The fate of mesenchymal stem cells transplanted into immunocompetent neonatal mice: implications for skeletal gene therapy via stem cells

To explore the feasibility of skeletal gene and cell therapies, we transduced murine bone marrow-derived mesenchymal stem cells (MSCs) with a retrovirus carrying the enhanced green fluorescent protein and zeocin-resistance genes prior to transplantation into 2-day-old immunocompetent neonatal mice. Whole-body imaging of the recipient mice at 7 days post-systemic cell injection demonstrated a wide distribution of the cells in vivo. Twenty-five days posttransplantation, most of the infused cells were present in the lung as assessed by examination of the cells cultured from the lungs of the recipient mice. The cells persisted in lung and maintained a high level of gene expression and could be recovered from the recipient mice at 150 days after cell transplantation. A significant number of GFP-positive cells were also present in the bones of the recipient mice at 35 days post-cell transplantation. Recycling of the cells recovered from femurs of the recipient mice at 25 days posttransplantation by repeated injections into different neonatal mice resulted in the isolation of a clone of cells that was detected in bone and cartilage, but not in lung and liver after systemic injection. These data demonstrate that MSCs persist in immunocompetent neonatal mice, maintain a high level of gene expression, and may participate in skeletal growth and development of the recipient animals.

Gene therapy approaches for osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heterogeneous group of genetic disorders that affect connective tissue integrity. The hallmark of OI is bone fragility, although other manifestations, which include osteoporosis, dentigenesis imperfecta, blue sclera, easy bruising, joint laxity and scoliosis, are also common among OI patients. The severity of OI ranges from prenatal death to mild osteopenia without limb deformity. Most forms of OI result from mutations in the genes that encode either the proalpha1or proalpha2 polypeptide chains that comprise type I collagen molecules, the major structural protein of bone. Treatment depends mainly on the severity of the disease with the primary goal to minimize fractures and maximize function. Current treatments include surgical intervention with intramedullarly stabilization and the use of prostheses. Pharmacological agents have also been attempted with limited success with the exception of recent use of bisphosphonates, which have been to shown to have some effect. Since OI is a genetic disease, these agents are not expected to alter the course of the collagen mutations. Cell and gene therapies as potential treatments for OI are therefore currently being actively investigated. The design of gene therapies for OI is however complicated by the genetic heterogeneity of the disease and by the factor that most of the OI mutations are dominant negative where the mutant allele product interferes with the function of the normal allele. The present review will discuss the molecular changes seen in OI, the current treatment options and the gene therapy approaches being investigated as potential future treatments for OI.

The contralateral effect conferred by intra-articular adenovirus-mediated gene transfer of viral IL-10 is specific to the immunizing antigen

We have demonstrated previously that local, adenoviral-mediated gene transfer of vIL-10 to a single joint of rabbits and mice with experimental arthritis can suppress disease in both the treated and untreated contralateral joints. These therapeutic effects observed in distant untreated joints following local intra-articular gene delivery have been termed the 'contralateral effect'. To begin to understand the underlying immunologic mechanism that confers this effect, a dual-antigen model of antigen-induced arthritis (AIA) in rabbit knee joints was utilized. Rabbits were immunized against two antigens, ovalbumin and keyhole limpet hemocyanin, and AIA generated by intra-articular injection of each antigen into contralateral knees. Intra-articular adenovirus-mediated gene transfer of vIL-10 significantly reduced intra-articular leukocytosis and cartilage matrix degradation, while preserving near normal levels of cartilage matrix synthesis within treated joints. However, no antiarthritic effect was conferred in the contralateral control joints that received only a marker gene, in contrast to the results seen in a single-antigen AIA model. These results suggest that the distant antiarthritic effects associated with local gene delivery to joints are antigen-specific, and not due to vIL-10-induced generalized immunosuppression of the animal.

