Development and systematic evaluation of decellularization protocols in different application models for diaphragmatic tissue engineering

BACKGROUND

Tissue engineered bioscaffolds based on decellularized composites have gained increasing interest for treatment of various diaphragmatic impairments, including muscular atrophies and diaphragmatic hernias. Detergent-enzymatic treatment (DET) constitutes a standard strategy for diaphragmatic decellularization. However, there is scarce data on comparing DET protocols with different substances in distinct application models in their ability to maximize cellular removal while minimizing extracellular matrix (ECM) damage.

METHODS

We decellularized diaphragms of male Sprague Dawley rats with 1 % or 0.1 % sodium dodecyl sulfate (SDS) and 4 % sodium deoxycholate (SDC) by orbital shaking (OS) or retrograde perfusion (RP) through the vena cava. We evaluated decellularized diaphragmatic samples by (1) quantitative analysis including DNA quantification and biomechanical testing, (2) qualitative and semiquantitative analysis by proteomics, as well as (3) qualitative assessment with macroscopic and microscopic evaluation by histological staining, immunohistochemistry and scanning electron microscopy.

RESULTS

All protocols produced decellularized matrices with micro- and ultramorphologically intact architecture and adequate biomechanical performance with gradual differences. The proteomic profile of decellularized matrices contained a broad range of primal core and ECM-associated proteins similar to native muscle. While no outstanding preference for one singular protocol was determinable, SDS-treated samples showed slightly beneficial properties in comparison to SDC-processed counterparts. Both application modalities proved suitable for DET.

CONCLUSION

DET with SDS or SDC via orbital shaking or retrograde perfusion constitute suitable methods to produce adequately decellularized matrices with characteristically preserved proteomic composition. Exposing compositional and functional specifics of variously treated grafts may enable establishing an ideal processing strategy to sustain valuable tissue characteristics and optimize consecutive recellularization. This aims to design an optimal bioscaffold for future transplantation in quantitative and qualitative diaphragmatic defects.

Effect of Preoperative Chemotherapy on the Isolation Outcome of Primary Human Hepatocytes

Primary human hepatocytes isolated from surgically resected liver tissue are an essential resource for pharmaceutical and toxicological studies. Patients undergoing partial liver resections have often received preoperative chemotherapy. The aim of our study was to investigate whether preoperative chemotherapy has effects on the outcome of cell isolation or the metabolic function of cultured hepatocytes. Liver specimens from 48 patients were used for hepatocyte isolation. Out of these, 21 patients had prior chemotherapy, with fluoropyrimidine-based regimen in 14 patients. Viability and cell yield as parameter for the outcome of isolation, as well as transaminase levels, urea or albumin secretion to the culture medium were not different between hepatocytes from pretreated and untreated donor. Furthermore, the transcription levels of cytochrome P450 (CYP) 1A2, CYP 2B6, and CYP 3A4 of cultured hepatocytes were not affected by prior chemotherapy of the tissue donors. In conclusion, hepatocytes from tissue donors that underwent fluoropyrimidine-based chemotherapy regimens before isolation seem to perform as well as hepatocytes without preoperative chemotherapy exposure. Our results suggest that hepatocytes from patients who received combination chemotherapy before liver resection are an uncompromised resource for pharmacological and toxicological studies. Impact statement Isolated primary human hepatocytes are an essential resource for pharmacological and toxicological studies. Our results present further evidence that isolated hepatocytes from patients who received combination chemotherapy before liver resection are an uncompromised resource for pharmacological and toxicological studies-especially when fluoropyrimidine-based regimens are used.

[Declined Liver Grafts - Analysis of the German Donor Population from 2010 to 2018]

BACKGROUND

 The lack of suitable allografts limits the availability of liver transplantation in Germany. The quality of potentially available German donor livers has to date not been analyzed.

METHODS

 Analysis of all donors for potential liver transplantations reported to the Eurotransplant by the German Organ Transplantation Foundation from 2010 to 2018. Categorization of transplanted and discarded organs utilizing available histopathological reports and predefined extended criteria for organ donation.

RESULTS

 A total of 8594 livers were offered for transplantation, of which 15.2 % were discarded. During the analysis period the proportion of donor livers from extended criteria donors increased from 65 % to 70 % (p = 0.005). In 2018, 21.3 % of offered donor livers were discarded, more than half (56.4 %) of these organs came from donors meeting multiple extended criteria. Livers were significantly more likely to be not transplanted, when from donors of older age (> 65 years; 41 vs. 28 %), BMI > 30 kg/m² (29 vs. 14 %) or elevated transaminase levels (all p < 0,001).

CONCLUSION

 Despite the consistent organ scarcity in Germany, a relevant amount of livers cannot be transplanted due to a multitude of organ quality limitations. This should stimulate the search for concepts such as normothermic ex vivo machine perfusion to evaluate, protect and potentially improve organ quality.