# Bioactive Glasses for Soft and Hard Tissue Healing Applications--A Short Review
###### Abstract  
Bioactive glasses have developed into a variety of items that are used in order to treat a wide range of medical problems. Apart from being mostly applied in the healing processes of hard tissues, bioactive glasses are becoming very popular materials in soft tissues healing. Bioactive glasses have exhibited the ability to accelerate skin regeneration by enhancing angiogenesis and collagen deposition in the proliferation stage, as well as positive effects on all the other important stages of wound healing. They can adhere to hard tissues such as bone and aid in the regeneration of those tissues by forming a calcium-phosphate-like layer on their surfaces. The formation of this apatite layer results in a linkage between the hard tissue and the glass, which further leads to bone healing. This short review summarizes the dynamic process of wound healing along with the basic concepts of bioactive glasses applied in this domain. We aimed to explore constructs which aid different phases of wound healing. Moreover, several research studies dedicated to bioactive glass thin films are briefly discussed.  
bioactive glasses; wound healing; dissolution; cellular activity; dopants; dressing +
Footnote †: journal: Medical  
Numerous research studies have investigated how BGs affect cells involved in tissue healing. Accordingly, BGs not only encourage fibroblast migration but also up-regulate growth factor release and extracellular matrix synthesis [11]. Additionally, it has been shown that BGs can polarize macrophages toward the M2 phenotype, which modifies the inflammatory responses that occur during wound healing [12; 13]. In order to increase neovascularization, BGs can also activate human umbilical vein endothelial cells (HUVECs') gap junction and encourage the expression of angiogenic genes in those cells [14]. In addition, it is assumed that BG may be able to modify the barrier functional behaviors of keratinocytes because the soluble ions released can activate diverse signal transduction pathways in cells [15].  
The number of papers mentioning BGs has increased significantly since their debut. The glass structure, dissolution kinetics, biology, and composites, thin films and coatings, scaffolds, etc., have all been the subject of substantial research. A Scopus and Web of Science search of articles with \"bioactive glass\" in the title, beginning in 1971, yields more than 5070 results (Figure 1a). The same search of articles by title was applied to Web of Science and the number of results was 4582. Of the total number of articles, more than 200 were review papers. Refining the article search using different keywords gives us an insight into which areas BGs receive more attention. Articles which refer to \"bone\" received the most results, with over 1200 publications. Articles which reference \"bone regeneration\" (\(\sim\)620 articles) represent almost half of articles referencing \"bone\". In contrast, when refining the articles for \"wound healing\", the results showed more than 150 articles. The refining for \"tissue regeneration\" gave us 409 articles. Figure 1b provides an insight into the top keywords associated with BGs in the scientific literature and shows the literature refinement for some subcategories which we considered to be useful for our present manuscript.  
In this short review, we aim to discuss the fundamental concepts of BGs as well as the dynamic process of healing damaged tissues. We present how BGs actively contribute to the regeneration of both soft and hard tissues during healing. Lastly, studies that have used BGs in applications for wound healing are briefly reviewed, and potential developments in this area are discussed.