No abstract

Rapid and controlled vascularization of engineered tissues remains one of the key limitations in tissue engineering applications. This study investigates the possible use of natural extracellular matrix-like scaffolds made of gelatin loaded with human vascular endothelial growth factor (VEGF), as a bioresorbable platform for long-term release and consequent angiogenic boosting. For this aim, gelatin was firstly electrospun and then cross-linked at two different concentrations (0.1% and 0.5% w/v) by using genipin, a low toxic agent, in order to fabricate a suitable substrate to be loaded with VEGF. Collected fibers were homogeneous and free of beads, the fibrous structure was retained after cross-linking. Mechanical properties were deeply affected by the chemical treatment showing a different behavior, depending on the testing conditions (i.e., dry or wet state). VEGF release was assessed by means of ELISA assay: a cumulative release of about 90% (0.1% w/v) and 60% (0.5% w/v) at 28 days was measured. Both VEGF loaded mats induced cell viability, endothelial differentiation and showed chemoattractive properties when tested on human mesenchymal stromal cells (hMSCs). In vitro and in vivo angiogenic assays demonstrated that the VEGF loaded mats induced an angiogenic potential in stimulating new vessel formation similar, if not superior, to fresh VEGF. VEGF retains bioactive and pro-angiogenic potential for up to 14 days. The results demonstrated that genipin cross-linked electrospun gelatin mats loaded with VEGF could be part of a useful strategy to stimulate and induce angiogenesis in tissue engineered applications.

NK cells have shown promise in therapy of hematological cancers, in particular against acute myeloid leukemia. In contrast, the more NK cell-resistant acute lymphoblastic leukemia (ALL) is difficult to treat with NK-cell-based therapies, and we hypothesized that pre-activation of NK cells could overcome this resistance. We show in pediatric and adult patients with T-cell ALL (T-ALL) perturbed NK cell effector functions at diagnosis. Using an rat model for T-ALL, Roser leukemia (RL), suppressed NK cell effector functions were observed. NK cells from T-ALL patients had reduced expression of the activating receptors NKp46 and DNAM-1, but not NKG2D. In contrast to T-ALL patients, NKG2D but not NKp46 was downregulated on NK cells during rat RL. Decreased frequencies of terminally differentiated NKG2ACD57CD56 NK cells in human T-ALL was paralleled in the rat by reduced frequencies of bone marrow NK cells expressing the maturation marker CD11b, possibly indicating impairment of differentiation during leukemia. RL was highly resistant to autologous NK cells, but this resistance was overcome upon pre-activation of NK cells with IL-12, IL-15, and IL-18, with concomitant upregulation of activation markers and activating receptors. Importantly, adoptive transfers of IL-12, IL-15, and IL-18 pre-activated NK cells significantly slowed progression of RL . The data thus shows that T-ALL blasts normally resistant to NK cells may be targeted by cytokine pre-activated autologous NK cells, and this approach could have potential implications for immunotherapeutic protocols using NK cells to more efficiently target leukemia.

Bone marrow transplantation (BMT) is the only therapeutic option for many hematological malignancies, but its applicability is limited by life-threatening complications, such as graft-versus-host disease (GvHD). The last decades have seen great advances in the understanding of BMT and its related complications; in particular GvHD. Animal models are beneficial to study complex diseases, as they allow dissecting the contribution of single components in the development of the disease. Most of the current knowledge on the therapeutic mechanisms of BMT derives from studies in animal models. Parallel to BMT, the understanding of the pathophysiology of GvHD, as well as the development of new treatment regimens, has also been supported by studies in animal models. Pre-clinical experimentation is the basis for deep understanding and successful improvements of clinical applications. In this review, we retrace the history of BMT and GvHD by describing how the studies in animal models have paved the way to the many advances in the field. We also describe how animal models contributed to the understanding of GvHD pathophysiology and how they are fundamental for the discovery of new treatments.