Mesenchymal stem cells, (MSCs), have been induced to produce bone, muscle and
fat cells in a predictable and repeatable manner by researchers at Osiris
Therapeutics in Baltimore Md, (Science 1999Apr2;284(5411):143-147,
"Multilineage Potential of Adult Human Mesenchymal Stem Cells.", Pittenger
MF, et al).
Over a million differentiated cells were grown from a single stem cell in
approx. 20 population doublings. Given that normal cells have a replicative
capacity of between 40 and 60 population doublings and that the cells
produced are normally quiescent, there should be no short term problems
involving telomeric shortening in these cells.
The mesenchymal stem cells are more differentiated than the pluripotent stem
cells under research by Geron and others in that they are the normal
progenitor cells for bone, muscle, fat, cartilage and tendons.
The pluripotent stem cells are capable of developing into any cell produced
by the body but processes to direct the differentiation of these stem cells
have not yet been developed.
Previous research at Osiris Therapeutics has shown that these Mesenchymal
stem cells can restore lost bone mass; (J Orthop Res 1998 Mar;16(2):155-62
"Bone regeneration by implantation of purified, culture-expanded human
mesenchymal stem cells.", Bruder SP, et al) and (Clin Orthop 1998 Oct;(355
Suppl):S247-56, "Mesenchymal stem cells in osteobiology and applied bone
regeneration.", Bruder SP, et al).
That telomeric shortening should not be a problem in these cell lines was
demonstrated in; (J Cell Biochem 1997 Feb;64(2):278-94, "Growth kinetics,
self-renewal, and the osteogenic potential of purified human mesenchymal stem
cells during extensive subcultivation and following cryopreservation.",
Bruder SP, et al), where they state "The use of population doubling potential
as a measure of biological age suggests that MSCs are intermediately between
embryonic and adult tissues..."
These developments will help to produce therapies beneficial to an aging
population and clinical trials will be initiated shortly.
Thomas Mahoney, Pres.
Lifeline Laboratories, Inc.
http://home.earthlink.net/~excelife/index.html
