Luis F. Tapias

Perfusion decellularization of whole organs

The native extracellular matrix (ECM) outlines the architecture of organs and tissues. It provides a unique niche of composition and form, which serves as a foundational scaffold that supports organ-specific cell types and enables normal organ function. Here we describe a standard process for pressure-controlled perfusion decellularization of whole organs for generating acellular 3D scaffolds with preserved ECM protein content, architecture and perfusable vascular conduits. By applying antegrade perfusion of detergents and subsequent washes to arterial vasculature at low physiological pressures, successful decellularization of complex organs (i.e., hearts, lungs and kidneys) can be performed. By using appropriate modifications, pressure-controlled perfusion decellularization can be achieved in small-animal experimental models (rat organs, 4–5 d) and scaled to clinically relevant models (porcine and human organs, 12–14 d). Combining the unique structural and biochemical properties of native acellular scaffolds with subsequent recellularization techniques offers a novel platform for organ engineering and regeneration, for experimentation ex vivo and potential clinical application in vivo.

Engineering pulmonary vasculature in decellularized rat and human lungs

Bioengineered lungs produced from patient-derived cells may one day provide an alternative to donor lungs for transplantation therapy. Here we report the regeneration of functional pulmonary vasculature by repopulating the vascular compartment of decellularized rat and human lung scaffolds with human cells, including endothelial and perivascular cells derived from induced pluripotent stem cells. We describe improved methods for delivering cells into the lung scaffold and for maturing newly formed endothelium through co-seeding of endothelial and perivascular cells and a two-phase culture protocol. Using these methods we achieved ∼75% endothelial coverage in the rat lung scaffold relative to that of native lung. The regenerated endothelium showed reduced vascular resistance and improved barrier function over the course of in vitro culture and remained patent for 3 days after orthotopic transplantation in rats. Finally, we scaled our approach to the human lung lobe and achieved efficient cell delivery, maintenance of cell viability and establishment of perfusable vascular lumens.

Decellularized scaffolds as a platform for bioengineered organs.

Purpose of reviewPatients suffering from end-stage organ failure requiring organ transplantation face donor organ shortage and adverse effect of chronic immunosuppression. Recent progress in the field of organ bioengineering based on decellularized organ scaffolds and patient-derived cells holds great promise to address these issues. Recent findingsPerfusion-decellularization is the most consistent method to obtain decellularized whole-organ scaffolds to serve as a platform for organ bioengineering. Important advances have occurred in organ bioengineering using decellularized scaffolds in small animal models. However, the function exhibited by bioengineered organs has been rudimentary. Pluripotent stem cells seem to hold promise as the ideal regenerative cells to be used with this approach but the techniques to effectively and reliably manipulate their fate are still to be discovered. Finally, this technology needs to be scaled up to human size to be of clinical relevance. SummaryThe search for alternatives to allogeneic organ transplantation continues. Important milestones have been achieved in organ bioengineering with the use of decellularized scaffolds. However, many challenges remain on the way to producing an autologous, fully functional organ that can be transplanted similar to a donor organ.

Risk factor analysis for the recurrence of resected solitary fibrous tumours of the pleura: a 33-year experience and proposal for a scoring system

