Balloon neck-plasty to create a wide-necked aneurysm in the elastase-induced rabbit model.

PURPOSE: The elastase-induced aneurysm (EIA) model in rabbits has been proposed for translational research; however, the adjustment of aneurysm neck size remains challenging. In this study, the technical feasibility and safety of balloon neck-plasty to create a wide-necked aneurysm in rabbit EIA model were investigated. METHODS: Male New Zealand White rabbits (N = 15) were randomly assigned to three groups: group A, EIA creation without neck-plasty; group B, neck-plasty immediately after EIA creation; group C, neck-plasty 4 weeks after EIA creation. The diameter of balloon used for neck-plasty was determined 1 mm larger than origin carotid artery diameter. All rabbits were euthanized 4 weeks after their final surgery. Aneurysm neck, height, dome-to-neck (D/N) ratio, and histologic parameters were compared among the groups. RESULTS: Aneurysm creation was technically successful in 14 out of 15 rabbits (93.3%), with one rabbit experiencing mortality due to an adverse anesthetic event during the surgery. Saccular and wide-necked aneurysms were successfully created in all rabbits. Aneurysm neck was significantly greater in groups B and C compared to group A (all P < .05). D/N ratio was significantly lower in groups B and C compared to group A (all P < .05). Additionally, tunica media thickness, vessel area, and luminal area were significantly greater in groups B and C compared to group A (all P < .05). These variables were found to be significantly greater in group B compared to group C (all P < .05). CONCLUSION: The creation of a wide-necked aneurysm using balloon neck-plasty after elastase induction in rabbits has been determined to be technically feasible and safe.

Mouse Abdominal Aortic Aneurysm Model Induced by Periarterial Incubation of Papain.

For decades, numerous experimental animal models have been developed to examine the pathophysiologic mechanisms and potential treatments for abdominal aortic aneurysms (AAAs) in diverse species with varying chemical or surgical approaches. This study aimed to create an AAA mouse model by the periarterial incubation with papain, which can mimic human AAA with advantages such as simplicity, convenience, and high efficiency. Eighty C57BL/6J male mice were randomly assigned to 1 of the 4 groups: papain (1.0 or 2.0 mg), porcine pancreatic elastase, and phosphate-buffered solution. The aortic segment was wrapped for 20 minutes, and the diameter was measured using ultrasound preoperatively and postoperative days 7 and 14. Then, the mice were killed for histomorphometric and immunohistochemical analyses. According to ultrasound measurements and histomorphometric analyses, on postoperative day 7, 65% of mice in the 1.0-mg papain group and 60% of mice in the 2.0-mg papain group developed AAA. In both papain groups, 100% of mice developed AAA, and 65% of mice in the porcine pancreatic elastase group developed AAA on postoperative day 14. Furthermore, hematoxylin/eosin, elastin van Gieson, and Masson staining of tissues from the papain group revealed thickened media and intimal hyperplasia, collagen sediments, and elastin destruction, indicating that AAA histochemical alteration was similar to that of humans. In addition, the immunohistochemical analysis was conducted to detect infiltrated inflammatory cells, such as macrophages and leukocytes, in the aortic wall and hyperplasic adventitia. The expression of matrix metalloproteinase 2 and 9 was significantly upregulated in papain and human AAA tissues. Periarterial incubation with 1.0 mg of papain for 20 minutes can successfully create an experimental AAA model in mice for 14 days, which can be used to explore the mechanism and treatment of human AAA.

Fibroblast growth factor 10 reverses cigarette smoke- and elastase-induced emphysema and pulmonary hypertension in mice.

