OPHTHALMOLOGY: STEM CELLS TO REPAIR THE CORNEA

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Ophthalmology: Stem Cells to Repair the Cornea

Italy - A study published the work of Italian doctors who restored sight to more than 100 people, restoring their corneas from stem cells taken from patients' eyes themselves.

Researchers at the Centre for Regenerative Medicine Stefano Modena Ferrari have taken on the limb - a membrane surrounding the iris - a few of each patient and healthy stem cells were grown in the laboratory before transplanting them onto the cornea, where zones accidentally destroyed have been regenerated in a quasi-natural.

The main advantage of this technique is that with a durability of 10 years, the effect is more durable than a conventional corneal transplant, and free from any risk of rejection because the subject itself provides the material for its healing . It is therefore an interesting alternative to installing artificial cornea, a potential source of infection and after a cornea transplant from a deceased donor, requiring anti-rejection drugs.

This method applies to people whose cornea has been burned by chemicals have also changed the blade, preventing it from playing its usual role of regeneration of corneal cells. Simply take a square millimeter of leaf - usually on the eye intact - to start the culture of stem cells. The study examined 112 patients and volunteers - including one with both eyes met - treaties between 1998 and 2007 with a success rate of 76.6% complete. Some progress seen as a miracle by some of these patients, partially or totally blind since sometimes many years after the failure of more conventional therapies.

SPINAL CORD INJURY: HOPE TO IMPROVE HEALING

Spinal Cord Injury: Hope To Improve Healing
The spinal cord often tragic consequences, about half of people suffering such an injury following an accident are paraplegic and have to undergo costly and lengthy hospitalization rehabilitation sessions. U.S. researchers have made a discovery that opens the way for new treatments. A protein called SUR1 (sulfonylurea receptor 1) plays a crucial role in the aggravation of an injury to the spinal cord according to this new study published in Science Translational Medicine

Paradox: a protective mechanism aggravates injury:
A sharp blow to the spine can break or dislocate the vertebrae, which then crush and destroy the axons, extensions of these nerve cells which pass into the spinal cord the signals between the brain and rest of body. Even if the spinal cord is not self-destruct after a serious injury, the paradox is that in attempting to protect herself is even more damaging its own cells.

Encoded by the gene ABCC8 activated after injury, the SUR1 protein is part of defense mechanism that protects cells from death due to excessive calcium entry. Sur1 also allows the introduction of sodium, which helps reduce the amount of calcium entering cells. In a serious injury, however, this protective mechanism goes awry and the SUR1 protein is hyperactivated, leading to a uncontrolled entry of sodium which is fatal to cells.

Acting quickly after spinal cord
Marc Simard and colleagues at the University of Maryland at Baltimore have discovered after studying the tissue injury of the spinal cord in humans and rodents that the same mechanism of cell death and cell destruction involving SUR1 is involved both in humans than in mice or rats. By suppressing the expression of the gene ABCC8, researchers have managed to stop in mice the process of self-destruction and to improve long-term recovery from spinal cord injuries. They showed in rats that if they stop short of ABCC8 expression using an oligonucleotide, a small sequence of DNA single strand-specific gene, the lesions after spinal cord injuries are much more limited ( 75% of lesions less).

The study indicates that treatment with this oligonucleotide as quickly as possible after spinal cord injury patients may reduce tissue destruction that follows and improve their long-term restoration. The researchers also show that a drug inhibitor of SUR1 (glibenclamide) has also yielded promising results.

References:
Brief ABCC8 Prevents Suppression of Self-destruction of Spinal Cord After Trauma. J. Marc Simard, S. Kyoon Woo, Michael D. Norenberg, Cigdem Tosun, Zheng Chen, Svetlana Ivanova, Orest Tsymbalyuk, Joseph Bryan, Douglas Landsman & Volodymyr Gerzanich. Science Translational Medicine.
Link: http://stm.sciencemag.org/content/2/28/28ra29.abstract

ANTAGONIZING ATHEROSCLEROSIS

Antagonizing Atherosclerosis
France - Atherosclerosis or fatty plaque build up on the arterial wall is the source of most cardiovascular diseases. While B cells of the immune system were previously considered as elements of protection against the formation of these plaques, researchers from Inserm now refute this hypothesis. These findings were published online in the Journal of Experimental Medicine.

Atherosclerosis is an inflammatory disease of the arteries triggered by several factors, including increased cholesterol and characterized by an accumulation of lipids (fats) in the arterial wall in the form of plaques. The rupture of these plaques is responsible for the majority of cardiovascular diseases, like myocardial infarction or stroke. These diseases are the leading cause of death in industrialized countries. It is therefore essential to identify patients at risk and to understand the progression of the disease, to prevent and treat it.

The immune response (macrophages, B lymphocytes, T lymphocytes) which varies among
individuals plays an important role in the progression of these plaques and thus in the development of complications of cardiovascular disease. To date, the role assigned to all B cells seemed protective of atherosclerosis.

