By Ali S Versi
Researchers at Oregon State University have produced stem cells from cloned human embryos providing a new route to grow tailor-made embryonic stem cells.
These stem cells are genetically personalised to the patient, thus dispensing with the need of immunesuppression to avoid immune rejection when used in therapies. In addition these cells are pluripotent conferring them with the capacity for perpetual self renewal and differentiation to generate any cell type.
Having important implications for the treatment of conditions entailing cell loss or impairment such as Parkinson’s and spinal cord injuries, for which there is currently no cure.
The researchers utilised a process known as Somatic Cell Nuclear Transfer (SCNT) where the DNA of a non-sex cell or somatic cell from a patient is taken and fused with a human egg stripped of its genetic identity. The human egg now with the genetic identity of the patient is coaxed by an electric shock into dividing until an early stage embryo known as a blastocyst is formed. Stem cells derived from the inner cell mass of the blastocyst, which contains the patient’s genetic make-up, are harvested.
However, this technique has not previously been successfully applied using human cells. The researchers used several minor adjustments to the process including the exposure of caffeine to the egg during the introduction of the somatic cell’s DNA into the egg cell to prevent pre-mature activation of cellular development.
The cells harvested were shown to have the same characteristics of embryonic stem cells including the expression of factors associated with pluripotency and the generation of a multi-cell lineage tumour when the stem cells were injected into mice. Furthermore, the researchers were able to generate beating heart cells by differentiating the stem cell using signalling molecules.
Amidst the excitement and promise generated by this progress in stem cell technology, there are ethical issues raised. The research team at Oregon University used 120 human eggs for the experiment. These came at a cost especially to cash poor donors along with serious short and long term health risks, involving ovarian hyper-stimulation. The human eggs are discarded once the relevant cell lines are harvested.
This destruction raises concerns regarding the beginning of life. Many experts are warning that this technology in the wrong hands can result in human clones. Dolly the sheep, who was cloned using SCNT where the resulting blastocyst was inserted in a surrogate mother, was abnormal and died sooner than expected.
An alternative route to making patient specific stem cells known as induced pluripotent stem cells (iPSC) involves the reprogramming of a somatic cell’s gene patterning to express factors associated with pluripotency. This is a much favoured approach from an ethical standpoint, as it does not involve, eggs, cloning or destruction of embryos.
However, the pluripotent cells derived from this technique have a greater occurrence of genetic abnormalities as they appear to be somewhat recalcitrant in completely surrendering their original cell lineage.
Ali S Versi Ali S Versi is MRes student in Systems and Synthetic Biology at Imperial College.