We performed an open, single-center, prospective, single-arm phase I/ II clinical trial (EC Code: CSM/FAP/2012 – EudraCT: 2013-000535-27). The trial was reviewed and approved by the Ethics Committee at Salamanca University Hospital and the AEMPS. All patients signed the approved informed consent form, and all the procedures where in accordance with the principles of the Declaration of Helsinki.
Additionally, perioperative, and long-term outcomes of two additional patients treated with MSCs after lung resection under compassionate use, outside of the clinical trial but with the same inclusion and exclusion criteria (see next section), were evaluated.
Study population
Before surgery, all the patients were studied through an extensive work-up, which included physical examination, haematological and biochemical tests, electrocardiogram, computed tomography scan (CT) of the chest as well as abdomen, positron emission tomography (PET) scan and bronchoscopy. Further investigations were performed only if deemed necessary according to clinical findings or abnormal laboratory results. Patients with a previous history of cardiovascular disease or any suspicious changes in the electrocardiogram were referred for assessment by a cardiologist. Pulmonary function tests were performed in all patients. For this study, we reviewed only forced expiratory volume in the first second in percent values (FEV1%) according to the patient’s age, gender, and height.
PAL risk was assessed preoperatively according to the PAL score proposed by Brunelli (15) in collaboration with our team in 2010. Risk factors included in the score were: age > 65 years (1 point), BMI < 25.5 kg/m2 (2 points), FEV1% < 80% (1.5 points) and pleural adhesions (1 point). According to the obtained score, PAL risk was rated in four grades: A (0 points), B (1 point), C (1.5–3 points) and D (> 3 points).
Inclusion criteria in the trial were capacity to consent, age between 18 and 70 years old, patients planned to undergo anatomical lung resection (excluding pneumonectomy) and PAL score grade C or D.
Exclusion criteria included insufficient fitness to tolerate the surgical intervention, clinical or anaesthetic contraindication for surgery (American Society of Anaesthesiologist (ASA) score IV or V), presence of severe non-controlled systemic disease, pregnancy, positive serology for hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV) or syphilis and absence or revocation of informed consent.
Study population also comprised a patient cohort treated with MSCs after lung resection under compassionate use, outside of the clinical trial but with the same criteria. All of them signed a specific informed consent.
Cell production and preparation
The ATMP was produced in our GMP Facility according to the Investigational Medicinal Product Dossier (IMPD) code PEI-13-072 approved by the AEMPS for this clinical trial. Briefly, 50–100 mL from BM were obtained from the patient under sedation in a sterile environment in the operating room and transferred to the GMP Facility. Then, mononuclear cells were obtained after density gradient centrifugation and seeded in culture flask with alpha-MEM with 5% of platelet lysate to isolate MSCs, that were grown in vitro until the following release criteria were met: >0.5x106 MSCs/Kg of recipient’s body weight, with > 80% viability and ISCT definition criteria regarding phenotype and differentiation ability (33).
Cell administration was coordinated with the thoracic surgery team. MSCs were collected, resuspended in saline and sent to the operating room properly labeled and in the shortest possible time. Then, cells were resuspended in the thrombin syringe of the Tissucol Duo® preparation immediately before administration.
Surgical procedure and cell administration
Perioperative management was uniform for all cases during the study period. Preoperative antibiotic regimen consisted of a single dose of Cefuroxime 1500 mg that was repeated 6 h later if surgery continued. Anaesthesia procedures were indicated and performed or supervised by a senior cardiothoracic anaesthesiologist and all cases were operated on by the same team of senior thoracic surgeons, either through video assisted thoracic surgery, anterolateral or muscle-sparing posterolateral thoracotomy approach.
Application of the final product (autologous MSCs embedded in Tissucol Duo®) into the parenchymal suture line was performed after specimen removal. This final product was the only substance used for air leak prevention.
In all patients, a 24F or 28F chest tube was left in the apex at the end of the procedure and connected to an Atrium® Ocean® Water Seal Chest Drain device. This device has a scale in the water seal, graded from 0 to 5, to visually quantify the air leak.
Extubation was performed in the operating theatre and patients were transferred to the cardiothoracic ward after an average of 6 hours in the recovery room.
Postoperative management
Postoperative analgesia was based on an epidural or paravertebral catheter that was inserted preoperatively, with a continuous bupivacaine and fentanyl infusion during the first 2 or 3 days, as well as intravenous analgesia as needed. Afterwards, oral paracetamol and non-steroid anti-inflammatory drugs were administered. Nursing care was also homogeneous in all cases and included incentive spirometry. All the patients were included in our specific pre- and postoperative chest physiotherapy programme, described elsewhere (34).
Evaluation of postoperative air leak
Twenty-four hours after the surgery, air leak through the chest tube was assessed by two observers when the patient was in the cardiothoracic surgery ward and after performing chest physiotherapy. The patient performed deep forced expirations while timed during 1 min. In every expiration, we recorded the air flow observed in the chest drain’s graded water seal. This manoeuvre and evaluation of air leak was repeated every postoperative day until chest tube removal.
In addition to air flow quantification, the occurrence of cardiorespiratory complications and the presence of pneumothorax in chest X-ray were recorded on every postoperative day.
Post-discharge follow-up
Postoperative follow-up was continued until at least 24 months, including five visits (at months 1, 3, 6, 12 and 24) where clinical outcomes (symptoms or sings of complications) and radiological assessments were recorded. Radiological tests included a chest X-ray to rule out the presence of pneumothorax in the follow/up visits at months 1, 3, 12 and 24 and a CT was performed at 6 months follow-up visit to detect potential pathological findings.
Although the established initial follow-up of the trial was 24 months, we followed all patients for an additional 5 years to assess safety and efficacy in the long term.