Multipotential Stromal Cell Abundance in Cellular Bone Allograft: Comparison with Fresh Age-Matched Iliac Crest Bone and Bone Marrow Aspirate

Abstract

Aim: To enumerate and characterize multipotential stromal cells (MSCs) in a cellular bone allograft and compare with fresh age-matched iliac crest bone and bone marrow (BM) aspirate. Materials & methods: MSC characterization used functional assays, confocal/scanning electron microscopy and whole-genome microarrays. Resident MSCs were enumerated by flow cytometry following enzymatic extraction. Results: Allograft material contained live osteocytes and proliferative bone-lining cells defined as MSCs by phenotypic and functional capacities. Without cultivation/expansion, the allograft displayed an ‘osteoinductive‘ molecular signature and the presence of CD45^-CD271⁺CD73⁺CD90⁺CD105⁺ MSCs; with a purity over 100-fold that of iliac crest bone. In comparison with BM, MSC numbers enzymatically released from 1 g of cellular allograft were equivalent to approximately 45 ml of BM aspirate. Conclusion: Cellular allograft bone represents a unique nonimmune material rich in MSCs and osteocytes. This osteoinductive graft represents an attractive alternative to autograft bone or composite/synthetic grafts in orthopedics and broader regenerative medicine settings.

Keywords::

• bone marrow
• cellular allograft
• multipotential stromal cells
• osteocytes

Acknowledgements

The authors thank A Steiner and A Lotfy for their help with culturing Osteocel^®-multipotential stromal cells (MSCs) and iliac crest bone-MSCs and with differentiation and immunoregulation experiments. Additionally, they would like to acknowledge EM Erbe for the initial project planning and discussion. The authors gratefully acknowledge HB Tan for his help with consenting patients, and M Shires and J Hudson for their assistance with histology and environmental scanning electron microscopy.

Financial & competing interests disclosure

E Jones and D McGonagle hold funding from Wellcome Trust/EPSRC through WELMEC, a Centre of Excellence in Medical Engineering, under grant number WT 088908/Z/09/Z. TG Baboolal is funded by WELMEC. E Jones, D McGonagle and PV Giannoudis are also part-funded by the National Institute of Health Research via the NIHR-Leeds Musculoskeletal and Biomedical Research Unit. The consumables and reagents for this study were supported by a grant from Nuvasive Inc; E Jones, D McGonagle and PV Giannoudis were grant holders but received no salary from this grant. TA Moseley is employed at NuVasive, Inc. as the Divisional Scientist of Biologics R&D. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all investigations. Informed written consent has been obtained from the individuals whose samples were involved in experimental investigations.

Additional information

Funding

E Jones and D McGonagle hold funding from Wellcome Trust/EPSRC through WELMEC, a Centre of Excellence in Medical Engineering, under grant number WT 088908/Z/09/Z. TG Baboolal is funded by WELMEC. E Jones, D McGonagle and PV Giannoudis are also part-funded by the National Institute of Health Research via the NIHR-Leeds Musculoskeletal and Biomedical Research Unit. The consumables and reagents for this study were supported by a grant from Nuvasive Inc; E Jones, D McGonagle and PV Giannoudis were grant holders but received no salary from this grant. TA Moseley is employed at NuVasive, Inc. as the Divisional Scientist of Biologics R&D. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.