The aging of the global population is becoming more and more serious, and it has become a hot spot in the field of modern gerontology to clarify the mechanism of aging and strengthen anti-aging treatment. Aging is the gradual irreversible degenerative changes in the structure and function of various tissues and organs of the body under the influence of various factors such as genetics, mental stress, environmental pollution, etc. in vivo and in vitro.
With the continuous development of modern medicine and social science and technology, the average life expectancy of human beings has been greatly improved. The continuous increase in the base and proportion of the elderly population has not only increased the economic and social burden and the burden on the working-age population, but also brought great challenges to the medical and health services and the social pension service industry.
Therefore, it is of great social significance to carry out research on the mechanism of human aging and develop anti-aging drugs to delay the speed of human aging and increase the healthy life span of the elderly.
Physiological and Pathological Aging
Aging is divided into physiological and pathological aging. The former refers to the natural aging state of body function and metabolism over time, such as protein degradation, tissue atrophy, decreased metabolic rate, and abnormal calcium metabolism; induced aging state. With the passage of age, diseases caused by aging, such as Alzheimer’s disease, Parkinson’s disease, cardiovascular and cerebrovascular diseases, and cancer, are increasing exponentially worldwide.
Mechanism of Aging
Aging is formed by the joint action of many complex factors, and there are differences among different organisms. At present, it is still impossible to explain all aging phenomena with one theory.
There are many different hypotheses about the mechanism of aging in modern medicine, such as free radical theory, mitochondrial DNA damage theory, genetic program theory, telomere theory, cross-linking theory, biofilm damage theory, chromosome mutation theory, error theory, cell apoptosis theory and waste accumulation theory, etc. Among them, free radical theory, mitochondrial DNA damage theory, genetic program theory and telomere theory are the most representative, which laid the theoretical foundation for the development of anti-aging drugs.
2.1. Free Radical Theory
This theory holds that the human body can both produce free radicals and carry a free radical scavenging system [such as superoxide dismutase (SOD), etc.], so as to maintain the normal activities of the body. As we grow older, it is difficult to maintain a balance between the two, resulting in excess free radicals. Excessive free radicals cause lipid peroxidation, severely damage cells, form lipid free radicals and produce lipid peroxide (LPO), further damage biological macromolecules and lead to aging and death. Excess free radicals or reduced scavenging capacity can lead to many diseases such as aging, cancer, shock and inflammation.
2.2. Mitochondrial DNA Damage Theory
Mitochondria regulate various cellular processes such as ATP production and apoptosis, and play an important role in the energy metabolism of the body. During the process of mitochondrial oxidative phosphorylation to generate ATP, about 1 % to 4 % of the ingested oxygen is converted into oxygen free radicals.
Due to the lack of protection of histones and DNA-binding proteins, mitochondrial DNA is extremely vulnerable to oxygen free radical damage, which eventually leads to Mitochondrial DNA fragment deletions, such as Alzheimer’s disease, Parkinson’s disease and other senile diseases, have fragment deletions of varying degrees. As we grow older, mitochondria are extremely vulnerable to oxygen free radical damage, resulting in morphological changes and resulting in functional decline, which eventually causes the body to age.
So far, anti-aging treatment can be roughly divided into chemical drug treatment and biological treatment according to physical and chemical properties.
Traditional synthetic anti-aging drugs, most of which are used clinically to delay aging are synthetic drugs, such as aspirin, piracetam and lamotrigine. In addition, the research and development of peptide/protein chemical components is currently a hot spot in the field of anti-aging.
Peptide drugs are often formed by separating and purifying 10-100 amino acid molecules after dehydration, and proteins can be composed of more than 100 amino acids. In clinical practice, it has specific therapeutic effects and can be used in cardiovascular, blood, muscle, bone, anti-aging and other systems, so it occupies an important position in the research and development of the pharmaceutical industry.
For example, the cosmetic peptides synthesized by Omizzur only need a small amount of peptides to be added to cosmetics, which can have anti-aging, facial beauty and other effects.
In addition to anti-aging drugs, in order to combat the aging of appearance and body shape, scientists have also developed a variety of anti-aging technologies for treatment, mainly including: stem cell transplantation, fecal microbial transplantation and hormone replacement therapy.
3.2.1 Stem Cell Transplant
Adipose stem cells and bone marrow mesenchymal stem cells are often used in anti-aging stem cell transplantation. These two types of stem cells have the characteristics of less tissue damage, convenient material collection, strong differentiation ability and long-lasting effect. Free radical ability, inhibit inflammatory response, accelerate wound healing to achieve anti-aging effect.
3.2.2 Fecal Microbiota Transplant
With age, body immunity decreases, intestinal physiological function and dietary structure change, resulting in the decrease of beneficial bacteria and diversity of intestinal flora and the increase of facultative anaerobic bacteria. The change of aging-related intestinal flora affects the brain-gut axis through the enteric nervous system, hinders nerve, endocrine and immune signals, and will cause central nervous system diseases such as Alzheimer’s disease and Parkinson’s syndrome. Therefore, fecal microbiota transplantation anti-aging technology targeting intestinal flora has been widely used clinically.
3.2.3 Hormone Replacement Therapy
Skin and overall appearance changes with age due to declining hormone levels, the most commonly used hormones are growth hormone, androgens, estrogens and progesterone. Healthy postmenopausal women treated with hormone replacement therapy reduced the incidence of colorectal cancer by 37%. Safe and reasonable hormone replacement therapy will effectively delay aging and improve the quality of life of the elderly.