New Frontiers of Skin Tissue Engineering: from the Laboratory to Clinical Practice

This thesis is focused on the key role of extracellular matrix in skin tissue engineering. Firstly, I presented three dimensional structures derived through the physiological secretion of extracellular matrix (ECM), that may be a bioinspired scaffold. I performed a biological characterization of cell-assembled ECMs from three different sub-populations of skin fibroblasts; papillary fibroblasts (Pfi), reticular fibroblasts (Rfi), and dermal papilla fibroblasts (DPfi). Fibroblast sub-populations were cultured with ascorbic acid to promote cell-assembled matrix production for 10 days. Cells were removed and the remaining matrices were characterized. I found that the ECM assembled by Pfi exhibited randomly oriented fibers, associated with highest interfibrillar space, reflecting ECM characteristics which are physiologically present within the papillary dermis. Mass spectrometry followed by immunofluorescence analysis showed that Thrombospondin is preferentially expressed within the DPfi ECM. In another experiment, keratinocytes were seeded on the top of cell depleted ECMs to generate epidermal skin constructs. I found that epidermal constructs grown on DPfi or Pfi matrices exhibited normal basement membrane formation, while Rfi matrices were unable to support membrane formation. Thus, inspiration should be taken from these different ECMs, to design therapeutic biomaterials in skin engineering applications. In the second part, I focused on human decellularized matrix for soft tissue repair and I investigated the biological interaction post-implant of this scaffold. The aims of this second part were to show the clinical results after the application of human decellularized matrix in patients suffering from abdominal hernia and to evaluate the response one year post implant, through morphological analysis of biopsy specimens. Clinical results showed that all the patients revealed a well tolerability of human decellularized matrix. Post-implant morphological results showed cellular repopulation, neo-angiogenesis, minimal inflammatory response and a well-organized collagen matrix in all biopsies. This scaffold can be considered a safe product to treat large abdominal defects

Unravelling similarities and differences in the role of circular and linear PVT1 in cancer and human disease

The plasmacytoma variant translocation 1 (PVT1) is a long non-coding RNA gene involved in human disease, mainly in cancer onset/ progression. Although widely analysed, its biological roles need to be further clarified. Notably, functional studies on PVT1 are complicated by the occurrence of multiple transcript variants, linear and circular, which generate technical issues in the experimental procedures used to evaluate its impact on human disease. Among the many PVT1 transcripts, the linear PVT1 (lncPVT1) and the circular hsa_circ_0001821 (circPVT1) are frequently reported to perform similar pathologic and pro-tumorigenic functions when overexpressed. The stimulation of cell proliferation, invasion and drug resistance, cell metabolism regulation, and apoptosis inhibition is controlled through multiple targets, including MYC, p21, STAT3, vimentin, cadherins, the PI3K/AKT, HK2, BCL2, and CASP3. However, some of this evidence may originate from an incorrect evaluation of these transcripts as two separate molecules, as they share the lncPVT1 exon-2 sequence. We here summarise lncPVT1/circPVT1 functions by mainly focusing on shared pathways, pointing out the potential bias that may exist when the biological role of each transcript is analysed. These considerations may improve the knowledge about lncPVT1/circPVT1 and their specific targets, which deserve further studies due to their diagnostic, prognostic, and therapeutic potential

Role of SIRT-3, p-mTOR and HIF-1\u3b1 in Hepatocellular Carcinoma Patients Affected by Metabolic Dysfunctions and in Chronic Treatment with Metformin

