Biomedical Engineering Reference
In-Depth Information
BMT. More recently, transplantation of hemopoietic stem cells has occurred with increasing
frequency to correct hematological disorders. These are all applications of cell therapies asso-
ciated with blood cells and blood cell generation (hematopoiesis). (The term
hematopoiesis
comes from the Greek
, meaning “generation of.”) There-
fore, a large population of patients already has benefitted from cell therapies, and this benefit
can be extended by developing new therapies using other progenitor cell sources.
Transplants can be xenogeneic (donor and recipient are members of different species),
allogeneic (donor and recipient are members of the same species but are not genetically
identical), or syngeneic (donor and recipient are genetically identical—e.g., clones in the
case of animals, or identical twins). Syngeneic transplants include autologous transplants
(cells from a patient being isolated and given back to the same person). The issues asso-
ciated with allogeneic transplants are well known because of the widespread use of organ
transplantation and chiefly involve prevention of immune rejection as well as longer-term
negative responses to transplanted tissues. However, with the advent of ex vivo cell culture
and advances in cell manipulation procedures, autologous transplantation is becoming
more common. In addition there are efforts under way in several laboratories to create
“universal donor” cell sources and cell lines that would alleviate many of these issues.
The ability to reconstitute tissues ex vivo and produce cells in clinically meaningful
numbers has broad implications. Table 6.1 summarizes the supply and demand of organs
and tissues versus the number of procedures performed annually in the United States.
Although the number of procedures is limited, the overall cost of these procedures was
still estimated at a staggering $400 billion per year. The potential socioeconomic impact
hemato
, meaning “blood,” and
poiesis
TABLE 6.1 Incidence of Organ and Tissue Deficiencies, or the Number
of Surgical Procedures Related to These Deficiencies in the United States
a
Indicator
Procedure or Patients per Year
Skin
Burns b
2,150,000
Pressure sores
150,000
Venous stasis ulcers
500,000
Diabetic ulcers
600,000
Neuromuscular disorders
200,000
Spinal cord and nerves
40,000
Bone
Joint replacement
558,200
Bone graft
275,000
Internal fixation
480,000
Facial reconstruction
30,000
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