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Cicione C, Vadalà G, Di Giacomo G, Tilotta V, Ambrosio L, Russo F, Zampogna B, Cannata F, Papalia R, Denaro V. Micro-fragmented and nanofat adipose tissue derivatives: In vitro qualitative and quantitative analysis. Front Bioeng Biotechnol 2023; 11:911600. [PMID: 36733959 PMCID: PMC9887143 DOI: 10.3389/fbioe.2023.911600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 01/06/2023] [Indexed: 01/18/2023] Open
Abstract
Introduction: Adipose tissue is widely exploited in regenerative medicine thanks to its trophic properties, mainly based on the presence of adipose-derived stromal cells. Numerous devices have been developed to promote its clinical use, leading to the introduction of one-step surgical procedures to obtain minimally manipulated adipose tissue derivatives. However, only a few studies compared their biological properties. This study aimed to characterize micro-fragmented (MAT) and nanofat adipose tissue (NAT) obtained with two different techniques. Methods: MAT, NAT and unprocessed lipoaspirate were collected from surgical specimens. RNA extraction and collagenase isolation of stromal vascular fraction (SVF) were performed. Tissue sections were analysed by histological and immunohistochemical (collagen type I, CD31, CD34 and PCNA) staining to assess tissue morphology and cell content. qPCR was performed to evaluate the expression of stemness-related (SOX2, NANOG and OCT3/4), extracellular matrix (COL1A1) and inflammatory genes (IL1β, IL6 and iNOS). Furthermore, multilineage differentiation was assessed following culture in adipogenic and osteogenic media and staining with Oil Red O and Alizarin red. ASC immunophenotype was assessed by flow cytometric analysis of CD90, CD105, CD73 and CD45. Results: Histological and immunohistochemical results showed an increased amount of stroma and a reduction of adipocytes in MAT and NAT, with the latter displaying the highest content of collagen type I, CD31, CD34 and PCNA. From LA to MAT and NAT, an increasing expression of NANOG, SOX2, OCT3/4, COL1A1 and IL6 was noted, while no significant differences in terms of IL1β and iNOS emerged. No statistically significant differences were noted between NAT and SVF in terms of stemness-related genes, while the latter demonstrated a significantly higher expression of stress-related markers. SVF cells derived from all three samples (LA, MAT, and NAT) showed a similar ASC immunoprofile as well as osteogenic and adipogenic differentiation. Discussion: Our results showed that both MAT and NAT techniques allowed the rapid isolation of ASC-rich grafts with a high anabolic and proliferative potential. However, NAT showed the highest levels of extracellular matrix content, replicating cells, and stemness gene expression. These results may provide precious clues for the use of adipose tissue derivatives in the clinical setting.
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Affiliation(s)
- Claudia Cicione
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Gianluca Vadalà
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy,Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy,*Correspondence: Gianluca Vadalà,
| | - Giuseppina Di Giacomo
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Veronica Tilotta
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Luca Ambrosio
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy,Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
| | - Fabrizio Russo
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy,Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
| | - Biagio Zampogna
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy,Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
| | - Francesca Cannata
- Operative Research Unit of Endocrinology and Diabetes, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
| | - Rocco Papalia
- Laboratory for Regenerative Orthopaedics, Research Unit of Orthopaedic and Trauma Surgery, Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy,Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
| | - Vincenzo Denaro
- Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy
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Han Y, Ouyang Z, Wawrose RA, Chen SR, Hallbaum M, Dong Q, Dando E, Tang Y, Wang B, Lee JY, Shaw JD, Kang JD, Sowa GA, Vo NN. ISSLS prize in basic science 2021: a novel inducible system to regulate transgene expression of TIMP1. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2021; 30:1098-1107. [PMID: 33523281 PMCID: PMC8550652 DOI: 10.1007/s00586-021-06728-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/14/2020] [Accepted: 01/09/2021] [Indexed: 11/28/2022]
Abstract
Purpose Inflammatory and oxidative stress upregulates matrix metalloproteinase (MMP) activity, leading to intervertebral disc degeneration (IDD). Gene therapy using human tissue inhibitor of metalloproteinase 1 (hTIMP1) has effectively treated IDD in animal models. However, persistent unregulated transgene expression may have negative side effects. We developed a recombinant adeno-associated viral (AAV) gene vector, AAV-NFκB-hTIMP1, that only expresses the hTIMP1 transgene under conditions of stress. Methods Rabbit disc cells were transfected or transduced with AAV-CMV-hTIMP1, which constitutively expresses hTIMP1, or AAV-NFκB-hTIMP1. Disc cells were selectively treated with IL-1β. NFκB activation was verified by nuclear translocation. hTIMP1 mRNA and protein expression were measured by RT-PCR and ELISA, respectively. MMP activity was measured by following cleavage of a fluorogenic substrate. Results IL-1β stimulation activated NFκB demonstrating that IL-1β was a surrogate for inflammatory stress. Stimulating AAV-NFκB-hTIMP1 cells with IL-1β increased hTIMP1 expression compared to unstimulated cells. AAV-CMV-hTIMP1 cells demonstrated high levels of hTIMP1 expression regardless of IL-1β stimulation. hTIMP1 expression was comparable between IL-1β stimulated AAV-NFκB-hTIMP1 cells and AAV-CMV-hTIMP1 cells. MMP activity was decreased in AAV-NFκB-hTIMP1 cells compared to baseline levels or cells exposed to IL-1β. Conclusion AAV-NFκB-hTIMP1 is a novel inducible transgene delivery system. NFκB regulatory elements ensure that hTIMP1 expression occurs only with inflammation, which is central to IDD development. Unlike previous inducible systems, the AAV-NFκB-hTIMP1 construct is dependent on endogenous factors, which minimizes potential side effects caused by constitutive transgene overexpression. It also prevents the unnecessary production of transgene products in cells that do not require therapy.