BACKGROUND: COPD is an incurable disease and a leading cause of death worldwide. In mice, fibroblast growth factor (FGF)10 is essential for lung morphogenesis, and in humans, polymorphisms in the human FGF10 gene correlate with an increased susceptibility to develop COPD. METHODS: We analysed FGF10 signalling in human lung sections and isolated cells from healthy donor, smoker and COPD lungs. The development of emphysema and PH was investigated in Fgf10+/- and Fgfr2b+/- (FGF receptor 2b) mice upon chronic exposure to cigarette smoke. In addition, we overexpressed FGF10 in mice following elastase- or cigarette smoke-induced emphysema and pulmonary hypertension (PH). RESULTS: We found impaired FGF10 expression in human lung alveolar walls and in primary interstitial COPD lung fibroblasts. In contrast, FGF10 expression was increased in large pulmonary vessels in COPD lungs. Consequently, we identified impaired FGF10 signalling in alveolar walls as an integral part of the pathomechanism that leads to emphysema and PH development: mice with impaired FGF10 signalling (Fgf10+/- and Fgfr2b+/- ) spontaneously developed lung emphysema, PH and other typical pathomechanistic features that generally arise in response to cigarette smoke exposure. CONCLUSION: In a therapeutic approach, FGF10 overexpression successfully restored lung alveolar and vascular structure in mice with established cigarette smoke- and elastase-induced emphysema and PH. FGF10 treatment triggered an initial increase in the number of alveolar type 2 cells that gradually returned to the basal level when the FGF10-mediated repair process progressed. Therefore, the application of recombinant FGF10 or stimulation of the downstream signalling cascade might represent a novel therapeutic strategy in the future.

A randomized trial of vonapanitase (PATENCY-1) to promote radiocephalic fistula patency and use for hemodialysis.

OBJECTIVE: Arteriovenous fistulas created in patients with chronic kidney disease often lose patency and fail to become usable. This prospective trial evaluated the efficacy of vonapanitase, a recombinant human elastase, in promoting radiocephalic fistula patency and use for hemodialysis. METHODS: PATENCY-1 was a double-blind, placebo-controlled trial that enrolled 349 patients on or approaching hemodialysis and being evaluated for radiocephalic arteriovenous fistula creation. Of these, 313 were randomized and 311 treated. Patients were assigned to vonapanitase (n = 210) or placebo (n = 103). The study drug solution was applied topically to the artery and vein for 10 minutes immediately after fistula creation. The primary and secondary end points were primary patency (time to first thrombosis or corrective procedure) and secondary patency (time to abandonment). Tertiary end points included use of the fistula for hemodialysis, fistula maturation by ultrasound, and procedure rates. RESULTS: The Kaplan-Meier estimates of 12-month primary patency were 42% (95% confidence interval [CI], 35-49) and 31% (95% CI, 21-42) for vonapanitase and placebo (P = .25). The Kaplan-Meier estimates of 12-month secondary patency were 74% (95% CI, 68-80) and 61% (95% CI, 51-71) for vonapanitase and placebo (P = .048). The proportions of vonapanitase and placebo patients were 39% and 25% (P = .035) with unassisted use for hemodialysis and 64% and 44% (P = .006) with unassisted plus assisted use. CONCLUSIONS: Vonapanitase treatment did not significantly improve primary patency but was associated with increased secondary patency and use for hemodialysis. Further research is needed to evaluate these end points.

Varenicline is a smoking cessation drug that blocks alveolar expansion in mice intratracheally administrated porcine pancreatic elastase.

Smoking cessation is the most effective treatment in patients with emphysema and lung inflammation. The aim of the present study was to examine the effect of varenicline, a smoking cessation drug, on emphysema in porcine pancreatic elastase (PPE)-inhaled mice. PPE-inhaled mice were treated with varenicline and an α7 nicotinic acetylcholine receptor (nAChR) antagonist, methyllycaconitine (MLA) for 5 and 21 days. Varenicline markedly ameliorated alveolar expansion and inflammatory response in bronchoalveolar lavage fluid in PPE-inhaled mice. These blocking effects were inhibited by MLA. Our findings demonstrate that varenicline likely has an anti-inflammatory property including reduced inflammatory cell recruitment in lung tissue to protect PPE-induced alveolar expansion via α7 nAChR.

