The identity and properties of mesenchymal stem cells César Nombela-Arrieta and Leslie E. Silberstein

MSCs are self-renewing, multipotent precursors. They were originally found to , and . In more recent studies multipotent reside in the stromal adherent fraction of the , where they sustain mesenchymal cultures have been derived from perivascular stem the homeostatic turnover of non-haematopoietic stromal cells, regulate HSC cells expressing markers in many postnatal tissues. The differentiation maintenance and might contribute to vascular stability. The physiological roles capabilities, extraordinary paracrine potential and ease of isolation of in vitro- MOLECULAR of MSCs in anatomical locations other than the bone marrow remain largely expanded mesenchymal stromal cells have attracted great interest into, and undefined. MSCs can be expanded in vitro to generate mesenchymal stromal efforts towards, the exploitation of MSCs and their expanded progeny as CELL BIOLOGY cell cultures, which, under appropriate conditions, can differentiate into therapeutic agents for tissue regeneration and repair.

MSCs in postnatal tissues Differentiation potential MSCs were first identified in the adherent fraction of bone The principal functional criterion defining multipotent mesenchymal­ marro­w . They were termed CFU-Fs because of their ability­ stromal cells is their ability to give rise to mature adipocytes (in which to generate single cell-derived colonies, in analogy to their oil-red-positive lipid vesicles accumulate), chondrocytes (identified by #FKRQE[VGU %JQPFTQE[VGU haematopoietic­ counterparts, CFU-Cs. CFU-Fs from almost all alcian blue or -specific­ staining) and osteoblasts (identified­ embryonic and postnatal tissues can be expanded in vitro to by alizari­n red or von Kossa staining) when placed in specific culture gener­ate cell cultures that conserve trilineage potential. The role conditions.­ This trilineage capability can be probed in vivo by sub­ of MSCs in multiple anatomical locations, and whether they cutaneous implantation inside ceramic cubes (hydroxyapatite­ constitute­ a specific homogeneous cell type or a mixed Mesenchymal stromal cell chambers) in mice. Within these implants, mesenchymal TGFβ, population­ of tissue-specific cells heterogeneous­ in expansion in vitro Isobutyl stromal­ cells differentiate into adipocytes, chondrocytes, nature and origin, is not well understood. However, /5% osteoblasts and haemosupportive­ stroma, giving­ rise to bony MSCs can be expanded in vitro when cultured methylxanthine, 1UVGQDNCUVU 0) 2&)(4β  dexamethasone, these progenitors express pericyte-specific in two-dimensiona­l mono­layers of adherent cells in structures termed ossicles,­ which recruit haematopoietic­ cell-surface markers, such as NG2 and PDGFRß, VKUUWGURGEKȮERTQIGPKVQT indomethacine, cells from the recipient mice to the implant. specialized medium. The expanded cells, sometimes insulin and are located­ in perivascular­ regions of the termed multipotent mesenchymal stromal­ cells, are different­ tissues­ in which they reside. defined by the expression of CD73, CD90 and Dexamethasone, CD105 and the lack of CD11b, CD19, CD34, CD45 l-ascorbic acid, P Markers defining cells enriched i and HLADR. Here we use the term mesenchymal in MSC activity stromal cells to refer to these in vitro-expanded cells. Marker Anatomical location Organism *CGOQUWRRQTVKXG 1 Hydroxy­apatite CD146 Bone marrow Humans 8CUEWNCVWTG In vitro culture UVTQOC $QPG 2 chamber PDGFRα–SCA1 Bone marrow Mice %JQPFTQE[VG CD146–NG2– Postnatal and Humans3 #FKRQE[VG PDGFRβ embryonic tissues Nestin–GFP Bone marrow Nestin–GFP transgenic 1UUKENGU $QPG mice4 5KPWUQKF 1UVGQDNCUV *CGOCVQRQKGVKEEGNN