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Affiliation(s)
- Yingchao Han
- Department of Spine Surgery, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.,Department of Spine Surgery, School of Medicine, Shanghai East Hospital, Tongji University, Shanghai, China.,Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zhihua Ouyang
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Spine Surgery, The First Affiliated Hospital of Nanhua University, Hengyang, China
| | - Richard A Wawrose
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephen R Chen
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Maximiliane Hallbaum
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Qing Dong
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Emily Dando
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ying Tang
- Molecular Therapeutics Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bing Wang
- Molecular Therapeutics Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joon Y Lee
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jeremy D Shaw
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - James D Kang
- Department of Orthopaedics, School of Medicine, Brigham and Women's Hospital, Harvard University, Boston, MA, USA
| | - Gwendolyn A Sowa
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA. .,Department of Physical Medicine and Rehabilitation, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Nam N Vo
- Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
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Chen S, Luo M, Kou H, Shang G, Ji Y, Liu H. A Review of Gene Therapy Delivery Systems for Intervertebral Disc Degeneration. Curr Pharm Biotechnol 2020; 21:194-205. [PMID: 31749423 DOI: 10.2174/1389201020666191024171618] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/13/2019] [Accepted: 10/14/2019] [Indexed: 02/08/2023]
Abstract
Background: :
Intervertebral Disc (IVD) degeneration is a major public health concern, and
gene therapy seems a promising approach to delay or even reverse IVD degeneration. However, the
delivery system used to transfer exogenous genes into intervertebral disc cells remains a challenge.
Methods::
The MEDLINE, Web of Science, and Scopus databases were searched for English-language
articles related to gene therapy for IVD degeneration articles from 1999 to May 2019. The keywords
included “gene therapy” AND “intervertebral disc”. The history of the development of different delivery
systems was analysed, and the latest developments in viral and non-viral vectors for IVD degeneration
treatment were reviewed.
Results: :
Gene therapy delivery systems for IVD degeneration are divided into two broad categories:
viral and non-viral vectors. The most commonly used viral vectors are adenovirus, adeno-associated
virus (AAV), and lentivirus. Enthusiasm for the use of adenovirus vectors has gradually declined and
has been replaced by a preference for lentivirus and AAV vectors. New technologies, such as RNAi
and CRISPR, have further enhanced the advantage of viral vectors. Liposomes are the classic non-viral
vector, and their successors, polyplex micelles and exosomes, have more potential for use in gene therapy
for IVD degeneration.
Conclusion::
Lentivirus and AAV are the conventional viral vectors used in gene therapy for IVD degeneration,
and the new technologies RNAi and CRISPR have further enhanced their advantages. Nonviral
vectors, such as polyplex micelles and exosomes, are promising gene therapy vectors for IVD degeneration.
