1
|
Cottrill E, Pennington Z, Sattah N, Jing C, Salven D, Johnson E, Downey M, Varghese S, Rocos B, Richardson W. Gene Therapy and Spinal Fusion: Systematic Review and Meta-Analysis of the Available Data. World Neurosurg 2024:S1878-8750(24)00560-6. [PMID: 38583566 DOI: 10.1016/j.wneu.2024.03.174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/31/2024] [Indexed: 04/09/2024]
Abstract
OBJECTIVE To analyze the extant literature describing the application of gene therapy to spinal fusion. METHODS A systematic review of the English-language literature was performed. The search query was designed to include all published studies examining gene therapy approaches to promote spinal fusion. Approaches were classified as ex vivo (delivery of genetically modified cells) or in vivo (delivery of growth factors via vectors). The primary endpoint was fusion rate. Random effects meta-analyses were performed to calculate the overall odds ratio (OR) of fusion using a gene therapy approach and overall fusion rate. Subgroup analyses of fusion rate were also performed for each gene therapy approach. RESULTS Of 1179 results, 35 articles met criteria for inclusion (all preclinical), of which 26 utilized ex vivo approaches and 9 utilized in vivo approaches. Twenty-seven articles (431 animals) were included in the meta-analysis. Gene therapy use was associated with significantly higher fusion rates (OR 77; 95% confidence interval {CI}: [31, 192]; P < 0.001); ex vivo strategies had a greater effect (OR 136) relative to in vivo strategies (OR 18) (P = 0.017). The overall fusion rate using a gene therapy approach was 80% (95% CI: [62%, 93%]; P < 0.001); overall fusion rates were significantly higher in subjects treated with ex vivo compared to in vivo strategies (90% vs. 42%; P = 0.011). For both ex vivo and in vivo approaches, the effect of gene therapy on fusion was independent of animal model. CONCLUSIONS Gene therapy may augment spinal fusion; however, future investigation in clinical populations is necessary.
Collapse
Affiliation(s)
- Ethan Cottrill
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA.
| | | | - Nathan Sattah
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA
| | - Crystal Jing
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA
| | - Dave Salven
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA
| | - Eli Johnson
- Department of Neurosurgery, Duke University Health System, Durham, NC, USA
| | - Max Downey
- Department of Surgery, NYU Grossman School of Medicine, NY, USA
| | - Shyni Varghese
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA; Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Brett Rocos
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA
| | - William Richardson
- Department of Orthopaedic Surgery, Duke University Health System, Durham, NC, USA
| |
Collapse
|
2
|
Cui L, Xiang S, Chen D, Fu R, Zhang X, Chen J, Wang X. A novel tissue-engineered bone graft composed of silicon-substituted calcium phosphate, autogenous fine particulate bone powder and BMSCs promotes posterolateral spinal fusion in rabbits. J Orthop Translat 2020; 26:151-161. [PMID: 33437634 PMCID: PMC7773983 DOI: 10.1016/j.jot.2020.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 11/15/2022] Open
Abstract
Background Autogenous bone graft is the gold standard bone grafting substrate available in spinal fusion because of its osteoconductive, osteogenic, and osteoinductive properties. However, several shortcomings including bleeding, infection, chronic pain, and nerve injury are known to be associated with the procedure. Bone tissue engineering has emerged as an alternative therapeutic strategy for bone grafts. New materials have been developed and tested that can substitute for the autogenous bone grafts used in the spinal fusion. The purpose of this study is to evaluate the role of a novel tissue-engineered bone graft with silicon-substituted calcium phosphate (Si-CaP), autogenous fine particulate bone powder (AFPBP), and bone marrow mesenchymal stem cells (BMSCs) using a rabbit posterolateral lumbar fusion model based on bone tissue engineering principles. The application of this graft can represent a novel choice for autogenous bone to reduce the amount of autogenous bone and promote spinal fusion. Methods BMSCs from New Zealand white rabbits were isolated and cultured in vitro. Then, BMSCs were marked by the cell tracker chloromethyl-benzamidodialkylcarbocyanine (CM-Dil). A total of 96 New Zealand White rabbits were randomly divided into four groups: (a) AFPBP, (b) Si-CaP, (c) Si-CaP/AFPBP, (d) Si-CaP/AFPBP/BMSCs.The rabbits underwent bilateral posterolateral spine arthrodesis of the L5-L6 intertransverse processes using different grafts. Spinal fusion and bone formation were evaluated at 4, 8, and 12 weeks after surgery by manual palpation, radiology, micro-computed tomography (micro-CT), histology, and scanning electronic microscopy (SEM). Results The rate of fusion by manual palpation was higher in the Si-CaP/AFPBP/BMSCs group than the other groups at 8 weeks. The fusion rates in the Si-CaP/AFPBP/BMSCs and the AFPBP groups both reached 100%, which was higher than the Si-CaP/AFPBP group (62.5%) (P > 0.05) and Si-CaP group (37.5%) (P < 0.05) at 12 weeks. New bone formation was observed in all groups after implantation by radiology and micro-CT. The radiographic and CT scores increased in all groups from 4 to 12 weeks, indicating a time-dependent osteogenetic process. The Si-CaP/AFPBP/BMSCs group showed a larger amount of newly formed bone than the Si-CaP/AFPBP and Si-CaP groups at 12 weeks. Bone formation in the Si-CaP/AFPBP/BMSCs group was similar to the AFPBP group. Histology showed that new bone formation continued and increased along with the degradation and absorption of Si-CaP and AFPBP from 4 to 12 weeks in the Si-CaP, Si-CaP/AFPBP, and Si-CaP/AFPBP/BMSCs groups. At 4 weeks, a higher proportion of bone was detected in the AFPBP group (23.49%) compared with the Si-CaP/AFPBP/BMSCs group (14.66%, P < 0.05). In the Si-CaP/AFPBP/BMSCs group at 8 weeks, the area percentage of new bone formation was 28.56%, which was less than the AFPBP group (33.21%, P < 0.05). No difference in bone volume was observed between the Si-CaP/AFPBP/BMSCs group (44.39%) and AFPBP group (45.06%) at 12 weeks (P > 0.05). At 12 weeks, new trabecular were visible in the Si-CaP/AFPBP/BMSCs group by SEM. CM-Dil-positive cells were observed at all stages. Compared with histological images, BMSCs participate in various stages of osteogenesis by transforming into osteoblasts, chondrocytes, and osteocytes. Conclusion This study demonstrated for the first time that Si-CaP/AFPBP/BMSCs is a novel tissue-engineered bone graft with excellent bioactivity, biocompatibility, and biodegradability. The graft could reduce the amount of autogenous bone and promote spinal fusion in a rabbit posterolateral lumbar fusion model, representing a novel alternative to autogenous bone. The Translational potential of this article The translational potential of this article lies in that this graft will be a novel spinal fusion graft with great potential for clinical applications.
Collapse
Affiliation(s)
- LiHuang Cui
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - ShouYang Xiang
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - DeChun Chen
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Rui Fu
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xin Zhang
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - JingTao Chen
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - XinTao Wang
- Department of Orthopedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| |
Collapse
|
3
|
May RD, Frauchiger DA, Albers CE, Tekari A, Benneker LM, Klenke FM, Hofstetter W, Gantenbein B. Application of Cytokines of the Bone Morphogenetic Protein (BMP) Family in Spinal Fusion - Effects on the Bone, Intervertebral Disc and Mesenchymal Stromal Cells. Curr Stem Cell Res Ther 2020; 14:618-643. [PMID: 31455201 PMCID: PMC7040507 DOI: 10.2174/1574888x14666190628103528] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 12/17/2022]
Abstract
Low back pain is a prevalent socio-economic burden and is often associated with damaged or degenerated intervertebral discs (IVDs). When conservative therapy fails, removal of the IVD (discectomy), followed by intersomatic spinal fusion, is currently the standard practice in clinics. The remaining space is filled with an intersomatic device (cage) and with bone substitutes to achieve disc height compensation and bone fusion. As a complication, in up to 30% of cases, spinal non-fusions result in a painful pseudoarthrosis. Bone morphogenetic proteins (BMPs) have been clinically applied with varied outcomes. Several members of the BMP family, such as BMP2, BMP4, BMP6, BMP7, and BMP9, are known to induce osteogenesis. Questions remain on why hyper-physiological doses of BMPs do not show beneficial effects in certain patients. In this respect, BMP antagonists secreted by mesenchymal cells, which might interfere with or block the action of BMPs, have drawn research attention as possible targets for the enhancement of spinal fusion or the prevention of non-unions. Examples of these antagonists are noggin, gremlin1 and 2, chordin, follistatin, BMP3, and twisted gastrulation. In this review, we discuss current evidence of the osteogenic effects of several members of the BMP family on osteoblasts, IVD cells, and mesenchymal stromal cells. We consider in vitro and in vivo studies performed in human, mouse, rat, and rabbit related to BMP and BMP antagonists in the last two decades. We give insights into the effects that BMP have on the ossification of the spine. Furthermore, the benefits, pitfalls, and possible safety concerns using these cytokines for the improvement of spinal fusion are discussed.