However, the work led by Ziad Mallat now clearly refute this hypothesis. The researcher showed in fact that using an antibody against B cells and causing the disappearance of 96% of
them provides significant protection against development of atherosclerosis. This antibody is
used very effectively in humans, in the treatment of certain inflammatory diseases. The protective effect is due to decreased production of an immune system hormone, interferon gamma which promotes atherosclerosis and increased interleukin-17 a protective hormone.

These findings have important clinical implications. They suggest that treatments directed against B cells currently administered to patients suffering from inflammatory diseases such as
lupus or rheumatoid arthritis, may reduce cardiovascular risk. Clinical trials have been undertaken in this direction by the team and aim to assess the extent of atherosclerosis before and after treatment.

Journal Reference:
Ait-Oufella, H., et al. B cell depletion reduces the development of atherosclerosis in mice. Journal of Experimental Medicine, 2010.
Link: http://jem.rupress.org/content/early/2010/06/30/jem.20100155

GENETICS : CREATING A CELL WITH SYNTHETIC DNA

Genetics: Creating a cell with synthetic DNA
United States - John Craig Venter, an American biologist shows for his research in genome sequencing, has managed his teams to create the first bacterium with a fully synthetic genome.

This bacterium has been made from the sequencing of the genome of the bacterium Mycoplasma mycoides. It's been 15 years since researchers at the J. Craig Venter Institute in Maryland, harnessed to the task. The cell contains more than one million base pairs, which is low compared to six billion contained in the human genome.

This is a great advance in the field of genetics, this research could lead to the design of artificial life forms that could help produce biofuels or pharmaceuticals. Important ethical issues arise, however, due to possible drifts around this technique.

Scanning electron micrographs of M. mycoides

More information can be found on the J. Craig Venter Institute web site at: http://www.jcvi.org/cms/research/projects/first-self-replicating-synthetic-bacterial-cell/

Journal Reference:
Daniel G. Gibson, John I. Glass, Carole Lartigue, Vladimir N. Noskov, Ray-Yuan Chuang, Mikkel A. Algire, Gwynedd A. Benders, Michael G. Montague, Li Ma, Monzia M. Moodie, Chuck Merryman, Sanjay Vashee, Radha Krishnakumar, Nacyra Assad-Garcia, Cynthia Andrews-Pfannkoch, Evgeniya A. Denisova, Lei Young, Zhi-Qing Qi, Thomas H. Segall-Shapiro, Christopher H. Calvey, Prashanth P. Parmar, Clyde A. Hutchison III, Hamilton O. Smith, and J. Craig Venter. Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome. Science, May 20, 2010 DOI: 10.1126 / science.1190719

THE CELLS CULTURED IN VITRO : FUTURE SUCESSOR OF ANIMALS?

The Cells Cultured In Vitro : Future Successor Of Animals?
England - The international conference on tissue engineering has highlighted the ability of this technique to replace laboratory animals, providing additional tools from tests in biomedical research.

The in vitro culture of mammalian cells allows all researchers to study them as testing new drugs or therapeutic procedures. But culture in vitro is different from cells in vivo, those of the living animal. Tissue engineering is now trying to mimic or recreate in vitro models as representative as possible of the living model.

The animal is not the most suitable model for studies of diseases of humans. The 3D cell cultures seem to be good models, but must still be improved and proven reliability. This technique is already applied to the modeling of spinal cord, sepsis, diabetic wounds, compaction of lumbar discs, among others.

From the point of view of trade, the tissue enginerring of interest but must cope with strict regulations. The development of a new molecule must necessarily go through a confirmation in vivo animal model. And the animal model is physiologically very different from humans. With the cultivation of human tissue, animal model tests would be useless. The molecule then quickly prove its effectiveness.

Stem cells also provide their share of promises but they are discussed by ethics. The stem cell adapts to the environment in which it operates and integrates perfectly. Its capabilities are very broad and open the door for developing new therapeutic agents.

Cellular systems will not immediately replace laboratory animals. The scientific community believes it will take between 5 and 7 years to accept and validate these cellular systems as alternative models to animal models.

IN VITRO FERTILIZATION (IVF)

Definition
IVF literally means "fertilization in a test tube." IVF (in vitro fertilization) is a method to achieve fertilization outside the human body by combining laboratory oocytes of women and the man's sperm. The fertilized eggs that result (embryos) are then placed in the woman's uterus.

The conduct of an IVF cycle involves several stages:

1. Ovarian stimulation
2. The timing of ovulation
3. The follicular puncture
4. The collection and preparation of semen
5. Fertilization
6. The development and transfer of embryos
7. Cryopreservation of supernumerary embryos

Ovarian stimulation
Oocytes grow within ovarian follicles in. In the natural menstrual cycle, several follicles are growing at the beginning of menstruation. Only one or two of these follicles will mature about 2 weeks later and will be released during the follicular rupture (ovulation). Follicles that are not mature stop growing and degenerate. Thus, very few oocytes reach the final stage of ovulation in a woman's life.

