Biomedical subjects

P D Robbins

Publications and source records attributed to P D Robbins.

At least 73 records · Page 4Linked to original sources

PubMed2000

Rapid generation of potent and tumor-specific cytotoxic T lymphocytes by interleukin 18 using dendritic cells and natural killer cells.

We hypothesized that antitumor-specific immunity, which is induced by interleukin (IL) 18 treatment in murine tumor models, is promoted by enhancing natural killer (NK)-mediated destruction of tumor and delivery to dendritic cells (DCs). These activated and antigen-pulsed DCs then critically and optimally induce an adoptive immune response, positioning IL-18 as an important bridge between the innate and adoptive immune response. The effect of IL-18 added to cultures of live tumor cells (MCA205, a mouse sarcoma cell line), NK cells, DCs, and T cells was assessed. When recombinant (r) mIL-18 protein was added to this culture, potent NK cytolytic activity with subsequent generation of CTLs was observed in a dose-dependent manner. Without introduction of either rmIL-18 or NK cells into this culture, systemic cytolytic activity was significantly decreased. Following the absence of direct contact of either NK cells or DCs with other cells in this cooperative coculture system using transwell, the systemic cytolytic activity of both NK cells and CTLs was greatly suppressed. The cytolysis mediated by effector cells harvested after completion of the culture was primarily restricted to MHC class I and highly specific for the tumor cells used in the coculture. Furthermore, we examined the efficiency in the induction of cytolytic T cells of other established IFN-gamma inducing T-cell growth factors, IL-2, and IL-12 in this culture system and compared them with that mediated by IL-18. Neither IL-2 nor IL-12 induced tumor-specific cytolytic T cells to the same degree as that mediated by IL-18. Efficacy of this system in induction of tumor-specific CTLs was also observed in the system using MC38 adenocarcinoma cells. These results are consistent with the notion that IL-18 induces tumor-specific immunity through enhancing NK activity, which in turn mediates tumor cell death and activates and primes DCs.

Adenocarcinoma↗

PubMed2000

Transduction of dendritic cells with Bcl-xL increases their resistance to prostate cancer-induced apoptosis and antitumor effect in mice.

We have shown that prostate cancer (PCa) causes apoptosis of dendritic cells (DC), which might block the development of specific antitumor immune responses. Analysis of murine prostatic carcinoma tissues revealed the significant decrease in intratumoral DC number during tumor progression. We demonstrated that the cytokine-mediated increase in DC survival was accompanied by an elevated expression of the anti-apoptotic protein Bcl-xL. Next, we evaluated the resistance to tumor-induced apoptosis and the antitumor efficiency of genetically engineered DC overexpressing Bcl-xL. DC were transduced with an adenoviral vector encoding the murine Bcl-xL gene and injected intratumorally. Data analysis revealed that treatment of PCa-bearing mice with Bcl-xL-transduced DC resulted in significant inhibition of tumor growth compared with the administration of nontransduced DC. Thus, our data suggest that the protection of DC from PCa-induced apoptosis might significantly increase the efficacy of DC-based therapies in cancer even in the absence of available tumor-specific Ags.

Animals↗

PubMed2000

Soluble tumor necrosis factor receptor abrogates myocardial inflammation but not hypertrophy in cytokine-induced cardiomyopathy.

BACKGROUND: Transgenic mice with cardiac-specific overexpression of tumor necrosis factor (TNF)-alpha develop dilated cardiomyopathy. The present study was designed to evaluate therapeutic effects of adenovirus-mediated neutralization of TNF-alpha on this model. METHODS AND RESULTS: An adenovirus encoding the 55-kDa TNF receptor-IgG fusion protein (AdTNFRI) was injected intravenously into 6-week-old transgenic mice, which resulted in high levels of TNFRI in both plasma and myocardium. AdTNFRI did not reverse cardiomegaly but abrogated myocardial inflammation. Furthermore, AdTNFRI blocked the myocardial expression of intercellular adhesion molecule-1 and downstream cytokines, including interleukin-1beta and monocyte chemotactic protein-1. Downregulation of alpha-myosin heavy chain was restored by the treatment, whereas upregulation of beta-myosin heavy chain was not reversed. In contrast, the downregulation of sarcoplasmic reticulum Ca(2+)-ATPase and phospholamban was normalized by AdTNFRI. Echocardiographic measurements showed that left ventricular end-systolic diameter was significantly larger in transgenic mice than in control mice, and this increase was reversed by the AdTNFRI treatment. However, left ventricular wall thickening was not reversed. CONCLUSIONS: These results suggest that anti-TNF therapy may hold promise in the treatment of end-stage heart failure.