Emphysema induced by elastase alters the mRNA relative levels from DNA repair genes in acute lung injury in response to sepsis induced by lipopolysaccharide administration in Wistar rats.

Purpose/Aim of the study: Patients suffering from chronic obstructive pulmonary disease (COPD) in association with acute respiratory distress syndrome (ARDS) present oxidative stress in lung cells, with production of free radicals and DNA lesions in pulmonary and adjacent cells. Once the DNA molecule is damaged, a set of enzymatic mechanisms are trigged to preserve genetic code integrity and cellular homeostasis. These enzymatic mechanisms include the base and the nucleotide excision repair pathways, as well as telomere regulation. Thus, the aim of this work was to evaluate the mRNA levels from APEX1, ERCC2, TP53, and TRF2 genes in lung tissue from Wistar rats affected by acute lung injury in response to sepsis and emphysema. MATERIALS AND METHODS: Adult male Wistar rats were randomized into 4 groups (n = 6, for each group): control, emphysema, sepsis, and emphysema with sepsis. Pulmonary emphysema was induced by intratracheal instillation of elastase (12 IU/animal) and sepsis induced by intraperitoneal Escherichia coli lipopolysaccharide (LPS) injection (10 mg/kg). Lungs were removed, and samples were withdrawn for histological analysis and total RNA extraction, cDNA synthesis, and mRNA level evaluation by real time quantitative polymerase chain reaction. RESULTS: Data show acute lung injury by LPS and emphysema by elastase and that APEX1, ERCC2, TP53, and TRF2 mRNA levels are increased significantly (p < 0.01) in emphysema with sepsis group. CONCLUSION: Our results suggest that alteration in mRNA levels from DNA repair and genomic stability could be part of cell response to acute lung injury in response to emphysema and sepsis.

Arteriovenous fistula patency in the 3 years following vonapanitase and placebo treatment.

OBJECTIVE: This study explored the long-term outcomes of arteriovenous fistulas treated with vonapanitase (recombinant human elastase) at the time of surgical creation. METHODS: This was a randomized, double-blind, placebo-controlled trial of 151 patients undergoing radiocephalic or brachiocephalic arteriovenous fistula creation who were randomized equally to placebo, vonapanitase 10 µg, or vonapanitase 30 µg. The results after 1 year of follow-up were previously reported. The current analysis occurred when the last patient treated was observed for 3 years. For the current analysis, the primary end point was primary patency; the secondary end points included secondary patency, use of the fistula for hemodialysis, and rate of procedures to restore or to maintain patency. RESULTS: There was no significant difference in the risk of primary patency loss with vonapanitase 10 µg or 30 µg vs placebo. When seven initial patency loss events related to cephalic arch and central vein balloon angioplasty were excluded, the risk of patency loss was reduced with vonapanitase overall (hazard ratio [HR], 0.63; P = .049) and 30 µg (HR, 0.51; P = .03). In patients with radiocephalic fistulas (n = 67), the risks of primary and secondary patency loss were reduced with 30 µg (HR, 0.37 [P = .02] and 0.24 [P = .046], respectively). The rate of procedures to restore or to maintain fistula patency was reduced with 30 µg vs placebo (0.23 vs 0.72 procedure days/patient/year; P = .03) and also reduced in patients with radiocephalic fistulas with 30 µg vs placebo (0.17 vs 0.85 procedure days/patient/year; P = .048). CONCLUSIONS: In this study, vonapanitase did not significantly improve primary patency in the primary analysis but did significantly improve primary patency in an analysis that excluded patency loss due to cephalic arch and central vein balloon angioplasty. In patients with radiocephalic fistulas, 30 µg significantly improved primary and secondary patency. Vonapanitase 30 µg decreased the rate of procedures to restore or to maintain patency in the analysis that included all patients and in the subset with radiocephalic fistulas.

