Simon Ashiku

Cultured Chondrocytes Produce Injectable Tissue-Engineered Cartilage in Hydrogel Polymer

The purpose of this study was to determine if chondrocytes cultured through several subcultures at very low plating density would produce new cartilage matrix after being reimplanted in vivo with or without a hydrogel polymer scaffold. Chondrocytes were initially plated in low-density monolayer culture, grown to confluence, and passaged four times. After each passage cells were suspended in purified porcine fibrinogen and injected into the subcutaneous space of nude mice while simultaneously polymerizing with thrombin to reach a final concentration of 40 million cells/cc. Controls were made by injecting fresh, uncultured cells with fibrin polymer and by injecting the cultured cells in saline (without polymer). All samples were harvested at 6 weeks. When injected in polymer, both fresh cells and cells that had undergone only one passage in culture produced cartilaginous nodules. Cultured cells did not produce cartilage, regardless of length of time spent in culture, when injected without polymer. Cartilage was also not recovered from samples with cells kept in culture for longer than one passage, even when provided with a polymer matrix. All samples harvested were subjected to histological analysis and assayed for total DNA, glycosaminoglycan (GAG), and type II collagen. There was histological evidence of cartilage in the groups that used fresh cells and cultured cells suspended in fibrin polymer that only underwent one passage. No other group contained areas that would be consistent with cartilage histologically. All experimental samples had a higher percent of DNA than native swine cartilage, and there was no statistical difference between the DNA content of the groups containing cultured or fresh cells in fibrin polymer. Whereas the GAG content of native cartilage was 8.39% of dry weight and fresh cells in fibrin polymer was 12.85%, cultured cells in fibrin polymer never exceded the 2.48% noted from first passage cells. In conclusion, this study demonstrates that porcine chondrocytes that have been cultured in monolayer for one passage will produce cartilage in vivo when suspended in fibrin polymer.

Tracheobronchomalacia: Evolving role of dynamic multislice helical CT

Paired inspiratory and dynamic expiratory multislice CT imaging is a promising method for diagnosing TBM. A low-dose technique should be considered for the dynamic portion to reduce radiation exposure. Visual and quantitative analysis of the central airways provide a comprehensive assessment by allowing for the accurate diagnosis of TBM, determining its extent, assessing for predisposing conditions, and aiding selection of candidates for stent placement or tracheoplasty procedures. This technique can also be helpful for assessing response of airway dynamics following therapeutic intervention.

Tracheobronchoplasty for Severe Tracheobronchomalacia: A Prospective Outcome Analysis

RATIONALE Central airway stabilization with silicone stents can improve respiratory symptoms in patients with severe symptomatic tracheobronchomalacia (TBM) but is associated with a relatively high rate of complications. Surgery with posterior tracheobronchial splinting using a polypropylene mesh has also been used for this condition but to date has not been evaluated prospectively and objectively for patient outcomes. OBJECTIVES To evaluate the effect of surgical tracheobronchoplasty on symptoms, functional status, quality of life, lung function, and exercise capacity in patients with severe and symptomatic TBM. METHODS A prospective observational study in which baseline measurements were compared to those obtained 3 months after surgical tracheobronchoplasty. MEASUREMENTS AND MAIN RESULTS Of 104 referred patients to our complex airway center for severe TBM, 77 had baseline measurements. Of this group, 57 patients had severe malacia and underwent stent placement for central airway stabilization. Of those, 37 patients reported improvement in respiratory symptoms and 35 were considered for surgical tracheobronchoplasty. Two patients were excluded from surgery for medical reasons. Median age was 61 years (range, 39 to 83 years), 20 patients were men, 11 patients (31%) had COPD, 9 patients (26%) had asthma, and 4 patients (11%) had Mounier-Kuhn syndrome. Thirty-three patients (94%) presented with severe dyspnea, 26 patients (74%) with uncontrollable cough, and 18 patients (51%) reported recurrent pulmonary infections. Two patients (3%) presented with respiratory failure requiring mechanical ventilation. After surgery, quality of life scores improved in 25 of 31 patients (p < 0.0001), dyspnea scores improved in 19 of 26 patients (p = 0.007), functional status scores improved in 20 of 31 patients (p = 0.003), and mean exercise capacity improved in 10 patients (p = 0.012). CONCLUSIONS In experienced hands, surgical central airway stabilization with posterior tracheobronchial splinting using a polypropylene mesh improves respiratory symptoms, health-related quality of life, and functional status in highly selected patients with severe symptomatic TBM.

Effects of cell concentration and growth period on articular and ear chondrocyte transplants for tissue engineering.

