Human palatine tonsil: a new potential tissue source of multipotent mesenchymal progenitor cells

INTRODUCTION: Mesenchymal progenitor cells (MPCs) are multipotent progenitor cells in adult tissues, for example, bone marrow (BM). Current challenges of clinical application of BM-derived MPCs include donor site morbidity and pain as well as low cell yields associated with an age-related decrease in cell number and differentiation potential, underscoring the need to identify alternative sources of MPCs. Recently, MPC sources have diversified; examples include adipose, placenta, umbilicus, trabecular bone, cartilage, and synovial tissue. In the present work, we report the presence of MPCs in human tonsillar tissue. ----- METHODS: We performed comparative and quantitative analyses of BM-MPCs with a subpopulation of adherent cells isolated from this lymphoid tissue, termed tonsil-derived MPCs (T-MPCs). The expression of surface markers was assessed by fluorescent-activated cell sorting analysis. Differentiation potential of T-MPCs was analyzed histochemically and by reverse transcription-polymerase chain reaction for the expression of lineage-related marker genes. The immunosuppressive properties of MPCs were determined in vitro in mixed lymphocyte reactions. ----- RESULTS: Surface epitope analysis revealed that T-MPCs were negative for CD14, CD31, CD34, and CD45 expression and positive for CD29, CD44, CD90, and CD105 expression, a characteristic phenotype of BM-MPCs. Similar to BM-MPCs, T-MPCs could be induced to undergo adipogenic differentiation and, to a lesser extent, osteogenic and chondrogenic differentiation. T-MPCs did not express class II major histocompatibility (MHC) antigens, and in a similar but less pronounced manner compared with BM-MPCs, T-MPCs were immunosuppressive, inhibiting the proliferation of T cells stimulated by allogeneic T cells or by non-specific mitogenic stimuli via an indoleamine 2,3-dioxygenase-dependent mechanism. ----- CONCLUSION: Human palatine T-MPCs represent a new source of progenitor cells, potentially applicable for cell-based therapies

A comparison of 3-dimensional calcium phosphate scaffolds for candidate bone tissue engineering constructs

grantor: University of TorontoMany materials are available for osseous repair of which calcium phosphates (CP) are generally considered materials of choice, and have been adopted as scaffolds for the restoration of bone stock through bone 'tissue engineering ' (TE) strategies. However, the ideal CP scaffold for a bone TE construct has yet to be found. It was hypothesized that one essential criterion for a successful CP-TE scaffold is a fully interconnecting macroporosity that would permit three dimensional tissue growth. Thus, five different types of porous CP scaffolds, obtained from Zimmer International Inc., CAM Implants, and School of Materials Engineering, Yeungnam University, Korea, ['CPP'], having different macroporosities, were investigated for their suitability as TE constructs. The highest degree of interconnecting macroporosity was found in the CPP scaffold-types. The Zimmer and CAM Implant scaffolds possessed macropores but little, or no, interconnecting macroporosity. All CPs supported bone growth ' in vitro'. However, the CPP scaffolds demonstrated bone growth throughout their porous network, while bone growth was on the Zimmer and CAM Implant scaffolds was restricted to their outer surfaces.M.A.Sc

Stem cells for osteochondral regeneration

Stem cell research plays a central role in the future of medicine, which is mainly dependent on the advances on regenerative medicine (RM), specifically in the disciplines of tissue engineering (TE) and cellular therapeutics. All RM strategies depend upon the harnessing, stimulation, or guidance of endogenous developmental or repair processes in which cells have an important role. Among the most clinically challenging disorders, cartilage degeneration, which also affects subchondral bone becoming an osteochondral (OC) defect, is one of the most demanding. Although primary cells have been clinically applied, stem cells are currently seen as the promising tool of RM-related research because of its availability, in vitro proliferation ability, pluri- or multipotency, and immunosuppressive features. Being the OC unit, a transition from the bone to cartilage, mesenchymal stem cells (MSCs) are the main focus for OC regeneration. Promising alternatives, which can also be obtained from the patient or at banks and have great differentiation potential toward a wide range of specific cell types, have been reported. Still, ethical concerns and tumorigenic risk are currently under discussion and assessment. In this book chapter, we revise the existing stem cell-based approaches for engineering bone and cartilage, focusing on cell therapy and TE. Furthermore, 3D OC composites based on cell co-cultures are described. Finally, future directions and challenges still to be faced are critically discussed.H2020-MSCA-RISE program, as this work is part of developments carried out in BAMOS project, funded from the European Union's Horizon 2020 research and innovation program under grant agreement Nº 734156. Thanks are also due to the Portuguese Foundation for Science and Technology (FCT) for the distinction attributed to J. M. Oliveira (IF/00423/2012 and IF/01285/2015) and to Rogério Pirraco (IF/00347/2015) under the Investigator FCT program. The authors also thank FCT for the Ph.D. scholarship provided to R. F. Canadas (SFRH/BD/92565/2013)info:eu-repo/semantics/publishedVersio