as novel approaches for improving islet cell encapsulation, are discussed.