Biomedical subjects

Mark Blackstad

Publications and source records attributed to Mark Blackstad.

7 recordsLinked to original sources

PubMed2006

Isolation and characterization of kidney-derived stem cells.

Acute kidney injury is followed by regeneration of damaged renal tubular epithelial cells. The purpose of this study was to test the hypothesis that renal stem cells exist in the adult kidney and participate in the repair process. A unique population of cells that behave in a manner that is consistent with a renal stem cell were isolated from rat kidneys and were termed multipotent renal progenitor cells (MRPC). Features of these cells include spindle-shaped morphology; self-renewal for >200 population doublings without evidence for senescence; normal karyotype and DNA analysis; and expression of vimentin, CD90 (thy1.1), Pax-2, and Oct4 but not cytokeratin, MHC class I or II, or other markers of more differentiated cells. MRPC exhibit plasticity that is demonstrated by the ability of the cells to be induced to express endothelial, hepatocyte, and neural markers by reverse transcriptase-PCR and immunohistochemistry. The cells can differentiate into renal tubules when injected under the capsule of an uninjured kidney or intra-arterially after renal ischemia-reperfusion injury. Oct4 expression was seen in some tubular cells in the adult kidney, suggesting these cells may be candidate renal stem cells. It is proposed that MRPC participate in the regenerative response of the kidney to acute injury.

Animals↗

PubMed2003

Neuroectodermal differentiation from mouse multipotent adult progenitor cells.

We recently showed that a rare cell from murine bone marrow, which we termed multipotent adult progenitor cells (MAPCs), can be expanded for >120 population doublings. Mouse (m)MAPCs differentiate into mesenchymal lineage cells as well as endothelium and endoderm, and, when injected in the blastocyst, mMAPCs contribute to most if not all somatic cell lineages including the different cell types of the brain. Our results, reported herein, demonstrate that mMAPCs can also be induced to differentiate into cells having anatomical and electrophysiological characteristics similar to those of midbrain neurons. Differentiation to a neuronal phenotype was achieved by coculturing mMAPCs with astrocytes, suggesting that neuronal differentiation may require astrocyte-derived factors similar to what is required for the differentiation of embryonic stem cells and neural stem cells to neurons. Differentiation of mMAPCs to neuron-like cells follows similar developmental steps as described for embryonic stem cells and neural stem cells. MAPCs therefore may constitute a source of cells for treatment of central nervous system disorders.

Animals↗

PubMed2003

Spontaneous circulation of myeloid-lymphoid-initiating cells and SCID-repopulating cells in sickle cell crisis.

The only curative therapy for sickle cell disease (SCD) is allogeneic hematopoietic stem cell (HSC) transplantation. Gene therapy approaches for autologous HSC transplantation are being developed. Although earlier engraftment is seen when cells from GCSF-mobilized blood are transplanted than when bone marrow is transplanted, administration of GCSF to patients with SCD can cause significant morbidity. We tested whether primitive hematopoietic progenitors are spontaneously mobilized in the blood of patients with SCD during acute crisis (AC-SCD patients). The frequency of myeloid-lymphoid-initiating cells (ML-ICs) and SCID-repopulating cells (SRCs) was significantly higher in blood from AC-SCD patients than in blood from patients with steady-state SCD or from normal donors. The presence of SRCs in peripheral blood was not associated with detection of long-term culture-initiating cells, consistent with the notion that SRCs are more primitive than long-term culture-initiating cells. As ML-ICs and SRCs were both detected in blood of AC-SCD patients only, these assays may both measure primitive progenitors. The frequency of ML-ICs also correlated with increases in stem cell factor, GCSF, and IL-8 levels in AC-SCD compared with steady-state SCD and normal-donor sera. Because significant numbers of ML-ICs and SRCs are mobilized in the blood without exogenous cytokine treatment during acute crisis of SCD, collection of peripheral blood progenitors during crisis may yield a source of autologous HSCs suitable for ex-vivo correction by gene therapy approaches and subsequent transplantation.

Adult↗

PubMed2002

Pluripotency of mesenchymal stem cells derived from adult marrow.

We report here that cells co-purifying with mesenchymal stem cells--termed here multipotent adult progenitor cells or MAPCs--differentiate, at the single cell level, not only into mesenchymal cells, but also cells with visceral mesoderm, neuroectoderm and endoderm characteristics in vitro. When injected into an early blastocyst, single MAPCs contribute to most, if not all, somatic cell types. On transplantation into a non-irradiated host, MAPCs engraft and differentiate to the haematopoietic lineage, in addition to the epithelium of liver, lung and gut. Engraftment in the haematopoietic system as well as the gastrointestinal tract is increased when MAPCs are transplanted in a minimally irradiated host. As MAPCs proliferate extensively without obvious senescence or loss of differentiation potential, they may be an ideal cell source for therapy of inherited or degenerative diseases.

Aging↗

PubMed2002

LATS1 tumor suppressor regulates G2/M transition and apoptosis.