Peroxidation and externalization of phosphatidylserine associated with release of cytochrome c from mitochondria

Production of reactive oxygen species (ROS) during apoptosis is associated with peroxidation of phospholipids particularly of phosphatidylserine (PS). The mechanism(s) underlying preferential PS oxidation are not well understood. We hypothesized that cytochrome c (cyt c) released from mitochondria into cytosol acts as a catalyst that utilizes ROS generated by disrupted mitochondrial electron transport for PS oxidation. Selectivity of PS oxidation is achieved via specific interactions of positively charged cyt c with negatively charged PS. To test the hypothesis we employed temporary transfection of Jurkat cells with a pro-apoptotic peptide, DP1, a conjugate consisting of a protein transduction domain, PTD-5, and an antimicrobial domain, KLA [(KLAKLAK)2], known to selectively disrupt mitochondria. We report that treatment of Jurkat cells with DP1 yielded rapid and effective release of cyt c from mitochondria and its accumulation in cytosol accompanied by production of H2O2. Remarkably, this resulted in selective peroxidation of PS while more abundant phospholipids such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE) remained nonoxidized. Neither PTD-5 alone nor KLA alone exerted any effect on PS peroxidation. Redox catalytic involvement of cyt c in PS oxidation was further supported by our data demonstrating that: (i) specific interactions of cyt c with PS resulted in the formation of EPR-detectable protein-centered tyrosyl radicals of cyt c upon its interaction with H2O2 in the presence of PS-containing liposomes, and (ii) integration of cyt c into cytochrome c null (Cyt c -/-) cells or HL-60 cells specifically stimulates PS oxidation in the presence of H2O2 or t-BuOOH, respectively. We further demonstrated that DP1 elicited externalization of PS on the surface of Jurkat cells and enhanced their recognition and phagocytosis by J774A.1 macrophages. Our results are compatible with the hypothesis that catalysis of selective PS oxidation during apoptosis by cytosolic cyt c is important for PS-dependent signaling pathways such as PS externalization and recognition by macrophage receptors.

Identification of a synovial fibroblast-specific protein transduction domain for delivery of apoptotic agents to hyperplastic synovium

Synovial hyperplasia, resulting in erosion of cartilage and bone, represents one of the major pathologies associated with rheumatoid arthritis. To develop an approach for efficient delivery of proteins or agents to synovium to induce targeted apoptosis of hyperplastic synovial tissue, we have screened an M13 peptide phage display library for synovial-specific transduction peptides. We identified a novel synovial-targeted transduction peptide, HAP-1, which is able to facilitate specific internalization of protein complexes into human and rabbit synovial cells in culture and rabbit synovial lining in vivo. HAP-1 and a non-tissue-specific cationic protein transduction domain, PTD-5, were fused to an antimicrobial peptide, (KLAK)(2), to generate two proapoptotic peptides termed DP2 and DP1, respectively. Administration of these peptides was able to induce apoptosis of rabbit and human synovial cells in culture, with DP2 inducing synovial cell-specific apoptosis. Intra-articular injection of DP1 and DP2 into arthritic rabbit joints with synovial hyperplasia induced extensive apoptosis of the hyperplastic synovium, while reducing the leukocytic infiltration and synovitis. These results suggest that proapoptotic peptides and, in particular, DP2 can be clinically useful for treatment of synovial hyperplasia, as well as inflammation. Moreover, the results demonstrate the feasibility of identifying tissue-specific transduction peptides capable of mediating efficient transduction in vivo.

Approaches for skeletal gene therapy

The role of gene therapy in the treatment of musculoskeletal disorders continues to be an active area of research. As the etiology of many musculoskeletal diseases becomes increasingly understood, advances in cellular and gene therapy maybe applied to their potential treatment This review focuses on current investigational strategies to treat osteogenesis imperfecta (OI). OI is a varied group of genetic disorders that result in the diminished integrity of connective tissues as a result of alterations in the genes that encode for either the pro alpha1 or pro alpha2 component of type I collagen. Because most forms of OI result from dominant negative mutations, isolated gene replacement therapy is not a logical treatment option. The combined use of genetic manipulation and cellular transplantation, however, may provide a means to overcome this obstacle. This article describes the recent laboratory and clinical advances in cell therapy, highlights potential techniques being investigated to suppress the expression of the mutant allele with antisense gene therapy, and attempts to deliver collagen genes to bone cells. The challenges that the investigators face in their quest for the skeletal gene therapy are also discussed.

