Aerosol delivery of recombinant human DNase I: in vitro comparison of a vibrating-mesh nebulizer with a jet nebulizer.

BACKGROUND: Inhaled recombinant human DNase I (rhDNase) improves clearance of visco-elastic secretions in patients with cystic fibrosis. Because of their portability, newer-generation vibrating-mesh nebulizers offer greater convenience for the patient, but their efficiency in delivering rhDNase has not been determined. METHODS: We compared a newer-generation vibrating-mesh nebulizer (Omron MicroAir) to a Pari LC+ with the Pari ProNeb Ultra compressor (a commonly employed rhDNase administration system). With the Next Generation Pharmaceutical Impactor, we determined aerosol particle distribution. We also measured mass output efficiency, nebulization time, and mass of rhDNase that deposited on a filter during simulated breathing. RESULTS: The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of aerosol from the MicroAir (MMAD 4.3 microm, GSD 2.8 microm) was equivalent to that from the Pari LC+ (MMAD 4.2 microm, GSD 2.7 microm). During simulated breathing the MicroAir had a higher total mass output efficiency (88%) than the Pari LC+ (68%) (P < .001), and total nebulization time was shorter with the MicroAir (6.1 min vs 7.2 min, P = .03). When nebulized to dryness, the mass of rhDNase delivered to the filter was comparable with the MicroAir (1.30 +/- 0.4 mg) and Pari LC+ (1.21 +/- 0.05 mg). CONCLUSION: The MicroAir could be employed as a portable nebulizer for rhDNase therapy in patients with cystic fibrosis.

Nebulized drug admixtures: effect on aerosol characteristics and albuterol output.

Although not recommended, co-administration of drugs separately prescribed for nebulization is done in real life. The impact of this practice on drug output and aerosol characteristics is poorly understood. We studied the effect of drug admixtures (DA) on aerosol characteristics and drug output of nebulized albuterol delivered by a continuous output (CONT) and a breath enhanced nebulizer (BEN). Albuterol was nebulized alone (ALB) and combined with cromolyn sodium (A+CRO), ipratropium bromide (A+IB), tobramycin (A+TOB), flunisolide (A+FLU), and n-acetylcysteine (A+NAC). A BEN (PARI LC Plus) and a CONT (Hudson T UP-DRAFT II) were tested at 8 liters per minute (Lpm) for 2 and 5 min, respectively. Albuterol output and aerosol characteristics were determined by impaction and chemical analysis. Mass median aerodynamic diameter (MMAD; microm) A+CRO reduced MMAD from 2.57 (ALB) to 1.29 with CONT. A+FLU increased MMAD from 2.71 (ALB) to 3.40 with BEN. Geometric standard deviation (GSD) A+CRO increased GSD from 2.66 (ALB) to 3.36 with CONT. GSD was 2.33 for ALB and was not changed by DA with BEN. BEN generated a smaller and less heterodisperse aerosol than CONT. Respirable fraction (RF%) was 74% for ALB and was not changed by DA with CON. A+TOB and A+FLU decreased RF% from 75%, to 70% and 67% (respectively) with BEN. Respirable mass (RM; microg) for ALB was 935 and was not changed by DA with CONT. A+IB and A+FLU increased RM from 917 (ALB) to 1172 and 1240, respectively, with BEN. Co-nebulization of albuterol with other drugs can affect its output and aerosol characteristics. In vivo data is needed to asses the clinical implications of our findings.

Aerosol delivery of PEI-p53 complexes inhibits B16-F10 lung metastases through regulation of angiogenesis.