*[FTQZ[CRCVKVG EJCODGT *CGOQUWRRQTVKXG UVTQOC +. /5% #FKRQE[VG

*5% 6KUUWGTGUKFGPV Immunoregulatory 0GWVTQRJKN Therapeutic potential RTQIGPKVQTEGNN 1UVGQRTQIGPKVQT #PIKQRQKGVKP properties in vitro Expanded multipotent mesenchymal stromal cells %:%..+( 6KUUWG MSCs are endowed with remarkable 0-EGNN *)(*.#)+&1 are being extensively studied for their possible /%5(5%( TGRCKT /5% 2TGQUVGQDNCUV 012)'6)(β %&  immunoregulatory properties. When 6EGNN therapeutic properties in numerous pre-clinical 5KPWUQKF co-cultured in vitro they modulate and clinical settings. Studies initially­ focused on 6TCPUHGTTGF +PLWTGF the responses of neutrophils, NK 0-6EGNN using their -like properties for tissue OGUGPEJ[OCN VKUUWG $QPGOCTTQY cells and NKT cells, and suppress the $EGNN regeneration and repair. However, it is now well UVTQOCNEGNNU maturation of DCs from monocytes, established that their beneficial effects are MSC roles in vivo %#4% *5% #PIKQRQKGVKP which may lead to defective antigen %& JGNRGT mostly­ derived from the secretion of immuno­ + ()()/%5( 8GUUGN The study of MSCs in their presentation to CD4 helper T cells. /QPQE[VG γδ6EGNN 6EGNN modulatory and cytoprotective­ factors that con- *)(+)(+. 4GIWNCVQT[ IGPGTCVKQP native environment­ has been 1UVGQDNCUV MSCs have also been shown to inhibit tribute to the regeneration­ of injured tissues. The 2+)(6)(β8')( + 6EGNN hindered by the inability to the activation of CD4 helper T cells current hypothesis­ is that paracrine factors secreted­  identif­y them in situ. Nonetheless, $QPG (potentially leading to defective T cell +. by mesenchymal­ stromal cells provide protective $NQQFXGUUGN rare cell populations in the bone help to B cells), the proliferation of B cells microenvironmental­ cues and promote the activation of marrow­ that are highly enriched in MSC and the activation and cytotoxic responses local tissue-resident­ progenitor populations.­ This explains +OOCVWTG&% activity have been isolated and studied­ mediated by γδ T cells and CD8+ T cells. why favourable effects can be observed even in the absence of in vitro and in vivo. In the bone marrow Furthermore, MSCs promote the activation of regu­ prolonged­ mesenchymal stromal cell engraftment in sites of injury. parenchyma,­ MSCs lie in perivascular niches, where latory T cells, which are a specialized subset of CD4+ T cells Systemic infusion of mesenchymal stromal cells has proved beneficial in they associate with HSCs, exerting a key regulatory effect on early stages of that can suppress the responses of other T cells. different pre-clinical models of acute lung injury, myocardial infarction, diabetes as well as renal and .­ MSCs enter differentiation­ pathways to replenish mature osteo­ The immunosuppresive effects of mesenchymal stromal cells mainly rely on their hepatic failure. Some of the human conditions for which the safety and efficacy of mesenchymal blasts, adipocytes and haemosupportive stroma in the bone marrow. Recent studies ability to secrete various soluble factors, such as IDO, NO and PGE2. Whether stromal cell-based therapies are being, or will soon be, studied in clinical trials include acute have shown that bone marrow-residing­ nestin+ MSCs are innervated by tissue‑resident MSCs play a physiological part in directly modulating immune graft-versus-host disease, , osteogenesis imperfecta, stroke, spinal injury, systemic sympathetic­ nervous system­ fibres and mediate neural control of haematopoiesis. responses in vivo is still unknown. erythematosus and cardiovascular disease.