Adenoviridae↗

PubMed2000

Gene therapy for established murine collagen-induced arthritis by local and systemic adenovirus-mediated delivery of interleukin-4.

To determine whether IL-4 is therapeutic in treating established experimental arthritis, a recombinant adenovirus carrying the gene that encodes murine IL-4 (Ad-mIL-4) was used for periarticular injection into the ankle joints into mice with established collagen-induced arthritis (CIA). Periarticular injection of Ad-mIL-4 resulted in a reduction in the severity of arthritis and joint swelling compared with saline- and adenoviral control groups. Local expression of IL-4 also reduced macroscopic signs of joint inflammation and bone erosion. Moreover, injection of Ad-mIL-4 into the hind ankle joints resulted in a decrease in disease severity in the untreated front paws. Systemic delivery of murine IL-4 by intravenous injection of Ad-mIL-4 resulted in a significant reduction in the severity of early-stage arthritis.

Adenoviridae↗

PubMed2000

CC chemokine receptor-7 on dendritic cells is induced after interaction with apoptotic tumor cells: critical role in migration from the tumor site to draining lymph nodes.

Dendritic cells (DCs) are very potent antigen-presenting cells and play critical roles in regulating immune responses in cancer. The migrating of DCs from the tumor site to the lymphoid organs is believed to be one of the critical events. To examine this important DC function in tumor situations, bone marrow-derived DCs, cultured for 6 days with granulocyte macrophage colony-stimulating factor and interleukin 4, were inoculated at the tumor site. We have shown (Y. Nishioka et al., Cancer Res., 59: 40354041, 1999) that DCs can migrate from tumor site to the draining lymph nodes within 24 h (approximately 0.1% of administrated DCs). The DCs then form clusters with adjacent lymphoid cells, which produce IFN-gamma (1500-3200pg/10(6) cells/48 h) in response to tumor stimulation. The number of the DCs migrating into lymph nodes were greater when they were inoculated into the tumor rather than the skin. Coculture of DCs and apoptotic tumor cells resulted in decreased expression of CC chemokine receptor (CCR) 1 and increased CCR7 expression at mRNA level without alteration in other phenotypical markers on DCs. Chemotaxis assay showed that CCR7 ligands, macrophage inflammatory protein 3beta and secondary lymphoid-tissue chemokine significantly (P < 0.05) induced the migration of DCs when cocultured with apoptotic tumor cells. To directly examine the involvement of CCR7 expression in DC migration, we investigated the functions of DCs genetically modified to express high levels of CCR7. CCR7 transduction promotes DC migration in response to relevant ligands in vitro and in vivo. These results suggest that the CCR7 expression of DCs is enhanced with direct contact with apoptotic tumor cells and may have a critical role for DC migrating to regional lymph nodes. The means to promote DC delivery to tumor and to nodal sites represent novel targets for the biological therapy of cancer.

Animals↗

PubMed2000

Genetic enhancement of matrix synthesis by articular chondrocytes: comparison of different growth factor genes in the presence and absence of interleukin-1.

