Evaluation of in vitro osteogenic activity of alumina/zirconia bioceramic scaffolds covered with hyaluronic acid and hydroxyapatite

Abstract

Tissue engineering and regenerative medicine has emerged, especially in the last three decades, as a multidisciplinary field of work of great interest for the development of new technologies aimed at replacing or assisting in the regeneration of damaged or injured tissues. Technologies applied in different combinations to create structures that mimic fabrics. Although certain animal tissues, such as bones, cartilage, nerves, skin and muscles, have the capacity for regeneration and good recovery of their original functions, many medical conditions require interventions. In this context, scaffolds are structures that stand out within regenerative medicine for bone regeneration and, as they provide a three-dimensional environment with the function of mimicking the natural tissue microenvironment, they have numerous advantages, such as: physical and mechanical support to the cells acting in the process of regeneration; creation of delivery systems; creation of an osteoinductive microenvironment; incorporation of osteoinductive molecules; possibility of implants. Furthermore, it is important that materials used in the field of tissue engineering are biocompatible, are not immunogenic or cytotoxic and have good interaction with cells. Ceramic materials constitute one of the types of viable alternatives for the production of scaffolds, mainly due to their high porosity and great versatility, both in relation to composition and manufacturing methods. Using alumina (Al2O3), zirconia (ZrO2) bioceramics and the combination of both (Al2O3/ZrO2) it is possible to manufacture biomaterials with good mechanical properties, high chemical stability and biocompatibility, compared to other materials. As they are classified as bioinert ceramics, they are rigid and can be used with advantages in prosthetics and implants. In order to provide a more favorable microenvironment for osteogenesis, surface coatings of bioceramic scaffolds with bioactive materials can stimulate more effective cellular responses. Hyaluronic acid (HA) is a biocompatible, biodegradable, bioresorbable and non-toxic biomolecule, naturally present in various living tissues, clinically well established, and abundant in the extracellular matrix (ECM). Its physical-chemical properties are remarkable, due to its hydrophilic nature, viscoelasticity, adhesiveness and possibility of combination with other components. The HA structure allows interaction with receptors that act in cell adhesion, with emphasis on the transmembrane receptor CD44, expressed by mesenchymal stem cells (MSC), osteoblasts and osteocytes. The combination of HA injectable hydrogels combined with hydroxyapatite (HAP) has also demonstrated excellent osteogenic properties in vitro and in vivo, which make HA an alternative for ectopic bone formation. The chemical structure of HA also allows for a stable and long-lasting interaction with ceramic materials in the presence of water, due to the formation of hydrogen bonds. In this way, the physical properties of Al2O3/ZrO2 scaffolds can be improved through surface coating with HA and HAP, creating a new product with potential use in bone regeneration. (AU)