Research and Therapy Developments 
139 
MSCs, and MAPCs) can be reproducibly expanded to substan- 
tially larger cell numbers in vitro, the cells can be stored frozen 
and recovered, and they can be characterized and compared 
by a variety of techniques. These cells are receiving a large 
share of the attention regarding possible future (non- 
hematopoietic) stem cell transplantation therapies. 
Preparations of ESCs, EGCs, MSCs, and MAPCs can be in- 
duced to differentiate in vitro into a variety of cells with prop- 
erties similar to those found in differentiated tissues. 
Research using these human stem cell preparations holds 
promise for: (a) increased understanding of the basic molecular 
process imderlying cell differentiation, (b) increased under- 
standing of the early stages of genetic diseases (and possibly 
cancer), and (c) future cell transplantation therapies for human 
diseases. 
The case study of developing stem cell-based therapies for 
Type-1 diabetes illustrates that, although insulin-producing 
cells have been derived from human stem cell preparations, 
we could still have a long way to go before stem cell-based 
therapies can be developed and made available for this dis- 
ease. This appears to be true irrespective of whether one 
starts from human embryonic stem cells or from human adult 
stem cells. The transplant rejection problem remains a major 
obstacle, but only one among many. 
Human mesenchymal stem cells are currently being evalu- 
ated in pre-clinical studies and clinical trials for several spe- 
cific human diseases. 
Much basic and applied research remains to be done if hu- 
man stem cells are to achieve their promise in regenerative 
medicine.^® This research is expensive and technically chal- 
lenging, and requires scientists willing to take a long perspec- 
tive in order to discover, through painstaking research, which 
combinations of techniques could turn out to be successful. 
Strong financial support, public and private, will be indispen- 
sable to achieving success. 
PRE -PUBLICATION VERSION 