OBJECTIVE: To determine whether articular chondrocytes express growth factor genes delivered by adenoviral vectors and whether expression of these genes influences matrix synthesis in the presence and absence of interleukin-1 (IL-1). METHODS: Monolayer cultures of rabbit articular chondrocytes were infected with recombinant adenovirus carrying genes encoding the following growth factors: insulin-like growth factor 1 (IGF-1), transforming growth factor beta1 (TGFbeta1), and bone morphogenetic protein 2 (BMP-2). As a control, cells were transduced with the lac Z gene. Cultures were also treated with each growth factor supplied as a protein. Levels of gene expression were noted, and the synthesis of proteoglycan, collagen, and noncollagenous proteins was measured by radiolabeling. Collagen was typed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The effects of growth factor gene transfer on proteoglycan synthesis in the presence of IL-1 were also measured. RESULTS: The expression of all transgenes was high following adenoviral transduction. Proteoglycan synthesis was stimulated approximately 8-fold by the BMP-2 gene and 2-3-fold by the IGF-1 gene. The effects of BMP-2 and IGF-1 genes were additive upon cotransduction. Synthesis of collagen and noncollagenous proteins, in contrast, was most strongly stimulated by the IGF-1 gene. In each case, collagen typing confirmed the synthesis of type II collagen. IL-1 suppressed proteoglycan synthesis by 50-60%. IGF-1 and TGFbeta genes restored proteoglycan synthesis to control levels in the presence of IL-1. The BMP-2 gene, in contrast, elevated proteoglycan synthesis beyond control levels in the presence of IL-1. CONCLUSION: Transfer of growth factor genes to articular chondrocytes can greatly increase matrix synthesis in vitro, even in the presence of the inflammatory cytokine IL-1. This result encourages the further development of gene therapy for the repair of damaged cartilage.

Animals↗

PubMed2000

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.

Adenoviridae↗

PubMed2000

Prolongation of cardiac allograft survival using dendritic cells treated with NF-kB decoy oligodeoxyribonucleotides.

Dendritic cells (DC) classically promote immune responses but can be manipulated to induce antigen-specific hyporesponsiveness in vitro. The expression of costimulatory molecules (CD40, CD86, CD80) at the DC cell surface correlates with their capacity to induce or suppress immune responses. Expression of these molecules is associated with NF-kB-dependent transcription of their genes. DC tolerogenicity has been associated with impaired NF-kB-dependent transcription of costimulatory genes as well as NF-kB translocation to the nucleus. In this report, we demonstrate that double-stranded oligodeoxyribonucleotides containing binding sites for NF-kB (NF-kB ODN) are efficiently incorporated by bone marrow-derived DC and specifically inhibit NF-kB-dependent transcription of a reporter gene. Moreover, exposure of DC to the oligonucleotide decoys inhibited lipopolysaccharide (LPS)-induced nitric oxide production, a marker of DC maturation. Treatment of bone marrow-derived DC progenitors with NF-kB ODN selectively suppressed the cell-surface expression of costimulatory molecules without interfering with MHC class I or class II expression. Furthermore, NF-kB ODN DC induced allogeneic donor-specific hyporesponsiveness in mixed leukocyte cultures, and this was associated with inhibition of Th1-type cytokine production. Finally, infusion of NF-kB ODN-modified bone marrow-derived DC into allogeneic recipients prior to heart transplantation resulted in significant prolongation of allograft survival in the absence of immunosuppression. Specific interference with NF-kB and other transcriptional pathways involved in immune stimulation in DC using ODN decoy approaches could be one means to promote tolerance induction in organ transplantation.

Animals↗

PubMed2000

Characterization of a class of cationic peptides able to facilitate efficient protein transduction in vitro and in vivo.

Protein transduction domains (PTDs), such as the third helix of the Drosophila Antennapedia homeobox gene (Antp) and the HIV TAT PTD, possess a characteristic positive charge on the basis of their enrichment for arginine and lysine residues. To determine whether cationic peptides are able to function as protein transduction domains, 12-mer peptide sequences from an M13 phage library were selected for synthesis on the basis of their varying cationic charge content. In addition, polylysine and polyarginine peptides were synthesized in order to assess the effect of charge contribution in protein transduction. Coupling of the biotinylated peptides to avidin-beta-galactosidase facilitated transduction in a wide variety of cell lines and primary cells, including islet beta-cells, synovial cells, polarized airway epithelial cells, dendritic cells, myoblasts, and tumor cells. Two of the peptides, PTD-4 and PTD-5, mediated transduction nearly 600-fold more efficiently than a random control peptide, but with an efficiency similar to the TAT PTD and the 12 mers of polylysine and polyarginine. Furthermore, confocal analysis of biotinylated peptide-streptavidin-Cy3 conjugates demonstrated that the internalized PTDs are found in both the nuclei and the cytoplasm of treated cells. When tested in vivo, the PTDs were able to facilitate efficient and rapid protein delivery into rabbit synovium and mouse solid tumors following intraarticular and intratumoral administration, respectively. These novel PTDs can be used to transfer therapeutic proteins and DNA for the treatment of a wide variety of diseases, including arthritis and cancer.

