Recent advances in bone tissue engineering scaffolds

doi:10.1016/j.tibtech.2012.07.005

Trends in Biotechnology

Volume 30, Issue 10, October 2012, Pages 546-554

https://doi.org/10.1016/j.tibtech.2012.07.005 Get rights and content

Bone disorders are of significant concern due to increase in the median age of our population. Traditionally, bone grafts have been used to restore damaged bone. Synthetic biomaterials are now being used as bone graft substitutes. These biomaterials were initially selected for structural restoration based on their biomechanical properties. Later scaffolds were engineered to be bioactive or bioresorbable to enhance tissue growth. Now scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous, made of biodegradable materials that harbor different growth factors, drugs, genes, or stem cells. In this review, we highlight recent advances in bone scaffolds and discuss aspects that still need to be improved.

Section snippets

Bone scaffolds

Bone tissue engineering is a complex and dynamic process that initiates with migration and recruitment of osteoprogenitor cells followed by their proliferation, differentiation, matrix formation along with remodeling of the bone. Major advances in bone tissue engineering with scaffolds are achieved through growth factors, drugs and gene deliveries. Bone scaffolds are typically made of porous degradable materials that provide the mechanical support during repair and regeneration of damaged or

Design and fabrication of scaffolds

Bone is a natural composite of collagen and hydroxycarbonate apatite with 10–30% porous hard outer layer, i.e., cortical bone; and 30–90% porous interior, i.e., cancellous bone. Mechanical properties of bone vary widely from cancellous to cortical bone which along with complex geometry makes it difficult to design an “ideal bone scaffold” (Box 1). The key factors for an ideal scaffold for bone tissue engineering are: (i) macro- (pore size >100 μm) and micro-porosity (pore size < 20 μm); (ii)

In vitro and in vivo evaluation of bone scaffolds

The following summary highlights scaffolds made with different materials that have been tested under in vitro and in vivo conditions.

Third generation scaffolds

Although CaP scaffolds allow new bone formation and biomineralization, next generation scaffolds are predicted to be osteoinductive. Different approaches have been investigated to make CaP scaffold osteoinductive, which includes but is not limited to modifying scaffold chemistry, seeding bone marrow stem cells, and incorporation of different growth factors such as TGF-β, BMP, and VEGF in the scaffold. Osteoinduction is associated with both material composition and porosity. Si-TCP/HA with 60%

Critical issues in bone tissue engineering scaffolds

Several in vitro and in vivo studies have demonstrated excellent biocompatibility and new bone formation for a variety of bone scaffolds, however, some key challenges still remain: (i) biocompatibility and biomechanical strength in polymeric scaffolds, (ii) metal ion release, limited bioactivity and biodegradation for metallic scaffolds, and (iii) toughness as well as reliable and reproducible manufacturing techniques for ceramic scaffolds. Moreover, controlling the degradation rate of any

Concluding remarks and future directions

Research on bone tissue engineering over the past decades have inspired innovation in new materials, processing techniques, performance evaluation, and applications. Significant progress has been made towards scaffold materials for structural support with desired osteogenesis and angiogenesis abilities. Bioresorbable scaffolds with controlled porosity and tailored properties are possible today due to innovation in scaffold fabrication using advanced technologies, e.g., SFF. One of the drawbacks

Acknowledgments

The authors like to acknowledge the support from the National Institute of Health, specifically NIBIB (Grant no. R01A1EB 007351).

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Trends in Biotechnology

ReviewRecent advances in bone tissue engineering scaffolds

Section snippets

Bone scaffolds

Design and fabrication of scaffolds

In vitro and in vivo evaluation of bone scaffolds

Third generation scaffolds

Critical issues in bone tissue engineering scaffolds

Concluding remarks and future directions

Acknowledgments

Bone

Gene

Trends Biotechnol.

Mater. Sci. Eng. R: Rep.

Scripta Mater.

Trends Biotechnol.

Dent Mater.

Acta Biomater.

Acta Biomater.

Biomaterials

Biomaterials

Polymer

Biomaterials

Biomaterials

Biomaterials

Acta Biomater.

Bone

Acta Biomater.

Biomaterials

Biomaterials

Injury

Adv. Drug Deliv. Rev.

Compos. Part B: Eng.

Acta Biomater.

Biomaterials

Scripta Mater.

Mater. Today

Biomaterials

Bone

Acta Biomater.

Drug Discov. Today

Biomaterials

J. Cranio-Maxillofacial Surg.

Acta Biomater.

Acta Biomater.

Mol. Aspects Med.

Biomaterials

Biomaterials

Tissue engineering of bone: material and matrix considerations

JBJS

The insulin and insulin-like growth factor receptor family in neoplasia: an update

Nat. Rev. Cancer

Review
Recent advances in bone tissue engineering scaffolds