FAQs: Bone Formation

What is Osteocel® Plus?

Osteocel® Plus is an allograft cellular bone matrix that retains its native bone-forming cells, including mesenchymal stem cells (MSCs) and osteoprogenitors. Osteocel® Plus is intended for the repair, replacement, and reconstruction of skeletal defects.

Does Osteocel® Plus provide a complete bone graft replacement?

Like autograft, Osteocel® Plus provides all three physiologic mechanisms that are instrumental in normal bone healing1:

 • Osteoconduction: Cancellous bone chips

 • Osteoinduction: Cell signaling and demineralized bone matrix

 • Osteogenesis: MSCs and osteoprogenitor cells

 • Osteoconductive matrices encourage new bone growth by providing a scaffold to support bone formation. The cancellous bone component of Osteocel® Plus provides
an ideal foundation for bone formation1.

 • Osteoinduction is the indirect promotion of bone formation through molecular signaling. Osteocel® Plus is osteoinductive due to the natural signaling action of its cell population, in addition to the reservoir of growth factors in its demineralized bone matrix component. Growth factors released by MSCs and osteoprogenitors signal one another to differentiate, and also recruit the patient’s cells to migrate to the defect site and participate in the bone formation process2,3.

 • Osteogenesis is the ability of cells to directly form bone. Prior to the development of Osteocel® Plus grafts in 2005, only autograft (i.e. harvested bone or bone marrow aspirate) had osteogenic capacity1. Osteocel® Plus retains the native mesenchymal stem cells and osteoprogenitor cells that are attached to the cancellous matrix; once implanted at the surgical site, these cells are able to differentiate into osteoblasts and produce new bone1,4,5. References
 1. Khan, SN et al., The biology of bone grafting. J.Am.Acad.Orthop.Surg. 13(1), 77-86. 2005.
 2. Osteoinductivity of Mesenchymal Stem Cells in Bone formation. Osiris Therapeutics white paper released 03-15-06 Baltimore, MD.
 3. Urist MR, Bone Formation by Autoinduction. Science 150: 893 (1965)
 4. Osteoprogenitor Cells Preserved in Osteocel® Plus Tissue Product Result in Enhanced Bone Formation. NuVasive/Osiris Therapeutics white paper released 2007 Baltimore, MD.
 5. Bruder SP et al., Mesenchymal Stem Cells in Osteobiology and Applied Bone Regeneration. CORR, 1998, S247-S256

How closely does bone formation using Osteocel® Plus mimic the body’s normal physiologic mechanisms?

As a cellular allograft, Osteocel® Plus is intended to mimic the biological profile and
osteogenic mechanisms of autograft. Specifically, Osteocel® Plus provides a physiologic level of osteopotent cells and concomitant growth factor production. Native MSCs and osteoprogenitors, like those in Osteocel® Plus , are normally recruited to repair bony defects1,6. Osteocel® Plus overcomes the supply limitations, morbidity, and variabilityassociated with harvesting bone or bone marrow aspirate to obtain autologous cells7,8, while still providing a reliable source of viable cells for osteogenesis at the site of implantation. References
 1. Khan, SN et al., The biology of bone grafting. J.Am.Acad.Orthop.Surg. 13(1), 77-86. 2005.
 6. Caplan AI and Dennis JE. Mesenchymal Stem Cells as Trophic Mediators. J Cell Biochem. 2006. 98:1076-1084
 7. Arrington ED et al., Complications of Iliac Crest Bone Graft Harvesting. CORR. 329:300-309. 1996
 8. Hernigou A et al., Percutaneous Autologous Bone-Marrow Grafting for Non-Unions. A. Hernigou, F. Beaujean, H. Rouard. The Journal of Bone and Joint Surgery 87 (2005) 1430-1437.

What measures are taken to ensure that Osteocel® Plus consistently promotes bone formation?

