. Although these
cells are very different from the natural beta cells of the pancreas, they mimic
the same functions. They are capable of sensing glucose levels, internally
transducing signals and dynamically secreting insulin via vesicle fusion.
The ABCs are constructed with a normal cell's bi-lipid membrane. The key
innovation in the ABCs are the insulin-stuffed vesicles. The synthetic
beta cells function based on fusion-mediated insulin secretion. A rise in the
blood glucose levels causes chemical changes in the coating of the insulin
filled vesicles. This change leads to the fusion of the vesicle to ABCs
bi-lipid outer membrane thereby releasing the insulin.
‘Artificial Beta Cells (ABCs) contain insulin filled vesicles that fuse with the outer membrane to release insulin when blood glucose levels rise.’
"This is the
first demonstration using such a vesicle fusion process for delivering insulin
that employs insulin-containing vesicles like those found in a beta cell and can
reproduce the beta cell's functions in sensing glucose and responding with
insulin 'secretion'," said Zhaowei Chen, PhD, a lead author and
postdoctoral researcher in the lab of Dr. Zhen Gu, the principal investigator and a professor in the Joint
UNC/NC State Department of Biomedical Engineering.
Current treatment for diabetes
While there are several treatment
measures available to maintain and control diabetes including periodic
injections, insulin pills and mechanical insulin pumps, none are able to perfectly
mimic the beta cells role in regulating glucose. More often than not,
imperfectly regulated blood glucose levels lead to hypoglycemia (low glucose
levels) which is associated with behavioral changes, brain damage and death.
While cell therapy based on transplantation of beta cells does provide
promising results, it is expensive and requires donor cells. Immunosuppression
after the transplant is another factor that limits the procedure.
ABCs on the other hand can be
administered transcutaneously and replaced every few days or be administered as
a disposable skin patch. In the study, the team reports that a single injection of the
ABCs into diabetic mice normalized glucose levels and kept the levels normal
for up to five days.
This is what Dr. Gu had to say
about the future prospects of ABCs: "Our plan now is to further optimize
and test these synthetic cells in larger animals, develop a skin patch delivery
system for them, and ultimately test them in people with diabetes."
- Zhaowei Chen, Jinqiang Wang, Wujin Sun, Edikan Archibong, Anna R Kahkoska, Xudong Zhang, Yue Lu, Frances S Ligler, John B Buse, Zhen Gu. Synthetic beta cells for fusion-mediated dynamic insulin secretion. Nature Chemical Biology, 2017; DOI: 10.1038/nchembio.2511