[Clinical application of split liver transplantation: a single center report of 203 cases]

Objective: To investigate the safety and therapeutic effect of split liver transplantation (SLT) in clinical application. Methods: This is a retrospective case-series study. The clinical data of 203 consecutive SLT, 79 living donor liver transplantation (LDLT) and 1 298 whole liver transplantation (WLT) performed at the Third Affiliated Hospital of Sun Yat-sen University from July 2014 to July 2023 were retrospectively analyzed. Two hundred and three SLT liver grafts were obtained from 109 donors. One hundred and twenty-seven grafts were generated by in vitro splitting and 76 grafts were generated by in vivo splitting. There were 90 adult recipients and 113 pediatric recipients. According to time, SLT patients were divided into two groups: the early SLT group (40 cases, from July 2014 to December 2017) and the mature SLT technology group (163 cases, from January 2018 to July 2023). The survival of each group was analyzed and the main factors affecting the survival rate of SLT were analyzed. The Kaplan-Meier method and Log-rank test were used for survival analysis. Results: The cumulative survival rates at 1-, 3-, and 5-year were 74.58%, 71.47%, and 71.47% in the early SLT group, and 88.03%, 87.23%, and 87.23% in the mature SLT group, respectively. Survival rates in the mature SLT group were significantly higher than those in the early SLT group (χ2=5.560,P=0.018). The cumulative survival rates at 1-, 3- and 5-year were 93.41%, 93.41%, 89.95% in the LDLT group and 87.38%, 81.98%, 77.04% in the WLT group, respectively. There was no significant difference among the mature SLT group, the LDLT group and the WLT group (χ2=4.016, P=0.134). Abdominal hemorrhage, infection, primary liver graft nonfunction,and portal vein thrombosis were the main causes of early postoperative death. Conclusion: SLT can achieve results comparable to those of WLT and LDLT in mature technology liver transplant centers, but it needs to go through a certain time learning curve.

Study on Efficacy and Safety of Low-Dose Apatinib Combined with Camrelizumab and SOX Regimen as First-Line Treatment of Locally Advanced and Unresectable Gastric/Gastroesophageal Junction Cancer: A Protocol for an Open-Label, Dose Escalation and Extension Phase Ib Clinical Trial

BACKGROUND

The standard treatment for advanced gastric/gastroesophageal junction cancer (AGC/GEJC) is palliative chemotherapy combined with targeted therapy. The SOX regimen (S-1 plus oxaliplatin) is recommended as neoadjuvant or palliative first-line chemotherapy in Asian patients. Apatinib, an oral VEGFR tyrosine kinase inhibitor, is associated with additional survival benefit as third- or subsequent-line therapy. However, the median overall survival time of AGC/GEJC is only 8-11 months in the West and 13-17 months in East Asia/Japan, even with the application of anti-angiogenic agents. Hence, the multimodal and individual management of patients is challenging standards to improve prognosis, including the preferential use of low-dose anti-angiogenic drugs and immunotherapy, as well as the application of multi-disciplinary treatment (MDT)-directed conversion therapy.

METHODS/DESIGN

This single-center study was designed to combine low-dose apatinib with camrelizumab plus the SOX regimen in diagnosed potentially resectable and initially unresectable AGC/GEJC. This a prospective, open-label, single-arm, dose escalation and extension phase Ib clinical trial, conducted in Jiangsu Province Hospital, beginning from June 2020. All patients will first receive this combined regimen (3 weeks/cycle) for at most eight cycles, then apatinib and camrelizumab in maintenance therapy until disease progression, intolerable toxicity, death, a maximum 2 years of treatment or discontinuation for any reason. Follow-up and evaluation will be carried out regularly. If surgery is allowed by MDT discussions, oral apatinib will be discontinued during the last preoperative cycle. The primary endpoints are the objective response rate and maximum tolerated dose according to the Response Evaluation Criteria In Solid Tumors (RECIST) criteria (version 1.1) and the Common Terminology Criteria for Adverse Events (CTCAE) criteria (version 5.0).

