Reconstitution of the functional human hematopoietic microenvironment derived from human mesenchymal stem cells in the murine bone marrow compartment

Abstract

IntroductionMesenchymal stem cells (MSCs) present in bone marrow (BM) are thought to give rise to cells that constitute the hematopoietic microenvironment (HME). 1 MSCs have been isolated from BM and various tissues from humans and many other species, expanded in culture, and shown to differentiate into osteocytes, chondrocytes, adipocytes, and myoblasts under defined conditions in vitro. 2 In culture, MSCs produce a number of cytokines and extracellular matrix proteins and express cell adhesion molecules, all of which are involved in the regulation of hematopoiesis. 3,4 They also support the development of hematopoietic colonies in vitro. 4 However, in contrast to hematopoietic stem cells (HSCs) that have been prospectively isolated and extensively studied at the singlecell level both in vitro and in vivo, MSCs have only been defined and isolated by physical and functional properties in vitro. Consequently, little is known about their phenotypic and functional characteristics in vivo.Systemic administration of MSCs for facilitation of bone marrow transplantation has been proposed based on the in vitro characteristics of MSCs. 5 In recent studies, cotransplantation of human MSCs and HSCs resulted in increased chimerism or accelerated hematopoietic recovery (or both) in animal models and in humans, 6-9 suggesting a role for MSCs in the engraftment and repopulation of HSCs. Although the existence of donor MSCs has been documented in the BM of recipient animals following MSC infusion, 9,10 the methods used to detect engraftment, such as polymerase chain reaction (PCR) or staining of cytospin samples, could not unambiguously distinguish engraftment from cell survival or nonspecific lodgment on the vascular bed. In addition, Awaya et al examined stromal cells of patients who received BM transplants and confirmed that all donor signals were, in fact, derived from macrophages. 11 To our knowledge, there is no physical evidence that transplanted human MSCs have indeed engrafted in the BM of adult animals and directly participated in the enhanced engraftment of HSCs.To assess the engraftment, spatial distribution, and lineage commitment of MSCs as well as their roles in hematopoiesis in vivo, we transplanted enhanced green fluorescent protein (eGFP)-marked human MSCs into the tibiae of nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice by intra-bone marrow transplantation (IBMT), a method previously shown to improve the engraftment of both hematopoietic and nonhematopoietic cells in mice. [12][13][14] We used a dual-color genetic marking strategy 15 along with immunofluorescent staining to distinguish and investigate transplanted cells in situ. We show that transplanted human MSCs integrated into the functional components of the HME and that these MSC-derived cells appeared to be actively involved in the maintenance of human hematopoiesis in murine BM. Materials and methods Isolation of human cord blood CD34 ؉ cellsHuman umbilical cord blood (CB) samples were obtained from full-term deliveries with infor...

Microarray profiling of preselected CHO host cell subclones identifies gene expression patterns associated with in‐creased production capacity

“…In combination with the results for the ER it seems that, although the ER is upregulated for high protein cargo, in the high producing subclones this is not happening under stress response. Rather, due to the upregulation of proteins that support folding and secretion as well as the upregulation of some components of the UPR, cells are able to handle high protein loads, and less protein needs to be degraded and is lost due to misfolding and lack of proper assembly [63,64].…”

Cell Therapy for Multiple Sclerosis

“…This was most thoroughly studied in bone marrow stromal (mesenchymal) stem cells (BMSC). These cells form the bone marrow stroma that support hematopoiesis [181] and serve as precursors of the various bone cell types (adipocytes, myocytes, and chondrocytes) [182]. They do not express hematopoietic markers and can be identified by expression of CD105, CD44, CD 90, and others.…”

Distinctive contact between CD34+ hematopoietic progenitors and CXCL12+ CD271+ mesenchymal stromal cells in benign and myelodysplastic bone marrow

“…MSCs are of particular interest because they are capable of supporting self-renewing proliferation of CD34 þ hematopoietic progenitors. [5][6][7] Those purified MSCs that show multipotency are called …”

“…MSCs are of particular interest because they are capable of supporting self-renewing proliferation of CD34 þ hematopoietic progenitors. [5][6][7] Those purified MSCs that show multipotency are called mesenchymal stem cells, 8 or osteoprogenitors when they demonstrate capability of reconstituting bone in vivo. 9 In our study we aimed to quantitatively and comprehensively map the normal MSC component of intact bone marrow to allow for identification of derangements of MSCs in myeloid neoplasia, particularly in MDS.…”