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Affiliation(s)
- Songfeng Chen
- Department of Orthopedic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Ming Luo
- Department of Orthopedic Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Hongwei Kou
- Department of Orthopedic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Guowei Shang
- Department of Orthopedic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Yanhui Ji
- Department of Orthopedic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Hongjian Liu
- Department of Orthopedic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
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Low-Pressure Lumbar Provocation Discography According to Spine Intervention Society/International Association for the Study of Pain Standards Does Not Cause Acceleration of Disc Degeneration in Patients With Symptomatic Low Back Pain: A 7-Year Matched Cohort Study. Spine (Phila Pa 1976) 2019; 44:E1161-E1168. [PMID: 31261283 DOI: 10.1097/brs.0000000000003085] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective matched cohort study. OBJECTIVE To determine if low-pressure lumbar provocation discography (PD) results in long-term accelerated disc degeneration, internal disc disruption, or disc herniation in patients with symptomatic low back pain (LBP). SUMMARY OF BACKGROUND DATA Study of subjects without clinically-significant LBP suggests that high-pressure PD may accelerate disc degeneration. METHODS Consecutive patients with symptomatic LBP who underwent magnetic resonance imaging (MRI), PD, and repeat MRI more than 7 years later, but did not undergo subsequent spinal fusion surgery, were included. Punctured discs were matched (1:2 to 1:4) to corresponding discs in a control cohort by age, BMI, Pfirrmann score (±2), and presence of disc herniation; control cohort inclusion required MRIs for symptomatic LBP, separated by more than 7 years. The primary outcome of the study was a progression in Pfirrmann score category (I-II, III-IV, V). MRI disc-to-CSF T2 signal-intensity ratio, disc height, disc herniations, high intensity zones (HIZs), and Modic changes were assessed. RESULTS Baseline and follow-up MRIs were available for 77 discs exposed to PD, and for 260 discs in the matched control cohort. There was no difference in the proportion of punctured discs that advanced in Pfirrmann score category in the PD group (17%, 95% CI 9-27%) compared with corresponding discs in the Control group (21%, 95% CI 17-27%), P = 0.3578, or in non-punctured discs in the PD group (35%, 95% CI 21-51%) compared with corresponding discs in the Control group (34%, 95% CI 27-42%), P = 0.1169. There were no differences in disc-to-CSF T2 signal-intensity ratio, presence of disc herniations, HIZs, or Modic changes following puncture in the PD versus matched cohort discs or in the non-punctured PD cohort discs versus corresponding control cohort discs (P > 0.05). CONCLUSION Patients with symptomatic LBP who underwent low-pressure PD, but who did not undergo a subsequent spinal fusion surgery, developed disc degeneration and new disc herniations at a similar rate to corresponding discs in matched control patients. LEVEL OF EVIDENCE 3.
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Silencing SUMO2 promotes protection against degradation and apoptosis of nucleus pulposus cells through p53 signaling pathway in intervertebral disc degeneration. Biosci Rep 2018; 38:BSR20171523. [PMID: 29700214 PMCID: PMC6023941 DOI: 10.1042/bsr20171523] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/28/2018] [Accepted: 04/25/2018] [Indexed: 01/07/2023] Open
Abstract
Objective: Intervertebral disc degeneration (IDD), as a common cause of back pain, is related to the promotion of cellular senescence and reduction in proliferation. Based on recent studies, small ubiquitin-related modifier (SUMO) proteins have been implicated in various biological functions. Therefore, in the present study, we investigated the effects of SUMO2 on proliferation and senescence of nucleus pulposus cells (NPCs) via mediation of p53 signaling pathway in rat models of IDD. Methods: After the establishment of rat models of IDD for the measurement of positive expression of SUMO2/3 protein, the mRNA and protein levels of SUMO2, molecular phenotype [matrix metalloproteinase-2 (MMP-2) and hypoxia-inducible factor-1α (HIF-1α)] and p53 signaling pathway-related genes [p21, murine double minute-2 (MDM2), growth arrest and DNA-damage-inducible protein 45 α (GADD45α), cyclin-dependent kinase 2/4 (CDK2/4), and CyclinB1] were determined, followed by the detection of cell proliferation, cell cycle, apoptosis, and cell senescence. Results: The rat models of IDD were successfully constructed. The results obtained showed that there was a higher positive expression of SUMO2/3 protein in IDD rats. Moreover, the silencing of the SUMO2 gene decreases the levels of SUMO2, p53, p21, MDM2, GADD45α, MMP-2, and HIF-1α expressions and p53 phosphorylation level while it increases the levels of CDK2/4 and CyclinB1 expressions. In addition, SUMO2 gene silencing enhances proliferation and suppresses apoptosis and cell senescence of NPCs. Conclusion: In conclusion, SUMO2 gene silencing promotes proliferation, and inhibits the apoptosis and senescence of NPCs in rats with IDD through the down-regulation of the p53 signaling pathway. Thus, SUMO2 is a potential target in the treatment of IDD.