OBJECTIVES Surveillance after resection of solitary fibrous tumours of the pleura (SFTP) remains undefined. This study reviews our experience with surgical treatment of SFTP to determine the specific risk factors to predict recurrence. METHODS A retrospective review of 59 patients surgically treated for SFTP during the years 1977-2010 was conducted. Clinico-pathological factors for recurrence were analysed by Kaplan-Meier and Cox proportional hazard methods. RESULTS The mean age was 57 ± 14 years. There were 32 (54%) men. Among 32 (54%) symptomatic patients, chest pain (22%), cough (19%) and dyspnoea (17%) were most frequent. The mean tumour size was 7.3 ± 6.7 cm, and 14 patients had SFTPs larger than 10 cm. An SFTP was pedunculated in 38 (67%) cases and had a visceral origin in 40 (68%). Paraneoplastic syndromes were observed in 3 (5%) patients. On histopathologic analysis, 4 (7%) presented ≥ 4 mitosis/10 high-power fields (HPFs), 8 (15%) atypia, 14 (24%) hypercellularity and 6 (10%) necrosis. After a mean follow-up of 8.8 ± 7.0 years, we observed 8 (14%) recurrences; median time to recurrence was 6 years (range 2-16 years). Two (3%) patients received adjuvant therapy. We constructed a predictive score for recurrence by assigning one point to each of the six variables: parietal (vs visceral) pleural origin, sessile (vs pedunculated) morphology, size >10 cm (vs <10 cm), the presence of hypercellularity, necrosis and mitotic activity ≥ 4/HPF (vs <4). A score of ≥ 3 best predicted recurrence (sensitivity: 100%, specificity: 92%, area under receiver operating characteristic curve = 0.966, P < 0.0001). With a score of ≥ 3, recurrence-free survival was 80%, 69, 23 and 23% at 3, 5, 10 and 15 years, whereas a score of <3 was 100% up to 15 years. Our scoring system was superior in predicting malignant behaviour and recurrence compared with Englands criteria or de Perrot staging. CONCLUSIONS The proposed scoring system is simple, easily obtained from existing pathological description and reliably predicts recurrence in this patient population harbouring SFTP. The SFTP score may stratify patient risk and guide postoperative surveillance. We recommend validation in additional clinical series.

A preliminary experience with minimally invasive Ivor Lewis esophagectomy

With several small series examining minimally invasive Ivor Lewis esophagectomies, we look to contribute to a growing experience. In reporting our initial results, safety, initial oncologic completeness, and preliminary outcomes with a minimally invasive Ivor Lewis esophagectomy were demonstrated. From 2007 to 2010, 40 minimally invasive Ivor Lewis esophagectomies were carried out. The approach was a laparoscopic mobilization of the stomach and a thoracoscopic esophageal mobilization and creation of a high intrathoracic anastomosis. Indications included esophageal cancer in 39 patients and esophageal gastrointestinal stromal tumor in one patient. Median age was 62 (range 39-77) with 31 (78%) male patients. Non-emergent conversion was required in two (5%) patients. Twenty-five (63%) patients underwent neoadjuvant therapy. Mean operative time was 364 minutes (range 285-455), and mean blood loss was 205 cc (range 100-400). All patients underwent an R0 resection including the removal of all Barretts esophagus, and mean number of nodes harvested was 21 (range 11-41). Median intensive care unit stay was 1 day (range 1-3), and hospital stay was 7 days (range 6-19). There were no anastomotic leaks and no 30-day mortality. Postoperative complications included eight (21%) patients with atrial fibrillation and two (5%) chylothorax, one requiring ligation. At a mean follow-up of 16.5 months (range 1-39 months), five (13%) patients have had a distant recurrence; there have been no local recurrences. Minimally invasive Ivor Lewis esophagectomy, although technically challenging, can be carried out with reasonable operative times, a short length of stay, and minimal complication. Final oncologic validity is pending longer follow-up and a larger series.