The incidence of hepatocellular carcinoma deriving from metabolic dysfunctions has increased in the last years. Sirtuin- (SIRT-3), phospho-mammalian target of rapamycin (p-mTOR) and hypoxia-inducible factor- (HIF-1\u3b1) are involved in metabolism and cancer. However, their role in hepatocellular carcinoma (HCC) metabolism, drug resistance and progression remains unclear. This study aimed to better clarify the biological and clinical function of these markers in HCC patients, in relation to the presence of metabolic alterations, metformin therapy and clinical outcome. A total of 70 HCC patients were enrolled: 48 and 22 of whom were in early stage and advanced stage, respectively. The expression levels of the three markers were assessed by immunohistochemistry and summarized using descriptive statistics. SIRT-3 expression was higher in diabetic than non-diabetic patients, and in metformin-treated than insulin-treated patients. Interestingly, p-mTOR was higher in patients with metabolic syndrome than those with different etiology, and, similar to SIRT-3, in metformin-treated than insulin-treated patients. Moreover, our results describe a slight, albeit not significant, benefit of high SIRT-3 and a significant benefit of high nuclear HIF-1\u3b1 expression in early-stage patients, whereas high levels of p-mTOR correlated with worse prognosis in advanced-stage patients. Our study highlighted the involvement of SIRT-3 and p-mTOR in metabolic dysfunctions that occur in HCC patients, and suggested SIRT-3 and HIF-1\u3b1 as predictors of prognosis in early-stage HCC patients, and p-mTOR as target for the treatment of advanced-stage HCC

circPVT1 and PVT1/AKT3 show a role in cell proliferation, apoptosis, and tumor subtype-definition in small cell lung cancer

Small cell lung cancer (SCLC) is treated as a homogeneous disease, although the expression of NEUROD1, ASCL1, POU2F3, and YAP1 identifies distinct molecular subtypes. The MYC oncogene, amplified in SCLC, was recently shown to act as a lineage-specific factor to associate subtypes with histological classes. Indeed, MYC-driven SCLCs show a distinct metabolic profile and drug sensitivity. To disentangle their molecular features, we focused on the co-amplified PVT1, frequently overexpressed and originating circular (circRNA) and chimeric RNAs. We analyzed hsa_circ_0001821 (circPVT1) and PVT1/AKT3 (chimPVT1) as examples of such transcripts, respectively, to unveil their tumorigenic contribution to SCLC. In detail, circPVT1 activated a pro-proliferative and anti-apoptotic program when over-expressed in lung cells, and knockdown of chimPVT1 induced a decrease in cell growth and an increase of apoptosis in SCLC in vitro. Moreover, the investigated PVT1 transcripts underlined a functional connection between MYC and YAP1/POU2F3, suggesting that they contribute to the transcriptional landscape associated with MYC amplification. In conclusion, we have uncovered a functional role of circular and chimeric PVT1 transcripts in SCLC; these entities may prove useful as novel biomarkers in MYC-amplified tumors.</p

Novel and Rare Fusion Transcripts Involving Transcription Factors and Tumor Suppressor Genes in Acute Myeloid Leukemia.

Approximately 18% of acute myeloid leukemia (AML) cases express a fusion transcript. However, few fusions are recurrent across AML and the identification of these rare chimeras is of interest to characterize AML patients. Here, we studied the transcriptome of 8 adult AML patients with poorly described chromosomal translocation(s), with the aim of identifying novel and rare fusion transcripts. We integrated RNA-sequencing data with multiple approaches including computational analysis, Sanger sequencing, fluorescence in situ hybridization and in vitro studies to assess the oncogenic potential of the ZEB2-BCL11B chimera. We detected 7 different fusions with partner genes involving transcription factors (OAZ-MAFK, ZEB2-BCL11B), tumor suppressors (SAV1-GYPB, PUF60-TYW1, CNOT2-WT1) and rearrangements associated with the loss of NF1 (CPD-PXT1, UTP6-CRLF3). Notably, ZEB2-BCL11B rearrangements co-occurred with FLT3 mutations and were associated with a poorly differentiated or mixed phenotype leukemia. Although the fusion alone did not transform murine c-Kit+ bone marrow cells, 45.4% of 14q32 non-rearranged AML cases were also BCL11B-positive, suggesting a more general and complex mechanism of leukemogenesis associated with BCL11B expression. Overall, by combining different approaches, we described rare fusion events contributing to the complexity of AML and we linked the expression of some chimeras to genomic alterations hitting known genes in AML