Protection of islets by in situ peptide-mediated transduction of the Ikappa B kinase inhibitor Nemo-binding domain peptide

We have previously demonstrated that adenoviral gene transfer of the NF-kappaB inhibitor IkappaB to human islets results in protection from interleukin (IL)-1beta-mediated dysfunction and apoptosis. Here we report that human and mouse islets can be efficiently transduced by a cationic peptide transduction domain (PTD-5) without impairment of islet function. PTD mediated delivery of a peptide inhibitor of the IL-1beta-induced IkappaB kinase (IKK), derived from IKKbeta (NBD; Nemo-binding domain), and completely blocked the detrimental effects of IL-1beta on islet function and NF-kappaB activity, in a similar manner to Ad-IkappaB. We also demonstrate that mouse islets can be transduced in situ by infusion of the transduction peptide through the bile duct prior to isolation, resulting in 40% peptide transduction of the beta-cells. Delivery of the IKK inhibitor transduction fusion peptide (PTD-5-NBD) in situ to mouse islets resulted in improved islet function and viability after isolation. These results demonstrate the feasibility of using PTD-mediated delivery to transiently modify islets in situ to improve their viability and function during isolation, prior to transplantation.

Adverse effects of adenovirus-mediated gene transfer of human transforming growth factor beta 1 into rabbit knees

To examine the effect of transforming growth factor (TGF)-beta1 on the regulation of cartilage synthesis and other articular pathologies, we used adenovirus-mediated intra-articular gene transfer of TGF-beta1 to both naïve and arthritic rabbit knee joints. Increasing doses of adenoviral vector expressing TGF-beta1 were injected into normal and antigen-induced arthritis rabbit knee joints through the patellar tendon, with the same doses of an adenoviral vector expressing luciferase injected into the contralateral knees as the control. Intra-articular injection of adenoviral vector expressing TGF-beta1 into the rabbit knee resulted in dose-dependent TGF-beta1 expression in the synovial fluid. Intra-articular TGF-beta1 expression in both naïve and arthritic rabbit knee joints resulted in significant pathological changes in the rabbit knee as well as in adjacent muscle tissue. The observed changes induced by elevated TGF-beta1 included inhibition of white blood cell infiltration, stimulation of glycosaminoglycan release and nitric oxide production, and induction of fibrogenesis and muscle edema. In addition, induction of chondrogenesis within the synovial lining was observed. These results suggest that even though TGF-beta1 may have anti-inflammatory properties, it is unable to stimulate repair of damaged cartilage, even stimulating cartilage degradation. Gene transfer of TGF-beta1 to the synovium is thus not suitable for treating intra-articular pathologies.

Redirecting adenovirus to pulmonary endothelium by cationic liposomes

Somatic gene transfer to the pulmonary endothelium may be a useful strategy for modifying the phenotype of endothelium and/or vascular smooth muscle in disorders such as primary pulmonary hypertension, ARDS or pulmonary metastatic disease. Adenoviral (Ad) vectors, although highly efficient in liver gene transfer, have proven to be limited for pulmonary gene transfer with respect to efficiency, in part because of difficulty in assuring significant residence time in the lung and/or paucity of receptors for adenovirus on the endothelium. A recent study has shown that the use of a bispecific antibody to endothelial cells and Ad vectors efficiently redirects Ad vectors to pulmonary endothelium and improves gene expression in the lung. In this study, we report that pulmonary gene transfer by Ad vectors can also be improved significantly via the use of cationic liposomes. Preinjection of cationic liposomes followed by adenovirus led to a significant increase in the level of gene expression in the lung. The improvement in pulmonary gene transfer was associated with a decrease in the level of gene expression in the liver. Gene expression in the lung lasted for up to 2 weeks. This protocol, together with genetic modification of adenovirus, may prove to be useful for pulmonary gene transfer for the treatment of pulmonary diseases. This method may also be extended to pulmonary gene transfer using other types of viral vectors via vascular route.

Differential effects of overexpression of two forms of ephrin-A5 on neonatal rat cardiomyocytes

