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Modulation of In Vitro Microenvironment Facilitates Synovium-Derived Stem Cell-Based Nucleus Pulposus Tissue Regeneration

Pei, Ming, MD, PhD*,†,‡; Shoukry, Mark, BS*,‡; Li, Jingting, MS*,†; Daffner, Scott D., MD*; France, John C., MD*; Emery, Sanford E., MD, MBA*

doi: 10.1097/BRS.0b013e31825150bf
Basic Science

Study Design. Two experiments were conducted. Experiment 1 evaluated the effect of 3 kinds of decellularized extracellular matrices (DECMs) deposited by synovium-derived stem cells (SDSCs) and/or nucleus pulposus cells (NPCs) on SDSC expansion and NP lineage differentiation. Experiment 2 evaluated the effect of DECM deposited by SDSCs on NPC expansion and redifferentiation capacity. In both experiments, hypoxia was evaluated in DECM preparation and pellet culture.

Objective. Modulating the in vitro microenvironment facilitates SDSC-based NP tissue regeneration.

Summary of Background Data. Autologous cell therapy is a promising approach for NP regeneration. Current in vitro expansion in monolayer results in cell dedifferentiation.

Methods. In Experiment 1, passage 3 SDSCs were expanded for 1 passage on DECM deposited by NPCs, SDSCs, or NPCs combined with SDSCs (50:50); DECM was prepared under either normoxia (21% O2) or hypoxia (5% O2). Expanded SDSCs were then cultured in a serum-free chondrogenic medium in hypoxia for 14 days. In Experiment 2, passage 2 NPCs were expanded for 1 passage on DECM deposited by SDSCs; DECM was prepared under either normoxia or hypoxia. Expanded NPCs were cultured in a serum-free chondrogenic medium under either hypoxia or normoxia for 14 days. Cell expansion on plastic flasks served as a control in both experiments. Fourteen-day pellets were evaluated for chondrogenesis using histology, immunostaining, biochemistry, and real-time polymerase chain reaction.

Results. DECM deposited by NPCs combined with SDSCs effectively enhanced expanded SDSC viability and guided SDSC differentiation toward an NP lineage; this effect is comparable with DECM deposited by SDSCs but higher than that deposited by NPCs. DECM prepared under normoxia favored SDSC viability and NP lineage differentiation whereas DECM prepared under hypoxia benefited NPC viability and redifferentiation. Low oxygen in a pellet culture system enhanced NPC viability and redifferentiation.

Conclusion. The in vitro microenvironment can be modulated by low oxygen and tissue-specific cell-based DECM to facilitate NP tissue regeneration.

An in vitro microenvironment was modulated using decellularized extracellular matrix (DECM) deposited by nucleus pulposus cells (NPCs), synovium-derived stem cells (SDSCs), or both to promote expanded SDSC or NPC proliferation and NP lineage differentiation capacity. Hypoxia played a role in both DECM preparation and pellet culture.

*Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics

Division of Exercise Physiology

Mechanical & Aerospace Engineering, West Virginia University, Morgantown, WV.

Address correspondence and reprint requests to Ming Pei, MD, PhD, Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, One Medical Center Dr., PO Box 9196, Morgantown, WV 26506; E-mail:

Acknowledgment date: December 19, 2011. First revision date: February 8, 2012. Acceptance date: February 20, 2012.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript: e.g., honoraria, gifts, consultancies, royalties, stocks, stock options, decision-making position.

© 2012 Lippincott Williams & Wilkins, Inc.