Decellularized human dermal matrix produced by a skin bank: A new treatment for abdominal wall defects

BACKGROUND; Interest is increasing for human decellularized scaffolds for their ability to favor healing and cell infiltration after transplantation, in the treatment of abdominal wall defects. The purpose of the present study is to show the clinical results obtained after the application of human decellularized dermal matrix (HDM) produced by RER Skin Bank, on patients suffering from different abdominal wall defects. METHODS: Between 2012 and 2014, 64 patients, average age 64 years, received HDM, to replace and cover the damage area during abdominal wall surgery. After surgical procedures, all patients were followed weekly for the first month and then monthly up to 6 months postoperative and any major problem or complication were recorded. Six months follow up included abdominal exams, serological tests and MRI analysis in order to evaluate integration of HDM with the patients surroundings tissues and eventual long-term complications. RESULTS: Incisional hernia was the most frequent clinical condition in which HDM was applied, requiring also the highest amount of human decellularized dermal matrix. One month after the surgical operation, 61 patients revealed a well tolerability of HDM and a normal wound healing was also identified in all the damage areas. Only 3 patients experienced postoperative infections. Moreover the follow up after 6 months reported no signs of dermis rejection and that none of the patients was positive to serological tests. CONCLUSIONS: Human decellularized dermal matrix can be considered a safe and useful bioproduct to treat large abdominal defects, characterized by minor complications and simplicity to be implanted

Magnetic Labelling of Mesenchymal Stem Cells with Iron-Doped Hydroxyapatite Nanoparticles as Tool for Cell Therapy

Superparamagnetic nanoparticles offer several opportunities in nanomedicine and magnetic cell targeting. They are considered to be an extremely promising approach for the translation of cell-based therapies from the laboratory to clinical studies. In fact, after injection, the magnetic labeled cells could be driven by a static magnetic field and localized to the target site where they can perform their specific role. In this study, innovative iron-doped hydroxyapatite nanoparticles (FeHA NPs) were tested with mesenchymal stem cells (MSCs) as tools for cell therapy. Results showed that FeHA NPs could represent higher cell viability in'respect to commercial superparamagnetic iron oxide nanoparticles (SPION) at four different concentrations ranging from 10 \u3bcg/ml up to 200 \u3bcg/ml and would also upregulate an early marker involved in commitment and differentiation of MSCs. Moreover, FeHA NPs were uptaken without negatively affecting the cell behavior and their ultrastructure. Thus obtained magnetic cells were easily guided by application of a static magnetic field. This work demonstrates the promising opportunities of FeHA NPs in MSCs labeling due to the unique features of fast degradation and very low iron content of FeHA NPs compared to SPIONs. Likewise, due to the intrinsic properties of FeHA NPs, this approach could be simply transferred to different cell types as an effective magnetic carrier of drugs, growth factors, miRNA, etc., offering favorable prospects in nanomedicin

Cold Atmospheric Plasma Treatment of Infected Skin Tissue: Evaluation of Sterility, Viability, and Integrity

Sterilization of equipment and tissues is a common clinical practice: there are different chemical, mechanical, and electromagnetic aseptic techniques for inactivating microorganisms. In particular, skin tissue banks are investigating new methods to efficiently decolonize skin tissues, while preserving their structural features. In recent years, cold atmospheric plasma (CAP) has demonstrated bactericidal, virucidal, and fungicidal properties, due to the generation of reactive species and charged particles. For this reason, the aim of this paper is to demonstrate that the implementation of a dielectric barrier discharge (DBD) treatment in air can effectively decontaminate skin tissue from Staphylococcus aureus, retaining cell viability and skin integrity. Fresh skin samples, taken from multitissue donors, were contaminated with Staphylococcus aureus and treated with a DBD source, to verify the level of bacterial decontamination induced by plasma. Cell viability and structural properties of skin tissue were investigated using MTT assay and hematoxylin-eosin staining, respectively. Our results show that CAP can sterilize skin tissue with a bacterial load up to 103 CFU/cm2; moreover, it does not affect cell viability, and no loss of skin structural properties was observed. Thus, CAP treatment could be considered an innovative method for decolonization of human skin, without inducing any microscopic tissue damage, while keeping good cell viability

