Trends in Alveolar Bone Grafting and the Use of Recombinant Bone Morphogenetic Protein (RhBMP) in the United States

Objectives:

To gather information about current practices and assess the opinions, preferences, and clinical knowledge of surgeons who perform alveolar bone grafts. In addition, surgical training differences in correlation to techniques and outcomes are evaluated.

Methods:

A survey with both multiple choice and narrative answers regarding surgeons’ practices for alveolar bone grafting was designed and sent via email to members of the American Cleft Palate/Craniofacial Association (ACPA) identified as general craniofacial or oral maxillofacial surgeons. Responses were collected via an anonymous online survey tool.

Participants:

Members (336) of ACPA identified as craniofacial or oral-maxillofacial surgeons were contacted, and 62 responses were recorded.

Results:

The majority of survey respondents were oral-maxillofacial surgeons in practice for more than 15 years. 98.4% of respondents had used iliac crest and at least one additional source for grafting, while only 52.7% had performed grafting using recombinant bone morphogenetic protein (RhBMP). 82% used cone beam CT as their evaluation of choice for graft assessment and the majority (62.9%) waited more than 8 weeks postoperatively to image. Chi-square analysis demonstrated significantly longer time in practice for practitioners without craniofacial fellowship training.

Conclusions:

The results of this study demonstrate that there remains significant variation in alveolar bone grafting practices among surgeons. While some consensus exists, new innovations and technologies will require continued evaluation of surgical practices and outcomes. Long-term follow-up studies are needed especially with regard to the use of RhBMP in alveolar clefts.

Peripheral nerve injuries: an international survey of current treatments and future perspectives

Peripheral nerve injuries are a serious health concern and leave many patients with lifelong disabilities. There is little information about incidences, current practice, outcomes, and type of research that may help delineate new strategies. A questionnaire was designed to determine characteristics of peripheral nerve injuries and the need for alternative strategies and sent to 889 plastic, hand, trauma, and orthopedic surgeons in 49 countries; 324 completed surveys were collected and analyzed (total response rate of 36.45%). The majority of institutions treat more than 3000 patients annually. Trauma was the leading cause of injury with the majority located on the upper extremity. In most cases, a primary repair was achieved, but 2.52% were unrepairable. The overall outcome was linked to their Sunderland classification (SCL). A grade 1 nerve injury (SCL-1) reached a maximum outcome after 7.15 months. SCL-2, -3, -4, and -5 needed 10.69, 14.08, 17.66, and 19.03 months, respectively. Tissue engineering was considered the most important research field, resulting in a visual analogue scale of 8.6. Despite marked advances in the treatment of peripheral nerve injuries, clinical outcomes still appear unsatisfactory. The importance of research in the field of tissue engineering should be emphasized as a pathway toward improving these outcomes.

Adenovirus-mediated gene transfer of insulin-like growth factor 1 stimulates proteoglycan synthesis in rabbit joints

OBJECTIVE

To examine the effect of insulin-like growth factor 1 (IGF-1) on the regulation of cartilage synthesis and other articular events in vivo.

METHODS

A first-generation adenoviral vector expressing human IGF-1 (AdIGF-1) from the cytomegalovirus promoter was constructed. Particles of AdIGF-1 (5 x 10(9)) were injected through the patellar tendon into normal rabbit knee joints and rabbit knee joints with antigen-induced arthritis (AIA), with the same dose of a control adenoviral vector injected into the contralateral knees. Lavage fluids were obtained from rabbit knee joints on days 3 and 7 postinjection and used for analysis of IGF-1 expression, white blood cell infiltration, and cartilage breakdown. Cartilage chips from rabbit joints were used for assay of new proteoglycan synthesis, and tissues also were harvested from the dissected knees for histologic study.

RESULTS

Intraarticular injection of AdIGF-1 resulted in a mean of 180.6 ng/ml of IGF-1 expression in the lavage fluid from rabbit joints. IGF-1 expression stimulated new proteoglycan synthesis in both naive and AIA rabbit knees, but had no significant chondroprotective or antiinflammatory effects. Histologic analysis showed that elevated levels of IGF-1 expression in both normal and arthritic knees had no adverse pathologic effects on synovium or adjacent muscles.

CONCLUSION

Gene transfer of IGF-1 into rabbit knee joints promotes proteoglycan synthesis without significantly affecting inflammation or cartilage breakdown. In addition, no adverse effects following intraarticular IGF-1 gene delivery were observed. Thus, local gene transfer of IGF-1 to joints could serve as a therapeutic strategy to stimulate new matrix synthesis in both rheumatoid arthritis and osteoarthritis.

