November 30, 2020 by admin 0 Comments

Biofabrication of 3D printed hydroxyapatite composite scaffolds for bone regeneration

Authors
Yoontae Kim(1), Eun-Jin Lee(1), Albert V. Davydov(2), Stanislav Frukhbeyen(1), Jonathan E. Seppala(3), Shozo Takagi(1), Laurence Chow(1) and Stella Alimperti(1)
Abstract
Biofabrication has been adapted in engineering patient-specific biosynthetic grafts for bone regeneration. Herein, we developed a 3D high-resolution, room-temperature printing approach to fabricate osteoconductive scaffolds using calcium phosphate cement (CPC). The non-aqueous CPC bioinks were composed of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA), and Polyvinyl butyral (PVB) dissolved in either ethanol (EtOH) or Tetrahydrofuran (THF). They were printed in an aqueous sodium phosphate bath, which performs as a hardening accelerator for hydroxyapatite (HA) formation and as a retainer for 3D microstructure. The PVB solvents, EtOH or THF, affected differently the slurry rheological properties, scaffold microstructure, mechanical properties, and osteoconductivity...

October 6, 2020 by admin 0 Comments

Fabrication of strontium-substituted hydroxyapatite scaffolds using 3D printing for enhanced bone regeneration

Authors
Hyun-Woo Kim & Young-Jin Kim
Abstract
The use of porous three-dimensional (3D) bioceramic scaffolds to facilitate the regeneration of bone defects has attracted great attention because their structures closely mimic the natural extracellular matrix. 3D printing is a versatile method for the fabrication of 3D scaffolds. In this study, 3D strontium-substituted hydroxyapatite (Sr-HA) bioceramic scaffolds were prepared by simple precipitation and 3D printing method. The resulting scaffolds exhibited interconnected microporous structures of strands and a single-phase crystal due to HA, meaning that no changes in the phase composition and microstructure of the scaffolds with the Sr content were observed. However, their dissolution rate and biological performance were substantially influenced by changes in the Sr content of the scaffolds. The optimal Sr content in the Sr-HA scaffolds for enhanced proliferation and differentiation of cells were identified by comparing four compositions of the Sr-HA scaffolds. The results of in vitro bioactivity tests demonstrated that the Sr5-HA scaffold with 0.05 of Sr/(Ca + Sr) molar ratio promoted more rapid cell proliferation, osteogenic differentiation, and cellular mineralization compared with the other scaffolds. Therefore, Sr-HA scaffolds have the potential for application in bone regeneration as new bone graft substitutes.

August 30, 2019 by admin 0 Comments

Bioprinting Technologies in Tissue Engineering

Authors
Bengi Yilmaz, Aydin Tahmasebifar, Erkan Türker Baran
Abstract
Bioprinting technology is a strong tool in producing living functional tissues and organs from cells, biomaterial-based bioinks, and growth factors in computer-controlled platform. The aim of this chapter is to present recent progresses in bioprinting of nerve, skin, cardiac, bone, cartilage, skeletal muscle, and other soft tissues and highlight the challenges in these applications. Various composite bioinks with bioactive ceramic-based scaffolds having patient-specific design and controlled micro-architectures were used at clinical and preclinical applications successfully for regeneration of bone. In nerve tissue engineering, bioprinting of alginate- and gelatin-based gel bioinks by extrusion presented a controllable 3D microstructures and showed satisfactory cytocompatibility and axonal regeneration. Bioprinting of cardiac progenitors in biopolymers resulted in limited success, while the use of bioinks from extracellular matrix induced satisfactory results in cardiac regeneration. Osteochondral scaffold bioprinting is challenging due to the complex hierarchical structure and limited chondral regeneration. Therefore, current approaches focused on osteochondral scaffold with vascular network and mimicking hierarchical structures. The applications of bioprinting in other types of tissues were also studied, and results showed significant potentials in regeneration of tissues such as cornea, liver, and urinary bladder.