Collapse
Affiliation(s)
- Rahel Deborah May
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | | | - Christoph Emmanuel Albers
- Department of Orthopaedic Surgery and Traumatology, Inselspital, University of Bern, Bern, Switzerland
| | - Adel Tekari
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Lorin Michael Benneker
- Department of Orthopaedic Surgery and Traumatology, Inselspital, University of Bern, Bern, Switzerland
| | - Frank Michael Klenke
- Department of Orthopaedic Surgery and Traumatology, Inselspital, University of Bern, Bern, Switzerland
| | - Willy Hofstetter
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Benjamin Gantenbein
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Department of Orthopaedic Surgery and Traumatology, Inselspital, University of Bern, Bern, Switzerland
| |
Collapse
|
4
|
Vukicevic S, Grgurevic L, Erjavec I, Pecin M, Bordukalo-Niksic T, Stokovic N, Lipar M, Capak H, Maticic D, Windhager R, Sampath TK, Gupta M. Autologous blood coagulum is a physiological carrier for BMP6 to induce new bone formation and promote posterolateral lumbar spine fusion in rabbits. J Tissue Eng Regen Med 2019; 14:147-159. [PMID: 31671243 PMCID: PMC7027565 DOI: 10.1002/term.2981] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 09/27/2019] [Accepted: 10/17/2019] [Indexed: 12/22/2022]
Abstract
In the present study, we describe autologous blood coagulum (ABC) as a physiological carrier for BMP6 to induce new bone formation. Recombinant human BMP6 (rhBMP6), dispersed within ABC and formed as an autologous bone graft substitute (ABGS), was evaluated either with or without allograft bone particles (ALLO) in rat subcutaneous implants and in a posterolateral lumbar fusion (PLF) model in rabbits. ABGS induced endochondral bone differentiation in rat subcutaneous implants. Coating ALLO by ABC significantly decreased the formation of multinucleated foreign body giant cells (FBGCs) in implants, as compared with ALLO alone. However, addition of rhBMP6 to ABC/ALLO induced a robust endochondral bone formation with little or no FBGCs in the implant. In rabbit PLF model, ABGS induced new bone formation uniformly within the implant resulting in a complete fusion when placed between two lumbar transverse processes in the posterolateral gutter with an optimum dose of 100‐μg rhBMP6 per ml of ABC. ABGS containing ALLO also resulted in a fusion where the ALLO was replaced by the newly formed bone via creeping substitution. Our findings demonstrate for the first time that rhBMP6, with ABC as a carrier, induced a robust bone formation with a complete spinal fusion in a rabbit PLF model. RhBMP6 was effective at low doses with ABC serving as a physiological substratum providing a permissive environment by protecting against foreign body reaction elicited by ALLO.
