BUSCADOR RECOLECTA

The development of three-dimensional environments to mimic the in vivo cellular response is a problem in the building of disease models. This study aimed to synthesize and validate three-dimensional support for culturing monoclonal plasma cells (mPCs) as a disease model for multiple myeloma. The three-dimensional environment is a biomimetic microgel formed by alginate microspheres and produced on a microfluidic device whose surface has been functionalized by a layer-by-layer process with components of the bone marrow’s extracellular matrix, which will interact with mPC. As a proof of concept, RPMI 8226 cell line cells were cultured in our 3D culture platform. We proved that hyaluronic acid significantly increased cell proliferation and corroborated its role in inducing resistance to dexamethasone. Despite collagen type I having no effect on proliferation, it generated significant resistance to dexamethasone. Additionally, it was evidenced that both biomolecules were unable to induce resistance to bortezomib. These results validate the functionalized microgels as a 3D culture system that emulates the interaction between tumoral cells and the bone marrow extracellular matrix. This 3D environment could be a valuable culture system to test antitumoral drugs efficiency in multiple myeloma.

Alginate hydrogels can be used to develop a three-dimensional environment in which various cell types can be grown. Cross-linking the alginate chains using reversible ionic bonds opens up great possibilities for the encapsulation and subsequent release of cells or drugs. However, al-ginate also has a drawback in that its structure is not very stable in a culture medium with cellu-lar activity. This work explored the stability of alginate microspheres functionalised by grafting specific biomolecules onto their surface to form microgels in which biomimetic microspheres surrounded the cells in the culture, reproducing the natural microenvironment. A study was made of the stability of the microgel in different typical culture media and the formation of polyelectrolyte multilayers containing polylysine and heparin. Multiple myeloma cell prolifer-ation in the culture was tested in a bioreactor under gentle agitation., The Microscopy Service of the UPV (Universitat Politècnica de València) is gratefully acknowl-edged for helping with cryoFESEM characterisation. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program. The Instituto de Salud Carlos III financed CIBER Actions with assistance from the European Regional Develop-ment Fund.

Mesenchymal stem cells (MSCs) osteogenic commitment before injection enhances bone regen-eration therapy results. Piezoelectric stimulation may be an effective cue to promote MSC pre-differentiation, and poly(vinylidene) fluoride (PVDF) cell culture supports, when combined with CoFe2O4 (CFO), offer a wireless in vitro stimulation strategy. Under an external magnetic field, CFO shift and magnetostriction deform the polymer matrix varying the polymer surface charge due to the piezoelectric effect. To test the effect of piezoelectric stimulation on MSCs, our approach is based on a gelatin hydrogel with embedded MSCs and PVDF-CFO electroactive mi-crospheres. Microspheres were produced by electrospray technique, favouring CFO incorpora-tion, crystallisation in -phase (85 %) and a crystallinity degree of around 55 %. The absence of cytotoxicity of the 3D construct was confirmed 24 hours after cell encapsulation. Cells were via-ble, evenly distributed in the hydrogel matrix and surrounded by microspheres, allowing local stimulation. Hydrogels were stimulated using a magnetic bioreactor, and no significant changes were observed in MSCs proliferation in short or long term. Nevertheless, piezoelectric stimula-tion upregulated RUNX2 expression after 7 days, indicating the activation of the osteogenic dif-ferentiation pathway. These results open the door for optimising a stimulation protocol allow-ing the application of the magnetically activated 3D electroactive cell culture support for MSCs pre-differentiation before transplantation.

Multiple myeloma is a hematologic neoplasm caused by an uncontrolled clonal proliferation of neoplastic plasma cells (nPCs) in the bone marrow. The development and survival of this disease is tightly related to the bone marrow environment. Proliferation and viability of nPCs depend on their interaction with the stromal cells and the extracellular matrix components, which also influences the appearance of drug resistance. Recapitulating these interactions in an in vitro culture requires 3D environments that incorporate the biomolecules of interest. In this work, we studied the proliferation and viability of three multiple myeloma cell lines in a microgel consisting of biostable microspheres with fibronectin (FN) on their surfaces. We also showed that the interaction of the RPMI8226 cell line with FN induced cell arrest in the G0/G1 cell cycle phase. RPMI8226 cells developed a significant resistance to dexamethasone, which was reduced when they were treated with dexamethasone and bortezomib in combination., CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, Iniciativa Ingenio 2010, and Consolider Program. CIBER Actions were financed by the Instituto de Salud Carlos III, with assistance from the European Regional Development Fund. The kind supplying of RPMI 8226 cells by Beatriz Martin (Josep Carreras Leukaemia Research Institute) is greatly acknowledged. The Microscopy Service of the UPV (Universitat Politècnica de València) is gratefully acknowledged.