Ingrid Skog

Fibroblast phenotypes and their activity are changed in the wound healing process after lung transplantation.

BACKGROUND Lung transplantation (LTx) is established as a life-saving treatment in end-stage lung disease. However, long-term survival is hampered by the development of chronic rejection, almost synonymous with bronchiolitis obliterans syndrome (BOS). The rejection is characterized by deposition of extracellular matrix in small airways. Fibroblasts/myofibroblasts are the main producers of extracellular matrix molecules such as proteoglycans. This study compared fibroblast phenotype and activity in the wound healing process at different points after LTx in patients who later did, or did not, develop BOS. METHODS Distally derived fibroblasts from patients 6 and 12 months after LTx and from healthy controls were analyzed for production of the proteoglycans versican, perlecan, biglycan, and decorin, with and without transforming growth factor (TGF)-β(1). Fibroblast migration and proliferation were also studied. RESULTS At 6 and 12 months after LTx, versican production was higher in fibroblasts from LTx patients (p < 0.01 p < 0.01) than from controls. Fibroblasts from patients who later developed BOS were more responsive to TGF-β(1)-induced synthesis of versican and biglycan than patients without signs of rejection (p < 0.05). Production of perlecan and decorin was negatively correlated with fibroblast proliferation in fibroblasts at 6 months after LTx. In a more detailed case study of 2 patients, one with and one without BOS, the altered proteoglycan profile was associated with impaired lung function. CONCLUSIONS LTx changes the phenotype of fibroblasts to a non-proliferative but extracellular matrix-producing cell due to wound healing involving TGF-β(1). If not controlled, this may lead to development of BOS.

Primary mesenchymal stem cells in human transplanted lungs are CD90/CD105 perivascularly located tissue-resident cells

Background Mesenchymal stem cells (MSC) have not only been implicated in the development of lung diseases, but they have also been proposed as a future cell-based therapy for lung diseases. However, the cellular identity of the primary MSC in human lung tissues has not yet been reported. This study therefore aimed to identify and characterise the ‘bona fide’ MSC in human lungs and to investigate if the MSC numbers correlate with the development of bronchiolitis obliterans syndrome in lung-transplanted patients. Methods Primary lung MSC were directly isolated or culture-derived from central and peripheral transbronchial biopsies of lung-transplanted patients and evaluated using a comprehensive panel of in vitro and in vivo assays. Results Primary MSC were enriched in the CD90/CD105 mononuclear cell fraction with mesenchymal progenitor frequencies of up to four colony-forming units, fibroblast/100 cells. In situ staining of lung tissues revealed that CD90/CD105 MSCs were located perivascularly. MSC were tissue-resident and exclusively donor lung-derived even in biopsies obtained from patients as long as 16 years after transplantation. Culture-derived mesenchymal stromal cells showed typical in vitro MSC properties; however, xenotransplantation into non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice showed that lung MSC readily differentiated into adipocytes and stromal tissues, but lacked significant in vivo bone formation. Conclusions These data clearly demonstrate that primary MSC in human lung tissues are not only tissue resident but also tissue-specific. The identification and phenotypic characterisation of primary lung MSC is an important first step in identifying the role of MSC in normal lung physiology and pulmonary diseases.

MSC from fetal and adult lungs possess lung-specific properties compared to bone marrow-derived MSC.

Mesenchymal stromal cells (MSC) are multipotent cells with regenerative and immune-modulatory properties. Therefore, MSC have been proposed as a potential cell-therapy for bronchiolitis obliterans syndrome (BOS). On the other hand, there are publications demonstrating that MSC might be involved in the development of BOS. Despite limited knowledge regarding the functional role of tissue-resident lung-MSC, several clinical trials have been performed using MSC, particularly bone marrow (BM)-derived MSC, for various lung diseases. We aimed to compare lung-MSC with the well-characterized BM-MSC. Furthermore, MSC isolated from lung-transplanted patients with BOS were compared to patients without BOS. Our study show that lung-MSCs are smaller, possess a higher colony-forming capacity and have a different cytokine profile compared to BM-MSC. Utilizing gene expression profiling, 89 genes including lung-specific FOXF1 and HOXB5 were found to be significantly different between BM-MSC and lung-MSC. No significant differences in cytokine secretion or gene expression were found between MSC isolated from BOS patients compared recipients without BOS. These data demonstrate that lung-resident MSC possess lung-specific properties. Furthermore, these results show that MSC isolated from lung-transplanted patients with BOS do not have an altered phenotype compared to MSC isolated from good outcome recipients.