Collapse
Affiliation(s)
- Slobodan Vukicevic
- Laboratory for Mineralized Tissues, Centre for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Lovorka Grgurevic
- Laboratory for Mineralized Tissues, Centre for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Igor Erjavec
- Laboratory for Mineralized Tissues, Centre for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Marko Pecin
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Tatjana Bordukalo-Niksic
- Laboratory for Mineralized Tissues, Centre for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Nikola Stokovic
- Laboratory for Mineralized Tissues, Centre for Translational and Clinical Research, University of Zagreb School of Medicine, Zagreb, Croatia
| | - Marija Lipar
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Hrvoje Capak
- Department of Radiology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Drazen Maticic
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Reinhard Windhager
- Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | | | - Munish Gupta
- Department of Orthopedic Surgery, Washington University, St. Louis, MO
| |
Collapse
|
5
|
Cottrill E, Ahmed AK, Lessing N, Pennington Z, Ishida W, Perdomo-Pantoja A, Lo SF, Howell E, Holmes C, Goodwin CR, Theodore N, Sciubba DM, Witham TF. Investigational growth factors utilized in animal models of spinal fusion: Systematic review. World J Orthop 2019; 10:176-191. [PMID: 31041160 PMCID: PMC6475812 DOI: 10.5312/wjo.v10.i4.176] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 01/03/2019] [Accepted: 01/26/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Over 400000 Americans annually undergo spinal fusion surgeries, yet up to 40% of these procedures result in pseudoarthrosis even with iliac crest autograft, the current “gold standard” treatment. Tissue engineering has the potential to solve this problem via the creation of bone grafts involving bone-promoting growth factors (e.g., bone morphogenetic protein 2). A broad assessment of experimental growth factors is important to inform future work and clinical potential in this area. To date, however, no study has systematically reviewed the investigational growth factors utilized in preclinical animal models of spinal fusion.
AIM To review all published studies assessing investigational growth factors for spinal fusion in animal models and identify promising agents for translation.
METHODS We conducted a systematic review of the literature using PubMed, Embase, Cochrane Library, and Web of Science databases with searches run on May 29th, 2018. The search query was designed to include all non-human, preclinical animal models of spinal fusion reported in the literature without a timespan limit. Extracted data for each model included surgical approach, level of fusion, animal species and breed, animal age and sex, and any other relevant characteristics. The dosages/sizes of all implant materials, spinal fusion rates, and follow-up time points were recorded. The data were analyzed and the results reported in tables and text. PRISMA guidelines were followed for this systematic review.
RESULTS Twenty-six articles were included in this study, comprising 14 experimental growth factors: AB204 (n = 1); angiopoietin 1 (n = 1); calcitonin (n = 3); erythropoietin (n = 1); basic fibroblast growth factor (n = 1); growth differentiation factor 5 (n = 4), combined insulin-like growth factor 1 + transforming growth factor beta (n = 4); insulin (n = 1); NELL-1 (n = 5); noggin (n = 1); P-15 (n = 1); peptide B2A (n = 2); and secreted phosphoprotein 24 (n = 1). The fusion rates of the current gold standard treatment (autologous iliac crest bone graft, ICBG) and the leading clinically used growth factor (BMP-2) ranged widely in the included studies, from 0-100% for ICBG and from 13%-100% for BMP-2. Among the identified growth factors, calcitonin, GDF-5, NELL-1, and P-15 resulted in fusion rates of 100% in some cases. In addition, six growth factors - AB204, angiopoietin 1, GDF-5, insulin, NELL-1, and peptide B2A - resulted in significantly enhanced fusion rates compared to ICBG, BMP-2, or other internal control in some studies. Large heterogeneity in animal species, fusion method, and experimental groups and time points was observed across the included studies, limiting the direct comparison of the growth factors identified herein.
CONCLUSION Several promising investigational growth factors for spinal fusion have been identified herein; directly comparing the fusion efficacy and safety of these agents may inform clinical translation.
