Bone Engineering via iPSCs, hBMSCs and hUCMSCs in Rat Cranium

Cell-based tissue engineering requires a reliable cell source that can respond properly to scaffolds and microenvironments. Induced pluripotent stem cells (iPSCs) emerged as a new seeding cell with great potential. Objectives: We compared three human stem cells— iPSCs, human umbilical cord mesenchymal stem cells (hUCMSCs) and bone marrow MSCs (hBMSCs) on biofunctionalized macroporous calcium phosphate cement (CPC) scaffold for bone regeneration. Methods: Macroporous CPC was fabricated using 40% mannitol as porogen, and biofunctionalized with Arg-Gly-Asp (RGD). iPSCs, hUCMSCs and hBMSCs were tested on CPC scaffold to assess attachment, viability, proliferation, osteogenic differentiation, mineralization, and capacity to repair critical-sized calvarial defects in nude rats. Results: All three types of cells spread and attached well to biofunctionalized CPC. Percentage of live cells and cell density increased dramatically from 1d to 14d; osteogenic genes (ALP, Runx2, COL1, and OCN) were up-regulated; and mineral synthesis increased with time but all without group differences (p>0.05). Histological examination indicated that new bone area fraction in iPSCs-CPC constructs (30.4±5.8)% was 2.8-fold that of CPC control (11.0±6.3)% at 3m (p<0.01). No significant differences were detected among the three types of stem cells (p>0.05). New bone deposition was found on the dura side and within the macro-pores of scaffolds, accompanied by angiogenesis. New blood vessel area fraction of iPSC-CPC was (2.0±1.1)%, versus hUCMSC-CPC (1.1±0.3)% (p>0.05), hBMSC-CPC (1.2±0.8)% (p>0.05)and CPC control (0.78±0.1)% (p<0.05). Conclusion: iPSCs have comparable osteogenic capability to hBMSCs and hUCMSCs in vitro and in vivo. iPSCs and hUCMSCs may represent viable alternatives to hBMSCs which require an invasive procedure to harvest and may lose potency in senior patients.  Biofunctionalized macroporous CPC-stem cell constructs displayed a robust capacity for bone regeneration and may be promising for bone tissue engineering in dental, craniofacial and orthopedic applications.