Nitric oxide inhibits chondrocyte response to IGF-I: inhibition of IGF-IRbeta tyrosine phosphorylation

Chondrocytes in arthritic cartilage respond poorly to insulin-like growth factor I (IGF-I). Studies with inducible nitric oxide synthase (iNOS) knockout mice suggest that NO is responsible for part of the cartilage insensitivity to IGF-I. These studies characterize the relationship between NO and chondrocyte responses to IGF-I in vitro, and define a mechanism by which NO decreases IGF-I stimulation of chondrocyte proteoglycan synthesis. Lapine cartilage slices, chondrocytes, and cartilage from osteoarthritic (OA) human knees were exposed to NO from the donors S-nitroso-N-acetylpenicillamine (SNAP) or (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1- ium-1, 2-diolate] (DETA NONOate), by transduction with adenoviral transfer of iNOS (Ad-iNOS), or by activation with interleukin-1 (IL-1). NO synthesis was estimated from medium nitrite, and proteoglycan synthesis was measured as incorporation of (35)SO(4). IGF-I receptor phosphorylation was evaluated with Western analysis. SNAP, DETA NONOate, endogenously synthesized NO in Ad-iNOS-transduced cells, or IL-1 activation decreased IGF-I-stimulated proteoglycan synthesis in cartilage and monolayer cultures of chondrocytes. OA cartilage responded poorly to IGF-I; however, the response to IGF-I was restored by culture with N(G)-monomethyl-L-arginine (L-NMA). IGF-I receptor phosphotyrosine was diminished in chondrocytes exposed to NO. These studies show that NO is responsible for part of arthritic cartilage/chondrocyte insensitivity to anabolic actions of IGF-I; inhibition of receptor autophosphorylation is potentially responsible for this effect.

Direct Adenoviral Gene Transfer of Viral IL-10 to Rabbit Knees with Experimental Arthritis Ameliorates Disease in Both Injected and Contralateral Control Knees

IL-10, a cytokine produced primarily by macrophages, B lymphocytes, and Th2 cells, has both immunostimulatory and immunosuppressive properties. A homologue of IL-10 encoded by EBV, known as viral IL-10 (vIL-10), is also able to suppress the immune response, but may lack some of the immunostimulatory properties of IL-10. To evaluate the potential of vIL-10 to block the progression of rheumatoid arthritis, we have utilized a replication-defective adenovirus vector to deliver the gene encoding vIL-10 to the knee joints of rabbits with Ag-induced arthritis. Intraarticular expression of vIL-10 significantly reduced leukocytosis, cartilage matrix degradation, and levels of endogenous rabbit TNF-α, as well as the degree of synovitis, while maintaining high levels of cartilage matrix synthesis. Interestingly, an antiarthritic effect was also observed in opposing contralateral control knee joints that received only a marker gene. An adenoviral vector carrying the enhanced green fluorescent protein marker gene was used to demonstrate that a morphologically similar subset of cells infected in the injected knee joint are able to traffic to the uninjected contralateral knee joint. Our results suggest that direct, local intraarticular delivery of the vIL-10 gene may have polyarticular therapeutic effects.

Direct adenoviral gene transfer of viral IL-10 to rabbit knees with experimental arthritis ameliorates disease in both injected and contralateral control knees

IL-10, a cytokine produced primarily by macrophages, B lymphocytes, and Th2 cells, has both immunostimulatory and immunosuppressive properties. A homologue of IL-10 encoded by EBV, known as viral IL-10 (vIL-10), is also able to suppress the immune response, but may lack some of the immunostimulatory properties of IL-10. To evaluate the potential of vIL-10 to block the progression of rheumatoid arthritis, we have utilized a replication-defective adenovirus vector to deliver the gene encoding vIL-10 to the knee joints of rabbits with Ag-induced arthritis. Intraarticular expression of vIL-10 significantly reduced leukocytosis, cartilage matrix degradation, and levels of endogenous rabbit TNF-alpha, as well as the degree of synovitis, while maintaining high levels of cartilage matrix synthesis. Interestingly, an antiarthritic effect was also observed in opposing contralateral control knee joints that received only a marker gene. An adenoviral vector carrying the enhanced green fluorescent protein marker gene was used to demonstrate that a morphologically similar subset of cells infected in the injected knee joint are able to traffic to the uninjected contralateral knee joint. Our results suggest that direct, local intraarticular delivery of the vIL-10 gene may have polyarticular therapeutic effects.