Eph receptors constitute the largest family of receptor tyrosine kinases. Multiple transcripts of ephrin-A5, the cognate ligand of the EphA3 receptor, were found in neonatal rat cardiomyocytes. Two cDNA clones encoding the full-length ephrin-A5 (ephrin-A5 alpha) and a 27-amino acid deletion form (ephrin-A5 beta) were isolated. To examine the role of ephrin-A5 in cardiomyocytes, the cDNAs were inserted into adenoviral vectors, termed Ad.ephrin-A5 alpha and Ad.ephrin-A5 beta, respectively, and overexpressed in cardiomyocytes. The effect of ephrin-A5 on cardiomyocyte gene expression was investigated using a cDNA expression array and Western blot analysis. The results showed that both ephrin-A5 alpha and ephrin-A5 beta downregulated cyclin D2, cyclin-dependent kinase-4 proteins, and their cognate receptor EphA3, which were associated with reduced bromodeoxyuridine incorporation in cardiomyocytes. Whereas ephrin-A5 alpha and ephrin-A5 beta also induced differential gene expression, only ephrin-A5 beta significantly upregulated the transcription of brain natriuretic peptide and downregulated ras-related protein RAB2, protein kinase C inhibitor protein-1, clusterin, and insulin-like growth factor-binding protein. The results suggest that the two forms of ephrin-A5 share similar function while differ in regulating different sets of genes in cardiomyocytes.

Increased adenosine in cerebrospinal fluid after severe traumatic brain injury in infants and children: association with severity of injury and excitotoxicity

OBJECTIVES

To measure adenosine concentration in the cerebrospinal fluid of infants and children after severe traumatic brain injury and to evaluate the contribution of patient age, Glasgow Coma Scale score, mechanism of injury, Glasgow Outcome Score, and time after injury to cerebrospinal fluid adenosine concentrations. To evaluate the relationship between cerebrospinal fluid adenosine and glutamate concentrations in this population.

DESIGN

Prospective survey.

SETTING

Pediatric intensive care unit in a university-based children's hospital.

PATIENTS

Twenty-seven critically ill infants and children who had severe traumatic brain injury (Glasgow Coma Scale < 8), who required placement of an intraventricular catheter and drainage of cerebrospinal fluid as part of their neurointensive care.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients ranged in age from 2 months to 14 yrs. Cerebrospinal fluid samples (n = 304) were collected from 27 patients during the first 7 days after traumatic brain injury. Control cerebrospinal fluid samples were obtained from lumbar puncture on 21 infants and children without traumatic brain injury or meningitis. Adenosine concentration was measured by using high-pressure liquid chromatography. Adenosine concentration was increased markedly in cerebrospinal fluid of children after traumatic brain injury vs. controls (p < .001). The increase in cerebrospinal fluid adenosine was independently associated with Glasgow Coma Scale < or = 4 vs. > 4 and time after injury (both p < .005). Cerebrospinal fluid adenosine concentration was not independently associated with either age (< or = 4 vs. > 4 yrs), mechanism of injury (abuse vs. other), or Glasgow Outcome Score (good/moderately disabled vs. severely disabled, vegetative, or dead). Of the 27 patients studied, 18 had cerebrospinal fluid glutamate concentration previously quantified by high-pressure liquid chromatography. There was a strong association between increases in cerebrospinal fluid adenosine and glutamate concentrations (p < .005) after injury.

CONCLUSIONS

Cerebrospinal fluid adenosine concentration is increased in a time- and severity-dependent manner in infants and children after severe head injury. The association between cerebrospinal fluid adenosine and glutamate concentrations may reflect an endogenous attempt at neuroprotection against excitotoxicity after severe traumatic brain injury.

A proapoptotic peptide for the treatment of solid tumors

We have designed a novel peptide, DP1, which is able to mediate significant induction of apoptosis in solid tumors by local injection. This peptide, comprised of a protein transduction domain (PTD), PTD-5, fused to an antimicrobial peptide, (KLAKLAK)2, was able to trigger rapid apoptosis in a variety of cell lines in vitro, including MCA205 murine fibrosarcomas and human head and neck tumors. Furthermore, direct injection of DP1 into day 7 established MCA205 tumors in C57BL/6 mice resulted in the induction of tumor apoptosis and subsequent reduction in tumor volume. These results suggest that DP1 may be used clinically to treat accessible solid tumors or as an adjuvant therapy in conjunction with radiotherapy, standard chemotherapy, immunotherapy, or surgical debulking.

