Characterization and evaluation of whey protein-based biofilms as substrates for in vitro cell cultures.

Whey proteins-based biofilms were prepared using different plasticizers in order to obtain a biomaterial for the human keratinocytes and fibroblasts in vitro culture. The film properties were evaluated by Fourier Transform Infrared Spectroscopy (FTIR) technique and mechanical tests. A relationship was found between the decrease of intermolecular hydrogen bond strength and film mechanical behavior changes, expressed by a breaking stress and Young modulus values diminishing. These results allow stating that the film molecular configuration could induce dissimilarities in its mechanical properties. The films toxicity was assessed by evaluating the cutaneous cells adherence, growth, proliferation and structural stratification. Microscopic observation demonstrated that both keratinocytes and fibroblasts adhered to the biofilms. The trypan blue exclusion test showed that keratinocytes grew at a significantly high rate on all the biofilms. Structural analysis demonstrated that keratinocytes stratified when cultured on the whey protein-based biofilms and gave rise to multi-layered epidermal structures. The most organized epidermis was obtained with whey protein isolate/DEG biofilm. This structure had a well-organized basal layer under supra-basal and corneous layers. This study demonstrated that whey proteins, an inexpensive renewable resource which can be obtained readily, were non-toxic to cutaneous cells and thus they could be useful substrates for a variety of biomedical applications, including tissue engineering.

Ligand-activated natural killer T lymphocytes promptly produce IL-3 and GM-CSF in vivo: relevance to peripheral myeloid recruitment.

Natural killer (NK) T cells are prominent for their prompt IL-4 and IFN-gamma production upon TCR ligation that enables them to influence acquired immune responses. In the present study we provide evidence that the regulatory functions of this particular T cell subset extend to the myeloid compartment of bone marrow and spleen through its production of hematopoietic growth factors. Bone marrow and spleen NKT cells responded to a single injection of their specific ligand alpha-galactosylceramide (alpha-GalCer) by producing both IL-3 and granulocyte-macrophage colony stimulating factor (GM-CSF), whose colony-stimulating activity became detectable in the serum as early as 1 h post treatment. These cytokines were not produced in mice lacking NKT cells (CD1d-/-), whose exclusive involvement in this biological activity was further confirmed by intracellular immuno-staining. Growth factor production was accompanied by significant changes in the myeloid compartment of treated mice, namely mobilization of myeloid progenitors (colony-forming unit cells, CFU-C) and neutrophils from the bone marrow to the periphery. Taken together, our data support the notion that activated NKT cells influence innate immune responses by recruiting myeloid progenitors and granulocytes to the periphery through their production of hematopoietic growth factors.