The Consiglio Nazionale delle Ricerche (CNR,  National Research Council) is the main Public Research Agency funded by the Italian Government. It is made up of several Institutes devoted to various fields. The Istituto di Tecnologie Biomediche (ITB) focuses on biological themes which include human and mouse genetics. Historically, the Human Genome Section of ITB has worked on genetics of human diseases, contributing to the identification of the genes responsible for primary immunodeficiency such as X-linked thrombocytopenia, JAK3-dependent SCID, Omenn syndrome, as well as osteopetrosis and X-linked Cornelia de Lange syndrome. A second line of pursued research has been the field of models transgenesis, whose technology was especially applied to the study of experimental models for human diseases, including cancer.

In September 2007, an Agreement between the ITB/CNR and the Istituto Clinico Humanitas (ICH) came into effect and portions of the ITB have been transferred to the Humanitas Research Centre in Rozzano. Two Research Units have been established there: the first, denominated “ Human Genome”, is led by Anna Villa, while the second, “Medical Biotechnologies” is coordinated by Paolo Vezzoni. These two Units, whose researchers shared a common origin, while still closely collaborating, started to diversify in the last couple of years and now have projects of their own. Therefore, while some achievements in the past are common to both Units, the future projects tend to investigate related but different topics.

MAIN RESULTS

In the last three years, while still working in collaboration with the other (Anna Villa’s) group, this Unit has focused on stem cell therapy and regenerative medicine. We will briefly review here the achievements of the last three years and will explain the further evolution of the research.

1. Genome stability and related issue, including the discovery of SMC1 cohesin subunity as the gene responsible for X-linked Cornelia de Lange syndrome.

Genome integrity is now recognized as fundamental in cell physiology and in cancer prevention. Building on our work on the role of the cohesin complex and other centromere-interacting proteins during mitosis, we decided to investigate the role of SMC1 (a cohesin subunit) in patients affected by Cornelia de Lange syndrome (CdLS). The identification of the involvement of this gene in this developmental defect has open up a new perspective on the role of cohesin complex in transcriptional regulation.

2. Stem cells for early treatment of severe genetic defects already present at birth.

Autosomal recessive osteopetrosis (ARO) is a severe genetic disease of the bone which has been extensively studied by our group. Severe bone defects are already present at birth, conditioning pancytopenia, blindness, deafness and, ultimately, death. The only available treatment is BMT, which when performed postnatally usually does not rescue all the bone defects. ARO therefore is the prototype of a number of genetic diseases which must be treated before birth in order to prevent all the stigmata of the disease and really cure it. In addition to collaborating with the other CNR/ICH Unit in the molecular basis of ARO, we have recently used the in utero stem cell injection approach to show that both adult bone marrow and fetal liver cells can completely rescue the phenotype and produce models indistinguishable from wild type ones.

3. Fusion in liver.

Investigation of adult stem cell potential for regenerative diseases have raised the possibility of a great plasticity of tissue-specific adult stem cells such as neural or hematopoietic stem cells. There is now a general consensus that this is not the case, and a set of data have been interpreted to be the result of cell fusion. This seems to be especially true for the liver, in which cell fusion with exogenous cells has been proposed to be of potential interest, even leading to the cure of degenerative liver diseases. We tried to understand the cellular basis of this phenomenon and set up a series of experiments to investigate whether cell fusion could occur also in normal liver. Our data point to cell fusion as being a normal event in mouse liver. This conclusion has been reached by work on chimeric models in which we were able to detect single hepatocytes bearing markers of two different genotypes. In fact, single polyploid hepatocytes containing both GFP and b-gal were detected in chimeric GFP/lacZ models; likewise, binucleated hepatocytes with an XX chromosomal content in one nucleus and an XY pattern in the other were also detected in XX/XY (female/male) chimeric models suggesting, again, a fusion event. We believe that, if confirmed, these results are of both biological and medical interest, since they challenge the old hypothesis which attribute liver polyploidy to endoduplication followed by aborted cytokinesis, and raises the possibility of fusion between defective endogenous and exogenously provided normal hepatocytes in degenerative liver diseases.

In summary, the overall goal of this study will be to use a knock-in experimental model to evaluate the feasibility of in utero cell therapy for Osteogenesis Imperfecta (OI), analysing the outcome at molecular, biochemical, histological and bone density levels.