Developmentally Engineered Callus Organoid Bioassemblies Exhibit Predictive In Vivo Long Bone Healing

Area of Science:

• Regenerative Medicine
• Biomaterials Science
• Skeletal Biology

Background:

• Clinical translation of cell-based therapies is limited by poor in vivo performance.
• Mimicking developmental and regenerative processes is key for engineering functional tissues.
• Large bone defects represent an unmet medical need requiring novel therapeutic strategies.

Purpose of the Study:

• To develop a scalable method for producing functional bone tissue constructs.
• To investigate the potential of periosteum-derived cells for bone regeneration.
• To create engineered tissues capable of healing critical-sized bone defects.

Main Methods:

• Scalable production of human periosteum-derived cell microspheroids.
• Differentiation of microspheroids into autonomous callus organoids.
• In vivo assessment of ectopic bone formation and critical-sized defect healing in murine models.
• Analysis of gene signatures associated with bone development and healing.

Main Results:

• Callus organoids demonstrated the capacity for ectopic bone microorgan formation in vivo.
• Organoids exhibited gene signatures mirroring those of developing and healing long bones.
• Spontaneous in vitro bioassembly of organoids into large engineered tissues.
• Engineered tissues successfully healed murine critical-sized long bone defects, regenerating native-like bone.

Conclusions:

• Human periosteum-derived callus organoids represent a promising cell-based therapeutic for bone regeneration.
• These organoids serve as a 'bio-ink' for bottom-up manufacturing of complex, multimodular engineered bone tissues.
• The study provides a novel strategy for addressing the clinical translation gap in cell-based regenerative medicine for bone defects.