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Does an Annular Puncture Influence the Herniation Path?: An In Vitro Mechanical and Structural Investigation. Spine (Phila Pa 1976) 2018; 43:467-476. [PMID: 28719550 DOI: 10.1097/brs.0000000000002336] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A study of mechanically induced herniation in punctured ovine discs followed by structural analysis. OBJECTIVE To investigate whether an annular puncture influences the path that herniation takes by providing direct passage for nucleus through the annulus and therefore whether it increases the risk of acute herniation from overload at the site of damage independent of any longer-term degeneration. SUMMARY OF BACKGROUND DATA Ten years after treatment with discography both degenerative changes and frequency of herniation have been shown to increase compared to untreated discs. Although the effect of an annular puncture over time has been widely investigated the question of whether it increases the risk of acute herniation has not been resolved. METHODS The posterolateral annuli of healthy ovine lumbar discs were punctured with either a 25-gauge (n = 8) or a larger 18-gauge (n = 8) needle and then compressed in a flexed posture of 10° until initial indications of failure. The entire volume of the disc was visually assessed for structural damage by obtaining progressive, full transverse cross-sections of its entire height thus exposing all regions of the disc. RESULTS There was no association between the 25-gauge puncture and disc disruption and herniation. In contrast, nuclear material was observed to migrate through the 18-gauge needle puncture. Disruption of the lateral inner annulus was observed in 12 out of the 16 discs tested. CONCLUSION The risk of acute herniation through the puncture site is dependent on the needle diameter used. Under the conditions employed the lateral inner annulus remains the site most vulnerable to disruption independent of the presence of a posterolateral puncture. LEVEL OF EVIDENCE N /A.
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Understanding the molecular biology of intervertebral disc degeneration and potential gene therapy strategies for regeneration: a review. Gene Ther 2018; 25:67-82. [DOI: 10.1038/s41434-018-0004-0] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/30/2017] [Accepted: 01/03/2018] [Indexed: 12/13/2022]
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Yue B, Lin Y, Ma X, Zhang G, Chen B. Effect of Survivin gene therapy via lentivirus vector on the course of intervertebral disc degeneration in an in vivo rabbit model. Mol Med Rep 2016; 14:4593-4598. [PMID: 27748828 PMCID: PMC5102010 DOI: 10.3892/mmr.2016.5830] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/03/2016] [Indexed: 01/28/2023] Open
Abstract
The aim of the current study was to use gene therapy to attenuate or reverse the degenerative process within the intervertabral disc. The effect of survivin gene therapy via lentiviral vector transfection on the course of intervertebral disc degeneration was investigated in the current study in an in vivo rabbit model. A total of 15 skeletally mature female New Zealand White rabbits were randomly divided into three groups: Punctured blank control group (group A, n=5), punctured empty vector control group (group B, n=5) and the treatment group (group C, n=5). Computed tomography‑guided puncture was performed at the L3‑L4 and L4‑L5 discs, in accordance with a previously validated rabbit annulotomy model for intervertebral disc degeneration. After 3 weeks, a lentiviral vector (LV) carrying survivin was injected into the nucleus pulposus. The results demonstrated that through magnetic resonance imaging, histology, gene expression, protein content and apoptosis analyses, group A and B were observed to exhibit disc degeneration, which increased over time, and no significant difference was observed between the two groups (P>0.05). However, there was reduced disc degeneration in group C compared with the punctured control groups, and the difference was statistically significant (P<0.05). Overall, the results of the present study demonstrated that injection of the LV carrying survivin into punctured rabbit intervertebral discs acted to delay changes associated with the degeneration of the discs. Although data from animal models should be extrapolated to the human condition with caution, the present study suggests potential for the use of gene therapy to decelerate disc degeneration.