Inhibition of pulmonary metastases poses a difficult clinical challenge for current therapeutic regimens. We have developed an aerosol system utilizing a cationic polymer, polyethyleneimine (PEI), for topical gene delivery to the lungs as a novel approach for treatment of lung cancer. Using a B16-F10 murine melanoma model in C57BL/6 mice, we previously demonstrated that aerosol delivery of PEI-p53 DNA resulted in highly significant reductions in the tumor burden (P < .001) in treated animals, and also lead to about 50% increase in the mean length of survival of the mice-bearing B16-F10 lung tumors. The mechanisms of this antitumor effect of p53 are investigated in this report. Here, we demonstrate that the p53 transfection leads to an up-regulation of the antiangiogenic factor thrombospondin-1 (TSP-1) in the lung tissue and the serum of the mice. Furthermore, there is a down-regulation of vascular endothelial growth factor (VEGF) in the lung tissue and serum of the B16-F10 tumor-bearing mice treated with PEI-p53 DNA complexes, compared with untreated tumor-bearing animals. In addition, staining for von Willebrand factor (vWF), a marker for the angiogenic blood vessels, revealed that p53 treatment leads to a decrease in the angiogenic phenotype of the B16-F10 tumors. Immunohistochemistry for transgene expression reveals that the PEI-p53 aerosol complexes transfect mainly the epithelial cells lining the airways, with diffuse transfection in the alveolar lining cells, as well as, the tumor foci in the lung tissue. There was also some evidence of apoptosis in the lung tumor foci of animals treated with p53. The data suggest that aerosol delivery of PEI-p53 complexes leads to inhibition of B16-F10 lung metastases, in part by suppression of angiogenesis.

Aerosol gene therapy.

Gene therapy is a novel field of medicine that holds tremendous therapeutic potential for a variety of human diseases. Targeting of therapeutic gene delivery vectors to the lungs can be beneficial for treatment of various pulmonary diseases such as lung cancer, cystic fibrosis, pulmonary hypertension, alpha-1 antitrypsin deficiency, and asthma. Inhalation therapy using formulations delivered as aerosols targets the lungs through the pulmonary airways. The instant access and the high ratio of the drug deposited within the lungs noninvasively are the major advantages of aerosol delivery over other routes of administration. Delivery of gene formulations via aerosols is a relatively new field, which is less than a decade old. However, in this short period of time significant developments in aerosol delivery systems and vectors have resulted in major advances toward potential applications for various pulmonary diseases. This article will review these advances and the potential future applications of aerosol gene therapy technology.

Alveolar fractal box dimension inversely correlates with mean linear intercept in mice with elastase-induced emphysema.

RATIONALE: A widely applicable model of emphysema that allows efficient and sensitive quantification of injury is needed to compare potential therapies. OBJECTIVES: To establish such a model, we studied the relationship between elastase dose and the severity of emphysema in female C57BL/6J mice. We compared alveolar fractal box dimension (D(B)), a new measure which is an assessment of the complexity of the tissue, with mean linear intercept (L(m)), which is commonly used to estimate airspace size, for sensitivity and efficiency of measurement. METHODS: Emphysema was induced in female C57BL/6J mice by administering increasing intratracheal doses of porcine pancreatic elastase (PPE). Changes in morphology and static lung compliance (C(L)) were examined 21 days later. Correlation of D(B) with L(m) was determined in histological sections of lungs exposed to PPE. The inverse relationship between D(B) and L(m) was supported by examining similar morphological sections from another experiment where the development of emphysema was studied 1 to 3 weeks after instillation of human neutrophil elastase (HNE). RESULTS: L(m) increased with PPE dose in a sigmoidal curve. C(L) increased after 80 or 120 U/kg body weight (P < 0.05), but not after 40 U/kg, compared with the control. D(B) progressively declined from 1.66 ± 0.002 (standard error of the mean) in controls, to 1.47 ± 0.006 after 120 U PPE/kg (P < 0.0001). After PPE or HNE instillation, D(B) was inversely related to L(m) (R = -0.95, P < 0.0001 and R = -0.84, P = 0.01, respectively), with a more negative slope of the relationship using HNE (P < 0.0001). CONCLUSION: Intratracheal instillation of increasing doses of PPE yields a scale of progression from mild to severe emphysema. D(B) correlates inversely with L(m) after instillation of either PPE or HNE and yields a rapid, sensitive measure of emphysema after elastase instillation.

Targeted combined aerosol chemotherapy in dogs and radiologic toxicity grading.