Collapse
Affiliation(s)
- Ethan Cottrill
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - A Karim Ahmed
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Noah Lessing
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Zachary Pennington
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Wataru Ishida
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | | | - Sheng-fu Lo
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Elizabeth Howell
- Department of Neurosurgery, Duke University Medical Center, Durham, NC 27710, United States
| | - Christina Holmes
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - C Rory Goodwin
- Department of Neurosurgery, Duke University Medical Center, Durham, NC 27710, United States
| | - Nicholas Theodore
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Daniel M Sciubba
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| | - Timothy F Witham
- Department of Neurosurgery, The Johns Hopkins Hospital, Baltimore, MD 21287, United States
| |
Collapse
|
6
|
Efficient in vitro delivery of Noggin siRNA enhances osteoblastogenesis. Heliyon 2017; 3:e00450. [PMID: 29167826 PMCID: PMC5686427 DOI: 10.1016/j.heliyon.2017.e00450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 10/20/2017] [Accepted: 11/03/2017] [Indexed: 11/22/2022] Open
Abstract
Several types of serious bone defects would not heal without invasive clinical intervention. One approach to such defects is to enhance the capacity of bone-formation cells. Exogenous bone morphogenetic proteins (BMP) have been utilized to positively regulate matrix mineralization and osteoblastogenesis, however, numerous adverse effects are associated with this approach. Noggin, a potent antagonist of BMPs, is an ideal candidate to target and decrease the need for supraphysiological doses of BMPs. In the current research we report a novel siRNA-mediated gene knock-down strategy to down-regulate Noggin. We utilized a lipid nanoparticle (LNP) delivery strategy in pre-osteoblastic rat cells. In vitro LNP-siRNA treatment caused inconsequential cell toxicity and transfection was achieved in over 85% of cells. Noggin siRNA treatment successfully down-regulated cellular Noggin protein levels and enhanced BMP signal activity which in turn resulted in significantly increased osteoblast differentiation and extracellular matrix mineralization evidenced by histological assessments. Gene expression analysis showed that targeting Noggin specifically in bone cells would not lead to a compensatory effect from other BMP negative regulators such as Gremlin and Chordin. The results from this study support the notion that novel therapeutics targeting Noggin have the clinically relevant potential to enhance bone formation without the need for toxic doses of exogenous BMPs. Such treatments will undeniably provide safe and economical treatments for individuals whose poor bone repair results in permanent morbidity and disability.
Collapse
|
7
|
Refaat M, Klineberg EO, Fong MC, Garcia TC, Leach JK, Haudenschild DR. Binding to COMP Reduces the BMP2 Dose for Spinal Fusion in a Rat Model. Spine (Phila Pa 1976) 2016; 41:E829-E836. [PMID: 26679888 PMCID: PMC7054986 DOI: 10.1097/brs.0000000000001408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN The aim of this study is to test the effect of cartilage oligomeric matrix protein (COMP) on enhancing rhBMP-2 induced spinal fusion in a prospective 8-week interventional trial of spinal fusion in rats. OBJECTIVE To determine whether the amount of bone morphogenetic protein-2 (BMP-2) required to achieve spinal fusion in a pre-clinical model can be reduced by the addition of COMP. SUMMARY OF BACKGROUND DATA BMPs are applied clinically at supraphysiological doses to promote spinal fusion by inducing osseous growth, but dose-related limitations include ectopic bone formation and local inflammatory reactions. COMP is a matricellular BMP-binding protein expressed during endochondral ossification and fracture healing. In vitro studies demonstrate enhanced activity of BMP bound to COMP. We hypothesized that BMP bound to COMP could achieve equivalent spinal fusion rates at lower doses and with fewer complications. METHODS Posterolateral intertransverse process spinal fusion at L4 to L5 was performed in 36 Lewis rats. COMP (10 μg) was tested with or without "low-dose" rhBMP-2 (2 μg), and the results were compared with the "low-dose" (2 μg rhBMP-2) and "high-dose" (10 μg rhBMP-2) groups. All groups utilized insoluble collagen bone matrix carrier (ICBM). Fusion was evaluated by radiology, histology, and manual palpation. BMP release kinetics were evaluated in vitro. RESULTS Fusion grading of microCT images demonstrated that the fusion rate with the COMP+LoBMP was statistically equivalent to HiBMP, and significantly better than LoBMP without COMP. These results were confirmed with radiographs and manual palpation. BMP release kinetics suggest that COMP increased local concentrations of BMP due to decreased growth factor retention on the scaffold. CONCLUSION COMP enhances BMP-induced bone formation, enabling lower doses of BMP to achieve the same level of spinal fusion. COMP may function by affecting the availability and biological presentation of BMP-2. A decrease of BMP-2 required for fusion may reduce dose-related adverse effects, surgical costs, and improve clinical outcomes. LEVEL OF EVIDENCE N/A.
Collapse
Affiliation(s)
- Motasem Refaat
- Lawrence J. Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis
| | - Eric O. Klineberg
- Lawrence J. Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis
| | - Michael C. Fong
- Lawrence J. Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis
| | - Tanya C. Garcia
- J.D. Wheat Veterinary Orthopaedic Laboratory, School of Veterinary Medicine, University of California Davis, One Shields Avenue, Davis CA 95616 USA
| | - J. Kent Leach
- Lawrence J. Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis
- Department of Biomedical Engineering, University of California Davis
| | - Dominik R. Haudenschild
- Lawrence J. Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis
| |
Collapse
|