Experimental left pneumonectomy in pigs: procedure and management

Genome-wide expression of the residual lung reacting to experimental Pneumonectomy

Background

Acute or chronic irreversible respiratory failure may occur in patients undergoing pneumonectomy. Aim of this study was to determine transcriptome expression changes after experimental pneumonectomy in swine model. Experimental left pneumonectomy was performed in five pigs under general anaesthesia. Both the resected and the remaining lung, after 60 post-operative completely uneventful days, underwent genome-wide bulk RNA-Sequencing (RNA-Seq).

Results

Histological analysis showed dilation of air spaces and rupture of interalveolar septa. In addition, mild inflammation, no fibrosis, radial stretch of the bronchus, strong enlargement of airspaces and thinning of the blood supply were observed. Bioinformatic analyses of bulk RNA-Seq data identified 553 Differentially Expressed Genes (DEGs) at adjusted P-value below 0.001, between pre- and post-pneumonectomy. The top 10 up-regulated DEGs were Edn1, Areg, Havcr2, Gadd45g, Depp1, Cldn4, Atf3, Myc, Gadd45b, Socs3; the top 10 down-regulated DEGs were Obscn, Cdkn2b, ENSSSCG00000015738, Prrt2, Amer1, Flrt3, Efnb2, Tox3, Znf793, Znf365. Leveraging digital cytometry tools, no difference in cellular abundance was found between the two experimental groups, while the analysis of cell type-specific gene expression patterns highlighted a striking predominance of macrophage-specific genes among the DEGs. DAVID-based gene ontology analysis showed a significant enrichment of “Extrinsic apoptotic signaling pathway” (FDR q = 7.60 × 10^− 3) and “Response to insulin” (FDR q = 7.60 × 10^− 3) genes, along with an enrichment of genes involved as “Negative regulators of DDX58/IFIH1 signaling” (FDR q = 7.50 × 10^− 4) found by querying the REACTOME pathway database. Gene network analyses indicated a general dysregulation of gene inter-connections.

Conclusion

This translational genomics study highlighted the existence both of individual genes, mostly dysregulated in certain cellular populations (e.g., macrophages), and gene-networks involved in pulmonary reaction after left pneumonectomy. Their involvement in lung homeostasis is largely supported by previous studies, carried out both in humans and in other animal models (under homeostatic or disease-related conditions), that adopted candidate-gene approaches. Overall, the present findings represent a preliminary assessment for future, more focused, studies on compensatory lung adaptation, pulmonary regeneration and functional reload.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08171-3.

The susceptibility of the aortic root: porcine aortic rupture testing under cardiopulmonary bypass

Background

In our earlier study on the functional limits of the aneurysmal aortic root we determined the pig root is susceptible to failure at high aortic pressures levels. We established a pig rupture model using cardiopulmonary bypass to determine the most susceptible region of the aortic root under the highest pressures achievable using continuous flow, and what changes occur in these regions on a macroscopic and histological level. This information may help guide clinical management of aortic root and ascending aorta pathology.

Methods

Five pigs underwent 4D flow MRI imaging pre surgery to determine vasopressor induced wall sheer stress and flow parameters. All pigs were then placed on cardiopulmonary bypass (CPB) via median sternotomy, and maximal aortic root and ascending aorta flows were initiated until rupture or failure, to determine the most susceptible region of the aorta. The heart was explanted and analysed histologically to determine if histological changes mirror the macroscopic observations.

Results

The magnetic resonance imaging (MRI) aortic flow and wall sheer stress (WSS) increased significantly in all regions of the aorta, and the median maximal pressures obtained during cardiopulmonary bypass was 497 mmHg and median maximal flows was 3.96 L/m. The area of failure in all experiments was the non-coronary cusp of the aortic valve. Collagen and elastin composition (%) was greatest in the proximal regions of the aorta. Collagen I and III showed greatest content in the inner aortic root and ascending aorta regions.

Conclusions

This unique porcine model shows that the aortic root is most susceptible to failure at high continuous aortic pressures, supported histologically by different changes in collagen content and subtypes in the aortic root. With further analysis, this information could guide management of the aortic root in disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01667-9.

