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Do mature pulmonary lobes grow after transplantation into an immature recipient?
L F Duebener1, Y Takahashi, H Wada
1Department of Thoracic and Cardiovascular Surgery, Hannover Medical School, Germany.
Insights
Mature adult lung grafts filled the recipient
Area of Science:
- Thoracic surgery
- Transplantation immunology
- Pediatric pulmonology
Background:
- Pediatric donor lung shortage is a critical issue.
- Reduced-size adult lung transplants offer a potential solution.
- Mature grafts require recipient-proportional growth for long-term function.
Purpose of the Study:
- To evaluate the long-term function and structural integrity of mature adult lung lobar grafts in pediatric recipients.
- To assess graft growth and morphological changes post-transplantation.
Main Methods:
- Mature adult mini-pig left lower lung lobes were transplanted into younger piglets.
- A 14-week holding period was used, followed by volumetric and morphological analysis.
- Light, scanning, and transmission electron microscopy were employed, alongside computer-aided image analysis.
Main Results:
- Grafts maintained specific volume relative to body weight but showed structural differences from native lungs.
- Transplanted lobes exhibited increased average alveolar diameter and dilated, rounded alveoli.
- Relative alveolar airspace volume tended to be higher in transplanted lobes compared to controls.
Conclusions:
- Mature pulmonary lobar grafts accommodated the growing hemithorax but developed emphysema-like alterations.
- No evidence of alveolar growth was observed in the mature grafts.
- The long-term gas exchange capacity of mature pulmonary grafts in growing recipients remains questionable.
Background:
The use of reduced-size adult lung transplants could help solve the profound pediatric donor lung shortage. However, adequate long-term function of the mature grafts requires growth in proportion to the recipient's development.
Methods:
Mature left lower lobes from adult mini-pigs (age: 7 months; mean body weight: 30 kg) were transplanted into 14-week-old piglets (mean body weight: 15 kg). By the end of the 14-week holding period, lungs of the recipients (n = 4) were harvested. After volumetric measurements, the lung morphology was studied using light microscopy, scanning, and transmission electron microscopy. Changes of alveolar airspace volume were determined using a computer aided image analysis system. Comparisons were made to age- and weight-matched controls.
Results:
Volumetric studies showed no significant differences (p = 0.49) between the specific volume (mL/kg body weight) of lobar grafts and left lower lobes of adult controls. Morphologic studies showed marked structural differences between the grafts and the right native lungs of the recipients, with increased average alveolar diameter of the grafts. On light microscopy and scanning electron microscopy, alveoli appeared dilated and rounded compared to the normal polygonal shape in the controls. The computer generated semi-quantitative data of relative alveolar airspace volume tended to be higher in transplanted lobes.
Conclusions:
The mature pulmonary lobar grafts have filled the growing left hemithorax of the developing recipient. Emphysema-like alterations of the grafts were observed without evidence of alveolar growth in the mature lobar transplants. Thus, it can be questioned whether mature pulmonary grafts can guarantee sufficient long-term gas exchange in growing recipients.