Page 203 - Clinical relevance of current materials for cranial implants

THE NEXT STEP
The development of a new material for cranioplasty should tackle the current disadvantages.
Recent developments in Bioprinting may be provide a solution for the development of materials used for cranioplasties. The past decade 3D bioprinting has increased in popularity, as well as the applicability in clinical practice. A lot of research has been performed in this field over the past decade. 3D bioprinting is the utilization of 3D printing and 3D printing–like techniques to combine cells, growth factors, and biomaterials to fabricate biomedical parts that maximally imitate natural tissue characteristics. 3D bioprinting utilizes the layer-by-layer method to deposit materials known as bio-inks, extrusion-based bioprinting, laser-assisted bioprinting and even 4D bioprinting, to create tissue-like structures that are later used in medical and tissue engineering fields18,19. Wang et al. and Gao et al. both describe the first steps towards bone bioprinting. Wang et al. introduced the use of hierarchical porous and recombinant human bone morphogenetic protein-2(rhBMP-2)-loaded calcium phosphate nanoparticle/poly(L-lactic acid) (PLLA) nanocomposite scaffolds. The well- designed 3D printed scaffolds exhibited hierarchical porous structure and tunable osteoconductivity and osteoinductivity20. Gao et al. used acrylated peptides and PEG hydrogel with human mesenchymal stem cells for the formation of robust bone combined with cartilage21.
If bioprinting could be used for the reconstruction of cranial defects, the patient’s own cells (e.g. stem cells) would ideally be used for the regrowth of a cranioplasty to replace the removed part of the skull. The anatomy of the human skull is complex because of its vascularity and multiple layers of bone. Apart from the complex anatomy the defects tend to be relatively large. Bioprinting a cranial reconstruction will therefore be challenging. To prevent bone resorption, a supplement developed from growth factors could be necessary to prevent the increased activity of osteoclasts.
Nowadays, bioprinting is relatively expensive, but it is expected that these costs will decrease in time. In the future this may become an affordable and stable solution for patient in the need for cranioplasty.
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General discussion and future perspectives
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