Amino Acid Sequence↗

PubMed2000

[TGF-beta-1 gene transfer in joint cartilage cells. Stimulating effect in extracellular matrix synthesis].

TGF beta-1 has been shown to upregulate matrix synthesis in articular chondrocytes. TGF beta-gene transfer to chondrocytes has the potential to increase the local production of this key component within regenerating cartilage after trauma and could support the repair process in articular cartilage lesions. Primary rabbit articular chondrocytes were cultured and retrovirally transfected with the experimental TGF beta-1 and the lacZ marker gene for control purposes. After radioactive labeling of new synthesized matrix proteins results were compared with normal primary chondrocytes. After TGF beta-1 gene transfer the endogenous growth factor concentration was doubled compared to normal chondrocytes and decreased in the lacZ control group. The proteoglycan synthesis in TGF beta-1 transfected chondrocytes showed a 96% increase compared to the basal production of normal chondrocytes. The LacZ transfected group revealed the opposite effect by a 44% decrease. The collagen synthesis of TGF beta-1 transfected chondrocytes was 304% compared to normal chondrocytes, predominantly type II collagen. The lacZ group collagen production was reduced by 35%. We conclude that TGF beta-1 gene transfer overcomes the decreasing effect observed by transfection with the LacZ marker gene and increases matrix synthesis in articular chondrocytes. Genetically altered chondrocytes might improve the repair of cartilage lesions by stimulating matrix synthesis and supporting the expression of the hyaline phenotype.

Animals↗

PubMed2000

Retroviral vectors.

Retroviral vectors are widely used for preclinical and clinical applications. Unlike many of the other types of vectors currently being developed for gene therapy, retroviral vectors are able to genetically modify cells stably without perturbing cell growth. Retroviral vectors based on murine retroviruses are well suited for ex vivo applications where the cells are rapidly dividing. In particular, retroviral viral vectors have been used for a variety of ex vivo gene therapy approaches for treating genetic diseases such as Gaucher and severe combined immunodeficiency (SCID) and for acquired diseases such as cancer and arthritis. However, recent advances in the production of retroviral vectors have allowed for their use in vivo such as for the treatment of cancer and human immunodeficiency virus. The ability to target retroviral vectors to specific cell types will also increase the utility of high titer retroviral vectors for in vivo applications. Clearly retroviral vectors have been extremely useful for both preclinical and clinical gene therapy studies, and it is likely that they will continue to be utilized for ex vivo and in vivo strategies in the future.

Animals↗

PubMed2000

Gene therapy for autoimmune disorders.

Although many autoimmune disorders do not have a strong genetic basis, their treatment may nevertheless be improved by gene therapies. Most strategies seek to transfer genes encoding immunomodulatory products that will alter host immune responses in a beneficial manner. Used in this fashion, genes serve as biological delivery vehicles for the products they encode. By this means gene therapy overcomes obstacles to the targeted delivery of proteins and RNA, and improves their efficacy while providing a longer duration of effect, and, potentially, greater safety. Additional genetic strategies include DNA vaccination and the ablation of selected tissues and cell populations. There is considerable evidence from animal studies that gene therapies work: examples include the treatment of experimental models of rheumatoid arthritis, multiple sclerosis, diabetes, and lupus. Pre-clinical success in treating animal models of rheumatoid arthritis has led to the first clinical trial of gene therapy for an autoimmune disease. In this Phase I study, a cDNA encoding the interleukin-1 receptor antagonist was transferred to the knuckle joints of patients with advanced rheumatoid arthritis. Two additional clinical trials are in progress. It is likely that gene therapy will provide effective new treatments for a wide range of autoimmune disorders.

Animals↗

PubMed2000

Negative regulation of the Apaf-1 apoptosome by Hsp70.

Release of cytochrome c from mitochondria by apoptotic signals induces ATP/dATP-dependent formation of the oligomeric Apaf-1-caspase-9 apoptosome. Here we show that the documented anti-apoptotic effect of the principal heat-shock protein, Hsp70, is mediated through its direct association with the caspase-recruitment domain (CARD) of Apaf-1 and through inhibition of apoptosome formation. The interaction between Hsp70 and Apaf-1 prevents oligomerization of Apaf-1 and association of Apaf-1 with procaspase-9. On the basis of these results, we propose that resistance to apoptosis exhibited by stressed cells and some tumours, which constitutively express high levels of Hsp70, may be due in part to modulation of Apaf-1 function by Hsp70.

