Cancer Tissue Engineering: development of new 3D models and technologies to support cancer research

The activity of research of this thesis focuses on the relevance that appropriate models reproducing the in vivo tumor microenvironment are essential for improving cancer biology knowledge and for testing new anticancer compounds. Animal models are proven not to be entirely compatible with the human system, and the success rates between animal and human studies are still unsatisfactory. On the other hand, 2D cell cultures fail to reproduce some aspects of tumor system. These limitations have a significant weight especially during the screening of novel antitumor drugs, as it was demonstrated that cells are less sensitive to treatments when in contact with their microenvironment. To obtain the same tumor cell inhibition levels observed in vivo, the culture environment has to reflect the 3D natural environment. Natural or synthetic hydrogels reported successful outcomes in mimicking ECM environment. During this PhD, I developed different gel-based scaffolds to be use as substrates for the culture of breast cancer cells. In detail, I developed different gels for low and highly aggressive cancer cell lines (i.e. MCF-7 and MDA-MB-231), obtaining significant results as regards the reproduction of key features normally present into the in vivo environment. Considering the importance of the metastasis process in breast cancer evolution, I then focused on a new set-up for the observation of cancer cell motility and invasion. In particular, I combined a bioreactor-based bioengineering approach with single cell analysis of Circulating Tumor Cells (CTCs). This part of work was carried out at the Dipartiment of Biomedicine of the University of Basel (CH) that, among its equipment, has a cell celector machine for single cell analysis. At the end of this work, I provided a proof-of-concept that the approach can work, as well as evidence that the cells can be extracted from the device and used for molecular analysis

Design of decorated self-assembling peptide hydrogels as architecture for mesenchymal stem cells

Hydrogels from self-assembling ionic complementary peptides have been receiving a lot of interest from the scientific community as mimetic of the extracellular matrix that can offer three-dimensional supports for cell growth or can become vehicles for the delivery of stem cells, drugs or bioactive proteins. In order to develop a 3D "architecture" for mesenchymal stem cells, we propose the introduction in the hydrogel of conjugates obtained by chemoselective ligation between a ionic-complementary self-assembling peptide (called EAK) and three different bioactive molecules: an adhesive sequence with 4 Glycine-Arginine-Glycine-Aspartic Acid-Serine-Proline (GRGDSP) motifs per chain, an adhesive peptide mapped on h-Vitronectin and the growth factor Insulin-like Growth Factor-1 (IGF-1). The mesenchymal stem cell adhesion assays showed a significant increase in adhesion and proliferation for the hydrogels decorated with each of the synthesized conjugates; moreover, such functionalized 3D hydrogels support cell spreading and elongation, validating the use of this class of self-assembly peptides-based material as very promising 3D model scaffolds for cell cultures, at variance of the less realistic 2D ones. Furthermore, small amplitude oscillatory shear tests showed that the presence of IGF-1-conjugate did not alter significantly the viscoelastic properties of the hydrogels even though differences were observed in the nanoscale structure of the scaffolds obtained by changing their composition, ranging from long, well-defined fibers for conjugates with adhesion sequences to the compact and dense film for the IGF-1-conjugate

Promising 3D in vitro models for studying tumour heterogeneity and testing novel therapeutic approaches in pancreatic cancer

In this study we produced 3D organotypic cultures and spheroids to mimic the complex microenvironment of pancreatic cancer and to test alternative therapeutic strategies

A Prognostic Model to Predict Ruxolitinib Discontinuation and Death in Patients with Myelofibrosis