DISCUSSION

This study will assess the response and side effects of AGC/GEJC patients in the use of low-dose apatinib combined with camrelizumab and the SOX regimen, and this combined therapy is expected to be a feasible and optimized first-line treatment option. In addition, this study will provide robust evidence and novel ideas for conversion therapy.

TRIAL REGISTRATION

ChiCTR.gov.cn: ChiCTR2000034109.

Current Progress and Future Perspectives of Immune Checkpoint Inhibitors in Biliary Tract Cancer

Biliary tract cancer (BTC) is an uncommon and aggressive neoplasm, with most patients presenting in an advanced stage. Systemic chemotherapy is the limited treatment available but is unsatisfactory, while targeted therapy is still awaiting validation from clinical trials. Given the potential effect of immune checkpoint inhibitors (ICIs) in the treatment of BTC, this review aims to summarize the evidence-based benefits and predictive biomarkers for using inhibitors of cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) ligand, or programmed cell death protein-1 and its ligand (PD-1 and PD-L1) as monotherapy or combined with other anti-tumor therapies, while also pointing out certain pitfalls with the use of ICIs which need to be addressed.

[Effect of renal function on sarcopenia in elderly male patients with chronic kidney disease]

Objective: To evaluate the effect of renal function on sarcopenia in elderly male patients with chronic kidney disease (CKD). Methods: A total of 105 male CKD patients aged ≥65 years who were admitted to the Chinese PLA General Hospital between October 1, 2018 and January 30, 2019 were included in this study. Using two different equations to estimate glomerular filtration rate (GFR), respectively. According to the sarcopenia criteria, the participants were categorized as the non-sarcopenia group (n=72) and the sarcopenia group (n=33), respectively. The association of estimated GFR (eGFR) and the sarcopenia in the male CKD patients was analyzed using the model of multivariate logistic regression. Results: Among the 105 patients, the median age was 74 (68, 77) years old. The prevalence of sarcopenia was 31.4% (33/105). According to the multivariate logistic regression analysis, eGFR based on serum creatinine and Cys-C (eGFRscr-cys) lower than 45 ml·min(-1)·(1.73 m(2))(-1) (OR=4.17, 95%CI:1.08-16.02, P=0.038) and eGFR based on Cys-C (eGFRcys) lower than 45 ml·min(-1)·(1.73 m(2))(-1) (OR=3.99, 95%CI:1.08-14.75, P=0.038) were independent risk factors for underlying sarcopenic, respectively. The area under the receiver operating characteristics curve (AUC) revealed that eGFRscr-cys (AUC=0.67) was more suitable than eGFRcys (AUC=0.64) to predict the sarcopenia in elderly male patients with CKD. Conclusion: The increased incidence of sarcopenia in elderly men with CKD is accompanied with deterioration of renal function.

Sildenafil might impair maternal-fetal immunotolerance by suppressing myeloid-derived suppressor cells in mice

Myeloid-derived suppressor cells (MDSCs) as an important population of immune cells were found to restrain T cell function, polarize T-helper cells (Th) 1/Th2 toward Th2 response and induce regulatory T cells (Tregs), therefore enhancing the immunotolerance during pregnancy. Sildenafil has been applied for poor endometrial quality in implantation failure patients. Nevertheless, investigations have shown that sildenafil could reduce MDSCs-dependent immunosuppression. Whether sildenafil affects embryo implantation by suppressing MDSCs? To address this question, using the mice model, we investigated the amounts of immune cells in peripheral blood and endometrial cells from control group (CG), sildenafil low-dose group (LDG) and high-dose group (HDG). We found that both treatment groups displayed a marked deficiency in polymorphonuclear (PMN)-MDSCs and Th2 from mice blood and endometrium as compared to these from CG. The frequency of Tregs in endometrium from HDG was lower than those from CG. Th1/Th2 ratio in both periphery and uterus from study groups showed a significant increase as compared to those from CG. By relevance analysis, we found that the level of Tregs positively correlated with the level of PMN-MDSCs, whereas the Th1/Th2 ratio negatively correlated with the frequency of PMN-MDSCs in uterus. Moreover, there was a positive relationship between the amount of blood PMN-MDSCs and endometrial PMN-MDSCs. These results suggest that we should carefully weigh the pros and cons of using sildenafil when applied to patients with poor endometrial receptivity.

