Design and characterization of calcium phosphate ceramic scaffolds for bone tissue engineering

Abstract

Objectives Our goal is to review design strategies for the fabrication of calcium phosphate ceramic scaffolds (CPS), in light of their transient role in bone tissue engineering and associated requirements for effective bone regeneration. Methods We examine the various design options available to meet mechanical and biological requirements of CPS and later focus on the importance of proper characterization of CPS in terms of architecture, mechanical properties and time-sensitive properties such as biodegradability. Finally, relationships between in vitro vs. in vivo testing are addressed, with an attempt to highlight reliable performance predictors. Results A combinatory design strategy should be used with CPS taking into consideration 3D architecture, adequate surface chemistry and topography, all of which are needed to promote bone formation. CPS represent the media of choice for delivery of osteogenic factors and anti-infectives. Non-osteoblast mediated mineral deposition can confound in vitro osteogenesis testing of CPS and therefore the expression of a variety of proteins or genes including collagen type I, bone sialoprotein and osteocalcin should be confirmed in addition to increased mineral content. Conclusions CPS are a superior scaffold material for bone regeneration because they actively promote osteogenesis. Biodegradability of CPS via calcium and phosphate release represents a unique asset. Structural control of CPS at the macro, micro and nanoscale and their combination with cells and polymeric materials is likely to lead to significant developments in bone tissue engineering.

Morphological, mechanical and biological assessment of PCL/pristine graphene scaffolds for bone regeneration

“…Autografts are considered to be the most effective approach, however, they present some drawbacks such as site morbidity, pain, and prolonged hospitalisation [2,3] . Allografts are associated with rejection problems, transmission of diseases and infections from donor to recipient, and cost [1,2,6] . Xenografts major limitations are related to their lack of osteogenic properties, risk of immunogenicity and transmission of infections and zoonotic diseases, and poor clinical outcome [5,6] .…”

“…Allografts are associated with rejection problems, transmission of diseases and infections from donor to recipient, and cost [1,2,6] . Xenografts major limitations are related to their lack of osteogenic properties, risk of immunogenicity and transmission of infections and zoonotic diseases, and poor clinical outcome [5,6] . Therefore, biofabrication-the combined use of additive manufacturing techniques, biocompatible and biodegradable materials, cells, growth factors, etc., for the fabrication of bioactive scaffolds (synthetic grafts)-is becoming a promising alternative for grafting [7][8][9][10][11][12][13][14] .…”

“…In these cases, the clinical approach is the use of bone grafts, defined as an implanted material that promotes bone healing alone or in combination with other materials, through osteogenesis, osteoinduction, and osteoconduction [5] . Bone grafts can be divided into autografts, allografts, and xenografts [1,2,6] . However, there are many inherent limitations with this procedure.…”

RALA complexed α-TCP nanoparticle delivery to mesenchymal stem cells induces bone formation in tissue engineered constructs in vitro and in vivo

“…Even though use of CaP based nanoparticles as carriers for intracellular delivery of nucleic acids has been explored for 40 years, the inherent osteogenic effect of calcium and phosphate ions released from such particles has not been considered in the majority of the studies. This is despite the fact that several studies have separately reported the osteoinductive properties of CaP based agglomerates and bulk scaffolding materials 26,27,59 .…”

“…In addition, the presence of the cell penetrating peptide RALA acts to mitigate the hydrophilicity-associated negative effects linked to bare CaP nanoparticles 28 in terms of their capability to enter the cell membrane. CaP based biomaterials, including α and β-TCP, hydroxyapatite (HA) and calcium sulphate, have been extensively used in orthopaedics as a bone substitute material 26,53,54 . Nanoparticles in a size range of 20-200 nm has been shown to be optimal for intracellular delivery, with bare CaP nanoparticles often undergoing significant levels of agglomeration leading to development of a much larger particle size over time [55][56][57][58] .…”