In order to restore a youthful appearance, more and more people are starting to use collagen to meet their beauty goals.
Collagen is the earliest and most abundant class of extracellular matrix proteins discovered, and as humans age, collagen production decreases, resulting in a gradual loss of elasticity and delicacy.
This article will introduce the nature and pros and cons of different types of collagen, so that readers can understand their advantages and limitations and make an informed decision.
What is collagenCollagen is a fibrous protein formed by the assembly of multiple procollagen.
Procollagen is the basic unit of collagen, which is composed of 3 polypeptide chains, and the primary structure has (gly-x-y)n repeat units, where x and y are often proline and hydroxyproline, and a few are lysine and hydroxylysine.
The three procollagen peptide chains are coiled around each other by interchain hydrogen bonds, forming a stable triple helix structure.
The hydroxyproline hydroxyl group forms strong hydrogen bonds that increase the strength of collagen;
Proline and hydroxyproline can cause sharp structural distortions and improve the stability of collagen.
Its unique structural features allow collagen to have five core advantages over other biomaterials:
Low immunogenicityCollagen structure has a higher repetition rate and is less immunogenic than other immunogenic proteins.
BiodegradableThe tight helix structure of collagen is such that most proteases can only cut the side chains of collagen, breaking the cross-links between collagen molecules.
BiocompatibleCollagen has a good affinity and can help cells and tissues maintain normal physiological functions.
Promotes cell growth
Collagen is a good culture medium for cell growth, and collagen not only provides a nutritional basis but also acts as a scaffold during cell migration and proliferation.
Haemostasis
Collagen has the function of promoting platelet coagulation and plasma clumping, and after contact with blood, platelets in the blood will be adsorbed together with collagen fibers for agglutination reaction, thereby generating fibrin, promoting plasma clumping, and then forming thrombosis, so as to prevent bleeding and promote coagulation.
Classification of collagen(1) L-type collagenMore than 90% of human collagen is type I collagen (the main collagen of the human body), which mainly exists in organs such as muscle eyelashes, bone tissue, blood vessels, etc., which is used to support hardness and make it tougher. (2) LL type collagenIt is mainly produced by chondrocytes and is present in bones, joints, myociliary and other tissues, and is used to maintain the normal function of soft tissues. (3) LLL type collagenMainly found in the superficial or vascular intima and intestinal fibers are fine, sparse and reticulated, with elasticity and repair functions to make them soft and elastic, and promote wound healing. (4) Type IV collagenIt is mainly found in the basal layer and is an important component of the basement membrane of liver, blood vessels, lymphatic vessels and other organs. (5) Type V collagenIt is mostly located on the cell surface, hair placenta, etc., which is used to protect the embryo, and it will be reduced accordingly after delivery.
Collagen of animal originThat is, collagen is extracted from animal connective tissues (mainly pig skin, bovine Achilles tendon, and bovine hide).
Animal tissue extraction is currently the mainstream route with the longest history and the widest range of applications, and its first commercial product applied in the domestic medical field has been on the market for nearly 20 years.
Due to its intact triple helix structure and ability to recognize and interact with a variety of biomolecules, animal-derived collagen has the advantage of biological activity, but the safety hazards are also difficult to ignore:
Animal tissues present a risk of contagion of diseases of animal origin;Similarly, there are uncertainties in all aspects of its collection, processing, etc.Although collagen is generally very safe, xenocollagen has a rejection reaction, which can lead to inflammation of the transplant site, and due to the presence of rejection, the effect cannot be maintained continuously after transplantation, and repeated implantation or injection is required
Collagen is rigid and easy to cause molecular chain breakage during processing
The vast majority of xenogene** collagen is insoluble in water, and the solvents used in the processing process are difficult to remove completely, resulting in cytotoxicity
The collagen directly extracted is divided into two categories: weak denaturation and strong denaturation, the component system is complex, even the weak denatured collagen will have trace amounts of other components, and the strongly denatured collagen includes a mixture of short peptides, long chains, double chains, fragment triple helix, and full-field complete structure, so the uniformity is poor and the clinical effect is uneven, which seriously restricts its application in the field of biomedicine.
** with the production process
The extraction rate of bovine collagen and porcine collagen is high, and it can be used in food, cosmetics, medical equipment and other fields, and is widely used in industrialization. Judging from the content of the characteristic amino acid hydroxyproline contained in the collagen peptides of different raw materials, livestock and poultry skin, freshwater fish skin and fish scales, deep-sea fish skin, in the actual production process, the raw materials of livestock and poultry skin bones and freshwater fish skin and fish scales can be fully guaranteed, and its collagen content is 20%-30%, which is higher than 10%-20% of cattle and pigs, but the application range is mainly food, and it is rarely used in the field of medical treatment and cosmetics.
Comparison of the preparation of high-purity collagen from four biological raw materials Bao Yi et al.", "Collagen Peptide Industry Status and Development Trend Zhou Xuesong", Shuangmei Announcement, Debang Research Institute.