Nitric oxide in osteoarthritis

Activated articular chondrocytes produce large amounts of nitric oxide (NO), and there is increasing evidence that this is involved in the etiopathogenesis of osteoarthritis (OA). Because of its short half-life, the biological effects of endogenously produced NO are likely to occur locally within the cartilage. We have observed that inhibitors of NO synthases relieve the inhibition of matrix synthesis that otherwise occurs in response to IL-1. To avoid the use of inhibitors, we have recently transduced chondrocytes with the iNOS (NOS-2) gene and confirmed the ability of the endogenously produced NO to inhibit matrix synthesis. Despite the high levels of NO made by these cells, there was no evidence of apoptosis or other forms of cell death. NO was also shown to inhibit the production of TGF-beta(1)by cells treated with IL-1, as well as to decrease matrix production in response to IGF-1. The hypothesis that NO inhibits matrix production by interfering with important autocrine and paracrine factors should be entertained.

Lessons learned from gene transfer approaches

Recent technological advances allow the transfer of genes to the synovial lining of joints. As well as opening novel opportunities for therapy, these techniques provide valuable new tools for the study of synovitis and other aspects of the biology of joints in health and disease. This article reviews briefly the results of experiments in which selected genes have been transferred to the knee joints of healthy rabbits and rabbits with antigen-induced arthritis.

The Human Genome Project: implications for the treatment of musculoskeletal disease

The ultimate goal of the Human Genome Project is the determination of the molecular sequence of the entire human chromosomal complement. Realization of this goal will include characterization of all the genes that cause or predispose to disease, which will most certainly lead to the development of powerful new tools for diagnosis, prevention, and treatment in all medical fields, including orthopaedics. The authors review the fundamentals of human genetics and gene mapping, summarize the progress of the Human Genome Project thus far, and discuss the implications of this research as it relates to the treatment of musculoskeletal diseases.

Constitutive intra-articular expression of human IL-1 beta following gene transfer to rabbit synovium produces all major pathologies of human rheumatoid arthritis

To investigate the pathophysiologic effects of chronically elevated intra-articular levels of IL-1 beta, we used an ex vivo gene transfer method to deliver and express human IL-1 beta (hIL-1 beta) in the knee joints of rabbits. Expression of hIL-1 beta resulted in a severe, highly aggressive form of arthritis analogous to chronic rheumatoid arthritis in humans. Intra-articular manifestations included intense inflammation, leukocytosis, synovial hypertrophy and hyperplasia, and highly aggressive pannus formation with erosion of the articular cartilage and periarticular bone. Systemic effects were also observed, including diarrhea, fever, weight loss, and an increased erythrocyte sedimentation rate. In addition, the hIL-1 beta was found to induce elevated levels of both rabbit IL-1 beta and TNF-alpha in synovial fluid. Following the loss of hIL-1 beta transgene expression between 14 and 28 days post-transplantation, many of these changes began to normalize. These results suggest that chronically elevated intra-articular levels of IL-1 beta alone are sufficient to produce virtually all the pathologies found in rheumatoid arthritis, and furthermore, demonstrate that gene transfer can be used to investigate the roles of specific gene products in the pathogenesis of arthritis.

Constitutive intra-articular expression of human IL-1 beta following gene transfer to rabbit synovium produces all major pathologies of human rheumatoid arthritis

To investigate the pathophysiologic effects of chronically elevated intra-articular levels of IL-1 beta, we used an ex vivo gene transfer method to deliver and express human IL-1 beta (hIL-1 beta) in the knee joints of rabbits. Expression of hIL-1 beta resulted in a severe, highly aggressive form of arthritis analogous to chronic rheumatoid arthritis in humans. Intra-articular manifestations included intense inflammation, leukocytosis, synovial hypertrophy and hyperplasia, and highly aggressive pannus formation with erosion of the articular cartilage and periarticular bone. Systemic effects were also observed, including diarrhea, fever, weight loss, and an increased erythrocyte sedimentation rate. In addition, the hIL-1 beta was found to induce elevated levels of both rabbit IL-1 beta and TNF-alpha in synovial fluid. Following the loss of hIL-1 beta transgene expression between 14 and 28 days post-transplantation, many of these changes began to normalize. These results suggest that chronically elevated intra-articular levels of IL-1 beta alone are sufficient to produce virtually all the pathologies found in rheumatoid arthritis, and furthermore, demonstrate that gene transfer can be used to investigate the roles of specific gene products in the pathogenesis of arthritis.

A sustained, cytoplasmic transgene expression system delivered by cationic liposomes

A plasmid containing the reporter gene, chloramphenicol acetyltransferase (CAT), driven by the bacteriophage T7 promoter was co-delivered with purified T7 RNA polymerase by the DC-chol cationic liposomes into human embryonic kidney 293 cells to obtain a transient (2 days) CAT gene expression. To prolong the expression, a T7 autogene which contains the T7 RNA polymerase gene driven by the T7 promoter was included in the transfection complex as a self-amplifying regeneration mechanism for the polymerase. High level CAT gene expression was observed up to 5 days after transfection. This strong and sustained expression system should be useful in gene transfer experiments.