Most patients with myelofibrosis (MF) discontinue ruxolitinib (JAK1/JAK2 inhibitor) in the first 5 years of therapy due to therapy failure. As the therapeutic possibilities of MF are expanding, it is critical to identify patients predisposed to early ruxolitinib monotherapy failure and worse outcomes. We investigated predictors of early ruxolitinib discontinuation and death on therapy in 889 patients included in the "RUX-MF" retrospective study. Overall, 172 patients were alive on ruxolitinib after ≥5 years (long-term ruxolitinib, LTR), 115 patients were alive but off ruxolitinib after ≥5 yrs (short-term RUX, STR), and 123 patients died while on ruxolitinib after <5 yrs (early death on ruxolitinib, EDR). The cumulative incidence of the blast phase was similar in LTR and STR patients (p = 0.08). Overall survival (OS) was significantly longer in LTR pts (p = 0.002). In multivariate analysis, PLT < 100 × 109/L, Hb < 10 g/dL, primary MF, absence of spleen response at 3 months and ruxolitinib starting dose <10 mg BID were associated with higher probability of STR. Assigning one point to each significant variable, a prognostic model for STR (STR-PM) was built, and three groups were identified: low (score 0-1), intermediate (score 2), and high risk (score ≥ 3). The STR-PM may identify patients at higher risk of failure with ruxolitinib monotherapy who should be considered for alternative frontline strategies

Ruxolitinib in cytopenic myelofibrosis: Response, toxicity, drug discontinuation, and outcome

Background: Patients with cytopenic myelofibrosis (MF) have more limited therapeutic options and poorer prognoses compared with patients with the myeloproliferative phenotype. Aims and methods: Prognostic correlates of cytopenic phenotype were explored in 886 ruxolitinib-treated patients with primary/secondary MF (PMF/SMF) included in the RUX-MF retrospective study. Cytopenia was defined as: leukocyte count <4 × 109 /L and/or hemoglobin <11/<10 g/dL (males/females) and/or platelets <100 × 109 /L. Results: Overall, 407 (45.9%) patients had a cytopenic MF, including 249 (52.4%) with PMF. In multivariable analysis, high molecular risk mutations (p = .04), intermediate 2/high Dynamic International Prognostic Score System (p < .001) and intermediate 2/high Myelofibrosis Secondary to Polycythemia Vera and Essential Thrombocythemia Prognostic Model (p < .001) remained associated with cytopenic MF in the overall cohort, PMF, and SMF, respectively. Patients with cytopenia received lower average ruxolitinib at the starting (25.2 mg/day vs. 30.2 mg/day, p < .001) and overall doses (23.6 mg/day vs. 26.8 mg/day, p < .001) and achieved lower rates of spleen (26.5% vs. 34.1%, p = .04) and symptom (59.8% vs. 68.8%, p = .008) responses at 6 months compared with patients with the proliferative phenotype. Patients with cytopenia also had higher rates of thrombocytopenia at 3 months (31.1% vs. 18.8%, p < .001) but lower rates of anemia (65.6% vs. 57.7%, p = .02 at 3 months and 56.6% vs. 23.9% at 6 months, p < .001). After competing risk analysis, the cumulative incidence of ruxolitinib discontinuation at 5 years was 57% and 38% in patients with cytopenia and the proliferative phenotype (p < .001), whereas cumulative incidence of leukemic transformation was similar (p = .06). In Cox regression analysis adjusted for Dynamic International Prognostic Score System score, survival was significantly shorter in patients with cytopenia (p < .001). Conclusions: Cytopenic MF has a lower probability of therapeutic success with ruxolitinib as monotherapy and worse outcome. These patients should be considered for alternative therapeutic strategies

Mechanically-tuned alginate gels as new 3D breast cancer models

Three-dimensional (3D) cell cultures represent fundamental tools for the comprehension of cellular phenomena both in normal and pathological conditions. In particular, mechanical stimuli not less than chemical ones have a relevant role on cell fate, cancer onset and malignant progression. Here, we realize mechanically tuned alginate hydrogels for studying the role of substrate elasticity on breast adenocarcinoma cells activity. Hydrogels Elastic Modulus (E) was measured via Atomic Force Microscopy and a remarkable range (20\u20134000 kPa) was obtained. A breast cancer cell line, MCF-7, was seeded within the 3D gels, on standard Petri and alginate-coated dishes (2D controls). Cells showed dramatic morphological differences when cultured in 3D vs. 2D, exhibiting a flat shape morphology in both 2D conditions, while they maintained within gels a circular, clusterorganized conformation similar to the in vivo one. In 3D culture, we observed a strict correlation between cells viability and substrate elasticity; in particular, MCF-7s constantly decreased in number with increasing hydrogel elasticity. The highest cellular proliferation rate, associated to a formation of cell clusters, occurred in two weeks of culture only within the softest hydrogels (E=20-40 kPa), highlighting the need of adopting more realistic and a priori defined models for in vitro cancer studies

