If you cut off the tail of a lizard, it soon grows back. What is the mechanism by which this happens? Can the same or a similar mechanism be applied to grow back a limb of a human being whose arm or leg has been accidentally cut off? In evolutionary terms lizards are closely related to humans and some common mechanisms may exist.
Scientists from have now discovered the genetic mechanisms by which lizards are able to regrow the cut organs. Three small genetic switches (micro RNAs) have been discovered using next-generation genomic and computer analysis, opening the way for human limb regeneration. These switches control the behaviour of hundreds of genes, just like a music conductor controls the manner in which he leads the musicians in a large orchestra. This represents one of a large number of exciting discoveries that have occurred in the current decade in the field of tissue engineering.
Can we slow down the ageing process? Can we reverse it? After all, ageing is nothing more than a series of chemical reactions, and many chemical reactions are known to be reversible. There are a number of reasons for ageing. One of them is programmed cell death (‘apoptosis’). After a cell has divided a number of times, a chemical signal goes out instructing the cell to stop dividing and die. This ‘death signal’ is in the form of a chemical command. Scientists have learned what these command signals are and how to disrupt them so that cells can keep on living.
Another reason for ageing is oxygen. Oxygen is necessary for our survival but it is also partly responsible for our ageing and death. A reactive form of oxygen (oxygen radicals) attacks our DNA and contributes to its erosion and to the ageing process – hence the use of anti-oxidants. A number of genes have also been identified which are responsible for ageing.
Mitochondria present in our cells serve as are our cells’ energy dynamos. They however weaken and become flaky as we age. It is believed that decaying of mitochondria is a key factor in ageing, leading to everything from heart failure to neurodegeneration. It has now been shown that certain dietary supplements may slow down or even reverse the ageing process.
In an experiment on mice, scientists at Harvard Medical School have found that giving older mice a chemical called NAD for just one week reversed their ageing and made the 2-year-old-mice look like six-month-old mice (in human years, that would be comparable to a 60-year-old’s cells becoming like those belonging to a 20-year-old).
The ‘clock of ageing’ in the human body is believed to be associated with a region of repetitive DNA at the end of the chromosome. This is a protective cap, called a “telomere”. As the cells divide repetitively during our life, the protective cap erodes. As a result the telomere gets shortened, and so do the number of remaining years for us to live. If somehow science could find a way to protect the telomere from degradation, one could slow down or even reverse the ageing process.
Researchers have now discovered a natural compound, code named TA-65, which has the remarkable property of activating the enzyme telomerase in the human body, thereby extending the length of the telomeres. This represents the first telomerase activating substance safe for human consumption reported so far and it may lead to the extension of human life spans to 125 years or beyond.
There is a huge demand of anti-ageing products, with annual sales of $50 billion in USA alone. These products range from anti-wrinkle skin creams, hormone replacements, vitamins, herbal preparations and nutritional items. However most of these have not been fully tested for their beneficial effects. Medical experts and medical associations have generally been critical of their use, considering their marketing as unscrupulous profiteering by companies. Recent advances in stem cell research for tissue rejuvenation, organ replacement and therapeutic gene therapy hold out hope for the future.
An exciting new rapidly developing field in medicine is that involving the use of stem cells to repair damaged organs. Stem cells along with certain other cells act to repair damaged tissues in the body since they can be transformed (“differentiated”) into other types of cells in the body cells (nerve, kidney, heart cells etc).
In an important recent development, it has been found that instead of providing patients stem cells from different donors, (in which case there may be problems associated with rejection), the patient’s own stem cells can be selectively released from the bone marrow. These can then help in the repair and regeneration of specific tissues, depending on which type of stem cell is released. This ability to selectively stimulate the release of a patient’s own stem cells represents a major breakthrough in this rapidly developing field.
Embryonic stem cells have now been used to produce red blood cells in large enough quantities to be employed for blood transfusions. The process has been developed by Advanced Cell Technology. Before long red blood manufacturing automated machines could be developed, which could supply an unlimited quantities of universally transfusable blood. We are at the beginning of an enormous revolution in medicine. Scientists at McMaster University in Canada have found a way to convert skin cells directly to blood. This opens the way for the large-scale production of a patient’s blood from his/her own skin cells.
Stems cells are also now being used as guided missiles to target cancers since they tend to accumulate near cancer cells. It is expected that the combined use of stem cell therapy and anti-cancer drugs will allow not only the main tumours to be attacked but secondary growths and even single cancer cells could be targeted in this manner. Clinical trials on human patients using this approach are now under way.
Research now plays a critically important role in the process of socio-economic development. Universities and companies undertaking such research with assistance from their respective governments are propelling those countries to become powerful knowledge based economies.
In Pakistan the status of science has been badly neglected except for the period 2000-2002 when a 6000 percent increase was witnessed under my charge as federal minister in the development budget of science. The S&T budget reached 0.8 percent of GDP but has been systematically reduced subsequently to only a pathetic 0.3 percent of GDP.
Pakistan can never progress unless our government gives the highest national priority to education, science, technology and innovation.
The writer is chairman of UN ESCAP Committee on Science Technology &
Innovation and former chairman of the HEC. Email: [email protected]