Stromal cell-induced immune regulation in a transplantable lymphoid-like cell constructs Yael Kaminer-Israeli a , Jenny Shapiro b , Smadar Cohen a, ** , Alon Monsonego b, * a Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel b The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, and the National Institute of Biotechnology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel article info Article history: Received 3 August 2010 Accepted 27 August 2010 Available online 24 September 2010 Keywords: Stromal cells Dendritic cells Alginate scaffold Immune regulation abstract Engineering of cell-based constructs for treating a variety of immune-related diseases by local trans- plantation of the cells in a pre-designed matrix is an emerging therapeutic approach, which can potentially reduce the side effects associated with systemic cell injection. Stromal cells have been shown to exert immunosuppressive properties and thus can be exploited for autoimmune regulation and cell transplantation. Here, we demonstrate the fabrication of a stromal cell-based construct, which serves as a lymphoid-like organ with immune regulatory characteristics. In the proposed system, stromal cells are co-seeded with dendritic cells (DC) in a macro-porous alginate scaffold containing the encephalitogenic myelin-derived peptide, proteolipid protein (PLP). We demonstrate that the presence of stromal cells attenuates DC maturation upon lipopolysaccharide stimulus. In vitro, we show that while the migration of pathogenic PLP-specific T cells to construct cultivated with or without stromal cells does not differ, their activation and proliferation are significantly suppressed in the presence of stromal cells. Upon in vivo transplantation, under the kidney capsule of mice, the pathogenic activation and proliferation of T cells which were drawn into the construct were suppressed in the co-seeded constructs. This system thus serves as a lymphoid-like organ with regulatory characteristics, which can be applied for local tolerance induction, for application in cell transplantations as well as autoimmune diseases. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Cell-based therapy for inducing tolerance has gained momentum in recent years following the identification of suppressor cells, such as regulatory T cells and dendritic cells (DCs), capable of inhibiting aggressive lymphocyte effector responses to self antigens or to cell/tissue transplants [1,2]. The therapy has limited success due to the profound systemic immunosuppression effect and the risk of developing opportunistic infections and malignancies [3]. A promising approach, which may address the problem of systemic side effects common with the classical injec- tion form of existing cell therapies, is tissue engineering using implantable three-dimensional (3D) constructs [4]. This strategy has the potential of enabling the induction of a cell-based local tolerogenic microenvironment, relevant for a variety of applica- tions, especially cell transplantation and autoimmune regulation. An important component in this strategy is culturing the immune cells within 3D porous scaffolds, which provide a defined and controllable microenvironment for cell growth and cellecell as well as cellematrix interactions. Scaffolds comprised of various biocompatible materials, such as collagen [5e7], poly-lactide-co- glycolide acid (PLGA) [8] and alginate [9] have been used both in vitro and in vivo for immune cell cultivation. Among these, the macro-porous alginate scaffold, which has been previously shown to enable blood vessel penetration and cell growth in vivo [10e13] and is inert to cellematrix interactions [14], constitutes an appro- priate milieu to facilitate cellecell interactions, a fundamental feature in immune cell responses. The initiators of immune cell responses are dendritic cells (DCs), which are professional antigen-presenting cells (APCs) acting in the interface between the innate and adaptive immune systems. DCs can induce either an immune pathogenic response or tolerance against a specific antigen. Antigen-specific negative regulation of the immune response by DCs is considered to be a promising approach for the treatment of autoimmune diseases [15]. Leading candidates for cell-based immune regulation are mesenchymal stem cells (MSCs), which are the precursors of terminally differentiated stromal cells [16]. In the last decade, it has * Corresponding author. Tel.: þ972 8 6479052; fax: þ972 8 6479051. ** Corresponding author. Tel.: þ972 8 6461798; fax: þ972 8 6472915. E-mail addresses: scohen@bgu.ac.il (S. Cohen), alonmon@bgu.ac.il (A. Monsonego). Contents lists available at ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2010.08.070 Biomaterials 31 (2010) 9273e9284