Emphysema induced by elastase enhances acute inflammatory pulmonary response to intraperitoneal LPS in rats.

Abnormalities in lungs caused by emphysema might alter their response to sepsis and the occurrence of acute lung injury (ALI). This study compared the extension of ALI in response to intraperitoneal lipopolysaccharide (LPS) injection in Wistar rats with and without emphysema induced by elastase. Adult male Wistar rats were randomized into four groups: control, emphysema without sepsis, normal lung with sepsis and emphysema with sepsis. Sepsis was induced, and 24 h later the rats were euthanised. The following analysis was performed: blood gas measurements, bronchoalveolar lavage (BAL), lung permeability and histology. Animals that received LPS showed significant increase in a lung injury scoring system, inflammatory cells in bronchoalveolar lavage (BAL) and IL-6, TNF-α and CXCL2 mRNA expression in lung tissue. Animals with emphysema and sepsis showed increased alveolocapillary membrane permeability, demonstrated by higher BAL/serum albumin ratio. In conclusion, the presence of emphysema induced by elastase increases the inflammatory response in the lungs to a systemic stimulus, represented in this model by the intraperitoneal injection of LPS.

Structurally Related Monoterpenes p-Cymene, Carvacrol and Thymol Isolated from Essential Oil from Leaves of Lippia sidoides Cham. (Verbenaceae) Protect Mice against Elastase-Induced Emphysema.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow obstruction and inflammation. Natural products, such as monoterpenes, displayed anti-inflammatory and anti-oxidant activities and can be used as a source of new compounds to COPD treatment. Our aim was to evaluate, in an elastase-induced pulmonary emphysema in mice, the effects of and underlying mechanisms of three related natural monoterpenes (p-cymene, carvacrol and thymol) isolated from essential oil from leaves Lippia sidoides Cham. (Verbenaceae). METHODS: Mices received porcine pancreatic elastase (PPE) and were treated with p-cymene, carvacrol, thymol or vehicle 30 min later and again on 7th, 14th and 28th days. Lung inflammatory profile and histological sections were evaluated. RESULTS: In the elastase-instilled animals, the tested monoterpenes reduced alveolar enlargement, macrophages and the levels of IL-1ß, IL-6, IL-8 and IL-17 in bronchoalveolar lavage fluid (BALF), and collagen fibers, MMP-9 and p-65-NF-κB-positive cells in lung parenchyma (p < 0.05). All treatments attenuated levels of 8-iso-PGF2α but only thymol was able to reduced exhaled nitric oxide (p < 0.05). CONCLUSION: Monoterpenes p-cymene, carvacrol and thymol reduced lung emphysema and inflammation in mice. No significant differences among the three monoterpenes treatments were found, suggesting that the presence of hydroxyl group in the molecular structure of thymol and carvacrol do not play a central role in the anti-inflammatory effects.

Inhibiting the Th17/IL-17A-related inflammatory responses with digoxin confers protection against experimental abdominal aortic aneurysm.

OBJECTIVE: T helper 17 cells and interleukin-17A have been implicated in the progression of abdominal aortic aneurysm (AAA). Retinoic acid-related orphan receptor gamma thymus, the master transcription factor of T helper 17 cell differentiation, is selectively antagonized by digoxin. However, the effect of antagonizing retinoic acid-related orphan receptor gamma thymus on AAA has not been investigated. APPROACH AND RESULTS: We used human aortic sample analysis and 2 different experimental AAA models: (a) Angiotensin II (Ang II)-induced ApoE(-/-) male mice (Ang II/APOE model) and (b) porcine pancreatic elastase perfusion C57BL/6 mice (porcine pancreatic elastase/C57 model). In the Ang II/APOE model, all mice (n=80) were divided into 4 groups: sham group (saline+0.5% dimethyl sulfoxide treatment), control group (Ang II+0.5% dimethyl sulfoxide treatment), low-dose group (Ang II+low-dose digoxin, 20 µg/d per mouse), and high-dose group (Ang II+high-dose digoxin, 40 µg/d per mouse). All treatments began on day 0 after surgery. Efficacy was determined via aortic diameter and systolic blood pressure measurements, histopathology and protein expression, and flow cytometry analysis when euthenized. Human aortic tissue analysis showed that both interleukin-17A and retinoic acid-related orphan receptor gamma thymus increased in AAA tissues. The low-dose and high-dose groups had AAA incidences of 60% and 35%, respectively, compared with 70% in the control group. The T helper 17- and interleukin-17A-related inflammatory responses were dose-dependently attenuated by digoxin treatment. Digoxin was also highly effective in the porcine pancreatic elastase/C57 model. CONCLUSIONS: Digoxin attenuates experimental AAA progression in a model-independent manner. Antagonizing retinoic acid-related orphan receptor gamma thymus activity by digoxin may become a novel strategy for nonsurgical AAA treatment.

