29 Aug Solving some doubts about Hyaluronic Acid
Today we bring you a very clarifying post about Hyaluronic Acid, created by our Medical Advisor Clara Serés.
Types of hyaluronic acid
Nowadays all people whom minimally care about their skin have heard about the famous hyaluronic acid (HA). We hear this name in anti-aging creams television ads, in magazines, we read that it is the most used component and that aesthetic doctors apply it regularly to celebrities to moisturize, enhance cheekbones, refresh lips and even restore the hydrolipidic balance of the vagina walls.
This boom of the cosmetic use of HA adds to other known applications of this component in medical specialties such as ophthalmology and traumatology. Indeed, the chambers that separate and protect the iris from the cornea and from the retina contain the vitreous humor, formed by HA. In the same way, joints that suffer from wear and tear due to some pathology are usually filled with HA, such as osteoarthritis.
These treatments are administered in the form of injections in the knee joint and their purpose is to increase the viscosity of the synovial fluid and lubricate the joint.
HA can also be used in post-operative procedures for tissue reconstruction, for example, after a cataract operation, or as a mucosal regeneration treatment when you suffer from canker sores.
However, what is Hyaluronic Acid?
HA is a molecule that occurs naturally and produces our body. With the passage of time, the organism loses its ability to synthesize it, and, at the same time, the body loses more and more quantity.
When we look at the face of a baby or child, we see it very round, plump. It is due to the large amount of HA that the body produces at these ages and, due to the characteristics and particularities of the molecule, the capacity to attract many water molecules around it. Hence, HA is known as a solution to hydrate the skin, for this ability to surround itself with water molecules. So wherever the AH molecule is, we will have at least 100 times its weight in water molecules around and, therefore, a well-hydrated environment.
These aspects have led the pharmaceutical industry to recreate this molecule synthetically in the laboratory to offer to the competent medical community a safe and effective tool to replenish this substance in areas where the body needs it most.
Why are there several HA?
As with other substances, laboratories have innovated in the treatment of this molecule to give it physicochemical characteristics with more or less dense textures, varying elasticity, cohesiveness and viscosity.
The molecule can vary in its molecular weight (MW), increasing its durability in the dermis while the MW is higher.
To these characteristics, we need to add the crosslinking process. This is another manipulation that is done to the HA to get different textures of this product. To understand this process and the reason why it is interesting to obtain different forms of the HA molecule, we are going to put a simple example with another substance (sugar) that we will consider represents HA for this example.
Therefore, we take as a model substance the sugar that would correspond to AH. We have five equal glasses that we fill with the same amount of water, and taking glass by glass, we add 8 gr. of sugar in each glass.
We have sugar in five different forms:
- In the first glass, table sugar.
- In the second glass, we add sugar, but in the form of honey.
- In the third glass, it will be in the form of a gummy candy.
- In the fourth glass will be a toffee type candy.
- In the fifth glass, the sugar will be in the form of hard traditional candy.
These different forms of sugar make the dissolution of the product in the water more or less fast. The same happens with the HA inside the skin.
The more compact forms (glasses 2, 3, 4 and 5) correspond to a cross-linked HA form (more or fewer links are stabilized in the mesh of the molecule, to give it a three-dimensional shape that makes it more gel and compact). These forms take more time to be degraded by the body, so its use is focused on taking advantage of its more gel or cohesive shape to give volume and/or fill facial depressions. Depending on the hardness of the candy, it would be used to correct nasolabial folds, shape or increase the volume of the lips, cheekbones, chin, buttocks …
The table sugar of the first glass has not been processed so it dissolves easily in the water, as well as its corresponding HA in the tissue. This untreated version of HA is called non-cross-linked, which makes it easier to spread on the skin (it would correspond to the ease of dissolving table sugar in water).
Thus, we find different HA in the market that vary according to whether or not they are cross-linked, in addition to the degree of cross-linking they have. This allows extending the use of HA to several indications. In one hand we find treatments for fine wrinkles in very superficial areas of the skin such as the eye and lip contour or the revitalization of tissue in general, which are performed with non-cross-linked HA. On the other hand, we find cross-linked HA-based fillers that allow filling tissue depressions or creating volume for months in some area (cheekbones, chin, etc.).
Doctors and other aesthetic professionals use non-cross-linked HA in mesotherapy or skin rejuvenation treatments with microneedling. However, the concentration of this substance in the same volume can vary.
Institute BCN offers three references of non-cross-linked HA with the following concentrations:
- 8mg / ml of HA in the form of sodium hyaluronate
- 20mg / ml
- 35mg / ml
These different presentations allow to use HA alone or combine it by diluting it with other substances to elaborate individualized formulas, adapted to the needs of each patient.