[Influence of different timing of Saccharomyces boulardii combined with bismuth quadruple therapy for Helicobacter pylori eradication]

Objective: To assess the efficacy and safety of different opportunity of Saccharomyces boulardii (S. Boulardii) Sachets combined with bismuth quadruple therapy for Helicobacter pylori(H. pylori)eradication. Methods: This experiment was a prospective study. A total of 300 H. pylori-infected patients were enrolled and randomized assigned into three groups. Quadruple therapy group received pantoprazole 40 mg+bismuth potassium citrate capsule 220 mg+amoxicillin 1 000 mg+furazolidone 100 mg, bid, oral for 14 days. The simultaneous probiotic group received pantoprazole 40 mg+bismuth potassium citrate capsule 220 mg+amoxicillin 1 000 mg+furazolidone 100 mg+S. Boulardii Sachets 500 mg,bid,oral for 14 days.There after probiotic group:S.Boulardii Sachets was added on the first day after the end of 14 days in the quadruple group, for 500 mg, bid 14 days. The eradication rates and adverse reactions of the three groups were compared. Results: The eradication rates of H.pylori were 89.0%,90.4% and 91.3% in the quadruple therapy group, the simultaneous probiotic group and the there after probiotic group according to Per-protocol(PP) analysis,respectively,with no statistical difference (P=0.870). According to intention-to-treat(ITT)analysis, 81.0%, 85.0% and 84.0%, respectively, the difference was not statistically significant (P=0.732).The overall incidence of adverse reactions and the incidence of diarrhea and nausea in the simultaneous probiotic group, and the there after probiotic group were lower than those in the quadruple group(P<0.05),and the difference was statistically significant.The overall incidence of adverse reactions and diarrhea in the simultaneous probiotic were lower than those in the there after probiotic group (P=0.021, P=0.007), and the difference was statistically significant. Conclusions: S. Boulardii Sachets combined with quadruple therapy at the same time or after eradication treatment can not improve the H.pylori eradication rate,but can reduce the overall incidence of adverse reactions and the incidence of diarrhea and nausea. It is safer to add S. Boulardii Sachets at the same time than after eradication therapy.

[The role of Th1/Th2 cells imbalance in the pathogenesis of secretory otitis media]

Objective:The aim of this study is to explore the role of Th1/Th2 cells imbalance in the pathogenesis of secretory otitis media. Method:Ninety secretory otitis media patients were enrolled in observation group. According to medical history, they were divided into acute and chronic group. In addition, 90 healthy volunteers during the same period were selected as the control group. The levels of Th1-type cytokines IFN-γ, Th2-type cytokines interleukin-4 (IL-4) and IFN-γ/IL-4 in peripheral blood were compared between observation group and control group. Compare with acute and chronic secretory otitis media patients IFN-γ, IL-4, IFN-γ/IL-4 levels as well as the compare with middle ear effusion and peripheral blood sIFN-γ, IL-4, IFN-γ/IL-4 levels in observation group. Result:The level of IFN-γ, IL-4 and IFN-γ/IL-4 in the peripheral blood in the observation group were higher than those of the control group (P<0.05). The levels of IFN-γ, IL-4 and IFN-γ/IL-4 in the peripheral blood of patients in the chronic group were higher than those in the acute group. There was no significant difference in IL4, IFN-γ/IL-4 levels between the observation group and the middle ear effusion (P>0.05), IFN-γ levels in peripheral blood were lower than those of the middle ear effusion IFN-γ (P<0.05). Conclusion:Abnormal IFN-γ, IL-4 levels of the peripheral blood and the middle ear effusion have some relationship with secretory otitis media, and Th1/Th2 imbalance may be a risk factor for secretory otitis media.