Gene mediated insulin-like growth factor-I delivery to the synovium

The feasibility of articular gene therapy using insulin-like growth factor-I transgene expression in synovial tissues was assessed in vitro by transfection of synovial explant and monolayer cultures. Synovial membrane was harvested from horses and distributed for explant culture in multiwell plates or digested for monolayer culture in multiwell plates and chamber slides. Synovial monolayers were cultured for 48 h after infection with 0, 100, 200, or 500 moi adenovirus-IGF-I (AdeIGF-I) to establish an optimum dose. Explants were then either infected with AdeIGF-I or adenoviral LacZ and cultured for 8 days, treated with 100 ng/ml recombinant IGF-I as a positive control, or remained as uninfected untreated culture controls. Expression of IGF-I in explants and monolayers was assessed by in situ hybridization and quantitative polymerase chain reaction (PCR), and translation confirmed by IGF-I radioimmunoassay (RIA) and tissue immunoreaction. Effects of IGF-I on synovial function was assessed by proteoglycan and hyaluronan assay, and northern blot assessment of decorin and collagen type I expression. Significant transgene expression in synovial cells was present for all AdeIGF-I concentrations. Similarly, medium IGF-I concentrations were significantly elevated in AdeIGF-I infected synovial monolayer and explant cultures at all time points. Peak IGF-I concentration of 246 +/- 43 ng/ml developed in explant cultures on day 4; IGF-I levels in control explant groups were unchanged over baseline values. In situ hybridization and immunolocalization for IGF-I indicated focal IGF-I expression in intimal and subintimal layers of infected explants, with diffuse immunoreaction throughout infected subintimal and fibrous layers. For monolayer cultures, intracellular immunoreaction to IGF-I was markedly higher in infected cells, and was most prominent at 100 moi. Effects of IGF-I on synoviocyte cultures were evident on northern blots, which showed decreased decorin expression and elevated type I collagen production in AdeIGF-I infected monolayers. Proteoglycan concentration in the medium from explant cultures rose over the initial 4 days but was similar between treatment groups. The concentration of hyaluronan in medium from explant cultures did not differ significantly within or between treated and control groups during the 8-day study period. These data indicate that IGF-I can be successfully introduced to synovial structures by adenoviral vectors and results in effective IGF-I ligand synthesis without untoward synovial morphologic effects.

Transfer of proalpha2(I) cDNA into cells of a murine model of human Osteogenesis Imperfecta restores synthesis of type I collagen comprised of alpha1(I) and alpha2(I) heterotrimers in vitro and in vivo

The oim mouse is a model of human Osteogenesis Imperfecta (OI) that has deficient synthesis of proalpha2(I) chains. Cells isolated from oim mice synthesize alpha1(I) collagen homotrimers that accumulate in tissues. To explore the feasibility of gene therapy for OI, a murine proalpha2(I) cDNA was inserted into an adenovirus vector and transferred into bone marrow stromal cells isolated from oim mice femurs. The murine cDNA under the control of the cytomegalovirus early promoter was expressed by the transduced cells. Analysis of the collagens synthesized by the transduced cells demonstrated that the cells synthesized stable type I collagen comprised of alpha1(I) and alpha2(I) heterotrimers in the correct ratio of 2:1. The collagen was efficiently secreted and also the cells retained the osteogenic potential as indicated by the expression of alkaline phosphatase activity when the transduced cells were treated with recombinant human bone morphogenetic protein 2. Injection of the virus carrying the murine proalpha2(I) cDNA into oim skin demonstrated synthesis of type I collagen comprised of alpha1 and alpha2 chains at the injection site. These preliminary data demonstrate that collagen genes can be transferred into bone marrow stromal cells as well as fibroblasts in vivo and that the genes are efficiently expressed. These data encourage further studies in gene replacement for some forms of OI and use of bone marrow stromal cells as vehicles to deliver therapeutic genes to bone.

Endogenous cyclic AMP-adenosine pathway regulates cardiac fibroblast growth

Our previous studies show that cardiac fibroblasts express the extracellular "cAMP-adenosine pathway," that is, the generation of adenosine from extracelluar cAMP. The goal of this study was to assess whether activation of the cAMP-adenosine pathway by stimulation of endogenous cAMP synthesis regulates cardiac fibroblast growth. Cardiac fibroblasts in 3D cultures were used as the model system. Treatment of cardiac fibroblasts with forskolin, isoproterenol, or norepinephrine increased cAMP production and extracellular levels of adenosine, and these effects were prevented by inhibition of adenylyl cyclase (2',5'-dideoxyadenosine). Treatment with forskolin, isoproterenol, or norepinephrine for 24 hours inhibited DNA synthesis ((3)H-thymidine incorporation), and this effect was enhanced by combined inhibition of adenosine deaminase (erythro-9-[2-hydroxy-3-nonyl] adenine) plus adenosine kinase (iodotubercidin). Inhibition of adenylyl cyclase or adenosine receptors (1,3-dipropyl-8-p-sulfophenylxanthine or KF17837) prevented the effects of forskolin, isoproterenol, and norepinephrine on DNA synthesis. Forskolin also inhibited protein synthesis ((3)H-leucine incorporation) and cell proliferation, and these effects were blocked by adenosine receptor antagonism. Treatment of cardiac fibroblasts with norepinephrine for >48 hours but not <48 hours increased DNA synthesis, protein synthesis, and cell number. However, blockade of adenylyl cyclase or antagonism of adenosine receptors caused norepinephrine to induce proliferation in <48 hours. Our findings indicate that the endogenous cAMP-adenosine pathway regulates cardiac fibroblast growth.

