No bones about it: HA is important.
On the 1960’s science fiction TV show Star Trek, the doctor was nicknamed “Bones”. The nickname was appropriate. Bones, the doctor, supported and protected the other characters, providing them with the means and support to act and keep the starship in tip-top shape so they could fight off the Klingons.
Like Bones, the doctor, the 208 bones in the human body support the muscles and organs of the body and give the body the ability to move and react. Bones give muscles an attachment point that allows the muscle to generate force that translates into movement. Bones, grouped together into the skeleton, protect the body’s inner organs from damage. The most obvious example of this protective role is the skull protecting our brains from damage, which in turn preserves the structure and function of our brains and nervous system.
Bones have other important roles. In this section, we will talk about HA’s role in general bone health. The next section describes a very important bone health role for Hyaluronic Acid that has not received enough interest from doctors and researchers: Using HA to prevent and treat osteoporosis. Keep reading!
Bones are the place where blood cells, fat cells, and some types of cells that make up connective tissue are created and grow to maturity. Bones also regulate calcium levels in our bodies. Calcium has many important roles in the body. Bones themselves are partially made up of calcium. Calcium is an important ion that allows our heart to beat and is necessary for some glands in our body to secrete substances, such as saliva and tears.
Bone is a tissue, and, like all tissues, bones require a support layer to be healthy. HA is an integral part of the support layer for other tissues. So, if HA also is an integral part of the support layer for bones, this suggests that oral HA supplements might contribute indirectly to healthy bone. However, there is little scientific and clinical evidence to suggest that oral HA supplements improve human bone health (Lee, et al., 2014). In fact, there are very few studies of HA’s direct role in human bone health at all.
Studies that use Hyaluronan to target other drugs to bone cells or to support bone cells while other drugs do their work offer indirect suggestions that HA is important to bone health. One drawback of applying these studies to understanding how HA contributes to human bone health, is that the studies have been conducted in cultured cells or animals rather than in humans. But we can use them to get a vision of where applications of HA in human bone health might go in the future after additional research is conducted.
Some animal studies suggest that HA gels or sponges in which building block molecules for bones are embedded, help to hold the bone building block molecules in place so they are able to crosslink to build new bone or to repair bone after injury (Chang, et al., 2016; Huang, et al., 2017; Holloway, et al., 2014; Kim, et al., 2007; Kisiel, et al., 2013). This suggests that HA in the bone support layer contributes to maintaining bone by maintaining a constant supply of building blocks, and by enhancing other molecules’ ability to regulate the balance between bone breakdown and bone buildup (Hulsart-Billström, et al., 2013; Huang, et al., 2017; Chang, et al., 2016).
Additional hints that HA in the bone support layer contributes to maintaining bone come from animal studies that use HA to target drugs and bone building proteins to bone. Then, HA holds the drugs and proteins at the site where bone needs to be regenerated (Chang, et al., 2019; Fujioka-Kobayashi, et al., 2016; Rammel, et al., 2018). The anti-osteoporosis drug, bisphosphonate, has been delivered to bone by using HA to target bone cells (Hulsart-Billström, et al., 2013; Kootala, et al, 2015). We will talk about osteoporosis in more detail in the next section. HA embedded in gels has been shown to promote growth of artificial bones to be used for bone grafts (Yeom, et al., 2014; Koca, et al., 2020). A magazine reported that the Food and Drug Administration, the government agency that approves drugs for use in the United States, has approved an HA based preparation that is injected into voids in bone created by surgery or traumatic injury. The HA-containing bone filler helps new bone grow to fill in the void.18
Currently, the best direct evidence for the importance of HA in human bone health comes from two sources. First, clinical trials suggest interest by the medical community in the medical benefits of HA-based treatments. Of the 25 clinical trials registered on ClinicalTrials.gov that were found in a search by using the keywords “bone” and “hyaluronan” (and the closely-related “hyaluronic acid” or “sodium hyaluronate”), six studies investigated using HA to regenerate bone after dental procedures.19The interest in HA in bone health is supported by numerous peer-reviewed dental practice articles describing the importance of HA in human bone health. These articles in dental journals describe how dentists successfully use non-invasive, topical HA gels after dental surgery and tooth extraction to help jawbone heal and regenerate (Eliezer, et al., 2019). Other dental clinical studies suggest that HA also is important to the health of the periodontal tissue that covers our jawbone. Healthy periodontal tissue is necessary for healthy jawbone and teeth (Ceccarelli, et al. 2017; Casale, et al., 2016).
18ClinicalTrials.gov. https://bit.ly/2MZVXme. Retrieved June 13, 2020.
19ClinicalTrials.gov. https://bit.ly/2MZVXme. Retrieved June 13, 2020.
In the next section, we will discuss a very important bone disease, osteoporosis. The medical community is just beginning to understand how HA can be used to prevent and treat osteoporosis.