Reoperation of biliary tract by laparoscopy: a consecutive series of 26 cases

BACKGROUND

In the past, previous operation of biliary tract represented a contraindication to perform reoperation by laparoscopy. As experience with laparoscopic techniques and instrumentation has expanded, reoperation of biliary tract with laparoscope has become an accepted procedure in the management of cholelithiasis. We present our interesting experience with regard to reoperation of biliary tract by laparoscopy.

MATERIAL AND METHODS

Laparoscopic operation of biliary tract was performed on 3,674 consecutive patients from April, 1992 till June, 2005. Among these patients, 26 had a previous open operation of biliary tract and their clinical data were retrospectively analyzed as follows: seven cases had complicated intrahepatic bile duct stones (restricted at hepatic duct of the first and second order). Diameter of common bile duct in patients with common duct stones was above 1.2 cm, the number of stones for each patient was more than 3 and all the biggest stones exceeded 1 cm. In the 26 patients, preoperatively, stenosis of bile duct and malignant tumour were excluded by both radiological examination and detection of serological tumour markers.

RESULTS

The mean operative time was 125 min (75-190 min). Reoperations of biliary tract by laparoscope were successfully accomplished in 25 patients. One patient was converted to open operation and the common duct stones were removed by right angle forceps through short incision. None of the patients developed any severe complication, all of them recovered and were successfully discharged. Three cases with retained calculuses were successfully cured by removing these through the sinus tract of T tube.

CONCLUSIONS

Laparoscopic procedure is minimally invasive, safe and feasible for laparoscopic experts in case of reoperation of biliary tract. It is also a first method for patients for whom endoscopic sphincterotomy is contraindicated.

Enhanced dissipation of phenanthrene and pyrene in spiked soils by combined plants cultivation

Polycyclic aromatic hydrocarbons (PAHs), a class of POPs, are widely distributed in the environment. Phytoremediation has long been recognized as a cost-effective method for removal of PAHs pollutants from soil. This study was conducted to investigate the capability of three plant species separately and their combination to promote the degradation of phenanthrene and pyrene in soil. The performance of three plant species, maize, ryegrass and white clover for phenanthrene and pyrene removal was also compared. The result showed that the presence of vegetation significantly enhances the dissipation of phenanthrene and pyrene in the soil environment. This effect was especially marked with maize. At the end of 60 days treatment, phenanthrene and pyrene concentrations in treated soils declined from an initial 52.52 mg kg-1 and 58.19 mg kg-1 to 4.15 mg kg-1 and 6.77 mg kg-1, respectively, indicating that phenanthrene and pyrene was successfully removed by maize. Around 92.10% of phenanthrene and 88.36% of pyrene were removed from soils planted with maize. Within approximately two months experimental period, the dissipation extent showed that the 4-ring pyrene was more recalcitrant than 3-ring phenanthrene. Although the extents did not differ significantly among three tested species, the rates of degradation were different. The maize treatment had the highest rate of contaminant removal after two months, followed by white clover and annual ryegrass. As compare to single plant cultivation, combined plants cultivation significantly enhanced the destruction rate and extent of phenanthrene and pyrene in soils. Around 98.22% of phenanthrene and 95.81% of pyrene were removed from soils planted with maize and ryegrass. This research indicates the potential for phenanthrene and pyrene mineralization in combined plants cultivation, which may be especially useful for phytoremediation of soils contaminated with PAHs.

Acoustic pulse propagation and localization in bubbly water

Acoustic pulse propagation in bubbly water is studied using a self-consistent method. The acoustic transmission and backscattering are evaluated numerically. Under proper conditions, the localization of acoustic waves is identified within a range of frequency. The results show that when a short pulse is transmitted the waves of frequencies within the localization regime will be trapped in the system and reveal a coherent behavior. A phase diagram approach is used to describe the localization behavior.