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Affiliation(s)
- Bin Yue
- Department of Orthopedic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Yazhou Lin
- Department of Orthopedic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Xuexiao Ma
- Department of Orthopedic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Guoqing Zhang
- Department of Orthopedic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Bohua Chen
- Department of Orthopedic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
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Colorimetric detection and efficient monitoring of a potential biomarker of lumbar disc herniation using carbon nanotube-based probe. Sci China Chem 2015. [DOI: 10.1007/s11426-015-5540-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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10
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Mern DS, Thomé C. Identification and characterization of human nucleus pulposus cell specific serotypes of adeno-associated virus for gene therapeutic approaches of intervertebral disc disorders. BMC Musculoskelet Disord 2015; 16:341. [PMID: 26552484 PMCID: PMC4640218 DOI: 10.1186/s12891-015-0799-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 11/02/2015] [Indexed: 12/31/2022] Open
Abstract
Background Intervertebral disc (IVD) disorders are often accompanied by painful inflammatory and immunopathological processes. Nucleus pulposus (NP) cells play a pivotal role in maintenance of IVD by organizing the expression of anabolic, catabolic, anti-catabolic and inflammatory cytokines. Human NP cells have been targeted by gene therapeutic approaches using lentiviral or adenoviral systems that could be critical due to genome incorporation or immunological side effects. Adeno-associated viruses (AAVs), which do not express any viral gene and are not linked with any known disease in humans, are attractive gene delivery vectors. However, their lack of specific tissue tropism and preexisting immune response are main problems for therapeutic applications. Heretofore, AAVs have not been studied in human IVD research. Therefore, we attempted to identify NP cell specific AAV serotype by targeting human NP cells with different self-complementary AAV (scAAV) serotypes. Identification and characterization of the proper serotype is crucial to establish less immunogenic and safer gene therapeutic approaches of IVD disorders. Methods Preoperative magnetic resonance imaging (MRI) was used for grading of IVD degeneration. NP cells were isolated, cultured with low-glucose and transduced with green fluorescent protein (GFP) packing scAAV serotypes (scAAV1-8) in a dose-dependent manner. scAAV titers were determined by quantitative polymerase chain reaction (qPCR). Transduction efficiencies were determined by fluorescence microscopy and fluorescence-activated cell sorting within 48 days of post-transduction. The 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine NP cell viability. Three-dimensional (3D) cell culture and enzyme-linked immunosorbant assay (ELISA) were performed to examine the expression levels of inflammatory, catabolic and matrix proteins in NP cells. Results scAAV6, scAAV2 and scAAV3 showed high and prolonged transgene GFP expressions with transdution efficiencies of 98.6 %, 91.5 % and 89.6 % respectively (p ≤ 0.002). Unlike scAAV6, the serotypes scAAV2 and scAAV3 declined the viability of NP cells by about 25 % and 10 % respectively (p ≤ 0.001). Moreover, scAAV6 did not affect the expression of the inflammatory, catabolic and matrix proteins. Conclusions As original primary research evaluating AAVs in degenerative human IVDs, this study identified scAAV6 as a proper serotype for high, stable and non-immunogenic target gene expression in human NP cells. The data could be very important to design efficient and safer gene therapeutic approaches of IVD disorders.
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Affiliation(s)
- Demissew S Mern
- Department of Neurosurgery, Innsbruck Medical University, Anichstrasse 35, Innsbruck, A-6020, Austria.
| | - Claudius Thomé
- Department of Neurosurgery, Innsbruck Medical University, Anichstrasse 35, Innsbruck, A-6020, Austria.
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Kadow T, Sowa G, Vo N, Kang JD. Molecular basis of intervertebral disc degeneration and herniations: what are the important translational questions? Clin Orthop Relat Res 2015; 473:1903-12. [PMID: 25024024 PMCID: PMC4418989 DOI: 10.1007/s11999-014-3774-8] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Intervertebral disc degeneration is a common condition with few inexpensive and effective modes of treatment, but current investigations seek to clarify the underlying process and offer new treatment options. It will be important for physicians to understand the molecular basis for the pathology and how it translates to developing clinical treatments for disc degeneration. In this review, we sought to summarize for clinicians what is known about the molecular processes that causes disc degeneration. RESULTS A healthy disc requires maintenance of a homeostatic environment, and when disrupted, a catabolic cascade of events occurs on a molecular level resulting in upregulation of proinflammatory cytokines, increased degradative enzymes, and a loss of matrix proteins. This promotes degenerative changes and occasional neurovascular ingrowth potentially contributing to the development of pain. Research demonstrates the molecular changes underlying the harmful effects of aging, smoking, and obesity seen clinically while demonstrating the variable influence of exercise. Finally, oral medications, supplements, biologic treatments, gene therapy, and stem cells hold great promise but require cautious application until their safety profiles are better outlined. CONCLUSIONS Intervertebral disc degeneration occurs where there is a loss of homeostatic balance with a predominantly catabolic metabolic profile. A basic understanding of the molecular changes occurring in the degenerating disc is important for practicing clinicians because it may help them to inform patients to alter lifestyle choices, identify beneficial or harmful supplements, or offer new biologic, genetic, or stem cell therapies.
