Scientists in the UK and Germany have found that cells extracted from human testis can be manipulated to make them act like human embryonic stem (ES) cells, resulting in another approach in the burgeoning stem cell field. ES cells can potentially be used to create 'repair tissue' specific to the individual for diseased or damaged tissue, as they can give rise to any tissue in the body. This could offer treatments for diseases such as Parkinson's and diabetes, and for spinal cord injuries. The use of ES cells, however, is surrounded with ethical controversy, as harvesting the cells from the embryo involves the subsequent destruction of the embryo.
The teams of scientists, at the University of Tubingen, Germany, and King's College London, used 22 samples taken from biopsies from testicles or from medical castrations. They extracted sperm precursor cells, called spermatogonial cells, and manipulated them chemically to become more stem cell-like. Thomas Skutella, who led the team in Germany, says: 'these cells
changed their properties, losing characteristics of spermatogonial cells and acquiring characteristics similar to those of human ES cells'. Depending on the chemical signals the cells were exposed to, the cells changed 'into skin, structures of the gut, cartilage, bone, muscle and neurons', he added.
The study, published in the journal Nature, follows on from studies in mice in 2006, and brings hope that these cells can in the future be used safely in humans to develop personalised tissue, thereby avoiding rejection after transplantation. Use of these cells would also avoid the ethical problems that prevent work with ES cells. The results are by no means conclusive. Professor Robin Lovell-Badge, a stem cell specialist from the UK's National Institute for Medical Research, pointed out that the testicle-derived stem cells are not identical to ES cells. 'The DNA in the stem cells in the testes lack some important
modifications that regulate the activity in certain genes, and this may affect ability of the reprogrammed cells to make specific mature tissue types' he said. The same cells are the likely root of testicular tumours, so there are safety concerns, and also the issue that the cells could only be used to treat men, leaving women without a similarly easy method.
