The techniques have been welcomed by those researching therapeutic cloning - in which stem cells could be created by substituting the genetic payload of an unfertilised human egg with a complete adult genome. Stem cells can be harvested from the resulting cloned cells could be used as to grow matched replacements for defective organs or tissue.
The work is controversial, as it could lay down the groundwork for those interested in reproductive cloning, i.e. using the resulting stem cell to create an identical copy of the DNA donor.
Investigators from the Memorial Sloan-Kettering Cancer Centre (MSKCC) took two lines of completely undifferentiated HESCs and by culturing them in the presence of mouse cells, stimulated them to turn into mesenchymal cells.
Mesenchymal precursors derived from HESCs are different from adult mesenchymal cells because they can efficiently differentiate into skeletal muscle (adult mesenchymal cells do not) in addition to fat, cartilage, and bone.
Limited numbers of mesenchymal stem cells have been isolated from adult bone marrow and connective tissues, but harvesting these cells from any of these sources requires invasive procedures and the availability of a suitable donor. The capacity of these cells for long-term proliferation is also poor. In contrast, HESCs could provide an unlimited number of specialised cells.
The researchers treated these cells with compounds to make them change into specialised bone, cartilage, fat, and muscle cells. According to the study, researchers were able to confirm these cells were all human cells and there was no evidence that the cells became cancerous.
The investigators have already taken the next step in this research and are testing the therapeutic potential of embryonic stem cell-derived muscle cells in animal models of muscle disorders.
According to Lorenz Studer, head of the Stem Cell and Tumour Biology Laboratory at MSKCC and senior author of the PLoS Medicine study, the high purity, unlimited availability, and multi-potentiality of mesenchymal precursors derived from HESCs will provide the basis for preclinical mouse studies to assess the safety of these cells.
The issue of research involving stem cells derived from human embryos is increasingly the subject of a national debate. The issue is confronted every day in laboratories as scientists question the ethical ramifications of their work.
Scientists believe further research using stem cells offers great promise that could help improve the lives of those who suffer from many terrible diseases - from juvenile diabetes to Alzheimer's, from Parkinson's to spinal cord injuries. And while scientists admit they are not yet certain, they believe stem cells derived from embryos have unique potential.
If something once thought impossible is eventually achieved and doctors can take a skin cell from a person with diabetes and use that to create immunologically matched tissue that can be injected into a patient to cure their condition, there is no doubt this will have an impact on the pharmaceutical industry.