BACKGROUND: We investigated whether combination chemotherapy, targeted with the AeroProbe® Intracorporeal Nebulizing Catheter (INC), could be safely administered, and developed a radiologic grading scheme to monitor subclinical effects on the lungs. METHODS: In anesthetized and mechanically ventilated healthy dogs (n = 3), we introduced the INC via a flexible bronchoscope into the right caudal lung lobe and administered escalating dosages of gemcitabine (1, 2, 3, or 6 mg/kg) followed by cisplatin (10 mg/m(2)). Treatments were performed every 2 weeks for 4 treatments and dogs were monitored weekly with physical examination, biochemical tests, and thoracic radiographs. Dogs were sacrificed 2 weeks after the final treatment and tissues examined histologically. A radiologic grading scheme was developed to monitor subclinical pulmonary toxicity. RESULTS: No significant side effects occurred in any dog. All dogs developed focal pneumonitis radiographically, and chronic, severe pneumonia with fibrosis histologically limited to the treated portion of the lung. Radiologic scores increased over time following increasing doses of chemotherapy. CONCLUSIONS: Targeted aerosol delivery of gemcitabine and cisplatin by INC was clinically well tolerated. This minimally invasive method is promising for lung cancer treatment, especially given the lack of clinical toxicity. The proposed radiologic grading scheme provides a method to monitor subclinical local drug toxicity.

Increasing p53 protein sensitizes non-small cell lung cancer to paclitaxel and cisplatin in vitro.

AIM: To determine whether increasing p53 protein levels confers enhanced chemosensitivity in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Three NSCLC cell lines, with different endogenous p53 expression, were transfected with wild-type p53 (wt-p53) or CD-1 (truncated wt-p53) genes. Cells were subsequently treated with cisplatin (CDDP) or paclitaxel (PAX). Cell viability was measured using Alamar Blue Assay. RESULTS: Cells transfected with CD-1 expressed 13-38% higher levels of p53 protein compared to cells transfected with the wt-p53 gene, despite their baseline endogenous levels. CD-1-transfected cells also had higher cell death when treated with CDDP (p<0.05) or PAX, exhibiting 30-60% higher death rates than cells transfected with the wt-p53 gene and 130-160% higher than untransfected cells. A significant positive correlation between p53 protein concentration and cytotoxic response was demonstrated (R(2) for CDDP=0.823; R(2) for PAX=0.909; p<0.001). CONCLUSION: Increasing intracellular p53 protein concentrations can augment the effect of CDDP and PAX in NSCLC, despite the baseline level of p53 protein expression.

Feasibility and safety of targeted cisplatin delivery to a select lung lobe in dogs via the AeroProbe intracorporeal nebulization catheter.

Delivery of drugs by airway can minimize systemic toxicity and maximize local drug concentrations. Most cancers metastasize to the lungs. Our purpose was to determine platinum concentrations in the lung after targeted delivery of cisplatin (CDDP) with an intracorporeal nebulizing catheter (INC), and to determine the safety of escalating doses of inhaled CDDP. In anesthetized and mechanically ventilated healthy dogs, the INC (AeroProbe) was introduced via flexible bronchoscope into the right caudal lung lobe (RCLL) and CDDP (10 mg/m2) administered. Tissue and serum platinum concentrations were compared to those after an equivalent intravenous dose of CDDP (n = 3 dogs/group). In three additional dogs, pharmacokinetics were performed after inhaled and intravenous CDDP. Increasing dosages of inhaled CDDP (10, 15, 20, and 30 mg/m2) were then administered every 2 weeks. Dogs were sacrificed for postmortem examination at week 10. One additional dog was treated with a single dose of 30 mg/m2 and sacrificed 2 weeks later. Immediately following a single inhaled dose, mean CDDP levels were 44 times greater in the RCLL than in most other tissues and 15.6 times lower in the serum compared to intravenous dosing. Pharmacokinetic comparison showed that the AUC0-24h was similar (p = 0.72), but maximum serum concentration was fivefold lower after inhalation than intravenous delivery (p = 0.02). Escalating doses of inhaled CDDP (cumulative 75 mg/m2) produced no significant clinical or hematological effects, but there was radiographic and histologic evidence of severe pneumonitis with mild to moderate fibrosis confined to the RCLL. Radiographic and histologic changes were similar in the single, high-dose dog. Targeted inhaled CDDP achieved high concentrations in the treated lobe, with lower peak serum levels than after intravenous administration. Escalating doses of inhaled CDDP produced focal pneumonitis and fibrosis in the treated lung lobe with minimal clinical and hematologic effects. Targeted inhaled chemotherapy could be a promising method of treatment for primary and secondary lung tumors.