Research and Therapy Developments 
137 
As the results described in Table 1 indicate, cells derived 
from some human stem cells transplanted into specific strains 
of mice mimicking major aspects of Type-1 human diabetes^^ 
were able to reverse high blood glucose concentrations. Al- 
though these results are encouraging, the transplant rejection 
question remains unanswered because the likely immune re- 
jection of the transplanted human cells was prevented in these 
experiments by using special strains of immunodeficient mice 
that lack the capacity to recognize and attack foreign cells. 
No tumors were observed in the transplanted mice, but the 
experiments were terminated after about three months, an in- 
sufficient time for much tumor development to occur. Because 
many Type-1 diabetes patients are children and because a 
largely effective therapy (insulin injection) is currently avail- 
able, the introduction of islet cell transplant therapy will need 
a high degree of certainty that the introduced cells or their de- 
rivatives "Will not become malignant over the course of the pa- 
tient's life. Stringent tests of the cancer-causing potential of 
candidate cell preparations will be required, including multi- 
year studies in animals that live longer than mice or rats. 
! Long-term follow-up of children and adult patients who had 
I received bone marrow transplants many years ago has re- 
I vealed an increased risk of severe neurologic complications®^ 
and a variety of types of cancer.®® 
C. Therapeutic Applications of Mesenchymal Stem Cells 
(MSCs) 
Before stem cell based therapies are used to treat human 
diseases, they will have to gain approval through the Food and 
I Drug Administration (FDA) regulatory process. The first step in 
this process is filing an Investigational New Drug (IND) appli- 
I cation. As of July 2003, four IND applications have been filed 
for clinical applications of mesenchymal stem cells. The dis- 
ease indications include: (1) providing MSG support for pe- 
! ripheral blood stem cell transplantation in cancer treatment, 
(2) providing MSG support for cord blood transplantation in 
cancer treatment, (3) using MSGs to stimulate regeneration of 
cardiac tissue after acute myocardial infarction (heart attack), 
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