Monday, June 9, 2014

Therapeutic Cloning

In April of 2014, a major breakthrough was established in human stem cell research.  In that month two laboratories independently reported the successful production of human embryonic stem (ES) cells derived from skin cells cultured in the laboratory ( in-vitro).  This a significant achievement in that an application of this technique could be exceedingly useful in the production of replacement tissues in-vitro for the treatment of such diseases as  juvenile (type 1)diabetes and Parkinson’s disease – both of which arise from the precipitous loss of the cells required to manufacture insulin and dopamine, respectively.  The added benefit of such an approach is that since the cells can be derived from the patient being treated, graft rejection is no longer an issue.

The cloning technique that was employed is referred to as somatic cell nuclear transfer (SCNT); an analogous method was used to clone the now famous sheep, Dolly.  It was subsequently applied to cloning cattle, mice dogs and other animals.  There is no desire among members of the scientific community to apply this approach to cloning humans but rather to produce early-stage human embryos from which ES cells could be derived.   Heretofore, human cells have been problematic in regards to cloning.

Dr. Dong Ryul Lee and his colleagues at CHA University in Seoul, Korea successfully created human ES cells from the skin cells of two individuals – men ranging in ages from 35 to 75 years old.  Later in April of the same year, Dr. Dieter Egli and his collaborators from the New York Stem Cell Foundation (NYSCF) Research Institute used the skin cells of a young woman patient suffering from type 1 diabetes to also produce ES cells and then induced these cells to become insulin-producing cells.  Following this momentous result, the investigative team then introduced these insulin-producing  cells into experimental mice where it was shown that the hormone insulin was made in-vivo.  This latter finding has yet to be published.

The overall technique that was employed in Egli’s laboratory is briefly described below –
·         DNA is removed from an unfertilized human egg cell (oocyte)
·         The DNA from skin cells grown in-vitro from a patient with type 1 diabetes is transferred to the oocyte that had its own DNA removed
·         If the transfer is successful, the oocyte begins to divide
·         At a very early point in cell division – the Blastocyst stage – ES cells are harvested
·         Finally, these cells are coaxed into differentiating into insulin-producing pancreatic cells.

These results are very exciting; however, the possible application to human disease faces considerable obstacles that need to be addressed.  Nonetheless, it is a significant step in the goal to successfully treat implacable diseases such as type 1 diabetes and Parkinson’s through tissue –replacement therapies. 

No comments:

Post a Comment