Toward a common interpretation of the 3Rs principles in animal research.

Many scientific breakthroughs have depended on animal research, yet the ethical concerns surrounding the use of animals in experimentation have long prompted discussions about humane treatment and responsible scientific practice. First articulated by Russell and Burch, the 3Rs Principles of Replacement, Reduction, and Refinement have gained widespread recognition as basic guidelines for animal research. Over time, the 3Rs have transcended the research community, influencing policy decisions, animal welfare advocacy and public perception of animal experimentation.

A robust high-throughput screening system to assess bacterial tyrosine ammonia lyase activity in the context of tyrosine inherited metabolic disorders.

Inborn errors of tyrosine metabolism result in patient's inability to degrade tyrosine. Current treatment consists of a phenylalanine and tyrosine restricted diet and nitisinone, causing a block in the tyrosine degradation pathway. However, tyrosine levels will increase, leading to acquired hypertyrosinemia, implying the need for an add-on treatment.

The Immunological Profile of Adipose Mesenchymal Stromal/Stem Cells after Cell Expansion and Inflammatory Priming.

Background: AT-MSCs display great immunoregulatory features, making them potential candidates for cell-based therapy. This study aimed to evaluate the "RBC lysis buffer" isolation protocol and immunological profiling of the so-obtained AT-MSCs.

Methods: We established an immune-comparative screening of AT-MSCs throughout in vitro cell expansion (PM, P1, P2, P3, P4) and inflammatory priming regarding the expression of 28 cell-surface markers, 6 cytokines/chemokines, and 10 TLR patterns.

Human skin stem cell-derived hepatic cells as in vitro drug discovery model for insulin-driven de novo lipogenesis.

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is characterized by intrahepatic triglyceride accumulation and can progress to metabolic dysfunction-associated steatohepatitis (MASH) and liver fibrosis. Hepatic de novo lipogenesis (DNL), activated by glucose and insulin, is a central pathway contributing to early-stage development of MASLD. The emerging global prevalence of MASLD highlights the urgent need for pharmaceutical intervention to combat this health threat.

Hereditary Tyrosinemia Type 1 Mice under Continuous Nitisinone Treatment Display Remnants of an Uncorrected Liver Disease Phenotype.

Hereditary tyrosinemia type 1 (HT1) is a genetic disorder of the tyrosine degradation pathway (TIMD) with unmet therapeutic needs. HT1 patients are unable to fully break down the amino acid tyrosine due to a deficient fumarylacetoacetate hydrolase (FAH) enzyme and, therefore, accumulate toxic tyrosine intermediates. If left untreated, they experience hepatic failure with comorbidities involving the renal and neurological system and the development of hepatocellular carcinoma (HCC).

A robust bacterial high-throughput screening system to evaluate single nucleotide polymorphisms of human homogentisate 1,2-dioxygenase in the context of alkaptonuria.

Alkaptonuria (AKU) is a rare inborn error of metabolism caused by a defective homogentisate 1,2-dioxygenase (HGD), an enzyme involved in the tyrosine degradation pathway. Loss of HGD function leads to the accumulation of homogentisic acid (HGA) in connective body tissues in a process called ochronosis, which results on the long term in an early-onset and severe osteoarthropathy. HGD's quaternary structure is known to be easily disrupted by missense mutations, which makes them an interesting target for novel treatment strategies that aim to rescue enzyme activity.

Mesenchymal Stem/Stromal Cells as a Therapeutic Tool in Cell-Based Therapy and Regenerative Medicine: An Introduction Expertise to the Topical Collection.

We are pleased to present this opening editorial, introducing our topical collection, "The New Era of Mesenchymal Stromal/Stem Cell Functional Application: State of the Art, Therapeutic Challenges and Future Directions" [...

Development of an adverse outcome pathway network for breast cancer: a comprehensive representation of the pathogenesis, complexity and diversity of the disease.

Adverse outcome pathways (AOPs), introduced in modern toxicology, intend to provide an evidence-based representation of toxicological effects and facilitate safety assessment of chemicals not solely based on laboratory animal in vivo experiments. However, some toxicological processes are too complicated to represent in one AOP. Therefore, AOP networks are developed that help understanding and predicting toxicological processes where complex exposure scenarios interact and lead to the emergence of the adverse outcome.

Light triggered nanoscale biolistics for efficient intracellular delivery of functional macromolecules in mammalian cells.

Biolistic intracellular delivery of functional macromolecules makes use of dense microparticles which are ballistically fired onto cells with a pressurized gun. While it has been used to transfect plant cells, its application to mammalian cells has met with limited success mainly due to high toxicity. Here we present a more refined nanotechnological approach to biolistic delivery with light-triggered self-assembled nanobombs (NBs) that consist of a photothermal core particle surrounded by smaller nanoprojectiles.