Dysregulation of extracellular adenosine levels by vascular smooth muscle cells from spontaneously hypertensive rats

-The objective of this investigation was to determine whether the regulation of extracellular adenosine levels by smooth muscle cells (SMCs) from conduit arteries (aorta) and resistance microvessels (renal arterioles) is different in spontaneously hypertensive rats (SHR) versus normotensive Wistar-Kyoto (WKY) rats. Basal extracellular adenosine levels were decreased in cultured aortic and arteriolar SHR SMCs, and the increase in extracellular adenosine levels induced by stimulation of the cAMP-adenosine pathway was less in aortic and arteriolar SHR SMCs. Extracellular adenosine levels were lower in SHR SMCs, however, even when the cAMP-adenosine pathway was inhibited with 3-isobutyl-1-methylxanthine. Inhibition of adenosine kinase with iodotubercidin and inhibition of adenosine deaminase with erythro-9-(2-hydroxy-3-nonyl) adenine increased extracellular adenosine; however, only inhibition of adenosine deaminase equalized extracellular adenosine levels in SHR versus WKY SMCs. Membrane-disrupted SHR SMCs metabolized exogenous adenosine faster than WKY SMCs did, and this difference was abolished by inhibition of adenosine deaminase but not adenosine kinase. SHR SMCs demonstrated a greater proliferative response than WKY SMCs. This enhanced proliferative response was not blocked by adenosine per se or inhibition of adenosine kinase but was blocked by inhibition of adenosine deaminase and by 2-chloroadenosine (adenosine deaminase-resistant adenosine analogue). We conclude that dysregulation of extracellular adenosine levels exists in SHR SMCs, that this dysregulation is not due to a defect in the cAMP-adenosine pathway but rather to enhanced activity of adenosine deaminase, and that the dysregulation of extracellular adenosine mediates the enhanced proliferative response of SHR SMCs.

Interstitial brain adenosine and xanthine increase during jugular venous oxygen desaturations in humans after traumatic brain injury

OBJECTIVE

Adenosine decreases the cerebral metabolic rate for oxygen and increases cerebral blood flow, and it may play an important role in cerebrometabolic and cerebrovascular responses to hypoperfusion after traumatic brain injury. Jugular venous oxygen saturation is monitored after traumatic brain injury to assess brain oxygen extraction, and desaturations may reflect secondary brain insults. We hypothesized that brain interstitial adenosine and related purine metabolites would be increased during jugular venous oxygen saturation desaturations (<50%) and determined associations between the purines, lactate, and glucose to assess the role of adenosine during secondary insults in humans.

DESIGN

Study of critically ill adults with severe traumatic brain injury.

SETTING

Adult neurointensive care unit.

PATIENTS

We prospectively defined periods of normal saturation and desaturation in six patients after severe traumatic brain injury.

INTERVENTIONS

During these periods, cerebral microdialysis samples of brain interstitial fluid were collected, and adenosine and purine metabolites were measured by high-pressure liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Adenosine increased 3.1-fold and xanthine increased 2.5-fold during desaturation periods (both p <.05 vs. normal saturation period, signed rank). Adenosine, xanthine, hypoxanthine, and cyclic-adenosine monophosphate correlated with lactate over both study periods (r(2) =.32,.14,.31,.07, and.26, respectively, all p <.05, Pearson product moment correlation).

CONCLUSION

The marked increases in interstitial brain adenosine that occur during jugular venous oxygen desaturations suggest that adenosine may play an important role during periods of secondary insults after traumatic brain injury. The correlation of these metabolites with lactate further suggests that adenosine is increased during periods of enhanced glycolytic metabolism.

