Christopher J. Rhodes, PhD
The Pancreatic ß-Cell Functional Differentiation Analysis Laboratory
Islet transplantation/ß-cell replacement therapy can be an effective way to treat type-1 diabetes. However, a major problem is obtaining sufficient numbers of human islets and/or ß-cells to make this therapy commonplace. As such, an active area of research is to find alternative sources of ß-cells that might be used for replacement therapy. These ‘new sources’ of ß-cells might be derived from stem cells (both embryonic and adult), ‘transdifferentiation’ of another cell type into ß-cells, ‘engineered cells’ altered to produce insulin, islet ß-cells that have been induced into replication in vitro, or immortalized human ß-cell lines, to name but a few. However, these potential ‘surrogate ß-cells’ need to be functionally analyzed to see if they appropriately produce and secrete insulin in a regulated manner and how close to bone fide primary islet ß-cells they might be. Here, at the University of Chicago Kovler Diabetes Center, a service laboratory (The Pancreatic ß-Cell Functional Differentiation Analysis Laboratory) has been established for that purpose, sponsored by the Juvenile Diabetes Research Foundation International (JDRF).
In addition, there is also a good deal of current interest in initiatives to promote regeneration of endogenous ß-cells, much encouraged by the JDRF. However, it should be examined whether pharmacological or genetic manipulations that promote ß-cell regeneration do not affect ß-cell function – especially in terms of insulin production and secretion. Again the service provided by the ‘Pancreatic ß-Cell Functional Differentiation Analysis Laboratory’ is valuable here too.
Thirdly, it is known (but not always appreciated) that different preparations of isolated human islets vary wildly in terms of insulin production and secretory function. This can be due to a variety of reasons ranging from differences in pancreas procurement, collagenase preparations, culture media, ischemia time etc. A consistent functional evaluation isolated human islet preparations would help narrow this variability. In this regard the ‘Pancreatic ß-Cell Functional Differentiation Analysis Laboratory’ can functionally evaluate isolated human islets.
Unfortunately, an evaluation of ß-cell function might not be as thorough as it should be and this is of particular concern with ‘candidate surrogate ß-cells’ often referred to as ‘insulin positive cells’. For the most part, ‘candidate ß-cells’ are often ‘characterized’ by RT-PCR analysis (to get an idea of insulin and other ß-cell gene expression patterns) and immunofluorescent staining to see the abundance of insulin positive ‘ß-cells’. The most well-meaning of researchers can be fooled by their own results. The RT-PCR gene expression analysis technique is notoriously prone to amplification artifacts. Some cells can take up insulin from the surrounding media, but do not synthesize it. As such, ‘insulin positive cells’ are not always insulin-producing cells.
Thus, there is a need for a more thorough functional characterization of ‘insulin positive cells’. Such an assessment can also be applied to examine the variance and ‘potency’ between different human islet preparations. What follows is a description of the ß-cell functional analysis service(s) that can be provided. The overall intention being to assist in more effectively pushing forward therapeutic strategies for ß-cell replacement and/or ß-cell regeneration to treat type-1 diabetes.
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