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Affiliation(s)
- Tiffany Kadow
- />Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, University of Pittsburgh, E1641 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261 USA
| | - Gwendolyn Sowa
- />Ferguson Laboratory for Orthopaedic and Spine Research, Department of Physical Medicine and Rehabilitation, University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, PA USA
| | - Nam Vo
- />Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, University of Pittsburgh, E1641 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261 USA
| | - James D. Kang
- />Ferguson Laboratory for Orthopaedic and Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, University of Pittsburgh, E1641 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261 USA
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Blanquer SBG, Grijpma DW, Poot AA. Delivery systems for the treatment of degenerated intervertebral discs. Adv Drug Deliv Rev 2015; 84:172-87. [PMID: 25451138 DOI: 10.1016/j.addr.2014.10.024] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 08/29/2014] [Accepted: 10/20/2014] [Indexed: 12/25/2022]
Abstract
The intervertebral disc (IVD) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production, abnormal enzyme activities and production of pro-inflammatory substances like cytokines. The established treatment strategy for IVD degeneration consists of physiotherapy, pain medication by drug therapy and if necessary surgery. This approach, however, has shown limited success. Alternative strategies to increase and prolong the effects of bioactive agents and to reverse the process of IVD degeneration include the use of delivery systems for drugs, proteins, cells and genes. In view of the specific anatomy and physiology of the IVD and depending on the strategy of the therapy, different delivery systems have been developed which are reviewed in this article.
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Affiliation(s)
- S B G Blanquer
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland
| | - D W Grijpma
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland; University of Groningen, University Medical Center Groningen, W.J. Kolff Institute, Department of Biomedical Engineering, P.O. Box 196, 9700 AD Groningen, The Netherlands.
| | - A A Poot
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland
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Current trends in biologics delivery to restore intervertebral disc anabolism. Adv Drug Deliv Rev 2015; 84:146-58. [PMID: 25174310 DOI: 10.1016/j.addr.2014.08.008] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/31/2014] [Accepted: 08/20/2014] [Indexed: 12/30/2022]
Abstract
Low back pain is generally attributed to intervertebral disc (IVD) degeneration. This is a multifactorial disease induced by genetic and environmental factors and that progresses with aging. Disc degeneration is characterized by a limited ability of IVD cells to produce functional matrix while producing abnormal amounts of matrix-degrading enzymes. The prolonged imbalance between anabolism and catabolism in degenerative discs alters their composition and hydration. In turn, this results in increased angiogenesis and the loss of the disc's ability to maintain its aneural condition. Inflammation in the IVD, in particular the presence of pro-inflammatory cytokines, was found to favor innervation and also sensitization of the nociceptive pathways, thereby exacerbating degenerative symptoms. In this review, we discuss anti-inflammatory approaches to encounter disc catabolism, potential treatments to lower discogenic pain and pro-anabolic approaches in the form of protein delivery, gene therapy and cell delivery, to trigger regeneration in the IVD.
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Ding L, Wu JP, Xu G, Zhu B, Zeng QM, Li DF, Lu W. Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro. ACTA ACUST UNITED AC 2014; 47:445-51. [PMID: 24878605 PMCID: PMC4086170 DOI: 10.1590/1414-431x20143198] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 02/20/2014] [Indexed: 01/27/2023]
Abstract
Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with
fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc
degeneration. Many more apoptotic cells have been identified in degenerated than in
normal endplates, and may be responsible for the degenerated grade. Previous findings
suggest that inhibition of apoptosis is one possible approach to improve disc
regeneration. It is postulated that inhibition of CEP cell apoptosis may be
responsible for the regeneration of endplates. Caspase-3, involved in the execution
phase of apoptosis, is a candidate for regulating the apoptotic process. In the
present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases
were detected to identify the apoptotic pathway, and apoptosis was quantified by flow
cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its
protective effects against serum deprivation. Silencing of caspase-3 expression was
quantified by reverse transcription-polymerase chain reaction and Western blots, and
inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased
apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral
caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced
endogenous caspase-3 expression. Surviving cells were protected by the downregulation
of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated
RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate
or premature apoptosis.