A(2b) receptors mediate the antimitogenic effects of adenosine in cardiac fibroblasts

Adenosine inhibits growth of cardiac fibroblasts; however, the adenosine receptor subtype that mediates this antimitogenic effect remains undefined. Therefore, the goals of this study were to determine which adenosine receptor subtype mediates the antimitogenic effects of adenosine and to investigate the signal transduction mechanisms involved. In rat left ventricular cardiac fibroblasts, PDGF-BB (25 ng/mL) stimulated DNA synthesis ((3)H-thymidine incorporation), cellular proliferation (cell number), collagen synthesis ((3)H-proline incorporation), and MAP kinase activity. The adenosine receptor agonists 2-chloroadenosine and 5'-N-methylcarboxamidoadenosine, but not N(6)-cyclopentyladenosine, 4-aminobenzyl-5'-N-methylcarboxamidoadenosine, or CGS21680, inhibited the growth effects of PDGF-BB, an agonist profile consistent with an A(2B) receptor-mediated effect. The adenosine receptor antagonists KF17837 and 1,3-dipropyl-8-p-sulfophenylxanthine, but not 8-cyclopentyl-1,3-dipropylxanthine, blocked the growth-inhibitory effects of 2-chloroadenosine and 5'-N-methylcarboxamidoadenosine, an antagonist profile consistent with an A(2) receptor-mediated effect. Antisense, but not sense or scrambled, oligonucleotides to the A(2B) receptor stimulated basal and PDGF-induced DNA synthesis, cell proliferation, and collagen synthesis. Moreover, the growth-inhibitory effects of 2-chloroadenosine, 5'-N-methylcarboxamidoadenosine, and erythro-9-(2-hydroxy-3-nonyl) adenine plus iodotubericidin (inhibitors of adenosine deaminase and adenosine kinase, respectively) were abolished by antisense, but not scrambled or sense, oligonucleotides to the A(2B) receptor. Our findings strongly support the hypothesis that adenosine causes inhibition of CF growth by activating A(2B) receptors coupled to inhibition of MAP kinase activity. Thus, A(2B) receptors may play a critical role in regulating cardiac remodeling associated with CF proliferation. Pharmacologic or molecular biological activation of A(2B) receptors may prevent cardiac remodeling associated with hypertension, myocardial infarction, and myocardial reperfusion injury after ischemia.

Direct adenovirus-mediated insulin-like growth factor I gene transfer enhances transplant chondrocyte function

Cell-based cartilage-resurfacing procedures may be enhanced by the addition of insulin-like growth factor I (IGF-I) to the transplant biomatrix. Given the relatively short half-life of IGF-I in biological systems, however, maintenance of effective concentrations of this peptide necessitates either high initial doses, or repeated treatment. This study investigated IGF-I delivery via adenoviral gene therapy, targeting graftable articular chondrocytes. Cultured articular chondrocytes were infected with an E1-deleted adenoviral vector containing IGF-I-coding sequence under CMV promoter control. Increased adenovirus-IGF-I concentrations resulted in coordinate increase in IGF-I mRNA and ligand expression; however, chondrocyte matrix synthesis was maximized by the lower adenovirus-IGF-I concentration (100 MOI) without additional increase at 200 or 500 MOI. Using 100 MOI, infected monolayers produced medium IGF-I content of at least 10 ng/ml in each 48-hr period for 28 days, reaching a day 4 peak concentration of 66 +/- 4.0 ng/ml. These concentrations were sufficient to produce significant stimulation of normal cartilage matrix gene expression. The concentration of secreted matrix products in medium from infected monolayers was increased up to 8-fold over uninfected control cultures. Moreover, compared with uninfected cultures, cells in infected cultures were more resistant to de-differentiation over time under serum-starved conditions, maintaining a normal chondrocyte molecular phenotype for at least 28 days. These data indicate that cultured chondrocytes are readily transduced by recombinant adenoviral vectors. The adenoviral-IGF transgene is abundantly expressed and its product secreted at therapeutic concentrations for at least 28 days, resulting in increased matrix biosynthesis and maintenance of the chondrocytic phenotype. Combined, this information suggests that there may be significant value in preimplantation adenoviral-IGF gene therapy for chondrocytes destined for cartilage resurfacing.