El biomodelo porcino en la investigación médica traslacional: del biomodelo al humano en trasplante pulmonar

Introducción. La anatomía humana y porcina son comparables. En consecuencia, el biomodelo porcino tiene el potencial de ser implementado para entrenar al profesional quirúrgico en áreas como el trasplante de órganos sólidos.Objetivo. Describir los procedimientos y hallazgos obtenidos mediante experimentos de medicina respiratoria traslacional con biomodelos porcinos realizados en un laboratorio de experimentación animal, y hacer una revisión comparativa entre el pulmón humano y el porcino.Materiales y métodos. El experimento se llevó a cabo en nueve cerdos de raza híbrida en un laboratorio de cirugía experimental. Se estudiaron la anatomía y la histología de las vías respiratorias mediante fibrobroncoscopia, biopsia bronquial y lavado broncoalveolar. El lavado broncoalveolar se estudió con citología en base líquida y se evaluó con las coloraciones de Papanicolau y hematoxilina y eosina. Se utilizaron técnicas de patología molecular, como inmunohistoquímica, citometría de flujo y microscopía electrónica. Los cerdos se sometieron a neumonectomía izquierda con posterior implante del injerto en otro cerdo experimental.Resultados. Los estudios histopatológicos y moleculares evidenciaron un predominio de macrófagos alveolares (98 %) y linfocitos T (2 %) en el lavado broncoalveolar porcino. En los estudios del parénquima pulmonar porcino se encontró tejido linfoide hiperplásico asociado a las paredes bronquiales. La microscopía electrónica evidenció linfocitos T dentro del epitelio y el diámetro de las cilias porcinas fue similar al de las humanas.Conclusiones. El biomodelo porcino es viable en la investigación traslacional para el entendimiento de la anatomía del sistema respiratorio y el entrenamiento en trasplante pulmonar. La implementación de este modelo experimental podría fortalecer los grupos que planean implementar un programa institucional de trasplante pulmonar en humanos.

Observational analysis on inflammatory reaction to talc pleurodesis: Small and large animal model series review

Talc pleurodesis has been associated with pleuropulmonary damage, particularly long-term damage due to its inert nature. The present model series review aimed to assess the safety of this procedure by examining inflammatory stimulus, biocompatibility and tissue reaction following talc pleurodesis. Talc slurry was performed in rabbits: 200 mg/kg checked at postoperative day 14 (five models), 200 mg/kg checked at postoperative day 28 (five models), 40 mg/kg, checked at postoperative day 14 (five models), 40 mg/kg checked at postoperative day 28 (five models). Talc poudrage was performed in pigs: 55 mg/kg checked at postoperative day 60 (18 models). Tissue inspection and data collection followed the surgical pathology approach currently used in clinical practice. As this was an observational study, no statistical analysis was performed. Regarding the rabbit model (Oryctolagus cunicoli), the extent of adhesions ranged between 0 and 30%, and between 0 and 10% following 14 and 28 days, respectively. No intraparenchymal granuloma was observed whereas, pleural granulomas were extensively encountered following both talc dosages, with more evidence of visceral pleura granulomas following 200 mg/kg compared with 40 mg/kg. Severe florid inflammation was observed in 2/10 cases following 40 mg/kg. Parathymic, pericardium granulomas and mediastinal lymphadenopathy were evidenced at 28 days. At 60 days, from rare adhesions to extended pleurodesis were observed in the pig model (Sus Scrofa domesticus). Pleural granulomas were ubiquitous on visceral and parietal pleurae. Severe spotted inflammation among the adhesions were recorded in 15/18 pigs. Intraparenchymal granulomas were observed in 9/18 lungs. Talc produced unpredictable pleurodesis in both animal models with enduring pleural inflammation whether it was performed via slurry or poudrage. Furthermore, talc appeared to have triggered extended pleural damage, intraparenchymal nodules (porcine poudrage) and mediastinal migration (rabbit slurry).

Technique and perioperative management of left pneumonectomy in neonatal piglets

BACKGROUND

Although commonly performed in adult swine, unilateral pneumonectomy in piglets requires significant modifications in the surgical approach and perioperative care because of their smaller size and limited physiological reserve.

METHODS

Nineteen neonatal piglets underwent a left pneumonectomy. They were allowed 5-7 d of preoperative acclimation and nutritional optimization. Preoperative weight gain and laboratory values were obtained before the time of surgery. A "ventro-cranial" approach is adopted where components of the pulmonary hilum were sequentially identified and ligated, starting from the most ventral and cranial structure, the superior pulmonary vein. The principle of gentle ventilation was followed throughout the entire operation.