Pulmonary Retransplantation in the Nordic Countries

BACKGROUND The increasing demand for pulmonary retransplantation (re-LTx) raises ethical issues on the correct allocation of the scarce donor pool. Thus, we performed a thorough review of the current results for re-LTx in the Nordic countries. METHODS Seventy-five patients with a median age of 50 years (range, 22 to 64 years) underwent re-LTx from 1992 until June 2013, of which 53 had single re-LTx, 21 had double re-LTx, and 1 patient underwent a heart-lung retransplantation. Primary graft dysfunction (PGD) was the primary indication in 9 cases, bronchiolitis obliterans syndrome (BOS) in 62 cases, and airway complications in 4 cases. RESULTS Patients who underwent re-LTx in the period 1992 to 1999 (n = 16) had a 1-year survival of 37.5% (95% confidence interval [CI], 19.9 to 70.6), whereas patients who underwent re-LTx in the period 2000 to 2013 (n = 64) had a 1-year survival of 81.0% (95% CI, 71.5 to 91.8). Corresponding 5-year survival was 25.0% (95% CI, 10.7 to 58.4) in the early era group (1992 to 1999) and 57.2% (95% CI, 44.3 to 73.7) in the more recent era group (2000 to 2013; p = 0.0151). Patients with BOS who underwent re-LTx in the period 1992 to 1999 (n = 13) had a 1-year survival of 38.5% (95% CI, 19.3 to 76.5), whereas patients with BOS who underwent re-LTx in the period 2000 to 2013 (n = 49) had a 1-year survival of 85.4% (95% CI, 75.9 to 96.0). Corresponding 5-year survival was 23.1% (95% CI, 8.6 to 62.3) in the early era group (1992 to 1999) and 56.1% (95% CI, 41.9 to 75.2) in the more recent era group (2000 to 2013; p = 0.0199). The cumulative incidence among patients who underwent re-LTx because of BOS and developed BOS again after re-LTX was analyzed. The cumulative incidence curves for time periods 1992 to 1999 and 2000 to 2013 are not statistically different for repeat BOS (p = 0.5087), but they are highly significant for time periods among patients who died (p = 0.02381). CONCLUSIONS Results for re-LTx have improved over time, especially when BOS is the primary indication. The cumulative incidence among patients who underwent re-LTx because of BOS and developed repeat BOS after re-LTX showed equal risk between 1992 to 1999 and 2000 to 2013 in the aspect of developing repeat BOS, but in the later era the patients had a significantly higher chance of surviving.

25-year follow-up after lung transplantation at Lund University Hospital in Sweden: superior results obtained for patients with cystic fibrosis

OBJECTIVES In Sweden, two centres perform lung transplantation for a population of about 9 million and the entire population is covered for lung transplantation by government health insurance. Lund University Hospital is one of these centres. This retrospective report reviews the 25-year experience of the Skåne University Hospital Lung Transplant Program with particular emphasis on short-term outcome and long-term survival but also between different subgroups of patients and types of transplant [single-lung transplantation (SLTx) versus double-lung transplantation (DLTx)] procedure performed. METHODS Between January 1990 and June 2014, 278 patients underwent lung transplantation at the Skåne University Hospital Sweden. DLTx was performed in 172 patients, SLTx was performed in 97 patients and heart-lung transplantation was performed in 9 patients. In addition, 15 patients required retransplantation (7 DLTx and 8 SLTx). RESULTS Overall 1-, 5-, 10-, 15- and 20-year survival rates were 88, 65, 49, 37 and 19% for the whole cohort. DLTx recipients showed 1-, 5-, 10- and 20-year survival rates of 90, 71, 60 and 30%, compared with SLTx recipients with 1-, 5-, 10- and 20-year survival rates of 83, 57, 34 and 6% (P < 0.05), respectively. Comparing the use of intraoperative extracorporeal membrane oxygenation, extracorporeal circulation (ECC) and no circulatory support in the aspect of survival, a significant difference in favour of intraoperative ECC was seen. CONCLUSIONS Superior long-term survival rates were seen in recipients diagnosed with cystic fibrosis, α1-antitrypsin deficiency and pulmonary hypertension. DLTx showed better results compared with SLTx especially at 10 years post-transplant. In the present study, we present cumulative incidence rates of bronchiolitis obliterans syndrome of 15% at 5 years, 26% at 10 years and 32% at 20 years post-transplant; these figures are in line with the lowest rates presented internationally.

Survival after lung transplantation for cystic fibrosis in Sweden

Objectives In Sweden, lung transplantation has been performed in patients with end-stage lung disease since 1990. We assessed survival after lung transplantation for cystic fibrosis (CF) with focus on early mortality and outcome for patients infected with certain multiresistant bacteria, considered a relative contraindication for lung transplantation. Methods Review of CF and transplant databases and patient charts. The Kaplan-Meier method and log-rank test were used for survival analysis and group comparison. Results From November 1991 to December 2014, 115 transplantations were performed in 106 CF patients (9 retransplantations): 3 heart-lung, 106 double lung-, 1 double lobar- and 5 single lung transplantations, constituting 13% (115/909) of all lung-transplant procedures performed in Sweden. The mean age at surgery was 31 (SD 10, range 10-61) years and there were 48% females. Overall 1-year survival after lung transplantation for CF was 86.4%, 5-year survival was 73.7% and 10-year survival was 62.4%. The mean and median survival after transplantation were 13.1 (95% confidence interval (CI): 11-15.3) and 14.6 (95% CI: 9.3-19.8) years, respectively, and there was no significant difference for gender or transplant centre. Extracorporeal membrane oxygenation was used as a bridge to transplantation in 11 cases and five patients received reconditioned lungs. Vascular and infectious complications contributed to eight deaths within the first three postoperative months. The mean survival for 14 patients infected pretransplant with Mycobacterium abscessus or Burkholderia cepacia complex was 8.8 (95% CI: 6.1-11.6) years compared to 13.2 (95% CI: 10.9-15.8) years for patients negative for these bacteria. Nineteen patients (14% of all listed), of whom three were listed for retransplantation, died while waiting a median time of 94 days (range 4 days-2.5 years) after listing. Conclusions Survival after lung transplantation in Sweden is good, also for patients with pretransplant infection with M. abscessus or B. cepacia complex, and comparable to international data.