This study determined the effects of chondrocyte source, cell concentration, and growth period on cartilage production when isolated porcine cells are injected subcutaneously in a nude mouse model. Chondrocytes were isolated from both ear and articular cartilage and were suspended in Hams F-12 medium at concentrations of 10, 20, 40, and 80 million cells per cubic centimeter. Using the nude mouse model, each concentration group was injected subcutaneously in 100-microl aliquots and was allowed to incubate for 6 weeks in vivo. In addition, cells suspended at a fixed concentration of 40 million cells per cubic centimeter were injected in 100-microl aliquots and were incubated for 1, 2, 3, 4, 5, 6, 9, and 12 weeks. Each concentration or time period studied contained a total of eight mice, with four samples harvested per mouse for a final sample size of 32 constructs. All neocartilage samples were analyzed by histologic characteristics, mass, glycosaminoglycan level, and DNA content. Control groups consisted of native porcine ear and articular cartilage. Specimen mass increased with increasing concentration and incubation time. Ear neocartilage was larger than articular neocartilage at each concentration and time period. At 40 million cells per cubic centimeter, both ear and articular chondrocytes produced optimal neocartilage, without limitations in growth. Specimen mass increased with incubation time up to 6 weeks in both ear and articular samples. No significant variations in glycosaminoglycan content were found in either articular or ear neocartilage, with respect to variable chondrocyte concentration or growth period. Although articular samples demonstrated no significant trends in DNA content over time, ear specimens showed decreasing values through 6 weeks, inversely proportional to increase in specimen mass. Although both articular and ear sources of chondrocytes have been used in past tissue-engineering studies with success, this study indicates that a suspension of ear chondrocytes injected into a subcutaneous location will produce biochemical and histologic data with greater similarity to those of native cartilage. The authors believe that this phenomenon is attributable to the local environment in which isolated chondrocytes from different sources are introduced. The subcutaneous environment of native ear cartilage accommodates subcutaneously injected ear chondrocyte transplants better than articular transplants. Native structural and biochemical cues within the local environment are believed to guide the proliferation of the differentiated chondrocytes.

Successful Treatment of Idiopathic Laryngotracheal Stenosis by Resection and Primary Anastomosis

We studied the early and long-term response of idiopathic laryngotracheal stenosis (ILTS) to treatment by 1-stage laryngotracheal or tracheal resection and reconstruction in 73 patients. Nineteen of the 72 (26%) noted no difference in their voices or any difficulty in breathing after reconstruction. Forty-seven (64%) described loss of ability to project their voices as loudly as before or noted some difficulty in singing as well as they did before. Five (7%) had various degrees of dyspnea or stridor on effort. One needed continued dilation. The median follow-up was 8 years. Surgical treatment gave good or excellent results in 90% of these patients with ILTS. Recurrence or progression of stenosis was not evident.

The Role of Surgery in N2 Non ^ Small Cell Lung Cancer

Historical series document the poor survival (7-16% at 5 years) for patients with N2-positive, stage IIIA non–small cell lung cancer (NSCLC) treated with primary surgery. In 1994, two small randomized trials showed the superiority of induction chemotherapy followed by surgery over surgery alone for stage IIIA NSCLC. These findings, as well as subsequent studies showing the superiority of chemoradiotherapy over chemotherapy alone in nonoperable stage III disease, prompted investigations of preoperative chemoradiotherapy for N2-positve patients. As induction therapy improved, the use of resection in stage IIIA NSCLC was called into question. An Intergroup trial addressing this issue randomized 392 patients to induction chemoradiotherapy followed by surgery versus definitive chemoradiotherapy. Surgery following induction chemoradiotherapy was associated with a significant improvement in progression-free survival and almost a 50% reduction in local failure. As distant relapse is common, survival is likely to be enhanced only in those patients who respond to the systemic arm of treatment. Identification of genetic or biochemical markers of response, minimally invasive techniques to pathologically restage, or improved statistical or chemosensitivity analyses are needed to enhance our ability to select patients who will benefit from resection.

Technical Aspects and Outcomes of Tracheobronchoplasty for Severe Tracheobronchomalacia

BACKGROUND Tracheobronchomalacia is an underrecognized cause of dyspnea, recurrent respiratory infections, and cough. Surgical stabilization with posterior membranous tracheobronchoplasty has been shown to be effective in selected patients with severe disease. This study examines the technical details and complications of this operation. METHODS A prospectively maintained database of tracheobronchomalacia patients was queried retrospectively to review all consecutive tracheobronchoplasties performed from October 2002 to June 2009. Posterior splinting was performed with polypropylene mesh. Patient demographics, surgical outcomes, and operative data were reviewed. RESULTS Sixty-three patients underwent surgical correction of tracheal and bilateral bronchial malacia. Twenty-three patients had chronic obstructive pulmonary disease, 18 had asthma, 5 had Mounier-Kuhn syndrome, and 4 had interstitial lung disease. Seven patients had a previous tracheotomy. Operative time was 373 ± 93 minutes. Median length of stay was 8 days (range, 4 to 92 days), of which 3 days (range, 0 to 91 days) were in intensive care. Seventy-five percent of patients were discharged home (28% with visiting nurse follow-up), and 25% went to a rehabilitation facility. Two patients (3.2%) died postoperatively-1 of worsening usual interstitial pneumonia, and the other of massive pulmonary embolism. Complications included a new respiratory infection in 14 patients, pulmonary embolism in 2, and atrial fibrillation in 6. Six patients required reintubation, and 9 received a postoperative tracheotomy; 47 patients required postoperative aspiration bronchoscopy. CONCLUSIONS In experienced hands, tracheobronchoplasty can be performed with a very low mortality rate and an acceptable perioperative complications rate in patients with significant pulmonary comorbidity. Intervention for postoperative respiratory morbidity is often necessary.