Adenosine Triphosphate↗

PubMed2000

Genetic enhancement of fracture repair: healing of an experimental segmental defect by adenoviral transfer of the BMP-2 gene.

This study evaluated the ability of gene transfer to enhance bone healing. Segmental defects were created surgically in the femora of New Zealand white rabbits. First generation adenoviruses were used as vectors to introduce into the defects genes encoding either human bone morphogenetic protein-2 (BMP-2) or, as a negative control, firefly luciferase. Representative specimens were evaluated histologically after 8 weeks. Healing of the defects was monitored radiographically for 12 weeks, after which time the repair tissue was evaluated biomechanically. By radiological criteria, animals receiving the BMP-2 gene had healed their osseous lesions after 7 weeks, whereas those receiving the luciferase gene had not. Histologic examination of representative rabbits at 8 weeks confirmed ossification across the entire defect in response to the BMP-2 gene, whereas the control defect was predominantly fibrotic and sparsely ossified. At the end of the 12-week experiment, the control femora still showed no radiological signs of stable healing. The difference in radiologically defined healing between the experimental and control groups was statistically significant (P < 0. 002). Biomechanical testing of the femora at 12 weeks demonstrated statistically significant increases in the mean bending strength (P < 0.005) and bending stiffness (P < 0.05) of the animals treated with the BMP-2 gene. Direct, local adenoviral delivery of an osteogenic gene thus led to the healing of an osseous lesion that otherwise would not do so. These promising data encourage the further development of genetic approaches to enhancing bone healing. Gene Therapy (2000) 7, 734-739.

Adenoviridae↗

PubMed2000

Feasibility of CTLA4Ig gene delivery and expression in vivo using retrovirally transduced myeloid dendritic cells that induce alloantigen-specific T cell anergy in vitro.

Dendritic cells (DC) are highly specialised, bone marrow (BM)-derived antigen-presenting cells (APC) that initiate and regulate immune responses. They provide costimulatory signals (in particular, CD40 and the CD28 ligands CD80 and CD86) necessary for naive T cell activation. Functional expression of CD80 and CD86 is blocked by the fusion protein cytotoxic T lymphocyte antigen 4-immunoglobulin (CTLA4Ig), that promotes tolerance induction in animals. Here, replicating mouse (B10; H2b) myeloid DC progenitors, were retrovirally transduced to express CTLA4Ig using the centrifugal enhancement method. Gene product was detected by immunocyto- or histochemistry. Maximal DC transduction efficiency was 62%. Compared with control, zeomycin-resistance gene (Zeo)-transduced DC, CTLA4Ig-expressing cells showed markedly impaired capacity to stimulate naive allogeneic (C3H; H2k) T cell proliferation and cytotoxic T lymphocyte (CTL) generation. Their ability to induce alloantigen-specific T cell hyporesponsiveness was reversed by exogenous IL-2 in secondary mixed leukocyte reactions (MLR). Following local (s.c.) transfer to allogeneic recipients, the genetically modified DC trafficked to T cell areas of draining lymphoid tissue, where transgene expression was detected. Ex vivo analysis of proliferative and CTL responses revealed donor-specific inhibition of alloimmune reactivity by the CTLA4Ig-transduced DC. This effect was associated with marked inhibition of interferon (IFN)-gamma production, but significant augmentation of IL-4 and IL-10 secretion. Thus, retroviral transduction of DC permits in vivo delivery of CTLA4Ig to the precise microenvironment where antigen (Ag) presentation occurs. Comparatively nonimmunogenic retroviral vectors, that allow permanent transgene expression in DC, and promote localized delivery of the immunosuppressive transgene product, promote immune deviation and Ag-specific T cell hyporesponsiveness.

Abatacept↗

PubMed2000

Immunogenicity of enhanced green fluorescent protein (EGFP) in BALB/c mice: identification of an H2-Kd-restricted CTL epitope.

