Chronic lung allograft dysfunction (CLAD) is the leading cause of mortality following lung transplantation. We conducted a retrospective cohort study including 397 bilateral lung recipients transplanted in from 1996 to 2009 to determine the association between ambient air pollution, CLAD and mortality. Pollution exposure was assessed using satellite‐based estimates of nitrogen dioxide, distance to major roadway and total length of roadways around a patient's home. Cumulative exposures to ozone and particulate matter were estimated from concentrations measured at fixed‐site stations near patients' homes using inverse distance weighted interpolation. Cox proportional hazards models were used to estimate the associations of CLAD with air pollution exposure, adjusting for various individual and neighborhood characteristics. During the follow‐up, 185 patients developed CLAD (47%) and 101 patients died (25%). Fifty‐four deaths (53%) were due to CLAD. We observed an association between CLAD development and road density within 200 m of a patient's home (HR 1.30 [95% CI 1.07–1.58]). Although based on a subgroup of 14 patients, living within 100 m of a highway was associated with a high risk for developing CLAD (HR 4.91 [95% CI 2.22, 10.87]). These data suggest that exposure to traffic‐related air pollution is associated with development of CLAD among lung transplant recipients.
Regeneration of damaged periodontal tissues is mediated by periodontal cells, but a major sub-population comprises highly differentiated cells that do not renew. To overcome the loss of specialized cell types caused by disease, various therapeutic approaches including cell transplants have been developed to promote cell re-population in periodontal tissues. As previous transplantation studies used unlabeled cells, that are indistinguishable from host cells, it has been difficult to assess the contributions of transplanted cells to the healing processes. To track the fate and differentiation of rat periodontal cells transplanted into periodontal wounds, we used collagen-coated fluorescent beads as a permanent endocytosed marker, or cells constitutively expressing -galactosidase. We assessed osteogenic cell differentiation with immunohistochemical staining for osteopontin and bone sialoprotein. Cells were transplanted into periodontal wounds created in Sprague-Dawley male rats that are null for -galactosidase. Defects were allowed to heal spontaneously (controls), or were closed with collagen implants mixed with -galactosidase-positive (Lac-Z) periodontal cells, or closed with collagen implants mixed with periodontal cells loaded with fluorescent beads. Animals were killed at 1 and 2 weeks after surgery and tissues were prepared for morphometric assessment and immunostaining for osteopontin (OPN) and bone sialoprotein (BSP). Transplanted cells were easily distinguished by fluorescent beads or by -galactosidase-positive expression and were distributed throughout the regenerating periodontal ligament (PL) and alveolar bone. At 1 week after wounding, animals treated with -galactosidase-positive cells exhibited a slightly higher percentage of labeled cells in the PL compared with the fluorescent bead-labeled cell implant group (2% vs. 1% respectively; P Ͼ 0.2). At Week 2 percentages of labeled cells were slightly increased in the regenerating PL (Ϸ3% for both groups, P Ͼ 0.2). In regenerating alveolar bone at 1 week, animals that were treated with -galactosidase-positive cells and fluorescent bead-loaded cells exhibited Ϸ30% and 25% of labeled cells respectively. At 2 weeks after wounding there was an increase in the percentage of transplanted -galactosidase-positive cells (Ϸ 39% at week 2; P Ͻ 0.05), but not of transplanted cells with fluorescent beads (Ϸ25% at week 2). In sites with transplanted cells there were higher percentages of OPN positive and BSP positive cells in nascent bone and more newly formed bone than in controls (Ͼ40%; P Ͻ 0.05). Transplantation of -galactosidase-positive cells or cells loaded with fluorescent beads is a useful method for assessing the fate and differentiation of periodontal cells in vivo. Fluorescent beads, however, are diluted at mitosis and this method underestimates the percentage of transplanted cells. As transplanted periodontal cells in both groups promoted regeneration of alveolar bone, cell transplantation could improve the restoration of periodontium destroy...
Regeneration of damaged periodontal tissues is mediated by periodontal cells, but a major sub‐population comprises highly differentiated cells that do not renew. To overcome the loss of specialized cell types caused by disease, various therapeutic approaches including cell transplants have been developed to promote cell re‐population in periodontal tissues. As previous transplantation studies used unlabeled cells, that are indistinguishable from host cells, it has been difficult to assess the contributions of transplanted cells to the healing processes. To track the fate and differentiation of rat periodontal cells transplanted into periodontal wounds, we used collagen‐coated fluorescent beads as a permanent endocytosed marker, or cells constitutively expressing β‐galactosidase. We assessed osteogenic cell differentiation with immunohistochemical staining for osteopontin and bone sialoprotein. Cells were transplanted into periodontal wounds created in Sprague–Dawley male rats that are null for β‐galactosidase. Defects were allowed to heal spontaneously (controls), or were closed with collagen implants mixed with β‐galactosidase‐positive (Lac‐Z) periodontal cells, or closed with collagen implants mixed with periodontal cells loaded with fluorescent beads. Animals were killed at 1 and 2 weeks after surgery and tissues were prepared for morphometric assessment and immunostaining for osteopontin (OPN) and bone sialoprotein (BSP). Transplanted cells were easily distinguished by fluorescent beads or by β‐galactosidase‐positive expression and were distributed throughout the regenerating periodontal ligament (PL) and alveolar bone. At 1 week after wounding, animals treated with β‐galactosidase‐positive cells exhibited a slightly higher percentage of labeled cells in the PL compared with the fluorescent bead‐labeled cell implant group (2% vs. 1% respectively; P > 0.2). At Week 2 percentages of labeled cells were slightly increased in the regenerating PL (≈3% for both groups, P > 0.2). In regenerating alveolar bone at 1 week, animals that were treated with β‐galactosidase‐positive cells and fluorescent bead‐loaded cells exhibited ≈30% and 25% of labeled cells respectively. At 2 weeks after wounding there was an increase in the percentage of transplanted β‐galactosidase‐positive cells (≈ 39% at week 2; P < 0.05), but not of transplanted cells with fluorescent beads (≈25% at week 2). In sites with transplanted cells there were higher percentages of OPN positive and BSP positive cells in nascent bone and more newly formed bone than in controls (>40%; P < 0.05). Transplantation of β‐galactosidase‐positive cells or cells loaded with fluorescent beads is a useful method for assessing the fate and differentiation of periodontal cells in vivo. Fluorescent beads, however, are diluted at mitosis and this method underestimates the percentage of transplanted cells. As transplanted periodontal cells in both groups promoted regeneration of alveolar bone, cell transplantation could improve the restoration of periodontium destroy...
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