Advanced analytical determination of volatile organic compounds (VOC) and other major contaminants in water samples using GC-ion trap MS

The GC-Ion Trap MS is recently one of the most efficient instrumental analysis recommended for understanding the chemistry of volatile organic compounds, not only in water but even in the food chain and other environmental media (air and soil). Results of the experiment conducted on water samples from Kuguri and Yatsutani sampling stations showed considerably higher levels of organic enrichment (COD = 10 mg/L and 11 mg/L respectively). Total concentrations of Pb (0.072 mg/L and 0.093 mg/L) and Cd (0.004 mg/L and 0.011 mg/L) on the other hand, invariably exceeded the maximum allowable concentrations for human health and the living environment (Pb = 0.005 mg/L; Cd = 0.001 mg/L respectively). And the toxicity levels for these contaminants at LC50 showed critical impact on rainbow trout (hypersensitive species) at 0.14 mg/L for Pb and 0.007 mg/L for Cd in 96 hours respectively. Although these major contaminants including phenol and 3-, 4-cresol, showed relatively higher toxicity impact in the experimental media, it would remain contentious to justify any associated potential dangers without regular routine water monitoring, at least for a period of one year. Nevertheless, the data could serve as a benchmark through which other phenomena can easily be investigated.

[Detection of distortion-product otoacoustic emissions in well-drilling workers]

OBJECTIVE

To understand the value of using distortion product of otoacoustic emissions(DPOAE) in monitoring noise-induced hearing-loss.

METHOD

The amplitude and the positive rates of DPOAE were detected in 102 well-drilling workers (195 ears).

RESULT

The amplitude and the positive rates of DPOAE declined significantly in noise groups against control. With the increase of working-age the positive rates of DPOAE was decrease. The DPOAE amplitudes and the positive rates of noise group with normal pure tone threshold were obvious lower than that in controls. There were negative relationship between pure tone threshold in high-frequency and the positive rates.

CONCLUSION

The DPOAE can reflect the cochlea's function of labors working in noise condition well. Contrast with the pure tone audiometry, DPOAE was more sensitive and more objective.

Restoration of cyclic adenosine monophosphate-stimulated chloride channel activity in human cystic fibrosis tracheobronchial submucosal gland cells by adenovirus-mediated and cationic lipid-mediated gene transfer

In human airways, the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is predominantly expressed in serous cells of the tracheobronchial glands. Despite considerable evidence that submucosal glands are important contributors to the pathophysiology of CF lung disease, most attempts at CFTR gene transfer have primarily targeted airway surface epithelial cells. In this study, we systematically evaluated CFTR gene transfer into cultures of immortalized CF human tracheobronchial submucosal gland (6CFSMEO) cells using adenovirus and cationic lipid vectors. We found that the efficiency of adenovirus-mediated gene transfer was comparable in 6CFSMEO and CFT1 cells (a surface airway epithelial cell line isolated from a subject with CF). So was the ranking order of adenovirus vectors containing different enhancers/promoters (CMV >> E1a approximately phosphoglycerokinase), as determined by both X-Gal staining and quantitative measurement of beta-galactosidase activity. Further, we provide the first demonstration that cationic lipids mediate efficient gene transfer into 6CFSMEO cells in vitro. The transfection efficiency at optimal conditions was higher in 6CFSMEO than in CFT1 cells. Finally, either infection with adenoviral vectors or transfection with cationic lipid:plasmid DNA complexes encoding CFTR significantly increased chloride (Cl-) permeability, as assessed using the 6-methoxy-N-(3-sulfopropyl)-quinolinium (SPQ) fluorescence assay, indicating restoration of functional CFTR Cl- channel activity. These data show that although the mechanisms of transfection may be different between the two cell types, 6CFSMEO cells are as susceptible as CFT1 cells to transfection by adenoviral and cationic-lipid gene transfer vectors.