The goal of ovarian stimulation in IVF is to prevent the degeneration of the follicles by exposure to a sufficient dose of FSH. Administering of FSH by injection, you get higher circulating levels that support the development of multiple follicles and maturation of several oocytes. This proliferation of follicular recruitment, also known as controlled ovarian hyperstimulation, improves the chances of success of IVF by increasing the number of embryos available

Of ovulation (the timing of ovulation)
When the follicles have reached the desired size and estrogen levels are sufficient, the final phase of maturation of oocytes is induced by an injection of hCG (Choriomon ® Ovitrelle ®, Pregnyl ®). Follicular aspiration (oocyte collection) is scheduled approximately 35 hours after injection.

Follicular puncture
Under light general anesthesia, an ultrasound probe with a guide is inserted into the vagina and the follicles are identified. A thin needle is inserted through the guide in the vaginal wall and the ovary and the follicles are punctures one by one. The follicular fluid containing the egg is sucked and collected in a tube. The intervention is short (15-20 minutes). During surgery, the tubes containing the follicular fluid are kept at body temperature in an incubator. They are then immediately transported to the laboratory where the biologist determines the number of oocytes harvested. After ovarian stimulation, we get an average of 8 to 10 oocytes. The patient is then transferred into a room where the result of the drain will be communicated in one hour. After 3 to 4 hours of observation, it can go home.

The collection and preparation of semen
On the day of oocyte aspiration, the spouse takes a sample by masturbation semen to be used for fertilization.

In the event of major difficulty of sampling, it is possible to arrange in advance, a cryopreservation of sperm, which can be used for fertilization.

In cases where semen was collected at surgery or testicular excretory channels before the treatment cycle is generally the cryo sperm to be used.

Whatever its origin, the sperm is analyzed and prepared in the same way. Seminal plasma that limits the power of the fertilizing sperm is eliminated and the most mobile sperm, which are a priori most pollinators are selected.

The oocyte insemination is performed. Depending on the type of infertility, fertilization is left to chance (IVF) or to run (ICSI).

Fertilization
There are two ways to fertilize ova:

1. in vitro fertilization "classic" (IVF) and
2. intra-cytoplasmic injection of sperm (ICSI).

IVF is used as the origin of infertility is female and the sperm quality is normal or slightly altered. A few hours after follicular puncture, the oocytes are reunited with sperm in a culture medium conducive to their survival. They are placed at 37 º C for a period of 4 to 20 hours. Only one spermatozoon - the most active - will cross the zona pellucida and the plasma membrane of the egg and achieve fertilization.

After 18-20 hours of incubation, the biologist look under a microscope if fertilization has occurred. The fertilized ovum (or "impregnated") comes in the form of a cell with two nuclei (pronuclei), one of paternal origin, the other of maternal origin. This stage is called the zygote.

The zygote is not yet an embryo because the genetic heritage maternal and paternal have not yet merged.

At this point, the biologist for the custody transfer 2 or 3 zygotes. The supernumerary zygotes were frozen (cryopreserved) and may be used at a future attempt.

There is sometimes fertilization anomalies that make it impossible to transfer or freezing that these zygotes.

The development and transfer of embryos
Two to three days after the collection of oocytes, embryos are transferred into the uterus. On Day 2, embryos were divided into 2 to 4 cells, the 3rd day, they reached 6 to 8 cells.

The transfer is a painless process. The embryos are placed in a thin flexible catheter. After explaining the cervix with a speculum, the doctor inserts the catheter gently into the uterine cavity. In some cases, the transfer is performed under ultrasound to guide the establishment of the catheter within the uterus and to ensure that the embryos have been tabled in the right place.

Two or three embryos are usually transferred. The number of embryos was decided after discussion with the doctor, depending on the age of the woman and the couple's choice.

Approximately 12 days after the transfer, a pregnancy test performed on a blood test will know the outcome. If the test is positive, an ultrasound will be scheduled approximately 4 weeks after transfer to verify the proper development of the pregnancy.

Cryopreservation of supernumerary zygotes
It is not uncommon that we get more zygotes than the desired number for the transfer. The supernumerary zygotes can be kept at very low temperatures in liquid nitrogen (freezing or cryopreservation).

The aim of cryopreservation of zygotes is to give the couple the best chance to achieve pregnancy, while limiting the occurrence of multiple pregnancy and its complications. The zygote can be thawed and transferred if no pregnancy in the first round. In this case, the stages of the ovarian stimulation and follicle puncture need not be repeated.

The five stages of IVF treatment: (short way of explanation)

1. Hormonal Stimulation of the Ovaries
The woman receives 10 to 14 days, a natural hormone preparations by injection, in order to develop more eggs. In a traditional cycle, one egg is released, but thanks to the hormonal preparation, there are several.

2. Grab or Ovum Pick Up
Puncture or ovum pick up takes place just before ovulation. In this way, the follicles are punctured and sucked so that eggs can be gathered. Around the same time, the man must give a semen sample.

3. Insemination
The insemination is to collect the eggs and sperm.

4. Fertilization
After 16 hours, we can examine whether fertilization took place. Two days later, we can see if the embryos are formed.

5. Transfer of Embryos
Finally, we introduce the (s) best (s) embryo (s) in the uterus.