Productizing Nano-Bioactive Glass-Based Bilayer Scaffolds: A Graft for Reconstruction of Mandibular and Femoral Bone Defects

This investigation aimed to construct a bilayer scaffold integrating alginate and gelatin with nanobioactive glass (BG), recognized for their efficacy in tissue regeneration and drug delivery. Scaffolds, namely, alginate/gelatin (AG), alginate-/actonel gelatin (AGD), alginate actenol/gelatin-45S5 BG (4AGD), and alginate-actonel/gelatin-59S BG (5AGD), were assembled using a cost-effective freeze-drying method, followed by detailed structural investigation via powder X-ray diffraction as well as morphological characterization using field emission scanning electron microscopy (FESEM). FESEM revealed a honeycomb-like morphology with distinct pore sizes for nutrient, oxygen, and drug transport. The scaffolds evidently exhibited hemocompatibility, high porosity, good swelling capacity, and biodegradability. In vitro studies demonstrated sustained drug release, particularly for scaffolds containing actonel. In vivo tests showed that the bilayer scaffold promoted new bone formation, surpassing the control group in bone area increase. The interaction of the scaffold with collagen and released ions improved the osteoblastic function and bone volume fraction. The findings suggest that this bilayer scaffold could be beneficial for treating critical-sized bone defects, especially in the mandibular and femoral regions.

Three-Dimensional Bioprinted MR-Trackable Regenerative Scaffold for Postimplantation Monitoring on T1-Weighted MRI

BACKGROUND

A three-dimensional (3D) bioprinted tissue scaffold is a promising therapeutic that goes beyond providing physical support for tissue regeneration by enabling precise spatial control over scaffold geometry and integration of different materials/cells. Critically important is in vivo confirmation of correct scaffold placement and retention during the initial 24 hours postimplantation, to detect unwanted implant migration.

PURPOSE

To incorporate a safe, efficient MR contrast agent into a bioprinting workflow, and to achieve bright-contrast scaffold monitoring in vivo postimplantation.

STUDY TYPE

In vitro and animal in vivo longitudinal study.

ANIMAL MODEL

Two female Sprague Dawley rats (~200 g) for labeled and unlabeled scaffold implantation in the subcutaneous dorsal space flanking the vertebral column.

FIELD STRENGTH/SEQUENCE

A 7.0 T/T₁ -weighted spin echo (SE) sequence and T₁ mapping using turbo SE with variable repetition times (TRs).

ASSESSMENT

Cell viability and proliferation were assessed over 2 weeks after labeling bioprinted gelatin/alginate scaffolds with MnPNH₂ (0.5 mM, 24 hours). In vitro MRI was performed 0, 12, and 24 hours postlabeling in nine labeled and three unlabeled (control) scaffolds to monitor T₁ evolution. In vivo MRI was performed immediately and 24 hours postimplantation to assess T₁ . Acute inflammation near surgical site was monitored in one rat to 3 days.

STATISTICAL TESTS

One-way analysis of variance with Tukey-Kramer post hoc analysis (P < 0.01).

RESULTS

Cell viability was unaffected by bioprinting/labeling: viability exceeded 90% in all scaffolds after 1 week. In vitro T₁ 's were significantly lower in labeled scaffolds compared to control (207 msec vs. 2257 msec) immediately postlabeling and 24 hours later (1227 msec vs. 2257 msec). In vivo T₁ 's were significantly different (243.6 msec vs. 2414.6 msec) immediately postimplantation, and no differences emerged compared to respective in vitro control/labeled counterparts. The 24-hours imaging and gross pathology confirmed migration of scaffolds beyond the imaging field.

DATA CONCLUSION

We report an MR-detectable, cell-compatible bioprinted scaffold, utilizing a T₁ -weighting contrast agent for high-resolution, postimplantation scaffold tracking.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 1.

[Gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting promotes cell adhesion and proliferation of human dental pulp cells in vitro]

OBJECTIVE

To evaluate the cytotoxicity of gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting in human dental pulp cells (HDPCs) and compare the cell adhesion and proliferation of the cells seeded in the biomaterial using two different methods.

METHODS

HDPCs isolated by tissue block culture and enzyme digestion were cultured and passaged. Gelatin/alginate hydrogel scaffolds were printed using a bioplotter, and the cytotoxicity of the aqueous extracts of the scaffold material was tested in the third passage of HDPCs using cell counting kit-8. Scanning electron microscopy and trypan blue were used to assess the adhesion and proliferation of the cells seeded in the scaffold material at a low or high concentration.

RESULTS

The aqueous extract of the scaffolds at different concentrations showed no obvious cytotoxicity and promoted the proliferation of HDPCs. The scaffolds had a good biocompatibility and HDPCs seeded in the scaffold showed good cell growth. Cell seeding at a high concentration in the scaffold better promoted the adhesion of HDPCs and resulted in a greater cell number on the scaffold surface compared with low-concentration cell seeding after a 5-day culture (P<0.05).

CONCLUSION

Gelatin<alginate hydrogel scaffolds prepared by 3D bioprinting has a good biocompatibility and promotes the proliferation of HDPCs, and can be used as a scaffold material for tooth regeneration. Cell seeding at a high concentration can better promote cell adhesion to the scaffold material.