Contribution of plasmid DNA to inflammation in the lung after administration of cationic lipid:pDNA complexes

Cationic lipid-mediated gene transfer to the mouse lung induces a dose-dependent inflammatory response that is characterized by an influx of leukocytes and elevated levels of the cytokines interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). We have examined the contribution of plasmid DNA (pDNA) to this observed toxicity, specifically the role of unmethylated CpG dinucleotides, which have been previously shown to be immunostimulatory. We report here that complexes of cationic lipid GL-67 and unmethylated pDNA (pCF1-CAT) instilled into the lungs of BALB/c mice induced highly elevated levels of the cytokines TNF-alpha, IFN-gamma, IL-6, and IL-12 in the bronchoalveolar lavage fluids (BALF). In contrast, BALF of animals administered either GL-67 alone or GL-67 complexed with SssI-methylated pDNA contained low levels of these cytokines. Similar results were observed using a plasmid (pCF1-null) that does not express a transgene, demonstrating that expression of chloramphenicol acetyltransferase (CAT) was not responsible for the observed inflammation. The response observed was dose dependent, with animals receiving increasingly higher amounts of unmethylated pDNA exhibiting progressively higher levels of the cytokines. Concomitant with this increase in cytokine levels were also elevated numbers of neutrophils in the BALF, suggesting a possible cause- and-effect relationship between neutrophil influx and generation of cytokines. Consistent with this proposal is the observation that reduction of neutrophils in the lung by administration of antibodies against Mac-1alpha and LFA-1 also diminished cytokine levels. This reduction in cytokine levels in the BALF was accompanied by an increase in transgene expression. In an attempt to abate the inflammatory response, sequences in the pDNA encoding the motif RRCGYY, shown to be most immunostimulatory, were selectively mutagenized. However, instillation of a plasmid in which 14 of the 17 CpG sites were altered into BALF/c mice did not reduce the levels of cytokines in the BALF compared with the unmodified vector. This suggests that other unmethylated motifs, in addition to RRCGYY, may also contribute to the inflammatory response. Together, these findings indicate that unmethylated CpG residues in pDNA are a major contributor to the induction of specific proinflammatory cytokines associated with instillation of cationic lipid:pDNA complexes into the lung. Strategies to abate this response are warranted to improve the efficacy of this nonviral gene delivery vector system for the treatment of chronic diseases.

Efficiency of cationic lipid-mediated transfection of polarized and differentiated airway epithelial cells in vitro and in vivo

Systematic analysis of a large number of different cationic lipids has led to the identification of novel structures (GL-67) and formulations of cationic lipid:plasmid DNA (pDNA) complexes that facilitate high levels of gene expression in lungs of mice. However, despite significant improvement in gene transfer activity, we show here that the efficiency of GL-67-mediated gene transduction of intact airway epithelia is still relatively low. Administration of GL-67:pCF1-CFTR (encoding the cystic fibrosis transmembrane conductance regulator) complexes into the nasal epithelium of cystic fibrosis (CF) transgenic mice resulted only in marginal correction of the ion transport defects. Measurements of nasal potential differences (PD) showed no correction of the sodium (Na+) transport defect, and only partial restitution of the chloride (Cl-) transport defect was achieved in a small proportion of the animals after perfusion of the nasal epithelium with the complexes. Furthermore, in contrast to results obtained following instillation of GL-67:pDNA complexes into the lungs of mice, perfusion of GL-67:pDNA into the nasal epithelium resulted only in a moderate enhancement of gene transduction activity relative to that attained with naked pDNA alone. To determine the basis for this low efficiency of transfection, a series of studies was conducted to identify some of the barriers governing cationic lipid-mediated gene transfer to the airway epithelium. We show here that the transfection activity of GL-67 was affected by the polarization, differentiation, and proliferative state of the cells. Diminished transfection activity was observed with nonmitotic, highly polarized and differentiated airway epithelial cells. This observed reduction in gene expression with nonmitotic cells was determined to be due in part to inefficient nuclear translocation of the pDNA from the cytoplasm. Together these data indicate that much improvement in the ability of cationic lipids to transfect polarized and differentiated airway epithelial cells is a necessary prerequisite for effective cationic lipid-mediated gene therapy of airway diseases such as CF.