Elevated permeability of the blood-brain barrier in mice intratracheally administered porcine pancreatic elastase.

Chronic obstructive pulmonary disease (COPD) shows progressive, irreversible airflow limitation induced by emphysema and lung inflammation. The aim of the present study was to determine if COPD conditions induce blood-brain barrier (BBB) dysfunction. We found that the intratracheal administration of porcine pancreatic elastase (PPE; 3 U) induced alveolar enlargement, increased neutrophil number in bronchoalveolar lavage fluid, and decreased blood oxygen saturation in mice at 21 days after inhalation. In parallel with these lung damages, BBB permeability to sodium fluorescein and Evans blue albumin was markedly increased. Our findings demonstrate that COPD conditions are associated with risk for BBB impairment.

Ceramides: a potential therapeutic target in pulmonary emphysema.

BACKGROUND: The aim of this manuscript was to characterize airway ceramide profiles in a rodent model of elastase-induced emphysema and to examine the effect of pharmacological intervention directed towards ceramide metabolism. METHODS: Adult mice were anesthetized and treated with an intratracheal instillation of elastase. Lung function was measured, broncho-alveolar lavage fluid collected and histological and morphometrical analysis of lung tissue performed within 3 weeks after elastase injection, with and without sphingomyelinase inhibitors or serine palmitoyltransferase inhibitor. Ceramides in broncho-alveolar lavage (BAL) fluid were quantified by tandem mass spectrometry. RESULTS: BAL fluid showed a transient increase in total protein and IgM, and activated macrophages and neutrophils. Ceramides were transiently upregulated at day 2 after elastase treatment. Histology showed persistent patchy alveolar destruction at day 2 after elastase installation. Acid and neutral sphingomyelinase inhibitors had no effect on BAL ceramide levels, lung function or histology. Addition of a serine palmitoyltransferase inhibitor ameliorated lung function changes and reduced ceramides in BAL. CONCLUSIONS: Ceramides were increased during the acute inflammatory phase of elastase-induced lung injury. Since addition of a serine palmitoyltransferase inhibitor diminished the rise in ceramides and ameliorated lung function, ceramides likely contributed to the early phase of alveolar destruction and are a potential therapeutic target in the elastase model of lung emphysema.

Measurement of quantifiable parameters by time-density curves in the elastase-induced aneurysm model: first results in the comparison of a flow diverter and a conventional aneurysm stent.

