Purpose: Immune-mediated graft-versus-tumor (GVT) effects can occur after allogeneic hematopoietic stem cell transplantation (HSCT), but GVT is tightly linked to its main complication, graft-versus-host disease (GVHD). Strategies aimed at modulating GVHD, while maintaining the GVT effect, are needed to improve the cure rate of transplant. Given the emerging role of Janus-activated kinase (JAK) signaling in lymphoproliferative and myeloproliferative diseases and its established function at dictating T-cell differentiation, we postulated that JAKs might be potential therapeutic targets through a pharmacologic approach.Experimental Design: We examined the effect of JAK1/JAK2 modulation by ruxolitinib in a mouse model of fully MHC mismatched bone marrow transplant comprising in vivo tumor inoculation.Results: JAK1/JAK2 inhibition by ruxolitinib improved both overall survival (P ¼ 0.03) and acute GVHD pathologic score at target organs (P 0.001) of treated mice. In addition, treatment with ruxolitinib was associated with a preserved GVT effect, as evidenced by reduction of tumor burden (P ¼ 0.001) and increase of survival time (P ¼ 0.01). JAK1/JAK2 inhibition did not impair the in vivo acquisition of donor T-cell alloreactivity; this observation may account, at least in part, to the preserved GVT effect. Rather, JAK1/JAK2 inhibition of GVHDwas associated withthe modulation of chemokine receptor expression, which may have been one factor in the reduced infiltration of donor T cells in GVHD target organs.Conclusions: These data provide further evidence that JAK inhibition represents a new and potentially clinically relevant approach to GVHD prevention.

Millions of people worldwide suffer from trauma- or age-related orthopedic diseases such as osteoarthritis, osteoporosis, or cancer. Tissue Engineering (TE) and Regenerative Medicine are multidisciplinary fields focusing on the development of artificial organs, biomimetic engineered tissues, and cells to restore or maintain tissue and organ function. While allogenic and future autologous transplantations are nowadays the gold standards for both cartilage and bone defect repair, they are both subject to important limitations such as availability of healthy tissue, donor site morbidity, and graft rejection. Tissue engineered bone and cartilage products represent a promising and alternative approach with the potential to overcome these limitations. Since the development of Advanced Therapy Medicinal Products (ATMPs) such as TE products requires the knowledge of diverse regulation and an extensive communication with the national/international authorities, the aim of this review is therefore to summarize the state of the art on the clinical applications of human bone marrow-derived stromal cells for cartilage and bone TE. In addition, this review provides an overview of the European legislation to facilitate the development and commercialization of new ATMPs.

Recombinant peptides have the power to harness the inherent biocompatibility of natural macromolecules, while maintaining a defined chemistry for use in tissue engineering. Creating scaffolds from peptides requires stabilization via crosslinking, a process known to alter both mechanics and density of adhesion ligands. The chemistry and mechanics of linear scaffolds from a recombinant peptide based on human collagen type I (RCP) was investigated after crosslinking. Three treatments were compared: dehydrothermal treatment (DHT), hexamethylene diisocyanate (HMDIC), and genipin. With crosslinking, mechanical properties were not significantly altered, ranging from 1.9 to 2.7 kPa. However, the chemistry of the scaffolds was changed, affecting properties such as water uptake, and initial adhesion of human mesenchymal stem cells (hMSCs). Genipin crosslinking supported the lowest adhesion, especially during osteoblastic differentiation. While significantly altered, RCP scaffold chemistry did not affect osteoblastic differentiation of hMSCs. After four weeks in vitro, all scaffolds showed excellent cellular infiltration, with up-regulated osteogenic markers (RUNX2, Osteocalcin, Collagen type I) and mineralization, regardless of the crosslinker. Thus, it appears that, without significant changes to mechanical properties, crosslinking chemistry did not regulate hMSC differentiation on scaffolds from recombinant peptides, a growing class of materials with the ability to expand the horizons of regenerative medicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1856-1866, 2017.

No abstract

The development of scaffold formulations based on extracellular matrix (ECM)-inspired synthetic materials constitutes an important resource for the advance of cell-based therapies in bone tissue engineering approaches, where both cell and scaffold implantation are often needed. Culturing cells on porous microcarriers (MCs) allows cell expansion in a three-dimensional microenvironment and constitutes a possible solution for minimally invasive cell and scaffold simultaneous delivery, but the reduced pore dimension and pore interconnection diameter of several commercially available MCs limits de facto cell ingrowth, and ultimately their suitability for in vivo cell delivery. In this study we investigated the potential of a new macroporous MC based on a collagen I-based recombinant peptide (Cellnest™) for C2C12 cells and human bone marrow-derived mesenchymal stromal cells (hBMSCs) expansion and we analyzed the influence of dehydrothermal (DHT), hexamethylene diisocyanate (HMDIC), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) cross-linking strategies on cell vitality, proliferation, and hBMSCs differentiation. We established a double emulsification protocol for the manufacturing of MCs characterized by external pores of 20-40 μm diameter, 73% porosity, and 20 ± 3 μm pore interconnection diameter supporting cell ingrowth and proliferation into the MC. MCs cross-linked with DHT and HMDIC supported higher cell proliferation comparing to a commercially available equivalent over the course of 7 days and resulted in higher cell yield by day 28. Moreover, while hBMSCs expansion on Cellnest-MCs did not lead to a significant upregulation of the early markers of osteogenic differentiation Col1a1 and Runx2, their differentiation potential into the osteogenic lineage was preserved when cultured in differentiation medium, as confirmed by mineralized ECM deposition. We believe that Cellnest-MCs will help in reaching clinically relevant cell quantities and ultimately help in accelerating the translation of cell-based therapies for bone tissue engineering in the clinical practice.