Advances in Osteoporotic Bone Tissue Engineering

Abstract

The increase in osteoporotic fracture worldwide is urging bone tissue engineering research to find new, improved solutions both for the biomaterials used in designing bone scaffolds and the anti-osteoporotic agents capable of promoting bone regeneration. This review aims to report on the latest advances in biomaterials by discussing the types of biomaterials and their properties, with a special emphasis on polymer-ceramic composites. The use of hydroxyapatite in combination with natural/synthetic polymers can take advantage of each of their components properties and has a great potential in bone tissue engineering, in general. A comparison between the benefits and potential limitations of different scaffold fabrication methods lead to a raised awareness of the challenges research face in dealing with osteoporotic fracture. Advances in 3D printing techniques are providing the ways to manufacture improved, complex, and specialized 3D scaffolds, capable of delivering therapeutic factors directly at the osteoporotic skeletal defect site with predefined rate which is essential in order to optimize the osteointegration/healing rate. Among these factors, strontium has the potential to increase osseointegration, osteogenesis, and healing rate. Strontium ranelate as well as other biological active agents are known to be effective in treating osteoporosis due to both anti-resorptive and anabolic properties but has adverse effects that can be reduced/avoided by local release from biomaterials. In this manner, incorporation of these agents in polymer-ceramic composites bone scaffolds can have significant clinical applications for the recovery of fractured osteoporotic bones limiting or removing the risks associated with systemic administration.

The Role of Adipose Stem Cells in Bone Regeneration and Bone Tissue Engineering

“…Their incorporation is lower compared to autografts [21]; they also present a risk of transmitting infections [59]. Furthermore, they can induce an immune response and can have a high batch variation [20]. Bone grafting is a well-established approach that is used in over 500,000 cases every year in the USA [20,60].…”

“…Furthermore, they can induce an immune response and can have a high batch variation [20]. Bone grafting is a well-established approach that is used in over 500,000 cases every year in the USA [20,60]. Nevertheless, bone grafts have disadvantages, as described above.…”

“…The hematoma creates a clot inside the fracture, which induces the recruitment of immune cells, including macrophages, monocytes, and lymphocytes. These cells influence the subsequent process of osteogenesis [ 20 , 21 ]. They initiate and modulate the fracture healing process.…”

“…They initiate and modulate the fracture healing process. In particular, macrophages are crucially involved in bone healing through their secretome [ 20 , 22 ] and by forming a layer above the osteoblast, which is called an osteomac [ 23 ]. The macrophages have different phenotypes, such as M1 (the so-called activated or proinflammatory phenotype) and M2 (the alternatively activated or anti-inflammatory phenotype), which are induced during different phases and, in turn, influence different processes of bone healing.…”

“…The remodeling aims to create compact bone at the center and lamellar bone at the edge. This process can take months to complete [ 2 , 3 , 20 ].…”