Appendix K. 
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Bone marrow stem cells have also shown the ability to 
participate in repair of damaged retinal tissues. When bone marrow 
stem cells were injected into the eyes of mice, they associated with 
retinal astrocytes and extensively incorporated into the vascular 
(blood vessel) network of the eye.'^’ The cells could also rescue and 
maintain normal vasculature in the eyes of mice with a degenerative 
vascular disease. In another animal study, bone marrow derived 
stem cells were observed to integrate into injured retina and 
differentiated into retinal neuronal cells. ^ Stromal stem cells have 
also shown capability in mice to repair spinal cord which was 
demyelinated.^® One of the problems related to spinal cord injury is 
loss of the protective myelin sheath from spinal cord after injury. A 
mixed bone marrow stem cell fraction was injected into the area of 
damage in the spinal cord, and remyelination of the area was seen. 
In another mouse study, marrow stromal cells injected into injured 
spinal cord formed guiding strands within the cord;^ interestingly, 
the effect was more pronounced when the stromal cells were 
injected 1 week after injury rather than immediately after injury. 
Because bone marrow stem cells are of mesodermal lineage, 
it is not surprising that they show capabilities at forming other 
tissues of mesodermal origin. Human marrow stromal cells, which 
have been shown to form cartilage cells, have been used in an in 
vitro system to define many of the molecular events associated with 
formation of cartilage tissue. Bone marrow derived stem cells have 
also been shown capable of regenerating damaged muscle tissue. 
In an elegant study following genetically marked bone marrow stem 
cells in mice, LaBarge and Blau were able to document multiple 
steps in the progression of the stem cells to form muscle fibers and 
repair muscle damage.^ The ability of human bone marrow derived 
stem cells to form muscle cells and persist in the muscle was 
recently documented. In this case, a patient had received a bone 
marrow transplant at age 1, and developed Duchenne muscular 
dystrophy at age 12. Biopsies at age 14 showed donor nuclei 
integrated within 0.5-0. 9% of the muscle fibers of the patient, 
indicating the abihty of donated marrow cells to persist in tissue over 
long periods of time.^ 
Bone marrow stem cells have also shown capability at 
forming kidney cells. Studies following genetically marked bone 
marrow stem cells in rats^^ and mice“ showed that the stem cells 
could form mesangial cells to repopulate the glomerulus of the 
kidney. In the mouse study, formation of cell fusion products was 
ruled out as a mechanism for differentiation of the bone marrow stem 
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