Surgical Therapy of Pulmonary Aspergillomas: A 30-Year North American Experience

BACKGROUND Pulmonary aspergilloma is resected to control life-threatening complications such as massive hemoptysis. The role of prophylactic resection in asymptomatic patients is unclear. METHODS A retrospective review was conducted of 60 patients treated at a tertiary center from 1980 to 2010. RESULTS The mean age in 34 (56.7%) men and 26 (43.3%) women was 51 years. Immunosuppression, most commonly from chronic steroid use, was present in 17 (28.3%) patients, and preexisting lung disease was present in 47 (78.3%) patients. Hemoptysis occurred in 33 (55%) patients, whereas 9 (15.0%) patients were asymptomatic. Aspergilloma was simple in 13 (21.7%) patients and complex in 47 (78.3%) patients. Surgical approach was by thoracotomy (n=51 [85.0%]), video-assisted thoracoscopic surgery (n=7 [11.7%]), or a cavernostomy (n=2 [3.3%]). Sublobar resections (n=28 [46.7%]) were most common, followed by lobectomy (n=27 [45%]) and pneumonectomy (n=3 [5%]). Postoperative morbidity occurred in 18 (30%) patients, with prolonged air leak the most frequent complication (n=9 [15%]). Two (3.3%) patients experienced empyema, and 4 (6.7%) patients had bronchopleural fistulas (BPFs). Two patients died within 30 days (3.3%). During a mean follow-up of 54.1±62.2 months, 3 patients had recurrent aspergillomas (5.0%). Actuarial 10-year survival was 62.5% for simple and 68.5% for complex aspergillomas (p=0.858). Comorbid conditions (human immunodeficiency virus [HIV] positivity, malignancy) and male sex were associated with lower survival. CONCLUSIONS Selective surgical treatment favoring lesser pulmonary resection results in fungal eradication and control in most patients. Overall survival is similar after surgical management of simple and complex aspergillomas.

Outcomes With Open and Minimally Invasive Ivor Lewis Esophagectomy After Neoadjuvant Therapy

BACKGROUND Neoadjuvant therapy is integral in the treatment of locally advanced esophageal cancer. Despite increasing acceptance of minimally invasive approaches to esophagectomy, there remain concerns about the safety and oncologic soundness after neoadjuvant therapy. We examined outcomes in patients undergoing open and minimally invasive (MIE) Ivor Lewis esophagectomy after neoadjuvant therapy. METHODS This was a retrospective series of 130 consecutive patients with esophageal cancer undergoing Ivor Lewis esophagectomy with curative intention after neoadjuvant therapy at a tertiary academic center (2008 to 2012). RESULTS An open procedure was performed in 74 patients (56.9%), and 56 (43.1%) underwent MIE after neoadjuvant therapy. MIE patients had shorter median intensive care unit (p = 0.002) and hospital lengths of stay (p < 0.0001). The incidence of postoperative complications was similar (open: 54.8% vs MIE: 41.1%, p = 0.155). However, observed respiratory complications were significantly reduced after MIE (8.9%) compared with open (29.7%; p = 0.004). Anastomotic leak rates were similar (open: 1.4% vs. MIE: 0%, p = 1.00). Mortality at 30 and 90 days was comparable (open: 2.7% and 4.1% vs MIE: 0% and 1.8%, p = 0.506 and p = 0.634, respectively). Complete resection rates and the number of collected lymph nodes was similar. Overall survival rates at 5 years were similar (open: 61% vs MIE: 50%, p = 0.933). MIE was not a significant predictor of overall survival (hazard ratio, 1.07; 95% confidence interval, 0.61 to 1.87; p = 0.810). CONCLUSIONS MIE proves its safety after neoadjuvant therapy because it leads to faster progression during the early postoperative period while reducing pulmonary complications. Open and MIE approaches appear equivalent with regards to perioperative oncologic outcomes after neoadjuvant therapy. Long-term outcomes need further validation.

Validation of a Scoring System to Predict Recurrence of Resected Solitary Fibrous Tumors of the Pleura

