A recent report on possible therapeutic uses of testicular stem cells helps to highlight the level of confusion and lack of focus
in stem cell biology today. Sources of stem cells such as embryos, testicles and ovaries are technically difficult to manipulate and have worrying, potentially malignant properties should they ever be transplanted to a human being. These stem cells also carry significant moral, ethical, legal and religious objections to their creation and use. UK researchers have been given the go-ahead to investigate the potential of human testicle stem cells to develop into other types of body tissue. The Human Fertilization and Embryology Authority (HFEA) has licensed the team, based at the Hammersmith Hospital in London, to
study the cells in order to find out if they are as versatile as stem cells isolated from early embryos. The scientists hope that the work may eventually lead to new therapies for conditions such as heart disease, Parkinson's disease and spinal injury.
Last year, German researchers isolated cells from adult mouse testicles that share some of the characteristics of embryonic stem (ES) cells. The team isolated stem cells that normally grow into sperm, and coaxed them into producing many different types of body cell. The researchers, based at the Georg-August-University of Goettingen, published their findings in the journal Nature. However, at the time, other scientists cautioned that stem cells from human testes might not behave in the same way as their mouse counterparts. The Gottingen team used genetically altered mice in which the sperm stem cells were permanently 'tagged' with a fluorescent protein, to enable them to isolate the elusive cells from mouse testes. They then grew the cells in the laboratory, and found that some of them resembled ES cells. These cells, which they dubbed multipotent adult germline stem cells (maGSCs), were able to grow into several different types of body cell - including heart, brain, liver and skin. The scientists also found that the maGSCs were able to form different tissues and organs when injected into mouse embryos. The ongoing controversy surrounding research into human ES cells in Germany, where such work is banned, and many other countries, has lead several groups to seek alternative sources of cells that can potentially develop into a wide range of different tissues. Even in countries where ES cell research is permitted, it hinges on the availability of donated human eggs.
There is another source of stem cells which is hardly ever mentioned in the news and is currently being discarded on a daily
basis. It has no moral, ethical, legal or religious objections to use and it has been transplanted safely over 6,000 times to date to treat 45 different diseases. This source of stem cells is human umbilical cord blood. Cord blood can be collected at every birth with no risk or pain to the mother or baby. Once collected cord blood is processed using tried and tested technology and can be frozen in liquid nitrogen for many years. Current applications of these stem cells are in the treatment
of leukemia, related blood disorders and the repair of the bone marrow following high dose chemotherapy for cancer. Perhaps the most important aspect of cord blood is that it contains mesenchymal stem cells capable of producing many cell types including neuronal and muscle tissue. These cells have an availability and potential far greater than embryonic or testicular stem cells and we must focus our time, energy, resources and expertise on the full utilization of these priceless stem cells. Cord blood stem cells are currently being assessed in a clinical trial in Canada in the treatment of multiple sclerosis. The umbilical cord itself also contains stem cells capable of producing a range of tissue types, most
notably bone tissue. If stem cell biology is to advance we must begin to collect, store and carry out research on as much cord blood as possible. According to advocates of umbilical cord blood banking, we have a readily available source of stem cells with massive potential which is currently, for whatever reason, being ignored by researchers, media and politicians alike. “We must stop talking about esoteric sources of stem cells and focus on cord blood stem cells as the source of stem cells for current therapeutic applications and ground breaking therapies of the future.”
Commenting on the planned research at Hammersmith Hospital, stem cell expert Professor Harry Moore, of Sheffield University, said: 'In this country, the ethical issues of obtaining stem cells from cloned embryos are really covered by the
HFEA, but there is still the major problem of where do you get eggs that are high enough quality and in sufficient quantity. The advantage of this work on human testicular cells is that it avoids both of these issues'. If testicular stem cells prove to be as versatile as their embryonic counterparts, it may be possible for men to bank testicular tissue early in life, and later use it to repair damaged or diseased areas of the body. Such tissue could also potentially be used to provide cell-based therapies for any men who share the same tissue type. Professor Chris Barratt, of the Birmingham Women's Hospital told the Guardian newspaper: “There are a lot of testicles around and you don't need a staggering number to have enough variety to match nearly all of the population”. In India, we have much larger numbers.