Basis of pulmonary toxicity associated with cationic lipid-mediated gene transfer to the mammalian lung

Studies have indicated that although abundant levels of transgene expression could be achieved in the lungs of mice instilled with cationic lipid:pDNA complexes, the efficiency of gene transfer is low. As a consequence, a relatively large amount of the complex will need to be administered to the human lungs to achieve therapeutic efficacy for indications such as cystic fibrosis. Because all cationic lipids exhibit some level of cytotoxicity in vitro, we assessed the safety profile of one such cationic lipid, GL-67, following administration into the lungs of BALB/c mice. Dose-dependent pulmonary inflammation was observed that was characterized by infiltrates of neutrophils, and, to a lesser extent, macrophages and lymphocytes. The lesions in the lung were multifocal in nature and were manifested primarily at the junction of the terminal bronchioles and alveolar ducts. The degree of inflammation abated with time and there were no apparent permanent fibrotic lesions, even in animals that were treated at the highest doses. Analysis of the individual components of the complex revealed that the pulmonary inflammation was primarily cationic lipid-mediated with a minor contribution from the neutral co-lipid DOPE. Associated with the lesions in the lungs were elevated levels of the pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) that peaked at days 1-2 post-instillation but resolved to normal limits by day 14. Total cell counts, primarily of neutrophils, were also significantly elevated in the bronchoalveolar lavage fluids of GL-67:pDNA-treated mice between days 1 and 3 but returned to normal limits by day 14. No specific immune responses were detected against the cationic lipid or plasmid DNA in mice that had been either instilled or immunized with the individual components or complex, nor was there any evidence of complement activation. These studies indicate that a significant improvement in the potency of cationic lipid:pDNA formulations is desirable to minimize the toxicity associated with cationic lipids.

Optimization of plasmid vectors for high-level expression in lung epithelial cells

Nonviral gene therapy approaches use a plasmid vector to express the desired transgene. We have systematically examined several regulatory elements within plasmid vectors that govern gene expression, e.g., the promoter, enhancer, intron, and polyadenylation signal, by constructing a series of plasmids that differed only in the particular sequence element being evaluated. Of the several promoters and polyadenylation signal sequences that were tested, the human cytomegalovirus (CMV) immediate early gene promoter and the addition of polyadenylation signal sequences from the bovine growth hormone (BGH) gene or rabbit beta-globin gene produced the highest levels of expression in vitro. The inclusion of a hybrid intron 3 to the promoter further increased expression 1.6-fold. The addition of a region of the CMV enhancer 5' to several weak promoters increased expression 8- to 67-fold, and co-transfection with a second plasmid encoding a chimeric transcription factor also enhanced expression. On the basis of these results, the CMV promoter, the hybrid intron, and the BGH polyadenylation signal were selected for consistent high level expression in vitro and in the mouse lung. However, expression was transient, with greater than 60% loss of activity in the first 7 days. This transient expression was not specific to CMV promoter-containing plasmids, because plasmids containing other heterologous promoters showed a similar profile of transient expression in vivo. These comparative analyses begin to provide a basis for the development of optimized expression plasmids for gene therapy of lung diseases.

Detailed analysis of structures and formulations of cationic lipids for efficient gene transfer to the lung

Cationic lipid-mediated gene transfer of cystic fibrosis transmembrane conductance regulator (CFTR) cDNA represents a promising approach for treatment of cystic fibrosis (CF). Here, we report on the structures of several novel cationic lipids that are effective for gene delivery to the lungs of mice. An amphiphile (#67) consisting of a cholesterol anchor linked to a spermine headgroup in a "T-shape" configuration was shown to be particularly efficacious. An optimized formulation of #67 and plasmid vector encoding chloramphenicol acetyl-transferase (CAT) was capable of generating up to 1 microgram of CAT enzyme/lung following intranasal instillation into BALB/c mice. This represents a 1,000-fold increase in expression above that obtained in animals instilled with naked pDNA alone and is greater than 100-fold more active than cationic lipids used previously for CFTR gene expression. When directly compared with adenovirus-based vectors containing similar transcription units, the number of molecules of gene product expressed using lipid-mediated transfer was equivalent to vector administration at multiplicities of infection ranging from 1 to 20. The level of transgene expression in the lungs of BALB/c mice peaked between days 1 and 4 post-instillation, followed by a rapid decline to approximately 20% of the maximal value by day 7. Undiminished levels of transgene expression in the lung could be obtained following repeated intranasal administration of #67:DOPE:pCF1-CAT in nude mice. Transfection of cells with formulations of #67:DOPE:pCF1-CFTR generated cAMP-stimulated CFTR chloride channel and fluid transport activities, two well-characterized defects associated with CF cells. Taken together, the data demonstrate that cationic lipid-mediated gene delivery and expression of CFTR in CF lungs is a viable and promising approach for treatment of the disease.