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Affiliation(s)
- L Ding
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - J P Wu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - G Xu
- Center Laboratory, Jinshan Hospital, Fudan University, China
| | - B Zhu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - Q M Zeng
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - D F Li
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
| | - W Lu
- Department of Orthopaedics, Jinshan Hospital, Fudan University, China
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Neidlinger-Wilke C, Galbusera F, Pratsinis H, Mavrogonatou E, Mietsch A, Kletsas D, Wilke HJ. Mechanical loading of the intervertebral disc: from the macroscopic to the cellular level. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2013; 23 Suppl 3:S333-43. [DOI: 10.1007/s00586-013-2855-9] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 05/10/2013] [Accepted: 06/03/2013] [Indexed: 12/24/2022]
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He B, Wang YH, Yang J, Peng FL, Li F. Normal and degenerated rabbit nucleus pulposus cells in in vitro cultures: A biological comparison. ACTA ACUST UNITED AC 2013; 33:228-233. [PMID: 23592135 DOI: 10.1007/s11596-013-1102-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Indexed: 12/30/2022]
Abstract
This study examined the biological characteristics of normal and degenerated rabbit nucleus pulposus (NP) cells in vitro in order to provide seed cells for intervertebral disc (IVD) tissue engineering. A total of 8 adult New Zealand white rabbits underwent annulus puncture to establish models of intervertebral disc degeneration (IDD). Four weeks later, normal and degenerated NP cells were obtained. Cell morphology was observed by light and electron microscopy. Cell viability was measured by MTT assay. Cell cycle and expression of extracellular matrix (ECM)-related genes (aggrecan and type II collagen) were determined by using flow cytometry and RT-PCR respectively. The growth curve of normal NP cells showed that the cells at passage 4 tended to slowly grow on the fifth day of culture. The density of normal NP cells at passages 5 to 7 was significantly less than that of the first-passage cells 2 or 3 days after seeding (P<0.05). The degenerated NP cells at passage 3 showed slow growth at 4th day. After 5 passages, the degenerated NP cells assumed stagnant growth and the growth seemed to stop at passage 7. The MTT assay revealed that for both normal and degenerated NP cells, the absorbance (A) value at passages 4-7 was obviously decreased as compared with that at passage 1 (P<0.05). Cell cycle analysis showed that the proportion of normal NP cells at Gl phase was 65.4%±3.5%, significantly lower than that of degenerated NP cells at the same cell cycle phase with the value being 77.6%±4.8%. The degenerated NP cells were predominantly arrested at G1 phase and failed to enter S phase. The expression of type II collagen and aggrecan was significantly decreased with passaging. It was concluded that normal NP cells possessed good viability and proliferative capacity by the third passage, and they could secrete large amounts of ECM within this period. The normal NP cells may serve as seed cells for IVD tissue engineering.
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Affiliation(s)
- Bin He
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Department of Orthopedics, the First Affiliated Hospital of Medical College of Shihezi University, Shihezi, 832008, China
| | - Yu-Huan Wang
- Medical College of Shihezi University, Shihezi, 832002, China
| | - Jian Yang
- Department of Orthopedics, the First Affiliated Hospital of Medical College of Shihezi University, Shihezi, 832008, China
| | - Fang-Liang Peng
- Department of Orthopedics, the First Affiliated Hospital of Medical College of Shihezi University, Shihezi, 832008, China
| | - Feng Li
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Maerz T, Herkowitz H, Baker K. Molecular and genetic advances in the regeneration of the intervertebral disc. Surg Neurol Int 2013; 4:S94-S105. [PMID: 23646279 PMCID: PMC3642750 DOI: 10.4103/2152-7806.109449] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 01/30/2013] [Indexed: 02/06/2023] Open
Abstract
Background: Owing to the debilitating nature of degenerative disc disease (DDD) and other spine pathologies, significant research has been performed with the goal of healing or regenerating the intervertebral disc (IVD). Structural complexity, coupled with low vascularity and cellularity, make IVD regeneration an extremely challenging task. Methods: Tissue engineering-based strategies utilize three components to enhance tissue regeneration; scaffold materials to guide cell growth, biomolecules to enhance cell migration and differentiation, and cells (autologous, or allogeneic) to initiate the process of tissue formation. Significant advances in IVD regeneration have been made utilizing these tissue engineering strategies. Results: The current literature demonstrates that members of the transforming growth factor beta (TGF-β) superfamily are efficacious in the regeneration of an anabolic response in the IVD and to facilitate chondrogenic differentiation. Gene therapy, though thwarted by safety concerns and the risk of ectopic transfection, has significant potential for a targeted and sustained regenerative response. Stem cells in combination with injectable, biocompatible, and biodegradable scaffolds in the form of hydrogels can differentiate into de novo IVD tissue and facilitate regeneration of the existing matrix. Therapies that address both anabolism and the inherent catabolic state of the IVD using either direct inhibitors or broad-spectrum inhibitors show extensive promise. Conclusion: This review article summarizes the genetic and molecular advances that promise to play an integral role in the development of new strategies to combat DDD and promote healing of injured discs.
