3D printed β-tricalcium phosphate versus synthetic bone mineral scaffolds: A comparative in vitro study of biocompatibility

BACKGROUND

β-tricalcium phosphate (β-TCP) has been successfully utilized as a 3D printed ceramic scaffold in the repair of non-healing bone defects; however, it requires the addition of growth factors to augment its regenerative capacity. Synthetic bone mineral (SBM) is a novel and extrudable carbonate hydroxyapatite with ionic substitutions known to facilitate bone healing. However, its efficacy as a 3D printed scaffold for hard tissue defect repair has not been explored.

OBJECTIVE

To evaluate the biocompatibility and cell viability of human osteoprecursor (hOP) cells seeded on 3D printed SBM scaffolds via in vitro analysis.

METHODS

SBM and β-TCP scaffolds were fabricated via 3D printing and sintered at various temperatures. Scaffolds were then subject to qualitative cytotoxicity testing and cell proliferation experiments utilizing (hOP) cells.

RESULTS

SBM scaffolds sintered at lower temperatures (600 °C and 700 °C) induced greater levels of acute cellular stress. At higher sintering temperatures (1100 °C), SBM scaffolds showed inferior cellular viability relative to β-TCP scaffolds sintered to the same temperature (1100 °C). However, qualitative analysis suggested that β-TCP presented no evidence of morphological change, while SBM 1100 °C showed few instances of acute cellular stress.

CONCLUSION

Results demonstrate SBM may be a promising alternative to β-TCP for potential applications in bone tissue engineering.

Direct inkjet writing type 1 bovine collagen/β-tricalcium phosphate scaffolds for bone regeneration

Bone tissue has the capacity to regenerate under healthy conditions, but complex cases like critically sized defects hinder natural bone regeneration, necessitating surgery, and use of a grafting material for rehabilitation. The field of bone tissue engineering (BTE) has pioneered ways to address such issues utilizing different biomaterials to create a platform for cell migration and tissue formation, leading to improved bone reconstruction. One such approach involves 3D-printed patient-specific scaffolds designed to aid in regeneration of boney defects. This study aimed to develop and characterize 3D printed scaffolds composed of type I collagen augmented with β-tricalcium phosphate (COL/β-TCP). A custom-built direct inkjet write (DIW) printer was used to fabricate β-TCP, COL, and COL/β-TCP scaffolds using synthesized colloidal gels. After chemical crosslinking, the scaffolds were lyophilized and subjected to several characterization techniques, including light microscopy, scanning electron microscopy, and x-ray diffraction to evaluate morphological and chemical properties. In vitro evaluation was performed using human osteoprogenitor cells to assess cytotoxicity and proliferative capacity of the different scaffold types. Characterization results confirmed the presence of β-TCP in the 3D printed COL/β-TCP scaffolds, which exhibited crystals that were attributed to β-TCP due to the presence of calcium and phosphorus, detected through energy dispersive x-ray spectroscopy. In vitro studies showed that the COL/β-TCP scaffolds yielded more favorable results in terms of cell viability and proliferation compared to β-TCP and COL scaffolds. The novel COL/β-TCP scaffold constructs hold promise for improving BTE applications and may offer a superior environment for bone regeneration compared with conventional COL and β-TCP scaffolds.