Published online Jul 26, 2017. doi: 10.4252/wjsc.v9.i7.98
Peer-review started: February 2, 2017
First decision: March 31, 2017
Revised: April 27, 2017
Accepted: June 6, 2017
Article in press: June 8, 2017
Published online: July 26, 2017
Processing time: 171 Days and 15.6 Hours
To establish a hypoxic environment for promoting osteogenesis in rat marrow stromal cells (MSCs) using osteogenic matrix cell sheets (OMCSs).
Rat MSCs were cultured in osteogenic media under one of four varying oxygen conditions: Normoxia (21% O2) for 14 d (NN), normoxia for 7 d followed by hypoxia (5% O2) for 7 d (NH), hypoxia for 7 d followed by normoxia for 7 d (HN), or hypoxia for 14 d (HH). Osteogenesis was evaluated by observing changes in cell morphology and calcium deposition, and by measuring osteocalcin secretion (ELISA) and calcium content. In vivo syngeneic transplantation using OMCSs and β-tricalcium phosphate discs, preconditioned under NN or HN conditions, was also evaluated by histology, calcium content measurements, and real-time quantitative PCR.
In the NN and HN groups, differentiated, cuboidal-shaped cells were readily observed, along with calcium deposits. In the HN group, the levels of secreted osteocalcin increased rapidly from day 10 as compared with the other groups, and plateaued at day 12 (P < 0.05). At day 14, the HN group showed the highest amount of calcium deposition. In vivo, the HN group showed histologically prominent new bone formation, increased calcium deposition, and higher collagen type I messenger RNA expression as compared with the NN group.
The results of this study indicate that modifying oxygen tension is an effective method to enhance the osteogenic ability of MSCs used for OMCSs.
Core tip: Bone tissue engineering using marrow stromal cells (MSCs) is a promising method in regenerative medicine. Here, we have reported a scaffold-free transplantation technique using hypoxic-preconditioned osteogenic matrix cell sheets (OMCSs) derived from MSCs. We show that modifying the oxygen tension before implantation of OMCS composites led to an increased osteogenic capacity of rat bone MSCs.