Delivery of purified, functional CFTR to epithelial cells in vitro using influenza hemagglutinin

To assess the feasibility of protein replacement as a potential therapy for cystic fibrosis, we have evaluated the ability of influenza hemagglutinin (HA) to mediate the delivery of purified cystic fibrosis transmembrane conductance regulator (CFTR) to recipient cells in vitro. CFTR was purified from both CHO cells and Sf9 cells and reconstituted into two different types of vesicular delivery vehicles. In one, CFTR and HA were co-reconstituted into the same lipid vesicle. After binding to the cell surface, delivery of CFTR to the recipient cell was achieved by a transient, low-pH activation of the fusion activity of HA. A second delivery strategy used HA virosomes together with purified CFTR that had been reconstituted into vesicles containing gangliosides, a receptor for HA. After binding of the HA virosomes and CFTR-containing vesicles to the recipient cells, delivery to the plasma membrane again was achieved by a transient pH drop. Delivery of functional CFTR was assessed using the SPQ fluorescence assay. Functional CFTR was detected in a fraction (> 20%) of the recipient cells using this assay. Quantitative binding and fusion assays using radiolabeled virosomes and lipid vesicles showed that on the order of 1,000 of the added CFTR-containing vesicles bound to each C127 cell under the conditions of our delivery protocols. However, only a fraction of these vesicles fused and delivered CFTR to the cell plasma membrane. The two delivery strategies were found to be approximately equivalent in their ability to deliver active CFTR, and there were no significant differences between deliveries using purified CFTR from either cell source. These feasibility studies suggest that purified CFTR can be delivered to a recipient cell in a functional form and therefore represent a significant step in establishing the concept of protein replacement as a therapy for cystic fibrosis.

Purification and characterization of recombinant cystic fibrosis transmembrane conductance regulator from Chinese hamster ovary and insect cells

We have developed procedures to purify highly functional recombinant cystic fibrosis transmembrane conductance regulator (CFTR) from Chinese hamster ovary (CHO) cells to high homogeneity. Purification of CHO-CFTR was achieved using a combination of alkali stripping, alpha-lysophosphatidylcholine extraction, DEAE ion-exchange, and immunoaffinity chromatography. Insect CFTR from Sf9 cells was purified using a modification of the method of Bear et al. (Bear, C. E., Li, C., Kartner, N., Bridges, R. J., Jensen, T. J., Ramjeesingh, M. and Riordan, J. R. (1992) Cell 68, 809-818), which included extraction with sodium dodecyl sulfate, hydroxyapatite, and gel filtration chromatography. Characterization of the properties of purified CFTR from both cell sources using a variety of electrophysiological and biochemical assays indicated that they were very similar. Both the purified CHO-CFTR and Sf9-CFTR when reconstituted into planar lipid bilayers exhibited a low pS, chloride-selective ion channel activity that was protein kinase A- and ATP-dependent. Both the purified CHO-CFTR and Sf9-CFTR were able to interact specifically with the nucleotide photoanalogue 8-N3-[alpha-32P]ATP with half-maximal binding at 25 and 50 microM, respectively. These values compare well with those reported for 8-N3-[alpha-32P]ATP binding to CFTR in its native membrane form. Thus CFTR from either insect or CHO cells can be purified to high homogeneity with retention of many of the biochemical and electrophysiological characteristics of the protein associated in its native plasma membrane form. The availability of these reagents will facilitate further investigation and study of the structure and function of CFTR and its interactions with cellular proteins.