BACKGROUND Solitary fibrous tumors of the pleura (SFTPs) are infrequent neoplasms with no standardized criteria to predict risk of recurrence after curative surgery. The aim of the present study is to validate a recently proposed recurrence score in a large European cohort of patients with SFTP. METHODS Validation of a previously published scoring system was assessed in a population of 113 patients who underwent complete resection of SFTPs. Patients were scored according to the pleural origin, morphology, size, hypercellularity, presence of necrosis or hemorrhage, and number of mitoses in their SFTPs. Receiver operating characteristic curves were plotted for the score. Time to recurrence analysis was performed using the Kaplan-Meier and Cox proportional hazards methods. RESULTS After a mean follow-up of 13.2 ± 7.3 years, there were nine recurrences (8.0%). Score performance to predict recurrence was as follows: sensitivity = 78%, specificity = 74%, positive likelihood ratio = 3.0, and negative likelihood ratio = 0.3. A cutoff of 3 points was used to classify 79 patients (69.9%) at low risk and 34 patients (30.1%) at high risk for recurrence. A high-risk classification was significantly associated with more recurrences during follow-up (P = .004), worse overall survival (P = .0008), more extensive lung resections (P = .001), and the use of adjuvant therapies (P = .009). The present score outperformed Englands criteria (P = .049) and de Perrot classification (P < .001) when predicting SFTP recurrence. CONCLUSIONS The proposed scoring system, which combines common clinical and histologic features of resected SFTPs, remains predictive of recurrence in a separate patient population. The simple score may guide the postoperative surveillance of this uncommon tumor.

Type I collagen–targeted PET probe for pulmonary fibrosis detection and staging in preclinical models

Positron emission tomography with a probe targeting type I collagen enables detection, staging, and treatment response monitoring in lung fibrosis. Focusing on fibrosis Although fibrosis is known to play a role in the progression of multiple diseases, affecting heart, lung, liver, and skin, among other organs, it remains difficult to visualize and diagnose noninvasively. To address this, Désogère and colleagues developed an imaging probe for positron emission tomography that detects type I collagen, an extracellular matrix protein present in fibrotic tissues. The probe detected fibrotic lung tissue in two mouse models of bleomycin-induced pulmonary fibrosis and in samples of human lungs from patients with idiopathic pulmonary fibrosis, where higher probe uptake correlated with regions of increasing fibrosis. Pulmonary fibrosis is scarring of the lungs that can arise from radiation injury, drug toxicity, environmental or genetic causes, and for unknown reasons [idiopathic pulmonary fibrosis (IPF)]. Overexpression of collagen is a hallmark of organ fibrosis. We describe a peptide-based positron emission tomography (PET) probe (68Ga-CBP8) that targets collagen type I. We evaluated 68Ga-CBP8 in vivo in the bleomycin-induced mouse model of pulmonary fibrosis. 68Ga-CBP8 showed high specificity for pulmonary fibrosis and high target/background ratios in diseased animals. The lung PET signal and lung 68Ga-CBP8 uptake (quantified ex vivo) correlated linearly (r2 = 0.80) with the amount of lung collagen in mice with fibrosis. We further demonstrated that the 68Ga-CBP8 probe could be used to monitor response to treatment in a second mouse model of pulmonary fibrosis associated with vascular leak. Ex vivo analysis of lung tissue from patients with IPF supported the animal findings. These studies indicate that 68Ga-CBP8 is a promising candidate for noninvasive imaging of human pulmonary fibrosis.

Molecular imaging of oxidized collagen quantifies pulmonary and hepatic fibrogenesis

Fibrosis results from the dysregulation of tissue repair mechanisms affecting major organ systems, leading to chronic extracellular matrix buildup, and progressive, often fatal, organ failure. Current diagnosis relies on invasive biopsies. Noninvasive methods today cannot distinguish actively progressive fibrogenesis from stable scar, and thus are insensitive for monitoring disease activity or therapeutic responses. Collagen oxidation is a universal signature of active fibrogenesis that precedes collagen crosslinking. Biochemically targeting oxidized lysine residues formed by the action of lysyl oxidase on collagen with a small-molecule gadolinium chelate enables targeted molecular magnetic resonance imaging. This noninvasive direct biochemical elucidation of the fibrotic microenvironment specifically and robustly detected and staged pulmonary and hepatic fibrosis progression, and monitored therapeutic response in animal models. Furthermore, this paradigm is translatable and generally applicable to diverse fibroproliferative disorders.