BACKGROUND: Quantifiable parameters to evaluate the effectiveness of flow diverters (FDs) are desirable. We measured time-density curves (TDCs) and calculated quantifiable parameters in the rabbit elastase-induced aneurysm model after stent (Neuroform [NF]) and FD (Pipeline embolisation device [PED]) treatment. METHODS: Sixteen rabbit elastase-induced aneurysms were treated with FD (n = 9) or NF (n = 5). Angiography was performed before and after treatment and TDCs were created. The time to peak (TTP), the full width at half maximum (FWHM) and the average slope of the curve which represent the inflow (IF) and outflow (OF) were calculated. RESULTS: Mean values before treatment were TTP = 0.8 s, FWHM = 1.2 s, IF = 153.5 and OF = -54.9. After PED treatment, the TTP of 1.8 s and FWHM of 47.8 s were extended. The IF was 31.2 and the OF was -11.5 and therefore delayed. The values after NF treatment (TTP = 1.1 s, FWHM = 1.8 s, IF = 152.9, OF = -33.2) changed only slightly. CONCLUSION: It was feasible to create TDCs in the rabbit aneurysm model. Parameters describing the haemodynamic effect of PED and NF were calculated and were different according to the type of device used. These parameters could possibly serve as predictive markers for aneurysm occlusion.

Significance of matrix metalloproteinase-9 inhibition by imidapril for prevention of abdominal aortic aneurysms in angiotensin II type 1 receptor-knockout mice.

To clarify the matrix metalloproteinase (MMP)-9 inhibitory effect of an angiotensin-converting enzyme (ACE) inhibitor in vivo, we evaluated the effect of an ACE inhibitor against elastase-induced abdominal aortic aneurysm (AAA) progression in mice. Molecular models showed that imidapril bound directly to the mouse MMP-9 active center. An active form of imidapril, imidaprilat, dose-dependently inhibited MMP-9 activity in the extract from elastase-induced AAA in wild-type mice. Imidapril (10 mg/kg per day) was administered to wild-type or angiotensin II type 1 (AT1) receptor knockout mice. Blood pressure was significantly lower in AT1 receptor-knockout mice than in wild-type mice, but imidapril did not affect blood pressure in AT1 receptor-knockout mice. The aortic diameter was significantly expanded after elastase application, but the expansion was significantly lower in AT1 receptor-knockout mice than in wild-type mice. In AT1 receptor-knockout mice, the aortic expansion was further attenuated by imidapril. MMP-9 activity in aorta was significantly augmented after elastase application. The MMP-9 activity was significantly lower in AT1 receptor-knockout mice than in wild-type mice, and it was further attenuated by imidapril. In conclusion, MMP-9 inhibition by imidapril might contribute to the attenuation of AAA progression in AT1 receptor-knockout mice.

Development of a unilateral porcine emphysema model induced by porcine pancreatic elastase.

Emphysema is one of the pathological hallmarks of chronic obstructive pulmonary disease. We have recently reported that radiofrequency therapy improves lung function in rodent models of emphysema. However, preclinical data using large animals is necessary for clinical translation. Here, we describe the work performed to establish a unilateral porcine emphysema model. Different doses of porcine pancreatic elastase (PPE) were instilled into the left lung of 10 Yucatan pigs. Three additional pigs were used as controls. Six weeks after instillation, lungs were harvested. Lung compliance was measured by a water displacement method and plethysmography. Systematic uniform random sampling of the left and right lungs was performed independently to measure alveolar surface area using micro-computed tomography (micro-CT) and histology. In pigs instilled with 725-750 U/kg of PPE (PPE group, n = 6), the compliance of the left lung was significantly higher by 37.6% than that of the right lung (P = 0.03) using the water displacement method. With plethysmography, the volume of the left lung was significantly larger than that of the right lung at 3, 5, and 10 cmH2O. Measurements from either micro-CT or histology images showed a significant decrease in alveolar surface area by 14.2% or 14.5% (P = 0.031) in the left lung compared with the right lung of the PPE group. A unilateral model for mild emphysema in Yucatan pigs has been established, which can now be used for evaluating novel therapeutics and interventional strategies.NEW & NOTEWORTHY For clinical translation, preclinical data using large animal models is necessary. However, papers describing an emphysema model in pigs, which are anatomically and physiologically similar to humans, are lacking. Here, we report success in creating a unilateral mild-emphysema model in pigs with only one single dose of porcine pancreatic elastase. This model will be useful in bringing novel technologies and therapies from small animals to humans with emphysema.