Osteocel® Plus was developed to provide a reliable source of viable cells for osteogenesis at the site of implantation. Each lot of Osteocel® Plus is tested, post-cryopreservation, for its potential to promote bone formation. 
The following three criteria must be met:
• Cell viability (minimum 70%)
• Cell concentration (minimum 250,000 viable cells/cc)
• Osteogenic potential, or capacity for osteoblastic differentiation and osteogenesis – an in vitro cell culture assay for the alkaline phosphatase enzyme activity that is involved in early osteogenesis.9,10 References
 9. Multipotential Differentiation of Mesenchymal Stem Cells (MSCs) from Osteocel® Plus . NuVasive/Osiris Therapeutics white paper released 06-23-05. Baltimore, MD.
 10. Pittenger M et al., Multilineage Potential of Adult Human Mesenchymal Stem Cells. Science 284 (1999) 143-147.

How is Osteocel® Plus processed?

Processing of Osteocel® Plus begins with the recovery of strictly screened and tested donor tissue and results in a cellular allograft that retains its native bone-forming cell population. While retaining mesenchymal stem cells and osteoprogenitor cells, the allograft is depleted of mmunogenic components through a proprietary selective immunodepletion process. This process was developed after 15+ years of research by Osiris® Therapeutics, a global leader in stem cell therapeutics. 2, 4, 5, 9, 11, 12, 13, 14, 19, 22 Following recovery from select procurement sites, donor tissue is transferred for processing on wet ice within 24 hours. To protect cell viability, tissue processing begins promptly upon arrival. All omponents of each lot of Osteocel® Plus are from the same donor, and the cells are not removed from their native matrix. Selective immunodepletion processing was developed to purify the cellular cancellous bone matrix. Cell-rich cancellous bone is processed to selectively deplete immunogenic components from the hematopoietic stem cell lineage (e.g. blood cells, lymphocytes,and osteoclasts), while retaining viable MSCs and osteoprogenitor cells9,12. Osteocel® Plus processing also includes a broad-spectrum antimicrobial and antimycotic treatment designed to eliminate potential contaminants while preserving the viability of the cells. In parallel, the cortical component of the donor bone is ground into a powder and undergoes demineralization. The processed tissue is combined with a cryopreservation agent and frozen down to –80°C, providing Osteocel® Plus with its five-year shelf life. Following successful completion of post-cryopreservation cell quality control testing and quality assurance review, Osteocel® Plus is released for distribution15. References
 2. Osteoinductivity of Mesenchymal Stem Cells in Bone formation. Osiris Therapeutics white paper released 03-15-06 Baltimore, MD.
 4. Osteoprogenitor Cells Preserved in Osteocel® Plus Tissue Product Result in Enhanced Bone Formation. NuVasive/Osiris Therapeutics white paper released 2007 Baltimore, MD.
 5. Bruder SP et al., Mesenchymal Stem Cells in Osteobiology and Applied Bone Regeneration. CORR, 1998, S247-S256
 9. Multipotential Differentiation of Mesenchymal Stem Cells (MSCs) from Osteocel® Plus. NuVasive/Osiris Therapeutics white paper released 06-23-05. Baltimore, MD.
 11. Bruder SP et al., Growth Kinetics, Self-Renewal, and the Osteogenic Potential of Purified Human Mesenchymal Stem Cells during Extensive Subcultivation and Following Cryopreservation. JCB.65 (1997) 278-294
 12. Fluorescent Activated Cell Sorting (FACS) Analysis of Osteocel® Plus Demonstrates a Stem Cell Profile.
NuVasive/Osiris Therapeutics white paper released 03-15-06 Baltimore, MD.
 13. Archambault et al. Allogeneic Mesenchymal Stem Cells Heal Bone Without Rejection in a Non-Human Primate Model. 29th Annual Meeting of the AATB, 2005
 14. Jaiswal N et al., Osteogenic differentiation of purified, culture-expanded human mesenchymal stem cells in vitro. J.Cell Biochem. 64(2), 295-312. 1997.
 15. Cellular Viability after Cryopreservation. NuVasive white paper released 2009. San Diego, CA.
 19. Low Immunogenicity of Cells from Osteocel® Plus . NuVasive white paper in progress. San Diego, CA.
 22. Osiris Therapeutics, Inc. Clinical Trials. http://www.osiristx.com/clinical_trials.php

What is the concentration of cells in Osteocel® Plus?

