Bone Regeneration in Small and Large Segmental Bone Defect Models after Radiotherapy Using Injectable Polymer-Based...

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Surgery

Background:

• Bone reconstruction after tumor removal and radiotherapy is difficult.
• Polysaccharide-based microbeads with hydroxyapatite (HA) show osteoconductivity and osteoinductivity.
• New composite microbeads with strontium (Sr)-doped HA particles were developed to improve biological performance.

Purpose of the Study:

• To evaluate the efficacy of Sr-doped microbeads in preclinical bone defect models.
• To assess the impact of strontium on bone formation, vascularization, and regeneration after irradiation.

Main Methods:

• Characterization of Sr-doped microbeads (8% and 50% Sr) using microscopy, particle size analysis, and phosphorus content.
• Implantation into rat femoral condyle and critical-size segmental bone defect models.
• Histological and immunohistochemical analyses to evaluate bone regeneration and vascularization.

Main Results:

• Sr-doped microbeads (8% and 50%) stimulated bone formation and vascularization in femoral condyle defects.
• In irradiated segmental bone defects, 8% Sr-doped microbeads significantly enhanced vascularization and new vessel formation.
• No significant differences in bone regeneration were observed between non-doped and Sr-doped microbeads in non-irradiated sites.

Conclusions:

• Strontium-doped microbeads show potential for improving bone regeneration, especially vascularization in irradiated bone.
• The 8% Sr substitution level appears optimal for enhancing vascularization in critical-size bone defects post-irradiation.
• These findings suggest Sr-doped matrices can stimulate vascularization crucial for bone tissue regeneration after radiation therapy.