http://www.biospectrumasia.com/content/051209SGP11476.asp

Singapore, Dec 5, 2009: Stem cells have long been proposed to hold promise for the treatment of a wide variety of dis­eases. Interestingly, last year saw some major breakthroughs in the development of stem cells as ther­apeutic products. Generally, it is accepted that there are three types of mammalian stem cells. Embry­onic stem cells derived from the inner cell mass of blastocysts have the ability to differentiate into all of the specialized embryonic tis­sues. In contrast, adult stem cells derive both from adult tissues where they act as a repair sys­tem for the body by replenishing specialized cells and maintaining normal turnover of organs with high regenerative capacities, such as blood, skin or intestinal tissues as well as from sources such as umbilical cord, blood and bone marrow, which give rise to highly plastic adult stem cells. Most re­cently, there has been much in­terest in mesenchymal stem cells (MSCs) which are adherent cells isolated from the bone marrow or adipose tissue. Unlike other stem cells, these cells seem to be able to evade the host immune system, due to the lack of MHC protein ex­pression. All three cell types have advantages and disadvantages as therapeutics.