Method for detecting and purifying pancreatic beta cells
The invention is based, in part, on the discovery that a polypeptide, referred to herein as Betacam, is selectively expressed on the surface of pancreatic islet cells. Thus, in one aspect, the invention is directed to compositions comprising Betacam or that can be used to detect Betacam. In another aspect, the invention provides methods of detecting (e.g., non-invasively) pancreatic beta cells from a mammalian cell source. Another aspect of the invention is directed to cellular purification of pancreatic beta cells from a heterogeneous cell source of multiple kinds. In another aspect, the invention provides methods of identifying agents that modulate activity of Betacam. In yet another aspect, the invention provides for improved treatment and diagnosis of diabetes.
1. A method of detecting beta cells in a mixture of pancreatic cells comprising detecting the presence of a polypeptide on the surface of the cells, wherein the polypeptide comprises SEQ ID NO: 14, SEQ ID NO: 15, an amino acid sequence that has at least 50% identity to SEQ ID NO: 14 or an amino acid sequence that has at least 50% identity to SEQ ID NO: 15, and detection of expression of the polypeptide on the surface of the cells indicates that the cells are pancreatic beta cells.
2. The method of claim 1 further comprising isolating the pancreatic beta cells from the mixture of cells.
3. The method of claim 2 wherein the pancreatic beta cells are isolated from a biological sample.
4. The method of claim 1 wherein the biological sample is pancreatic tissue.
5. The method of claim 4 wherein the pancreatic tissue is obtained from a cadaver.
6. The method of claim 1 wherein expression of the polypeptide is detected using an antibody that has binding affinity for the polypeptide.
7. An in vivo method of detecting pancreatic beta cells in an individual in need thereof, comprising administering to the individual a molecule labeled with a positron emission tomography (PET) tracer that detects the presence of a polypeptide on the surface of the pancreatic beta cells, wherein the polypeptide comprises SEQ ID NO: 14, SEQ ID NO: 15, an amino acid sequence that has at least 50% identity to SEQ ID NO: 14 or an amino acid sequence that has at least 50% identity to SEQ ID NO: 15, wherein upon binding of said molecule to the surface of the pancreatic beta cells and the emittance of a signal from said PET tracer, the pancreatic beta cells are detected with a PET scanner.
8. The method of claim 7 wherein the individual is being screened for a risk of developing diabetes.
9. The method of claim 7 wherein the individual has diabetes.
10. The method of claim 9 wherein the diabetes is Type I diabetes or Type II diabetes.
11. The method of claim 7 wherein the individual has had an islet cell transplantation.
12. A method of isolating pancreatic beta cells from a mixture of pancreatic cells comprising:
a) contacting the mixture with a reagent that specifically binds to a polypeptide present on the surface of pancreatic beta cells, wherein the polypeptide comprises SEQ ID NO: 14, SEQ ID NO: 15, an amino acid sequence that has at least 50% identity to SEQ ID NO: 14 or an amino acid sequence that has at least 50% identity to SEQ ID NO: 15, thereby producing a combination;
b) maintaining the combination under conditions in which the reagent binds to the polypeptide present on the surface of the pancreatic beta cells, thereby producing a complex of pancreatic beta cells bound to the reagent; and
c) separating the complex from the combination, thereby isolating pancreatic beta cells from the mixture of pancreatic cells.
13. The method of claim 12 further comprising d) separating the pancreatic beta cells from the reagent.
14. The method of claim 12 wherein the mixture of pancreatic beta cells is pancreatic tissue.
15. The method of claim 14 wherein the pancreatic tissue is obtained from a cadaver.
16. The method of claim 12 wherein the reagent is an antibody that has binding affinity for the polypeptide.