Chronic type IV phosphodiesterase inhibition protects glomerular filtration rate and renal and mesenteric blood flow in a zymosan-induced model of multiple organ dysfunction syndrome treated with norepinephrine

To examine the effects of chronic type IV phosphodiesterase (PDE4) inhibition on renal function and renal and mesenteric vascular resistance and blood flow in a sublethal model of multiple organ dysfunction syndrome (MODS) we used a prospective, randomized, controlled laboratory animal study. Twenty-eight rats had mini-infusion pumps placed to deliver vehicle or PDE4 inhibition with Ro 20-1724 at doses of either 0.3 or 2.0 microg/kg/min. Simultaneously, MODS was induced by intraperitoneal injection of zymosan (0.25 mg/g). Mean arterial blood pressure, heart rate, renal blood flow, and superior mesenteric blood flow (SMABF) were measured at 48 h. Renal vascular resistance (RVR), superior mesenteric artery vascular resistance (SMAVR), and glomerular filtration rate were calculated. A dose-response effect of norepinephrine was also evaluated at 48 h. Chronic Ro 20-1724 treatment prevented norepinephrine-induced vasoconstriction in control rats. Inhibition of PDE4 with Ro 20-1724 (2.0 microg/kg/min) increased urinary cAMP, and attenuated the increase in RVR and SMAVR (p < 0.05) and the decrease in RBF and SMABF (p < 0.05) that occurred from zymosan and norepinephrine. Glomerular filtration rate was also preserved (p < 0. 05), despite a reduction in blood pressure. Chronic PDE4 inhibition protects renal function and mesenteric perfusion during MODS by increasing cAMP in the presence and absence of catecholamines. Higher doses of PDE4 inhibition result in clinically tolerated decreases in mean arterial blood pressure, with improved end-organ function. Chronic PDE4 inhibition is protective, likely through cAMP-mediated attenuation of vasoconstriction.

Prevention of beta cell dysfunction and apoptosis activation in human islets by adenoviral gene transfer of the insulin-like growth factor I

Interleukin-1beta is a potent pro-inflammatory cytokine that has been shown to inhibit islet beta cell function as well as to activate Fas-mediated apoptosis in a nitric oxide-dependent manner. Furthermore, this cytokine is effective in recruiting lymphocytes that mediate beta cell destruction in IDDM onset. The insulin-like growth factor I (IGF-I) has been shown to block IL-1beta actions in vitro. We hypothesized that gene transfer of the insulin-like growth factor I to intact human islets could prevent IL-1beta-induced beta cell dysfunction and sensitization to Fas-triggered apoptosis activation. Intact human islets were infected with adenoviral vectors encoding IGF-I as well as beta-galactosidase and enhanced green fluorescent protein as controls. Adenoviral gene transfer of human IGF-I prevented IL-1beta-mediated nitric oxide production from human islets in vitro as well as the suppression of beta cell function as determined by glucose-stimulated insulin production. Moreover, IGF-I gene transfer prevented IL-1beta-induced, Fas-mediated apoptosis. These results suggest that locally produced IGF-I from cultured islets may be beneficial in maintaining beta cell function and promoting islet survival before and following islet transplantation as a potential therapy for type I diabetes.

[Detection of Mycoplasma genitalium in throat by nested polymerase chain reaction and analysis of DNA sequencing in pediatric patients with acute upper respiratory tract infections]

OBJECTIVE

To explore the relation between Mycoplasma genitalium (Mg) and acute upper respiratory tract infection in pediatric patients by using nested polymerase chain reaction(nPCR) and analysis of DNA sequencing techniques.

METHODS

The specimens of throat swab were obtained in 62 acute upper respiratory tract infections children and 80 health children. The two kinds of Mg species-specific, in which the sequences of I-III and V-VII variable regions of Mg 16Sr RNA gene were detected by using nPCR technique. DNA sequences of positive product were detected and analysed.

RESULTS

The Positive rate of health children is 5% (4/80), while the acute upper respiratory tract infection children is 21% (13/62). The difference is significant (P < 0.001). The DNA sequences of positive product shows that: there are two point mutation(T-->C) in the sequences of V-VII variable regions of throat swab of one pediatric patient, other sequences are same as those Mg type strain(G-37T).

CONCLUSIONS

Acute upper respiratory tract infection of pediatric patients have relation with Mg. There are Mg mutant strain in China.