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Scaffold-free human mesenchymal stem cell construct geometry regulates long bone regeneration
Samuel Herberg1,2, Daniel Varghai1, Daniel S Alt1
1Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA.
Communications Biology
|January 20, 2021
Summary
Engineered human mesenchymal stem cell (hMSC) tubes with localized growth factors promote bone healing. This biomimetic approach, mimicking natural bone development, enhances defect repair more effectively than cell sheets.
Area of Science:
- Biomaterials Science
- Regenerative Medicine
- Orthopedic Engineering
Background:
- Biomimetic strategies partially replicate developmental processes for bone tissue engineering.
- Previous work demonstrated functional restoration of femoral defects using scaffold-free hMSC condensates with localized morphogen delivery and delayed mechanical loading.
- The impact of construct geometry on bone healing outcomes remains largely unexplored.
Purpose of the Study:
- To investigate the hypothesis that engineered hMSC tubes, mimicking femoral diaphyses, induce endochondral ossification via localized transforming growth factor (TGF)-β1 and bone morphogenetic protein (BMP)-2.
- To compare the efficacy of TGF-β1 + BMP-2 presenting hMSC tubes against hMSC sheets in enhancing defect healing with delayed in vivo loading.
Main Methods:
- Engineered hMSC tubes with localized presentation of TGF-β1 and BMP-2.
- In vitro assessment of chondrogenic priming and endochondral differentiation.
- In vivo subcutaneous and orthotopic implantation in a femoral defect model with delayed mechanical loading.
Main Results:
- Localized morphogen presentation stimulated chondrogenic priming and endochondral differentiation in vitro.
- Subcutaneous implantation resulted in hMSC tubes forming cartilage templates that underwent subsequent bony remodeling.
- Orthotopic implantation demonstrated that hMSC tubes significantly enhanced endochondral defect healing compared to hMSC sheets, with minimal ectopic bone formation and tissue resembling normal growth plate.
Conclusions:
- Engineered hMSC tubes with localized morphogen delivery effectively promote endochondral ossification and bone defect healing.
- Construct geometry (tubes vs. sheets) significantly influences healing outcomes, with tubes showing superior performance.
- This study highlights the interplay between hMSC condensation geometry, morphogen availability, and mechanical stimuli in recapitulating developmental processes for advanced biomimetic bone tissue engineering.