Development and internal validation of a model for predicting 60-day risk of invasive mould disease in patients with haematological malignancies

Objective: Our objective was to develop a model that predicts a patient's risk of developing invasive mould disease (IMD) within 60 days of admission for treatment of a haematological malignancy. Methods: We analysed 19 risk factors for IMD in a cohort of 1944 adult patients with haematological malignancies over 4127 admissions at a haematology referral centre in Northern Italy (2007-2016). We used a multivariable logistic regression to estimate the 60-day probability of developing probable or proven IMD. The model was internally validated using a bootstrap resampling procedure. Results: The prevalence of IMD was 3.3% (90 probable cases, 43 proven cases). Seven risk factors were retained in the final risk model: (1) uncontrolled malignancy, (2) high-risk chemotherapy regimen, (3) high-dose corticosteroids, (4) severe lymphopenia, (5) CMV reactivation or disease, (6) prolonged neutropenia, and (7) a history of previous IMD within 90 days. The model displayed good calibration and discrimination in both the derivation (aROC 0.85, 95% CI 0.84-0.86) and validation (aROC 0.83 95% CI 0.79-0.89) populations. Conclusions: Our model differentiated with 85% accuracy whether or not patients developed IMD within 60-days of admission. Individualized risk assessment, aided by validated prognostic models, could assist IMD management and improve antifungal stewardship

A new cell-laden 3D Alginate-Matrigel hydrogel resembles human breast cancer cell malignant morphology, spread and invasion capability observed “in vivo”

Abstract Purpose of this study was the development of a 3D material to be used as substrate for breast cancer cell culture. We developed composite gels constituted by different concentrations of Alginate (A) and Matrigel (M) to obtain a structurally stable-in-time and biologically active substrate. Human aggressive breast cancer cells (i.e. MDA-MB-231) were cultured within the gels. Known the link between cell morphology and malignancy, cells were morphologically characterized and their invasiveness correlated through an innovative bioreactor-based invasion assay. A particular type of gel (i.e. 50% Alginate, 50% Matrigel) emerged thanks to a series of significant results: 1. cells exhibited peculiar cytoskeleton shapes and nuclear fragmentation characteristic of their malignancy; 2. cells expressed the formation of the so-called invadopodia, actin-based protrusion of the plasma membrane through which cells anchor to the extracellular matrix; 3. cells were able to migrate through the gels and attach to an engineered membrane mimicking the vascular walls hosted within bioreactor, providing a completely new 3D in vitro model of the very precursor steps of metastasis

Microenvironment complexity and matrix stiffness regulate breast cancer cell activity in a 3D in vitro model

Three-dimensional (3D) cell cultures represent fundamental tools for the comprehension of cellular phenomena both in normal and in pathological conditions. In particular, mechanical and chemical stimuli play a relevant role on cell fate, cancer onset and malignant evolution. Here, we use mechanically-tuned alginate hydrogels to study the role of substrate elasticity on breast adenocarcinoma cell activity. The hydrogel elastic modulus (E) was measured via atomic force microscopy (AFM) and a remarkable range (150-4000 kPa) was obtained. A breast cancer cell line, MCF-7, was seeded within the 3D gels, on standard Petri and alginate-coated dishes (2D controls). Cells showed dramatic morphological differences when cultured in 3D versus 2D, exhibiting a flat shape in both 2D conditions, while maintaining a circular, spheroid-organized (cluster) conformation within the gels, similar to those in vivo. Moreover, we observed a strict correlation between cell viability and substrate elasticity; in particular, the number of MCF-7 cells decreased constantly with increasing hydrogel elasticity. Remarkably, the highest cellular proliferation rate, associated with the formation of cell clusters, occurred at two weeks only in the softest hydrogels (E = 150-200 kPa), highlighting the need to adopt more realistic and a priori defined models for in vitro cancer studies