Normothermic ex vivo lung perfusion(NEVLP)has emerged as a modernized organ preservation tech-nique that allows for detailed assessment of donor lung function prior to transplantation.The main goal of this study was to identify potential biomarkers of lung function and/or injury during a prolonged(19 h)NEVLP procedure using in vivo solid-phase microextraction(SPME)technology followed by liquid chromatography-high resolution mass spectrometry(LC-HRMS).The use of minimally invasive in vivo SPME fibers for repeated sampling of biological tissue permits the monitoring and evaluation of biochemical changes and alterations in the metabolomic profile of the lung.These in vivo SPME fibers were directly introduced into the lung and were also used to extract metabolites(on-site SPME)from fresh perfusate samples collected alongside lung samplings.A subsequent goal of the study was to assess the feasibility of SPME as an in vivo method in metabolomics studies,in comparison to the traditional in-lab metabolomics workflow.Several upregulated biochemical pathways involved in pro-and anti-inflammatory responses,as well as lipid metabolism,were observed during extended lung perfusion,especially between the 11th and 12th hours of the procedure,in both lung and perfusate samples.However,several unstable and/or short-lived metabolites,such as neuroprostanes,have been extracted from lung tissue in vivo using SPME fibers.On-site monitoring of the metabolomic profiles of both lung tissues through in vivo SPME and perfusate samples on site throughout the prolonged NEVLP procedure can be effectively performed using in vivo SPME technology.

Solid phase microextraction(SPME)in combination with high-resolution mass spectrometry was employed for the determination of metabolomic profile of mouse melanoma growth within in vitro 2D,in vitro 3D,and in vivo models.Such multi-model approach had never been investigated before.Due to the low-invasiveness of SPME,it was possible to perform time-course analysis,which allowed building time profile of biochemical reactions in the studied material.Such approach does not require the multiplication of samples as subsequent analyses are performed from the very same cell culture or from the same individual.SPME already reduces the number of animals required for experiment;therefore,it is with good concordance with the 3Rs rule(replacement,reduction,and refinement).Among tested models,the largest number of compounds was found within the in vitro 2D cell culture model,while in vivo and in vitro 3D models had the lowest number of detected compounds.These results may be connected with a higher metabolic rate,as well as lower integrity of the in vitro 2D model compared to the in vitro 3D model resulting in a lower number of compounds released into medium in the latter model.In terms of in vitro-in vivo extrapolation,the in vitro 2D model performed more similar to in vivo model compared to in vitro 3D model;however,it might have been due to the fact that only compounds secreted to medium were investigated.Thus,in further experiments to obtain full metabolome infor-mation,the intraspheroidal assessment or spheroid dissociation would be necessary.

In vivo lung perfusion(IVLP)is a novel isolated lung technique developed to enable the local,in situ administration of high-dose chemotherapy to treat metastatic lung cancer.Combination therapy using folinic acid(FOL),5-fluorouracil(F),and oxaliplatin(OX)(FOLFOX)is routinely employed to treat several types of solid tumours in various tissues.However,F is characterized by large interpatient variability with respect to plasma concentration,which necessitates close monitoring during treatments using of this compound.Since plasma drug concentrations often do not reflect tissue drug concentrations,it is essential to utilize sample-preparation methods specifically suited to monitoring drug levels in target organs.In this work,in vivo solid-phase microextraction(in vivo SPME)is proposed as an effective tool for quantitative therapeutic drug monitoring of FOLFOX in porcine lungs during pre-clinical IVLP and intravenous(Ⅳ)trials.The concomitant extraction of other endogenous and exogenous small molecules from the lung and their detection via liquid chromatography coupled to high resolution mass spec-trometry(LC-HRMS)enabled an assessment of FOLFOX's impact on the metabolomic profile of the lung and revealed the metabolic pathways associated with the route of administration(IVLP vs.Ⅳ)and the therapy itself.This study also shows that the immediate instrumental analysis of metabolomic samples is ideal,as long-term storage at-80 ℃ results in changes in the metabolite content in the sample extracts.

Development of a novel in vivo lung perfusion(IVLP)procedure allows localized delivery of high-dose doxorubicin(DOX)for targeting residual micrometastatic disease in the lungs.However,DOX delivery via IVLP requires careful monitoring of drug level to ensure tissue concentrations of this agent remain in the therapeutic window.A small dimension nitinol wire coated with a sorbent of biocompatible morphology(Bio-SPME)has been clinically evaluated for in vivo lung tissue extraction and determina-tion of DOX and its key metabolites.The in vivo Bio-SPME-IVLP experiments were performed on pig model over various(150 and 225 mg/m2)drug doses,and during human clinical trial.Two patients with metastatic osteosarcoma were treated with a single 5 and 7 μg/mL(respectively)dose of DOX during a 3-h IVLP.In both pig and human cases,DOX tissue levels presented similar trends during IVLP.Human lung tissue concentrations of drug ranged between 15 and 293 μg/g over the course of the IVLP procedure.In addition to DOX levels,Bio-SPME followed by liquid chromatography-mass spectrometry analysis generated 64 metabolic features during endogenous metabolite screening,providing information about lung status during drug administration.Real-time monitoring of DOX levels in the lungs can be per-formed effectively throughout the IVLP procedure by in vivo Bio-SPME chemical biopsy approach.Bio-SPME also extracted various endogenous molecules,thus providing a real-time snapshot of the physi-ology of the cells,which might assist in the tailoring of personalized treatment strategy.