we  must be able to manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation, and engraftment.

The following is a list of steps in successful cell-based treatments that scientists will have to learn to control to bring such treatments to the clinic.

To be useful for transplant purposes, stem cells must be reproducibly made to:

• Proliferate extensively and generate sufficient quantities of tissue.
• Differentiate into the desired cell types.
• Survive in the recipient after transplant.
• Integrate into the surrounding tissue after transplant.
• Function appropriately for the duration of the recipient’s life.
• Avoid harming the recipient in any way.

Graft rejection is a major problem and the methods need to be designed  to avoid the problem. Scientists are experimenting different strategies to overcome the problem.

Here is major categorization

Permissive:

This policy allows various embryonic stem cell derivation techniques including somatic cell nuclear transfer (SCNT), also called research or therapeutic cloning.

SCNT is the transfer of a cell nucleus from a somatic or body cell into an egg from which the nucleus has been removed.

United Kingdom, Belgium, Sweden, Iran, Israel, India, Singapore, China, Japan, South Korea and  South Africa follow a permissive policy.

Flexible

This policy permits fertility clinic donations only, excluding SCNT, and often under certain restrictions. Research is permitted only on remaining embryos no longer needed for reproduction.

Examples are Australia, Brazil, Canada, France, Spain, The Netherlands, Taiwan

Somewhat restrictive

research permitted on imported embryonic stem cell lines only or on a limited number of previously established stem cell lines.

Germany, Italy, United States

Very restrictive

This generally means a banned research.

Austria, Ireland, Norway, Poland follow this.

To know more about it visit http://www.isscr.org/public/regions/index.cfm

Stem cells taken from human embryos have been used to form tissues of the cerebral cortex, according to experts at the government backed research institute Riken. The tissues self-organised into four distinct zones very similar to the structure seen in human fetuses, and conducted neuro-activity such as transmitting electrical signals.

“Transplanting tissues could raise hopes for greater functional recovery,” the institute said.

But study of invitro cultivation of more mature cortex tissue, such as those with six zones like in the adult human brain, will be stepped up. The tissues could also serve as “a mini organ” for studying the causes of Alzheimer’s disease.

Embryonic stem cells are harvested by destroying a viable embryo, a process that some find unacceptable. Riken said cortex tissues were also obtained from “induced pluripotent stem cells,” which are similar to embryonic stem cells but artificially induced.

I needed a separate place to write on this topic as this topic is itself quite vast with all kind of possible ramifications.

Research in stem cells is quite promising and still evolving.

Be with me as I search and write.

If you are interested in this topic, you might like to visit this blog again and again. I would suggest you to bookmark the blog.