Enhanced green fluorescent protein (EGFP) is a novel marker gene product, which is readily detectable using techniques of fluorescence microscopy, flow cytometry, or macroscopic imaging. In the present studies, we have examined the immunogenicity of EGFP in murine models. A stable transfectant of the transplantable CMS4 sarcoma of BALB/c origin expressing EGFP, CMS4-EGFP-Zeo, was generated. Splenocytes harvested from mice immunized with a recombinant adenovirus expressing EGFP (Ad-EGFP) were restimulated in vitro with CMS4-EGFP-Zeo. Effector lymphocytes displayed strong cytotoxicity against CMS4-EGFP-Zeo, but not against mock-transfected CMS4-Zeo tumor cells. A number of candidate H2-Kd-binding peptides derived from the EGFP protein were chosen according to an epitope prediction program and synthesized. These peptides were tested for their ability to bind to H2-Kd molecules and stimulate IFNgamma-production by splenocytes harvested from Ad-EGFP-immunized mice. Using this methodology, the peptide, HYLSTQSAL (corresponding to EGFP200-208) which strongly binds to H2-Kd molecules, was identified as a naturally occurring epitope of EGFP. These results should facilitate the use of EGFP as a model tumor antigen in BALB/c mice.

Animals↗

PubMed2000

Gene therapy for meniscal injury: enhanced synthesis of proteoglycan and collagen by meniscal cells transduced with a TGFbeta(1)gene.

Objective To determine whether meniscal cells can express a TGFbeta(1)transgene delivered by a retroviral vector, and respond to the gene product by increasing matrix synthesis. Methods Monolayer cultures of human and canine meniscal cells were infected with retroviruses carrying either a human TGFbeta(1)cDNA or marker genes. Conditioned media were assayed for the presence of TGFbeta(1). Biosynthesis assays using radiolabeled precursors were employed to determine the effects of the transgenes on the synthesis of proteoglycan, collagen and noncollagenous proteins. Collagen phenotyping was performed by SDS-PAGE. Results Media conditioned by canine and human meniscal cells transduced with the TGFbeta(1)gene, accumulated several nanograms/10(6)cells of TGFbeta(1)during a 48 h incubation. Media conditioned by control cells contained very little TGFbeta(1). Transduction with the TGFbeta(1)gene, but not marker genes, increased the synthesis of collagen and proteoglycan by 8-15-fold. The synthesis of noncollagenous proteins was enhanced more modestly. Monolayers of meniscal cells synthesized types I, III, V and VI collagen. The TGFbeta(1)gene increased the synthesis of all types of collagen without altering the ratios between them. Conclusions Meniscal cells are readily transduced by retroviral vectors and respond to the transfer of a TGFbeta(1)cDNA by greatly increasing matrix synthesis. These findings encourage the further development of genetic approaches to the healing of meniscal lesions.

Animals↗

PubMed2000

Potential role of direct adenoviral gene transfer in enhancing fracture repair.

Gene therapy has much to offer in the treatment of conditions in which it is necessary to increase the formation of bone. Nonunions, segmental defects, and aseptic loosening are examples of conditions where the local expression of genes that inhibit osteolysis and promote osteogenesis might be helpful. Studies in which one such possibility has been evaluated experimentally are described. These investigations used a surgically produced segmental defect in the femurs of New Zealand White rabbits as the model system. Adjacent muscle was fashioned around the defect to form a chamber into which adenoviral vectors were injected. High levels of transgene expression were found in the muscle surrounding the defect after injection of vectors carrying marker genes. Transgene expression also was seen in the cut ends of the bone and the scar tissue within the gap. No transgene expression was seen in the contralateral limb, spleen, or lung; transient, low levels of expression were found in the liver. Transgene expression declined with time, disappearing from all tissue but bone by Day 26; expression persisted in bone for at least 6 weeks. The control defects did not heal spontaneously. Injection of adenovirus carrying a human bone morphogenetic protein-2 complementary deoxyribonucleic acid led to healing of the segmental defect within 12 weeks, as judged by radiographic, histologic, and biomechanical criteria. Adenovirus carrying a human transforming growth factor-beta 1 complementary deoxyribonucleic acid showed signs of improved healing, but not to the extent seen with the bone morphogenetic protein-2 complementary deoxyribonucleic acid. This approach to therapy holds much promise as a novel means of promoting osteogenesis.

Adenoviridae↗