Mannitol-containing macroporous calcium phosphate cement encapsulating human umbilical cord stem cells.

Stem cell-based tissue engineering offers immense promise for bone regeneration. The objective of this study was to develop a self-setting, mannitol-containing calcium phosphate cement (CPC) encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs) for bone tissue engineering. hUCMSCs could be an inexhaustible and low-cost alternative to the gold-standard bone marrow MSCs, which require an invasive procedure to harvest. hUCMSCs were encapsulated in alginate beads and mixed into the CPC paste. Water-soluble mannitol porogen was incorporated into CPC to create macropores. The porosity was increased from 49% for the hUCMSC-encapsulating CPC to 64% after adding mannitol and absorbable-fibres (p < 0.05). Flexural strength of the construct was increased from 0.3 MPa to 2.0 MPa via fibres. Live cell percentage was > 80% for all constructs. The ALP and OC gene expressions were low at 1 day and greatly increased at 14 days. The constructs that contained mannitol had significantly higher ALP and OC expressions than that without mannitol. ALP activity of hUCMSCs inside CPC with mannitol and fibre was significantly higher than that without mannitol. At 14 days, mineralization by the encapsulated hUCMSCs was eight-fold higher than that at 1 day. In conclusion, a novel mannitol-containing porous CPC-hUCMSC construct was developed for bone tissue engineering. Its advantages include cell delivery inside a load-bearing CPC that has injectable and in situ setting capabilities. hUCMSCs inside CPC had good viability and successfully osteodifferentiated. The self-setting and strong hUCMSC-encapsulating CPC scaffold is promising for bone tissue engineering in a wide range of orthopaedic and craniofacial applications.