Bone tissue engineering via nanostructured calcium phosphate biomaterials and stem cells

Abstract

Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate (CaP) biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review: nanostructured calcium phosphate cement (CPC); nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/morphology, differentiation and in vivo bone regeneration. Several trends can be seen: (i) nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; (ii) the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; (iii) nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; (iv) combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and (v) cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.

Tissue engineering: New approach could replace traditional bone grafts

A new approach to regenerating bone has the potential to overtake traditional bone grafting techniques following fracture or trauma. Standard procedures for replacing bone tissue are hampered by the need to use stem cells from patients or donors, resulting in a need to develop new techniques. Hockin Xu and colleagues from the University of Maryland in Baltimore reviewed the use of nano-sized calcium phosphate (nano-CaP) biomaterials in bone repair. These bio-materials mimic the major inorganic component of bone and easily bond with neighbouring bone. They work by influencing stem cells to produce bone but the underlying mechanisms are not fully understood. The chemical composition, surface roughness, stiffness and size of the biomaterial are all thought to play a role. The researchers conclude that learning more about these mechanisms could help translate the findings into clinical treatments.

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