Researchers created mouse embryos from lab-grown sperm
In the picture: some of the spermatozoa formed primary embryos
Scientists believe they have succeeded in creating working sperm cells from cells taken from another part of the body. The cells were able to "fertilize" a mouse egg and began the process of creating an embryo.
It has now been safely proven that stem cells can be a source of essential sperm cells for infertile men, although scientists believe this is still many years away. A British expert says that there is no certainty that these embryos created can also divide normally.
A large number of men either cannot produce sperm or have lost the ability to do so as a result of medical treatment. For many, the only chance they have of having a child is to use a donor's sperm - there is no chance they will become fathers themselves.
One of the possible answers is to use stem cells - the progenitor cells of the body, which under the right conditions can become any needed tissue. The richest source of these cells is now in fetuses, although such cells may survive in the body throughout life.
The scientists believe that, in theory, some specialized types of stem cells could become sperm cells.
The latest study, from the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, in collaboration with Boston Hospitals and Harvard University, took stem cells from an area in early mouse embryos known to be the source of "primary germ cells."
These cells will eventually develop into complete sperm cells necessary for the reproduction of the embryo. The researchers isolated the right type of embryonic cells, and managed to produce a renewed and continuous line of germ cells in the laboratory - similar to those found in the testicles of mice. In addition, they found a way to encourage these cells to become sperm cells. These cells were injected into the eggs of mice and started the first stage of fertilization. In half of the experiments, the first division occurred, and in one out of five experiments the embryo managed to develop to the blastocyst stage and produced a ball of cells ready for implantation in the uterus.
In any case, not a single live birth has been achieved so far, and some experts believe that the sperm cells created in this way do not carry all the information necessary to produce a healthy mouse.
Doubts
Prof. Azim Surani from the University of Cambridge said that in addition to the genes themselves, each cell also has information as to which genes will work and which will not and at what essential stage of development. "There is no evidence from all the studies for the presence of such a 'tag'. Without the tag, the function of the cell will not be normal. Germ cells can be produced - the problem at the moment is the missing details. We don't have full control over the system now." He concludes. And adds that therefore the use of the process in humans is still far away.
from stem to seed
20.9.2003
Japanese researchers reported at the beginning of the week that they succeeded for the first time in causing embryonic stem cells to turn into sperm cells. The research, which was done on mice in the laboratory, was described as "preliminary".
Stem cells are the progenitor cells of the body: they differentiate into the cells that make up the various tissues in the body during the growth of the embryo. In recent years, researchers have succeeded in turning embryonic stem cells into different types of cells, including egg cells, but so far they have not succeeded in turning them into sperm cells. At the head of the new study, which he reported on in the online edition of the journal, "National Academy of Sciences Proceedings of the" was Toshiaki Nosa of the Mitsubishi Kageko Institute of Life Sciences in Japan.
Nosa and his team grew the embryonic stem cells together with cells that produce the protein BMP4, which is known to encourage the creation of sperm cells during the development of the embryo. In the study, the stem cells turned into sperm cells within one day. This process takes three days when it occurs naturally in the fetus.
Prof. Brett Vogelstein, a stem cell expert from Johns Hopkins University, said that this is an innovative study, "which provides a great example of the ability to create different types of cells using new technologies."