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Affiliation(s)
- Tristan Maerz
- Department of Orthopaedic Research, Beaumont Health System, Royal Oak, MI, USA
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Vadalà G, Russo F, Di Martino A, Denaro V. Intervertebral disc regeneration: from the degenerative cascade to molecular therapy and tissue engineering. J Tissue Eng Regen Med 2013; 9:679-90. [PMID: 23512973 DOI: 10.1002/term.1719] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 12/21/2012] [Accepted: 01/05/2013] [Indexed: 12/21/2022]
Abstract
Low back pain is one of the major health problems in industrialized countries, as a leading source of disability in the working population. Intervertebral disc degeneration has been identified as its main cause, being a progressive process mainly characterized by alteration of extracellular matrix composition and water content. Many factors are involved in the degenerative cascade, such as anabolism/catabolism imbalance, reduction of nutrition supply and progressive cell loss. Currently available treatments are symptomatic, and surgical procedures consisting of disc removal are often necessary. Recent advances in our understanding of intervertebral disc biology led to an increased interest in the development of novel biological treatments aimed at disc regeneration. Growth factors, gene therapy, stem cell transplantation and biomaterials-based tissue engineering might support intervertebral disc regeneration by overcoming the limitation of the self-renewal mechanism. The aim of this paper is to overview the literature discussing the current status of our knowledge from the degenerative cascade of the intervertebral disc to the latest molecular, cell-based therapies and tissue-engineering strategies for disc regeneration.
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Affiliation(s)
- Gianluca Vadalà
- Department of Orthopaedics and Trauma Surgery, Campus Bio-Medico University of Rome, Italy
| | - Fabrizio Russo
- Department of Orthopaedics and Trauma Surgery, Campus Bio-Medico University of Rome, Italy
| | - Alberto Di Martino
- Department of Orthopaedics and Trauma Surgery, Campus Bio-Medico University of Rome, Italy
| | - Vincenzo Denaro
- Department of Orthopaedics and Trauma Surgery, Campus Bio-Medico University of Rome, Italy
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Leckie SK, Bechara BP, Hartman RA, Sowa GA, Woods BI, Coelho JP, Witt WT, Dong QD, Bowman BW, Bell KM, Vo NV, Wang B, Kang JD. Injection of AAV2-BMP2 and AAV2-TIMP1 into the nucleus pulposus slows the course of intervertebral disc degeneration in an in vivo rabbit model. Spine J 2012; 12:7-20. [PMID: 22023960 PMCID: PMC4896143 DOI: 10.1016/j.spinee.2011.09.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 07/27/2011] [Accepted: 09/07/2011] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Intervertebral disc degeneration (IDD) is a common cause of back pain. Patients who fail conservative management may face the morbidity of surgery. Alternative treatment modalities could have a significant impact on disease progression and patients' quality of life. PURPOSE To determine if the injection of a virus vector carrying a therapeutic gene directly into the nucleus pulposus improves the course of IDD. STUDY DESIGN Prospective randomized controlled animal study. METHODS Thirty-four skeletally mature New Zealand white rabbits were used. In the treatment group, L2-L3, L3-L4, and L4-L5 discs were punctured in accordance with a previously validated rabbit annulotomy model for IDD and then subsequently treated with adeno-associated virus serotype 2 (AAV2) vector carrying genes for either bone morphogenetic protein 2 (BMP2) or tissue inhibitor of metalloproteinase 1 (TIMP1). A nonoperative control group, nonpunctured sham surgical group, and punctured control group were also evaluated. Serial magnetic resonance imaging (MRI) studies at 0, 6, and 12 weeks were obtained, and a validated MRI analysis program was used to quantify degeneration. The rabbits were sacrificed at 12 weeks, and L4-L5 discs were analyzed histologically. Viscoelastic properties of the L3-L4 discs were analyzed using uniaxial load-normalized displacement testing. Creep curves were mathematically modeled according to a previously validated two-phase exponential model. Serum samples obtained at 0, 6, and 12 weeks were assayed for biochemical evidence of degeneration. RESULTS The punctured group demonstrated MRI and histologic evidence of degeneration as expected. The treatment groups demonstrated less MRI and histologic evidence of degeneration than the punctured group. The serum biochemical marker C-telopeptide of collagen type II increased rapidly in the punctured group, but the treated groups returned to control values by 12 weeks. The treatment groups demonstrated several viscoelastic properties that were distinct from control and punctured values. CONCLUSIONS Treatment of punctured rabbit intervertebral discs with AAV2-BMP2 or AAV2-TIMP1 helps delay degenerative changes, as seen on MRI, histologic sampling, serum biochemical analysis, and biomechanical testing. Although data from animal models should be extrapolated to the human condition with caution, this study supports the potential use of gene therapy for the treatment of IDD.
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Affiliation(s)
- Steven K. Leckie
- Corresponding author. Department of Orthopedic Surgery, University of Pittsburgh Medical Center, BST E1641, 200 Lothrop St, Pittsburgh, PA 15213, USA. Tel.: (412) 648-1090. (S.K. Leckie)
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