RESULTS

The median age of the piglets at the time of surgery was 12 (10-12) d. The median preoperative weight gain and albumin level were 20% (16-26%) and 2.3 (2.1-2.4) g/dL, respectively. The median operative time was 59 (50-70) min. Five of the first nine piglets died from complications, two from poor preoperative nutritional optimization (both with <10% weight gain and 2 g/dL for albumin), one from an intubation complication, one from intra-operative bleeding, and one in the postoperative period from a ruptured bulla. No mortality occurred for the next 10 cases.

CONCLUSIONS

Successful outcomes for unilateral pneumonectomy in piglets require special attention to preoperative nutritional optimization, gentle ventilation, and meticulous surgical dissection. Preoperative weight gain and albumin levels should be used to identify appropriate surgical candidates. The "ventro-cranial" approach allows for a technically straightforward completion of the procedure.

Comparison of acute phase reaction and postoperative stress in pigs undergoing video-assisted thoracoscopic versus thoracotomy pneumonectomy

Background

Video-assisted thoracoscopic surgery (VATS) has been used for many thoracic diseases as an alternate approach to thoracotomy. The aim of this study was to compare the surgical outcome of pneumonectomy using VATS with that using thoracotomy pneumonectomy in pigs. Fourteen pigs were equally divided into two groups; one group underwent VATS and the other group underwent transthoracic pneumonectomy. We monitored pre-, intra-, and post-operative physiologic parameters, along with blood cell count, serum C-reactive protein (CRP), serum amyloid A (SAA), interleukin-6 (IL-6) and cortisol. The differences between the two approaches were analyzed.

Results

Mean surgical time in the VATS group (160.6 ± 16.2 min) was significantly longer than that in the thoracotomy group (123.7 ± 13.2 min). In both groups, CRP and IL-6 concentrations were significantly increased at postoperative 4 h, and then gradually decreased to preoperative levels. CRP and IL-6 at postoperative day 1 were significant lower in the VATS group compared with the thoracotomy group. SAA was significantly increased at postoperative days 1 and 3 in both groups compared with preoperative levels. Cortisol was significantly increased immediately after surgery in both groups compared with preoperative levels, and was significantly higher in the thoracotomy group than the VATS group at postoperative 4 h and 1 day.

Conclusions

There was no difference between the two groups in physiologic parameters and blood cell count. However, the results indicate that VATS resulted in a smaller incision, less acute-phase reaction, less stress and less pain compared with thoracotomy pneumonectomy.

Effectiveness and predictability of pleurodesis with the Tachosil® surgical patch compared with talc poudrage: an experimental study

OBJECTIVES

The human fibrinogen/thrombin surgical patch is proposed for videothoracoscopic pleurodesis after recurrent observation in routine clinical practice of site-specific pleuro-pulmonary adhesions.

METHODS

A total of 36 experimental videothoracoscopies were performed on 18 pigs, all of which underwent a bilateral sequential procedure. The right or left side was casually approached and two 4.8 × 4.8 cm Tachosil® patches were placed over the dorsal lung surface in the highest antigravitary position through a double-port thoracoscopy. The contralateral side was subsequently entered by a single-port thoracoscopy to perform talc poudrage in accordance with current recommendations (1 g/18 kg). Thoracoscopy and autopsy were performed after 60 days to evaluate the outcome. Pleurodesis was graded on a predefined three-tier scale (none-moderate-firm); specimens were then submitted to the pathologist. The statistical analyses performed were: frequencies distribution, variables association test and hypothesis testing using binomial distribution.

RESULTS

Pleurodesis was firm in 15/18 cases (P = 0.004), moderate in 2/18, and none in 1/18 cases with the sealant matrix. Talc pleurodesis was firm in 7/18 cases and moderate in 11/18. No surgical, medical, behavioural or growth disorders were recorded. There was complete correspondence between lung surface covered by the sealant patch and pleural adhesion topography (P < 0.001) and no other sites of adhesion were found at autopsy, whereas talc effect was commonly found to produce random pleural cavity obliteration, most frequently in declivous places, with inhomogeneous pleural adhesion for tissue density and rough/smooth outline (P < 0.001). The pathologist disclosed that talc creates a variable and unpredictable inflammatory background, sometimes severe, with the development of many granulomas. Fibrin sealant patch pleurodesis is caused by connective tissue irrespective of the pleural and pulmonary anatomy.

CONCLUSIONS

The fibrin sealant patch is effective in producing localized pleurodesis in swine. The morphology and topography of the adhesions, 2 months after the patch placement, are consistent and more predictable than after talc poudrage. The latter causes a diffuse pleurodesis which is not predictable, with a predominantly gravitational location and produces a much more serious inflammatory response.