Vein Suturing Results in Worse Lung Graft Outcomes Compared to the Cuff Method

Comparison of Ex Vivo Lung Perfusion, With or Without Albumin, With Static Cold Storage in a Rat Ex Vivo Lung Perfusion Model

Ex vivo lung perfusion is an alternative to static cold storage for lung preservation in clinical lung transplantation. This study aimed to compare ex vivo lung perfusion with an acellular solution versus static cold storage and to assess the role of albumin as an additive to the acellular perfusion solution. Rat heart-lung blocks from Sprague-Dawley rats, after 1 hour of warm ischemia, were immersed in a low-potassium dextran solution for another hour. Blocks were then placed on ex vivo lung perfusion for 3 hours, with or without the addition of 70 g/L of albumin. Parameters such as gas exchange, dynamic lung compliance, and pulmonary vascular resistance were evaluated every 30 minutes. Control lungs were preserved in low-potassium dextran solution at 4 °C for 4 hours (static cold storage group). Lung injury was assessed using wet-to-dry ratio, histology, immunohistochemistry, and TUNEL assay. Pulmonary vascular resistance significantly decreased between 30 and 60 minutes of ex vivo lung perfusion, whereas other lung function parameters remained stable throughout the 3 hours. No significant differences were observed between the ex vivo lung perfusion and ex vivo lung perfusion + albumin groups in terms of lung function or pathology assessment. Pathological findings indicated that ex vivo lung perfusion, with or without albumin, resulted in increased edema and apoptotic activity compared with lungs preserved by static cold storage. The addition of albumin to the ex vivo lung perfusion solution did not result in significant improvements in functional parameters or pathological findings.

Improvement of surgical techniques for orthotopic single lung transplantation in rats

Background

Although orthotopic single lung transplantation in rats has long been established, this model is still highly challenging. Therefore, we made several modifications in anesthesia, lung extraction, vascular clamp, and transplantation procedures for this model.

Methods

Fifty cases of rat left lung transplantation were performed using traditional procedures and modified surgical techniques, respectively. Two hundred Sprague Dawley male rats, half as donors and half as recipients, were randomized equally to the two groups. The modifications included orotracheal intubation via a video laryngoscope, retrograde perfusion following anterograde perfusion, a Rummel tourniquet for the occlusion of pulmonary vessels, flushing the vessels and cuffs before anastomosis with heparin, and a simple pleural drainage. The surgical time, warm and cold ischemia time, vascular complications, and survival rate on postoperative day seven were compared between the two groups.

Results

The modified surgical techniques significantly reduced the surgical duration (35.7 vs. 46.3 min, P<0.01), warm ischemia time (16.3 vs. 28.8 min, P<0.01), and vascular complications (2% vs. 16%, P=0.04). Moreover, the survival rate on postoperative day 7 was higher in the improved surgical techniques group (96% vs. 80%, P=0.03).

Conclusions

We described the improvement of surgical techniques for orthotopic single lung transplantation in rats, which could shorten anastomoses time, reduce vascular complications, and improve survival rate.

Chronic lung allograft pathology lesions in two rat strain combinations

Background

Chronic lung allograft dysfunction remains an obstacle to long-term survival after lung transplantation. Two phenotypes have been described: obliterative bronchiolitis and restrictive allograft syndrome. Preclinical models are essential to analyze chronic lung allograft dysfunction pathophysiology.

Methods

Orthotopic lung transplants from 38 Lewis into Fischer 344 (Lew→F344) and 67 Brown-Norway into Lewis (BN→Lew) rats were performed in our center in the last decade. We carefully reviewed and quantified all grafts with chronic rejection (40 cases) (18 Lew→F344, 22 BN→Lew) with the aim to investigate if histological changes of chronic lung allograft dysfunction could be also detected in rat grafts.

Results

All animals showed human reminiscent histological lesions. Early chronic rejection lesions were detected in BN→Lew. End-stage chronic rejection with features of obliterative bronchiolitis was observed in 33% of Lew→F344; end-stage with restrictive allograft syndrome chronic rejection in 67% and 80% of Lew→F344 and BN→Lew, respectively. BN→Lew showed higher grades of endotheliitis, vascular fibrosis, and lower grades of lymphoid aggregates than Lew→F344 (P=0.007, P=0.043, P=0.004, respectively).

Conclusions

Chronic rejection lesions in rat lung allografts mimic those in humans. The frequent occurrence of restrictive allograft syndrome-like lesions in BN→Lew may be related to a higher degree of mismatch in this strain combination. These animal models could allow future mechanistic studies to better understand chronic lung allograft dysfunction pathogenesis.