Nucleic-acid- and cell-based therapeutics - Pharmaceutical Biotechnology: Concepts and Aapplications

Biomedical Engineering Reference

In-Depth Information

blood vessels, the brain and spinal cord, skeletal muscle, skin, liver, pancreas, digestive system,

cornea and retina. Identifi cation and study of such cells can be made diffi cult by the low levels in

which they are normally found, the presence of many additional cell types and the diffi culties in

culturing them. Much basic research is required to answer fundamental questions regarding adult

stem cells, including: How many types exist and where are they located? What was their ultimate

source? What level of plasticity (see below) do they exhibit? What factors stimulate their reloca-

tion and differentiation at a site of tissue damage?

The use of adult, as opposed to embryonic, stem cells in regenerative medicine would have a number

of signifi cant advantages. It would overcome moral/ethical diffi culties associated with blastocyst

destruction. It would also allow for autologous transplantation of cells, i.e. adult stem cells could be har-

vested from a patient, cultured and differentiated in vitro a nd t h e n r ei nt r o du c e d ba ck i nt o t h e p a t ie nt . T h i s

would overcome potential immunological complications and a requirement to use immunosuppressive

drugs. Hurdles to this approach not only include the diffi culties in isolating and successfully culturing

these cells, but also ascertaining the level of plasticity exhibited by adult stem cells. This refers to the

range of potential fully differentiated cell types that could be produced from adult stem cell popula-

tions, and such investigations represent a very active area of current stem cell research.

14.11 Conclusion

Every few decades a medical innovation is perfected that profoundly infl uences the practice of

medicine. Widespread vaccination against common infectious agents and the discovery of antibiotics

serve as two such examples. Many scientists now believe that the potential of nucleic-acid- and

cell-based technologies rivals even the most signifi cant medical advances achieved to date.

It is now just over a decade since the fi rst nucleic-acid-based drugs began initial tests. Several

such drugs will likely be in routine medical use in less than a decade more. The application of gene

technology could also change utterly the profi le of biopharmaceutical drugs currently on the mar-

ket. Virtually all such products are proteins, currently administered to patients for short or pro-

longed periods, as appropriate. Gene therapy offers the possibility of equipping the patient's own

body with the ability to synthesize these drugs itself, and over whatever time-scale is appropriate.

Taken to its logical conclusion, gene therapy thus offers the potential to render obsolete most of

the biopharmaceutical products currently on the market. Regenerative medicine, too, although

still in its infancy, harbours enormous future medical potential. Of all the biopharmaceuticals

discussed throughout this text, nucleic-acid- and cell-based drugs may well turn out to have the

most profound infl uence on the future practice of molecular medicine.