Effects of elastase-induced emphysema on muscle and bone in mice.

Chronic obstructive pulmonary disease (COPD) causes sarcopenia and osteoporosis. However, the mechanisms underlying muscle and bone loss as well as the interactions between muscle and bone in the COPD state remain unclear. Therefore, we herein investigated the effects of the COPD state on muscle and bone in mice intratracheally administered porcine pancreatic elastase (PPE). The intratracheal administration of PPE to mice significantly reduced trabecular bone mineral density (BMD), trabecular bone volume, trabecular number, cortical BMD and cortical area. It also significantly decreased grip strength, but did not affect muscle mass or the expression of myogenic differentiation-, protein degradation- or autophagy-related genes in the soleus and gastrocnemius muscles. Among the myokines examined, myostatin mRNA levels in the soleus muscles were significantly elevated in mice treated with PPE, and negatively related to grip strength, but not bone parameters, in mice treated with or without 2 U PPE in simple regression analyses. Grip strength positively related to bone parameters in mice treated with or without PPE. In conclusion, we showed that a PPE model of COPD in mice exerts dominant effects on bone rather than skeletal muscles. Increased myostatin expression in the soleus muscles of mice in the COPD state may negatively relate to a reduction in grip strength, but not bone loss.

A modified method of elastase-induced saccular aneurysm creation in rabbits: Schematic representation of the method.

BACKGROUND: The purpose of our study was to investigate the safety and effectiveness of a modified technique using a short guiding catheter for instillation of elastase in comparison with the previously described method of creating elastase-induced aneurysm in rabbits. METHODS: Following right common carotid artery (RCCA) access using an arterial sheath and inflating the Fogarty balloon in the subclavian artery, a short guiding catheter was used for the instillation of the elastase in the experimental group (n = 5) while it was performed with a microcatheter in the control group (n = 5). The procedure duration was recorded from the RCCA puncture to the sheath removal. The histological changes were characterized using H&E and Masson's trichrome (MT) staining. RESULTS: The procedure time was 23 ± 2 min in the experimental group and 29 ± 2 min in the control group. All the rabbits (100%) in the experimental group survived without neurologic deficits, but two rabbits (40%) survived in the control group. All aneurysms were created in the saccular shape (100%) with a neck size of 2.3 ± 0.29 mm, a width of 2.75 ± 0.36 mm, and height of 6.37 ± 0.46 mm, and a dome to neck ratio of 1.21 ± 0.23. The aneurysm walls were partly thickened due to the degradation of the media tunica and adventitia proliferation with loss of the internal elastic lamina. CONCLUSION: By using a short guiding catheter, we could instill the elastase in a more effective and safe manner in the creation of the elastase-induced aneurysm model in rabbits.

Intratracheally injected human-induced pluripotent stem cell-derived pneumocytes and endothelial cells engraft in the distal lung and ameliorate emphysema in a rat model.

OBJECTIVES: Pulmonary emphysema is characterized by the destruction of alveolar units and reduced gas exchange capacity. In the present study, we aimed to deliver induced pluripotent stem cell-derived endothelial cells and pneumocytes to repair and regenerate distal lung tissue in an elastase-induced emphysema model. METHODS: We induced emphysema in athymic rats via intratracheal injection of elastase as previously reported. At 21 and 35 days after elastase treatment, we suspended 80 million induced pluripotent stem cell-derived endothelial cells and 20 million induced pluripotent stem cell-derived pneumocytes in hydrogel and injected the mixture intratracheally. On day 49 after elastase treatment, we performed imaging, functional analysis, and collected lungs for histology. RESULTS: Using immunofluorescence detection of human-specific human leukocyte antigen 1, human-specific CD31, and anti--green fluorescent protein for the reporter labeled pneumocytes, we found that transplanted cells engrafted in 14.69% ± 0.95% of the host alveoli and fully integrated to form vascularized alveoli together with host cells. Transmission electron microscopy confirmed the incorporation of the transplanted human cells and the formation of a blood-air barrier. Human endothelial cells formed perfused vasculature. Computed tomography scans revealed improved vascular density and decelerated emphysema progression in cell-treated lungs. Proliferation of both human and rat cell was higher in cell-treated versus nontreated controls. Cell treatment reduced alveolar enlargement, improved dynamic compliance and residual volume, and improved diffusion capacity. CONCLUSIONS: Our findings suggest that human induced pluripotent stem cell-derived distal lung cells can engraft in emphysematous lungs and participate in the formation of functional distal lung units to ameliorate the progression of emphysema.