Pharmacological Inhibition of WIP1 Sensitizes Acute Myeloid Leukemia Cells to the MDM2 Inhibitor Nutlin-3a

In acute myeloid leukemia (AML), the restoration of p53 activity through MDM2 inhibition proved efficacy in combinatorial therapies. WIP1, encoded from PPM1D, is a negative regulator of p53. We evaluated PPM1D expression and explored the therapeutic efficacy of WIP1 inhibitor (WIP1i) GSK2830371, in association with the MDM2 inhibitor Nutlin-3a (Nut-3a) in AML cell lines and primary samples. PPM1D transcript levels were higher in young patients compared with older ones and in core-binding-factor AML compared with other cytogenetic subgroups. In contrast, its expression was reduced in NPM1-mutated (mut, irrespective of FLT3-ITD status) or TP53-mut cases compared with wild-type (wt) ones. Either Nut-3a, and moderately WIP1i, as single agent decreased cell viability of TP53-wt cells (MV-4-11, MOLM-13, OCI-AML3) in a time/dosage-dependent manner, but not of TP53-mut cells (HEL, KASUMI-1, NOMO-1). The drug combination synergistically reduced viability and induced apoptosis in TP53-wt AML cell line and primary cells, but not in TP53-mut cells. Gene expression and immunoblotting analyses showed increased p53, MDM2 and p21 levels in treated TP53-wt cells and highlighted the enrichment of MYC, PI3K-AKT-mTOR and inflammation-related signatures upon WIP1i, Nut-3a and their combination, respectively, in the MV-4-11 TP53-wt model. This study demonstrated that WIP1 is a promising therapeutic target to enhance Nut-3a efficacy in TP53-wt AML

Tumor-Stroma Crosstalk in Bone Tissue: The Osteoclastogenic Potential of a Breast Cancer Cell Line in a Co-Culture System and the Role of EGFR Inhibition

Although bone metastases represent a major challenge in the natural history of breast cancer (BC), the complex interactions involved have hindered the development of robust in vitro models. The aim of this work is the development of a preclinical model of cancer and bone stromal cells to mimic the bone microenvironment. We studied the effects on osteoclastogenesis of BC cells and Mesenchymal stem cells (MSC) cultured alone or in combination. We also analyzed: (a) whether the blockade of the Epithelial Growth Factor Receptor (EGFR) pathway modified their influence on monocytes towards differentiation, and (b) the efficacy of bone-targeted therapy on osteoclasts. We evaluated the osteoclastogenesis modulation of human peripheral blood monocytes (PBMC) indirectly induced by the conditioned medium (CM) of the human BC cell line SCP2, cultured singly or with MSC. Osteoclastogenesis was evaluated by TRAP analysis. The effect of the EGFR blockade was assessed by treating the cells with gefitinib, and analyzed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Western Blot (WB). We observed that SCP2 co-cultured with MSC increased the differentiation of PBMC. This effect was underpinned upon pre-treatment of the co-culture with gefitinib. Co-culture of SCP2 with MSC increased the expression of both the bone-related marker Receptor Activator of Nuclear Factor κB (RANK) and EGFR in BC cells. These upregulations were not affected by the EGFR blockade. The effects of the CM obtained by the cells treated with gefitinib in combination with the treatment of the preosteoclasts with the bone-targeted agents and everolimus enhanced the inhibition of the osteoclastogenesis. Finally, we developed a fully human co-culture system of BC cells and bone progenitor cells. We observed that the interaction of MSC with cancer cells induced in the latter molecular changes and a higher power of inducing osteoclastogenesis. We found that blocking EGFR signaling could be an efficacious strategy for breaking the interactions between cancer and bone cells in order to inhibit bone metastasis