There are various methods of animal source extraction, and acid method and enzymatic method have been industrialized.
Animal-derived collagen can be extracted by acid method, alkali extraction, enzymatic hydrolysis method, neutral salt method extraction and hot water extraction, and can also be extracted by compound method, such as acid enzyme composite method, acid and hot water composite method, etc., and the compound use can be used to improve the extraction effect.
Gene Biotech Prospectus, "Research Progress on Extraction and Application of Animal-derived Collagen Zhi Hui et al.", "Research Progress on Extraction, Modification and Application of Collagen Liu Zhenfeng, et al.".
Traceability and immunogenic clearance
Animal collagen extraction faces two major problems of immunity and virality, which has become a difficulty in animal extraction, and through strict control of raw materials, the occurrence of zoonotic diseases such as mad cow disease and foot-and-mouth disease can be effectively avoided.
Immunogenicity**: The immunogenicity of collagen extracted from animal sources is affected by six factors: purity, structure, donor and recipient species characteristics, extraction method, implantation site, and cross-linking method.
The hazards of the materials mainly involve: bacterial, mold or yeast contamination, viral contamination, transmissible spongiform encephalopathy (TSE) factor contamination, parasite or other unclassified pathogen contamination, etc.;Immunological and pyrogenic reactions caused by impurities and uncleared cellular antigens, such as the common -gal antigen. 
Immunogenicity Clearance of Animal-Derived Collagen and Its Medical Application Lei Jing
There are multiple approaches to immunogenicity clearance, including decellularization and cellular antigens;Removal of impurities such as denatured impurities or non-target proteins;Cross-linking treatment to block the epitope of the material;Degreasing and removal of exogenous microorganisms, low-temperature freezing treatment, removal of lipopolysaccharides, etc., and the removal methods of different tissue materials are different. Recombinant collagenCompared with traditional animal collagen, recombinant collagen has the characteristics of no viral hazards, excellent biological compatibility and efficacy, and low immunogenicity, which effectively avoids the virus hidden dangers and rejection reactions of traditional animal-derived collagen, and overcomes the disadvantages of traditional animal collagen due to the inaccurate clinical efficacy and unstable quality of the terminal product due to animal age differences and species differences, and has created a milestone major breakthrough in the field of collagen biomaterials.
However, the biological activity of recombinant collagen is still doubtful, and the E. coli and yeast used in fermentation cannot synthesize prolyl hydroxylase by themselves, and the resulting peptide chain is difficult to form a triple helix structure. Up to now, recombinant human collagen with a full-length amino acid sequence and a triple helix structure is still under development.
Classification of recombinant collagen
According to the ** of recombinant collagen, collagen can be divided into three categories:
(1) Recombinant human collagen.
Recombinant proteins prepared by DNA recombinant technology containing full length or partial gene sequences (at least containing helix domains) encoded by specific types of human collagen, with or without a three-strand helix structure, have the physicochemical properties and biological functions of collagen. It has the advantage of high consistency of gene sequences and activity, but has the disadvantages of large molecular weight, difficult synthesis and a large number of useless non-functional regions.
(2) Recombinant humanoid collagen.
Human collagen analogues prepared by DNA recombinant technology, containing partial sequences encoded by specific or different types of collagen genes, and prepared by gene editing, combination, assembly, editing, etc., have a protein structure, with or without a three-strand helix structure. It has many advantages, such as high consistency of gene sequences, better histocompatibility, higher biological activity, support and elasticity, lower immunogenicity, low allergic reactions, and no risk of pathogen infection. However, the triple helix structure is very difficult and can only be achieved at the fragment level.
(3) Recombinant collagen.
The collagen analogues prepared by DNA recombinant technology have low homology with the gene-coding sequences or amino acid sequences of human collagen, but have the physicochemical properties and biological functions of collagen.
Collagen.
The vast majority of research on recombinant collagen has focused on different types of human collagen. Research includes the identification, characterization, and functional studies of humanoid and collagen-type proteins, as well as some of them for large-scale production of biomedical materials.
applications. Different expression systems have been used to prepare recombinant collagen.
Due to the lack of proline hydroxylase, Escherichia coli cannot obtain hydroxylated collagen when expressing collagen alone, and cannot effectively form a triple helix structure, thereby inhibiting the self-assembly of collagen molecules from natural structure collagen molecules to collagen fibers.
So far, there have been many studies on the expression of human collagen using yeast, such as Pichia pastoris, Hansen's yeast and Saccharomyces cerevisiae, among which the expression level and hydroxylation efficiency of recombinant human collagen obtained by the expression of Pichia pastoris engineering bacteria are the highest.
Features of recombinant collagen
Compared with collagen extracted by traditional methods, recombinant collagen has good water solubility, low rejection reaction, good processability, and a single component.
First, the process is controllable, the production cycle is short, the product is controllable, there is no hidden danger of the virus, etc., and the product quality is more stable. Therefore, recombinant collagen has the following characteristics:
1.No hidden danger of viruses.
