• ingegneria tissutale
• cellule staminali mesenchimali
• nanograting
• differenziamento osteoblastico
• meccanotrasduzione

Human Bone Marrow Mesenchymal Stem Cells (hBM-MSC) are non-hematopoietic Adult Stem Cells (ASC) isolated from bone marrow. In vitro, hBM-MSCs can differentiate into mesenchymal cell types such as adipocytes, condrocytes and osteoblasts. In vivo, they are involved in bone tissue homeostasis. Thanks to their differentiation potential and immunologic and pro-regenerative properties, hBM-MSCs are commonly retained the best candidate for bone regeneration medical protocols. Tissue engineering, a branch of regenerative medicine, applies principles of engineering and life sciences for developming living elements to be transplanted in the patient. One of the main goals of tissue engineering is to design and fabricate biofunctional scaffolds, i.e. artificial structures capable of actively supporting three-dimensional tissue formation. Scaffolds, differently from grafts, must promote cell proliferation, growth and, eventually, differentiation. The scaffold bioactive properties can be improved by modifying its chemical and physical properties, such as the surface nanotopography.
Indeed, cell-nanotopography interactions can control many cell functions. Among these and the differentiation of hBM-MSCs is one of the most promising applications driven by nanotophography.
In this thesis the interactions between nanogratings (NGs), alternating line of submicron ridges and grooves, and hBM-MSCs have been investigated to find the best conditions promoting osteoblastogenic differentiation.
Two types of NGs, named t1 and t2, different in ridges and grooves size, were fabricated by Nanoimprinting Litography (NIL) applied to PolyEthylene Terephthalate (PET) films.
Adhesion and viability assays showed that both t1 and t2 do not reduce hBM-MSC attachment on PET and do not reduce cell viability. The anisotropy of the two tested substrates influenced cell morphology and orientation inducing anisotropic spreading. Indeed, the morphology analysis demonstrated that t1 and t2 can elongate and align cells along the NG direction. hBM-MSC fixed and stained for microfilaments (MFs) and microtubules (MTs) showed that NGs affect cytoskeleton spatial organization: both MF and MT were assembled in fibers parallel to the NGs. Finally, MFs and MTs acted on nuclei forcing their orientation, morphological change, and positioning.
We demonstrated that t2 is the most efficient NG geometry for aligning cells, their cytoskeleton and nucleus to the NG direction. Conversely, cells seeded on t1 showed a significant reduction of fibers
dispersion and nucleus area. Both elongation and nucleus deformation can induce a change in osteblastic genes expression, so we conclude that T1 is more promising than T2 for osteo-differentiation enhancement.