The LATS1 gene is a mammalian member of the novel lats tumor suppressor family. Both lats mosaic flies and LATS1 deficient mice spontaneously develop tumors. Our previous studies have shown that inactivation of Drosophila lats leads to up-regulation of cyclin A in the fly, and the human LATS1 protein associates with CDC2 in early mitosis in HeLa cells, suggesting that the lats gene family may negatively regulate cell proliferation by modulating CDC2/Cyclin A activity. We demonstrate here that transduction of the human breast cancer cell MCF-7 with recombinant LATS1 adenovirus (Ad-LATS1), but not with EGFP adenovirus (Ad-EGFP), inhibits in vitro cell proliferation. Ectopic expression of LATS1 in MCF-7 cells specifically down-regulates Cyclin A and Cyclin B protein levels and dramatically reduces CDC2 kinase activity, leading to a G2/M blockade. Furthermore, Ad-LATS1 suppresses anchorage-independent growth of MCF-7 cells in soft agar and tumor formation in athymic nude mice. We also demonstrate that ectopic expression of LATS1 in MCF-7 cells and human lung cancer cell H460 up-regulates the level of BAX proteins and induces apoptosis. Finally, we show that LATS1 kinase activity is required for its ability to inhibit cell growth and induce apoptosis. The results indicate that the LATS1 tumor suppressor may play an important role in the control of human tumor development and that LATS1 suppresses tumorigenesis by negatively regulating cell proliferation and modulating cell survival.

Adenoviridae↗

PubMed2002

Multipotent progenitor cells can be isolated from postnatal murine bone marrow, muscle, and brain.

OBJECTIVE: Recent studies have shown that cells from bone marrow (BM), muscle, and brain may have greater plasticity than previously known. We have identified multipotent adult progenitor cells (MAPC) in postnatal human and rodent BM that copurify with mesenchymal stem cells (MSC). BM MAPC proliferate without senescence and differentiate into mesodermal, neuroectodermal, and endodermal cell types. We hypothesized that cells with characteristics similar to BM MAPC can be selected and cultured from tissues other than BM. MATERIALS AND METHODS: BM, whole brain, and whole muscle tissue was obtained from mice. Cells were plated on Dulbecco modified Eagle medium supplemented with 2% fetal calf serum and 10 ng/mL epidermal growth factor (EGF), 10 ng/mL platelet-derived growth factor (PDGF-BB), and 1000 units/mL leukemia inhibitory factor (LIF) for more than 6 months. Cells were maintained between 0.5 and 1.5 x 10(3) cells/cm(2). At variable time points, we tested cell phenotype by FACS and evaluated their differentiation into endothelial cells, neuroectodermal cells, and endodermal cells in vitro. We also compared the expressed gene profile in BM, muscle, and brain MAPC by Affimetrix gene array analysis. RESULTS: Cells could be cultured from BM, muscle, and brain that proliferated for more than 70 population doublings (PDs) and were negative for CD44, CD45, major histocompatibility complex class I and II, and c-kit. Cells from the three tissues differentiated to cells with morphologic and phenotypic characteristics of endothelium, neurons, glia, and hepatocytes. The expressed gene profile of cells derived from the three tissues was identical (r(2) > 0.975). CONCLUSIONS: This study shows that cells with MAPC characteristics can be isolated not only from BM, but also from brain and muscle tissue. Whether MAPC originally derived from BM are circulating or all organs contain stem cells with MAPC characteristics currently is being studied. Presence of MAPC in multiple tissues may help explain the "plasticity" found in multiple adult tissues.

Animals↗

PubMed2002

Multipotent adult progenitor cells from bone marrow differentiate into functional hepatocyte-like cells.

We have derived from normal human, mouse, and rat postnatal bone marrow primitive, multipotent adult progenitor cells (MAPCs) that can differentiate into most mesodermal cells and neuroectodermal cells in vitro and into all embryonic lineages in vivo. Here, we show that MAPCs can also differentiate into hepatocyte-like cells in vitro. Human, mouse, and rat MAPCs, cultured on Matrigel with FGF-4 and HGF, differentiated into epithelioid cells that expressed hepatocyte nuclear factor-3beta (HNF-3beta), GATA4, cytokeratin 19 (CK19), transthyretin, and alpha-fetoprotein by day 7, and expressed CK18, HNF-4, and HNF-1alpha on days 14-28. Virtually all human, as well as a majority of rodent cells stained positive for albumin and CK18 on day 21; 5% (rodent) to 25% (human) cells were binucleated by day 21. These cells also acquired functional characteristics of hepatocytes: they secreted urea and albumin, had phenobarbital-inducible cytochrome p450, could take up LDL, and stored glycogen. MAPCs, which can be expanded in vitro and maintained in an undifferentiated state for more than 100 population doublings, can thus differentiate into cells with morphological, phenotypic, and functional characteristics of hepatocytes. MAPCs may therefore be an ideal cell for in vivo therapies for liver disorders or for use in bioartificial liver devices.

Adult↗