Annexin V decreases PS-mediated macrophage efferocytosis and deteriorates elastase-induced pulmonary emphysema in mice.

Efferocytosis is believed to be a key regulator for lung inflammation in chronic obstructive pulmonary disease. In this study we pharmacologically inhibited efferocytosis with annexin V and attempted to determine its impact on the progression of pulmonary emphysema in mouse. We first demonstrated in vitro and in vivo efferocytosis experiments using annexin V, an inhibitor for phosphatidylserine-mediated efferocytosis. We then inhibited efferocytosis in porcine pancreatic elastase (PPE)-treated mice. PPE-treated mice were instilled annexin V intranasally starting from day 8 until day 20. Mean linear intercept (Lm) was measured, and cell apoptosis was assessed in lung specimen obtained on day 21. Cell profile, apoptosis, and mRNA expression of matrix metalloproteinases (MMPs) and growth factors were evaluated in bronchoalveolar lavage (BAL) cells on day 15. Annexin V attenuated macrophage efferocytosis both in vitro and in vivo. PPE-treated mice had a significant higher Lm, and annexin V further increased that by 32%. More number of macrophages was found in BAL fluid in this group. Interestingly, cell apoptosis was not increased by annexin V treatment both in lung specimens and BAL fluid, but macrophages from mice treated with both PPE and annexin V expressed higher MMP-2 mRNA levels and had a trend for higher MMP-12 mRNA expression. mRNA expression of keratinocyte growth factor tended to be downregulated. We showed that inhibited efferocytosis with annexin V worsened elastase-induced pulmonary emphysema in mice, which was, at least partly, attributed to a lack of phenotypic change in macrophages toward anti-inflammatory one.

Cathepsin L activity is essential to elastase perfusion-induced abdominal aortic aneurysms in mice.

OBJECTIVE: The development of abdominal aortic aneurysms (AAA) requires extensive aortic wall matrix degradation. Human AAA lesions express high levels of cathepsin L (CatL), one of the most potent mammalian elastases. Whether this protease participates directly in AAA pathogenesis, however, is unknown. METHODS AND RESULTS: We generated experimental AAA with aortic elastase perfusion in mice and established an essential role of CatL in AAA formation. After 14 days postperfusion, most wild-type (Ctsl(+/+)) mice developed AAA, but none of the CatL-deficient (Ctsl(-/-)) mice did. AAA lesion macrophage contents, CD4(+) T cell numbers, CD31(+) and laminin-5 angiogenic fragment γ2(+) microvessel numbers, and elastin fragmentation were all significantly lower in Ctsl(-/-) mice than in Ctsl(+/+) mice. While lesions from Ctsl(-/-) mice contained fewer Ki67(+) proliferating cells than did Ctsl(+/+) mice, the absence of CatL did not affect lesion apoptotic cell contents or medial smooth-muscle cell loss significantly. Mechanistic studies indicated that the absence of CatL reduced lesion chemokine monocyte chemotactic protein-1 content, macrophage and T-cell in vitro transmigration, and angiogenesis, and altered the expression and activities of matrix metalloproteinases and other cysteinyl cathepsins in inflammatory cells, vascular cells, and AAA lesions. CONCLUSION: CatL contributes to AAA formation by promoting lesion inflammatory cell accumulation, angiogenesis, and protease expression.