Tracheal Replacement With a Silicone-Stented, Fresh Aortic Allograft in Sheep

BACKGROUND Tracheal tissue regeneration after allogeneic aortic transplants in sheep has been reported. We sought to confirm these findings and elucidate the mechanism of this transformation. METHODS Ten male sheep underwent cervical tracheal replacement with fresh, descending thoracic aortic allografts, 8 cm long, from female sheep, without postoperative immunosuppressive therapy. A 10-cm silicone stent was placed to prevent airway collapse. Graft evaluations with flexible bronchoscopy and computed tomography were conducted between 2 weeks and 1 year after surgery. RESULTS There were no procedural deaths, but 6 animals died or required euthanasia between 12 days and 3 months postoperatively owing to severe tracheitis, cervical lymphadenitis, pneumonia, graft necrosis, stent migration, or airway obstruction after stent removal. The 4 remaining sheep were euthanized as planned at 6 to 12 months after surgery. Harvested tracheas revealed no evidence of graft incorporation into the surrounding tissue, and there was no histologic evidence of any neocartilage within or around the graft at any point. Bronchoscopy revealed marked graft necrosis in the 4 animals surviving to planned euthanasia. In all sheep, computed tomography imaging revealed that the graft was replaced by connective tissue without any signs of cartilage regeneration. Image analysis also indicated profound shortening of the grafted area up to 87.5% at 1 year after implantation, secondary to axial shift of the native trachea. CONCLUSIONS Fresh aortic allografts appear to be unsuitable for primary tracheal replacement. However, the observed graft shortening may allow for two-staged, end-to-end reconstruction of large tracheal defects with temporary grafting techniques.

Comparison of expiratory CT airway abnormalities before and after tracheoplasty surgery for tracheobronchomalacia

Objectives The purpose of this study is to assess the prevalence and severity of expiratory multidetector computer tomography airway abnormalities, including central airway collapse and peripheral air trapping, before and after tracheoplasty, a novel surgical treatment for tracheomalacia. Materials and Methods Our hospital information system retrospectively identified all patients with bronchoscopically diagnosed tracheobronchomalacia referred for computer tomography airway imaging pretracheoplasty and posttracheoplasty during a 41-month period. All patients underwent a standard multidetector computer tomography protocol comprised of imaging both at end inspiration and dynamic expiration. Two observers simultaneously reviewed the images. Maximal expiratory tracheal collapse and total air-trapping scores were calculated pretracheoplasty and posttracheoplasty for each patient. Statistical analysis was performed using the paired t test and Wilcoxon signed-ranks test. Results The study cohort was comprised of 16 patients, 12 men and 4 women, with mean age of 60 years (range: 41 to 80). Mean percentage expiratory tracheal collapse pretracheoplasty was 70%±28 compared with 36%±27 posttracheoplasty (P<0.0001). Fifteen (94%) of sixteen patients demonstrated air trapping both pretracheoplasty and posttracheoplasty. Median total air-trapping scores were similar between preoperative (median 6, range: 0 to 9) and postoperative (median 6, range: 0 to 10) scans (P=0.43). All patients experienced symptomatic improvement after surgery. Conclusions Tracheoplasty is associated with a significant reduction in expiratory tracheal collapse and subjective symptomatic improvement, but it does not change the severity of air trapping.

Idiopathic laryngotracheal stenosis.

ILTS is a rare inflammatory disease that results in a cicatricial stenosis of the cricoid and upper trachea. It occurs almost exclusively in women and is without known cause. Patients present with dyspnea on exertion that progresses to dyspnea at rest, often with stridor. The diagnosis is usually made on the basis of patient history, physical examination, and radiography. Rigid bronchoscopy is usually reserved for the day of proposed surgery to confirm diagnosis and to plan the operative strategy. On occasion, the presence of active inflammation extending into the immediate subglottis or the patients use of corticosteroids requires that surgery be postponed. In these cases, a patent airway is temporarily restored with careful bronchoscopic dilation. Single-staged laryngotracheal resection is successful in more than 90% of patients and is the most effective treatment when performed by experienced hands. Long-term follow-up shows stable airway and improvement in voice quality. Palliative procedures such as repeated airway dilations should be reserved for poor surgical candidates. Protective tracheostomy is rarely required.