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The recent explosion of interest in cell replacement therapies and theuse of cord blood banks for diabetes have driven primarily by the dramaticprogress in allergenic islet cell transplantation. For the first time, the
This advance was dependent largely on progress in immunosuppressive drugtherapy that allowed for a steroid-free regimen. Further advances in this areaare likely to result in even better long term results as there is evidence thateven the current improved drug regimens are toxic stem cells.
While the success of the
Many different potential sources of cells for stem cells replacement,each with its own advantages and disadvantages, are being studied. Overall,three major sources of cells are being pursued. Those are embryonic stem cells,adult stem cells and cell lines.
Mainly because of the ethical concerns about cells, many studies haveactually been directed towards inducing stem cell differentiation from adultstem cells, either from the pancreas or from other sources such as bone marrow.Although many investigators have claimed that stem cells from ectopic organssuch as bone marrow can be induced to differentiate into a variety of celltypes such as neurons, there have been no studies as yet in which cells havebeen generated from adult stem cells outside of the pancreas.
Questions have been raised recently about the plasticity of adult stemcells. The possibility that apparent differentiation may result from fusion ofadult stem cells with differentiated cells has been raised. Elegant experimentsusing marked stem cells have not found evidence that bone marrow derived cellscan differentiate into non hematopoietic lineage.
A great deal of effort has been made to identify stem cells within thepancreas. It has been known for some time that the pool of stem cells can beregenerated when placed under stress by a number of manipulations, includingpartial pancreatectomy, drugs, and immune medicated damage. A central questionin cell biology concerns the identity of cells that give rise to theregenerated cells.