Scaffold-cell bone engineering in a validated preclinical animal model: precursors vs differentiated cell source.

Area of Science:

• Orthopedics
• Regenerative Medicine
• Biomaterials Science

Background:

• Osteoblasts (OBs) from different skeletal origins (axial vs. orofacial) exhibit distinct properties due to embryological differences.
• Understanding these differences is crucial for optimizing bone defect regeneration strategies.

Purpose of the Study:

• To compare the bone regenerative potential of allogenic mesenchymal progenitor cells (MPCs), axial skeleton-derived OBs (tOBs), and orofacial skeleton-derived OBs (mOBs).
• To evaluate these cells in combination with a polycaprolactone-tricalcium phosphate (mPCL-TCP) scaffold in a sheep tibia critical-sized defect model.

Main Methods:

• Critical-sized segmental bone defects were created in sheep tibiae.
• Defects were treated with allogenic MPCs, tOBs, or mOBs, each combined with an mPCL-TCP scaffold.
• Evaluations included biomechanical testing, micro-computed tomography (microCT), and histological/immunohistochemical analyses after 6 months.

Main Results:

• Allogenic MPCs showed a trend towards improved biomechanical performance and higher newly formed bone volume compared to OBs.
• No significant differences in bone regeneration potential were observed between tOBs and mOBs, either in vitro or in vivo.
• Biomechanical, microCT, and histological analyses did not reveal significant differences in the regenerative capacity of the different cell types tested in vivo.

Conclusions:

• Mesenchymal progenitor cells may offer a more promising approach for bone regeneration compared to axial or orofacial osteoblasts in this sheep model.
• Axial and orofacial osteoblasts exhibit comparable bone regeneration potential when used with mPCL-TCP scaffolds in critical-sized defects.