Due to selective depletion processing and quality control testing, Osteocel® Plus provides a physiologic level of bone-forming cells. Osteocel® Plus is processed to deplete potentially immunogenic components, while retaining the native osteopotent cell population. In addition, each lot of Osteocel® Plus is tested against strict standards for cell count, viability, and bone-forming activity. Osteocel® Plus can thus be compared to fresh autograft from a healthy individual, which has long been regarded as the gold standard for bone repair.

FAQs: Safety and Regulation

Will the cells wash out of Osteocel® Plus? Are they retained at the site of implantation?

Osteocel® Plus should be treated, and will behave, very much like autograft. Because the cells are attached to the allograft matrix, they will not “wash out”, even with irrigation. In preclinical studies, culture-expanded mesenchymal cells delivered in various matrices were fluorescently-labeled and then detected within newly-formed bone several months after surgery. Using this technique, it was confirmed that the cells persist at the site of implantation and actively participate in new bone formation 5,13. References
 5. Bruder SP et al., Mesenchymal Stem Cells in Osteobiology and Applied Bone Regeneration. CORR, 1998, S247-S256
 13. Archambault et al. Allogeneic Mesenchymal Stem Cells Heal Bone Without Rejection in a Non-Human Primate Model. 29th Annual Meeting of the AATB, 2005

How does Osteocel® Plus form bone instead of other tissues?


Adult mesenchymal stem cells have the ability to differentiate into a variety of tissue types including bone, fat, muscle, or cartilage; however, differentiation is dependent upon their local environment9. Cancellous bone matrix and cortical demineralized bone matrix provide an optimal environment for promoting osteoblastic stem cell differentiation1. Histological studies have confirmed that maintaining the osteopotent cell population within its native bone matrix is effective for promoting bone formation4,16.
Protected by U.S. Pat. No. 5,811,094 and 6,355,239. Other patents pending. 9500257 C.0 References
 1. Khan, SN et al., The biology of bone grafting. J.Am.Acad.Orthop.Surg. 13(1), 77-86. 2005.
 4. Osteoprogenitor Cells Preserved in Osteocel® Plus Tissue Product Result in Enhanced Bone Formation. NuVasive/Osiris Therapeutics white paper released 2007 Baltimore, MD.
 9. Multipotential Differentiation of Mesenchymal Stem Cells (MSCs) from Osteocel® Plus. NuVasive/Osiris Therapeutics white paper released 06-23-05. Baltimore, MD.
 16. McAllister BS et al., Histologic evaluation of a stem cell-based sinus-augmentation procedure.
J.Periodontol. 80(4), 679-686. 2009.

FAQs: Implantation of Osteocel® Plus

What is the shelf life of Osteocel® Plus?

Osteocel® Plus’ expiration date is 5 years from the date of processing when stored at -80±5°C. This date is provided on the Osteocel® Plus label. The graft can be stored for a shorter duration at warmer temperatures. See package insert for details.

How long will the cells stay viable once thawed?

Osteocel® Plus should be thawed shortly before use. Once thawed, the cryoprotectant should be decanted off and replaced with sterile saline (not water). Osteocel® Plus should not be allowed to dry out. Once in saline, the graft should be used within 4 hours to maintain cell viability. A 15-cc volume thaws in approximately 15-20 minutes in a water bath at physiologic temperatures (37°C/98.6°F), or slightly longer at room temperature. Osteocel® Plus should not be heated above physiologic temperatures. Any remaining tissue cannot be refrozen.

What is the liquid in which Osteocel® Plus is frozen?

The liquid is a cryoprotectant that is commonly used in clinical settings for cell and tissue preservation; it contains dimethyl sulfoxide (DMSO) and Dulbecco’s Modified Eagle Medium (DMEM, which may give the fluid and tissue a pink tint) and allows the cells in Osteocel® Plus to be frozen and remain viable11,15. The cryoprotectant should be decanted after thawing the tissue and replaced with 37°C (98.6°F) sterile saline.