From NAFLD to MAFLD: Aligning Translational In Vitro Research to Clinical Insights.

Although most same-stage non-alcoholic fatty liver disease (NAFLD) patients exhibit similar histologic sequelae, the underlying mechanisms appear to be highly heterogeneous. Therefore, it was recently proposed to redefine NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) in which other known causes of liver disease such as alcohol consumption or viral hepatitis do not need to be excluded. Revised nomenclature envisions speeding up and facilitating anti-MAFLD drug development by means of patient stratification whereby each subgroup would benefit from distinct pharmacological interventions.

Decellularization of Male Reproductive Tissue.

Decellularized testicular matrix (DTM) enables researchers to focus on the specific composition of the testicular extracellular matrix (ECM) and elucidate its role in spermatogenesis. Furthermore, it provides the natural architectural arrangement that could guide the reorganization of dissociated testicular cells in vitro. This is a key consideration as the presence of an authentic nutritive and endocrine support has been proven to be essential for in vitro spermatogenesis, at least in the mouse (Oliver and Stukenborg in Andrology 8:825-834, 2020; Richer et al.

Transcriptional Profile of Cytokines, Regulatory Mediators and TLR in Mesenchymal Stromal Cells after Inflammatory Signaling and Cell-Passaging.

Adult human subcutaneous adipose tissue (AT) harbors a rich population of mesenchymal stromal cells (MSCs) that are of interest for tissue repair. For this purpose, it is of utmost importance to determine the response of AT-MSCs to proliferative and inflammatory signals within the damaged tissue. We have characterized the transcriptional profile of cytokines, regulatory mediators and Toll-like receptors (TLR) relevant to the response of MSCs.

Infections at the nexus of metabolic-associated fatty liver disease.

Metabolic-associated fatty liver disease (MAFLD) is a chronic liver disease that affects about a quarter of the world population. MAFLD encompasses different disease stadia ranging from isolated liver steatosis to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis and hepatocellular carcinoma. Although MAFLD is considered as the hepatic manifestation of the metabolic syndrome, multiple concomitant disease-potentiating factors can accelerate disease progression.

Direct reprogramming of somatic cells into induced hepatocytes: Cracking the Enigma code.

There is an unmet need for functional primary human hepatocytes to support the pharmaceutical and (bio)medical demand. The unique discovery, a decade ago, that somatic cells can be drawn out of their apparent biological lockdown to reacquire a pluripotent state has revealed a completely new avenue of possibilities for generating surrogate human hepatocytes. Since then, the number of papers reporting the direct conversion of somatic cells into induced hepatocytes (iHeps) has burgeoned.

Oxidative Stress, Glutathione Metabolism, and Liver Regeneration Pathways Are Activated in Hereditary Tyrosinemia Type 1 Mice upon Short-Term Nitisinone Discontinuation.

Hereditary tyrosinemia type 1 (HT1) is an inherited condition in which the body is unable to break down the amino acid tyrosine due to mutations in the fumarylacetoacetate hydrolase (FAH) gene, coding for the final enzyme of the tyrosine degradation pathway. As a consequence, HT1 patients accumulate toxic tyrosine derivatives causing severe liver damage. Since its introduction, the drug nitisinone (NTBC) has offered a life-saving treatment that inhibits the upstream enzyme 4-hydroxyphenylpyruvate dioxygenase (HPD), thereby preventing production of downstream toxic metabolites.

High-throughput quantification of ochronotic pigment formation in to evaluate the potency of human 4-hydroxyphenylpyruvate dioxygenase inhibitors in multi-well format.

4-hydroxyphenylpyruvate dioxygenase (HPD) is a key enzyme in the catabolism of tyrosine and therefore of great importance as a drug target to treat tyrosine-related inherited metabolic disorders (TIMD). Inhibition of this enzyme is therapeutically applied to prevent accumulation of toxic metabolites in TIMD patients. Nowadays an ex-herbicide, nitisinone, is used for this purpose and many more inhibitors are being explored and need to be tested.

Inflammation Differentially Modulates the Biological Features of Adult Derived Human Liver Stem/Progenitor Cells.

Unlabelled: The progression of mesenchymal stem cell-based therapy from concept to cure closely depends on the optimization of conditions that allow a better survival and favor the cells to achieve efficient liver regeneration. We have previously demonstrated that adult-derived human liver stem/progenitor cells (ADHLSC) display significant features that support their clinical development. The current work aims at studying the impact of a sustained pro-inflammatory environment on the principal biological features of ADHLSC in vitro.