Stem Cells: Introduction
"When I think about old age, I see four reasons why
we habitually consider it an unhappy period of our life:
it removes us from active life, weakens our physiological strength,
deprives us of sensual pleasures and brings death closer."Cicero
People have been interested in the causes of aging since time immemorial.
Judgments and reflections on old age as a natural final period of a person's life are found in many thinkers of the past. But it was only in the twentieth century, especially in its last decades, that humanity faced the problem of aging as a completely new social phenomenon. The acceleration of the aging process of society, which is acquiring a progressive character, has become quite obvious.
If in 1990 there were 18% of people of retirement age in Western countries, then by 2030 this figure will rise to 30%. In 1939, there were 4% of elderly people in Russia, in 2000 — 12%. People over the age of 60 are the fastest growing population group. It is expected that by 2015 the share of the elderly in Russia will increase to 20.5%.
In Russia, the aging process began much later than in most Western European countries, in which it has been going on since about the end of the century, but since the mid-60s of the twentieth century it has proceeded more intensively than in the West. XIX
Old age becomes a long and significant stage of individual development, the proportion of which is about a quarter of a person's life.
In connection with these demographic shifts, the idea of old age as the final stage of life also does not remain unchanged. The age threshold of old age is changing. In 1962, the symposium of gerontologists approved the age gradations: 40-60 — middle age; 60-75 elderly; 75-90 senile; over 90 — centenarians. At present, civilization has provided an average life expectancy of about 70-80 years, which seems absolutely incredible in comparison with the prehistoric era, when it was only 35 years.
In the history of human development, for a long time, old age was considered as a symptom and expression of the withering away, attenuation of all life processes. Old age seemed inextricably linked with death as the beginning of the end, unable to give a person positive strength.
However, with the increase in life expectancy, the increase in research on gerontology, sociology and psychology, the realization of old age has come not just as an organic dying, but as a new long life full of dramatic contradictions. There was a fundamentally new discovery of old age. It began to be regarded as an equal human age among others, not reduced to the processes of decay, but an independent and special age in its characteristics.
Old age as a phenomenon of human life is represented by two qualitatively different aspects of its existence - biological and social. Focusing on the biological characteristics of the phenomenon, we will consider the aging process as a decrease in the viability of an individual organism during life.
The human body is a very complex self–governing and self-regulating system, which in order to maintain its integrity must constantly self-renew. This is what makes it possible to exist in equilibrium with constantly changing environmental conditions. Finding out the causes, patterns and features of the processes of self-renewal of the human body is the key that opens up approaches to methods of influence on the aging process. One of the most relevant modern approaches is related to stem cells.
Not only scientists working in the field of genetics, molecular biology and reproductive medicine, but also many practitioners of various specialties associate very high hopes with this area of research.
Millions of cells die or break down in us every day. They are replaced by new ones specializing in special stem cells, which, as an inviolable reserve, are stored in all human organs and systems from the first hours and days of the embryo's life.
Stem cells are called progenitor cells, from which, if necessary, all other types of cells that make up various human organs and tissues are formed. The practical use of stem cells will change traditional approaches in the treatment of many diseases and give people the main thing - health, youth, longevity.
See next: how stem cells differ from other specialized cells; stem cells and processes of cell differentiation and regeneration; types of stem cells; stem cells and longevity, practical application of stem cells; prospects and warnings, etc.