MesenCult™: Your High-Performance Platform for MSC Derivation, Culture human ES or iPS cells. MPCs generated using STEMdiff™ Mesenchymal Progenitor Human MSC Differentiation and Characterization: Abbreviations References Contact information and Differentiation Kit have a robust proliferation rate and maintain trilineage differentiation capacity. Differentiate human MSCs into chondrogenic, adipogenic, and osteogenic lineage cells CARC, CXCL12-abundant reticular cell; CFU-Cs, colony-forming unit-cells; 1. Sacchetti, B. et al. Cell 131, 324–336 (2007). Cesar.NombelaArrieta@childrens. using MesenCult™-ACF Chondrogenic Differentiation Medium (Catalog #05455), STEMCELL Technologies is committed to serve scientists along the basic to CFU-Fs, colony-forming unit-; CXCL12, CXC-chemokine ligand 12; 2. Morikawa, S. et al. J. Exp. Med. 206, 2483–2496 (2009). harvard.edu; Leslie.Silberstein@ MesenCult™ Adipogenic Differentiation Medium (Human; Catalog #05412), and translational research continuum by providing high-quality, standardized media and MSC Derivation and Expansion: DC, dendritic cell; FGF, growth factor; GFP, green fluorescent protein; 3. Crisan, M. et al. Cell Stem Cell 3, 301–313 (2008). childrens.harvard.edu MesenCult™ Osteogenic Differentiation Kit (Human; Catalog #05465), respectively. GM-CSF, granulocyte macrophage colony-stimulating factor; HGF, 4. Mendez-Ferrer, S. et al. Nature 466, 829–834 (2010). reagents for MSC (also known as mesenchymal stromal cell) research. Choose from • MesenCult™-ACF Plus Culture Kit (Catalog #05448): animal component- and The authors declare no competing growth factor; HLA, human leukocyte antigen; HSC, haematopoietic stem cell; a range of MesenCult™ specialty products to derive, expand, differentiate and serum-free culture kit for derivation and culture of human MSCs. Cells cultured in financial interests. Mouse MSC Differentiation and Characterization: IDO, indoleamine 2,3-dioxygenase; IGF1, insulin growth factor 1; IL, interleukin; Further reading characterize human and mouse MSCs. This platform is optimized to standardize MesenCult™-ACF Plus expand faster compared to cells cultured in serum-based Differentiate mouse MSCs into adipogenic and osteogenic lineage cells using LIF, leukaemia inhibitory factor; NG2, nerve/glial antigen 2; NK, natural killer; Salem, H. K. & Thiemermann, C. Stem Cells 28, Edited by Rachel David; your system and minimize experimental variability. media and demonstrate robust differentiation potential. Human platelet lysate- and MesenCult™ Adipogenic Differentiation Kit (Mouse; Catalog #05507) and NKT, natural killer T; NO, nitric oxide; PGE2, ; MSC, 585–596 (2010). | Meirelles Lda, S. et al. Cytokine Growth copyedited by Antony Bickenson; serum-based media for human MSC derivation and expansion are also available. MesenCult™ Osteogenic Stimulatory Kit (Mouse; Catalog #05504), respectively. ; PDGFR; platelet-derived growth factor receptor; Factor Rev. 20, 419–427 (2009). | Nombela-Arrieta, C., designed by Vicky Summersby. MPC Generation from hPSCs: • MesenCult™ Expansion Kit (Mouse: Catalog #05513): enrich for and expand Ritz, J. & Silberstein, L. E. Nature Rev. Mol. Cell Biol. 12, 2019 Springer Nature Limited. Pi, inorganic phosphate; PIGF, placental insulin growth factor; SCA1, surface © STEMdiff™ Mesenchymal Progenitor Kit (Catalog #05240): animal component-free kit mouse MSCs in culture without serial passaging and generate purified MSC For more information on how STEMCELL Technologies can help your MSC research, cell antigen 1; SCF, stem cell factor; TGFβ, transforming growth factor-β; 126–131 (2011). | Uccelli, A., Moretta, L. & Pistoia, V. http://www.nature.com/nrm/ for the differentiation and culture of mesenchymal progenitor cells (MPCs) from cultures as early as passage 0. please visit our website: https://www.stemcell.com/products/brands/mesencult.html. VEGF, vascular endothelial growth factor. Nature Rev. Immunol. 8, 726–736 (2008). posters/mscs