In general, collagen extracted from animal tissues has a hidden danger of viruses, and this fatal shortcoming limits the application and development of collagen to a large extent. Recombinant collagen can completely compensate for this deficiency and significantly improve its biosecurity.
2.Lower rejection.
Recombinant collagen can be either a natural human collagen sequence and therefore very low immunogenicity, or an unnatural human collagen sequence. In order to reduce the immunogenicity of recombinant collagen, the native collagen gene sequence is usually re-optimized. Therefore, recombinant immunogenogenized collagen is less likely to cause immune rejection in humans.
3.Good water solubility.
Animal collagen is usually less water-soluble because it retains a relatively intact fibrous structure. Single-chain recombinant collagen has good water solubility, and collagen with a three-strand helix structure can improve the hydrophilicity of recombinant collagen by replacing the hydrophobic amino acids in the non-coding amino acid sequence with hydrophilic amino acids.
4.Non-cytotoxic.
The recombinant collagen has good water solubility, so that its separation process does not require acid-base solvent treatment, so there is no residue of acid-base solvents, which avoids the impact on cell metabolism.
5.Good machinability.
Natural collagen is a three-strand helix structure, and its structure changes when dissolved, and the molecular weight also changes, which is not conducive to the post-processing application of collagen. Recombinant collagen, on the other hand, often exists in the form of a single chain, which does not change its molecular weight and basic properties when dissolved, and has good processability.
6.The quality is controllable and easy to produce on a large scale.
Genetic engineering technology can express collagen molecules of specific molecular weight, and the fermentation cost is low, the production cycle is short, the yield is high, it is easy to be industrialized in large quantities, and the molecular weight uniformity and quality stability of the product are higher. The animal extraction method is not conducive to quality control due to problems such as process and raw materials.
Collagen, is it really for you?Collagen fillers are highly sought after in modern society due to their many benefits as a common beauty method.
First of all, collagen fillers are able to give the face a natural look. Since collagen is a naturally occurring substance in the human body, it is highly integrated with tissues after filling and is not easy to detect.
Moreover, its filling effect is long-lasting. Compared to other fillers, collagen fillers can last longer, reducing the need for frequent injections.
In addition, collagen-filled facial surgery is relatively less invasive. The filling process usually does not require a surgical incision, but is performed by way of injection, which requires only a slight puncture**, reducing the risk of surgery and the recovery period after surgery. This makes collagen filling a safer and more convenient cosmetic method.
The injection site of collagen filler can be adjusted according to individual needs, not only to fill in wrinkles and hollows on the face, but also to plump up lips, improve cheekbone contours, and more.
Overall, collagen-filled facials have many benefits such as natural appearance, long-lasting results, and minimal trauma, making them the most popular beauty method for a wide range of people.
However, there are some drawbacks that also need to be paid more attention to by readers.
The biggest pain point of collagen extracted from animal sources is the allogeneic rejection reaction, which can easily lead to aseptic inflammation or affect the absorption rate of collagen in the process of clinical use. This is also the main reason why some people have an allergic reaction to collagen, causing discomfort or inflammation.
Therefore, it is very important to make sure that you have an allergy test before proceeding with the filling.
As an advanced product to solve the rejection reaction of animal-derived collagen, there is no clear solution to the problem of recombinant collagen for the time being.
The imaginative injectable gel products have a high threshold for approval and marketing, and it is difficult to mass produce in a short period of time, and the existing mass-produced products are mainly concentrated in the skin care market.
The first question is, can recombinant collagen really be absorbed through the skin?
Traditionally, it is believed that components with a molecular weight of more than 500DA are difficult to be absorbed through the skin, while the molecular weight of collagen reaches tens of thousands of DA, even if collagen is active and compatible as a biomaterial, there are quite a few brands and manufacturers who have responded, but solving the problem of penetration efficiency is still the top priority of recombinant collagen at the application level.
The second problem is to solve the problem of infiltration, how to solve the problem of activity
In the field of skin care products, in order to solve the problem of osmotic efficiency, some manufacturers reduce the molecular weight by enzymatic digestion, but this also destroys the triple helix structure, making it unable to reach the inside of the ** and maintain a good supporting effect.
The third question is how long the collagen units contained in recombinant collagen are better
At present, the fragments and sequences screened by different manufacturers are different, and different sequences will produce different efficacy differences, and the lack of a clear market standard will lead to further market chaos.
In addition to this, the downstream hospital quality of collagen is uneven. The filling technique of collagen is very demanding, and the injection requires a certain amount of professional knowledge and experience to achieve the desired results. If not done properly, it can lead to uneven distribution, agglomeration, and uneven inequality.
From the current point of view, there are still many technologies to overcome in collagen, many problems to be solved, for collagen products, whether it is injections, or skin care, may not be suitable for everyone, so it is wise to fully consider your own needs and risk factors, and seek professional advice to choose whether to use collagen.