Resident cardiac stem cells: how to find and use them

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1 Resident cardiac stem cells: how to find and use them G. Hasenfuß Cardiology and Pneumology Heart Research Center Göttingen Georg-August-University Göttingen

2 Definition: Stem cell Selfrenewal Stem cell Differentiation Proliferation Pluripotency: Potential for differentiation into all cells of the body

3 Bone marrow stem cells Bone marrow cells regenerate infarcted rat hearts C-kit +, lineage-negative EGFP mouse bone marrow cells in rat hearts 3-5h after infarction. 9 Days after injection myocytes and vascular cells: Transdifferentiation Orlic et al., Nature 2001

4 Lack of transdifferentiation of bone marrow cells into cardiomyocytes Bone-marrow-derived haematopoietic cells generate cardiomyocytes at a low frequency through cell fusion, but not transdifferentiation Nygren et al., Nat. Med 2004 Haematopoietic stem cells do not transdifferentiate into cardiac myocytes in myocardial infarcts Murry et al., Nature 2004 Haematopoietic stem cells adopt mature haematopoietic fates in ischemic myocardium Balsam et al., Nature 2004 After 6 weeks cell-treated mice showed a statistically significant, although modest, improvement of fractional shortening, and left ventricular dimensions

5 Cardiomyogenic stem cells mouse heart Blastocysts Brachyury Precursors Precardiac mesoderm Embryos MSP; Flk +/- RV, OT, RA, LA ES Cells EC Cells EG Cells Embryonic Heart Isl1; Nkx2.5; c-kit+ LV, RA, LA Cardiac progenitor cells Cardiac commitment Myocytes, VSNC, EC Neonatal Heart Adult Heart Sca 1 c-kit Side Population Cardiosphere L. Field

6 Cardiac stem cells in mice Green: c-kit pos White: NKx2,5 Blue: nuclei Red: -actin Sca1 cells: Oh et al. PNAS 2003 SP cells: Martin et al. Dev Biol 2004 ATP-binding cassette transporter ABCG2 Beltrami et al., Cell 2003

7 Human resident cardiac stem cells?

8 Human Cardiospheres from biopsies Atrial and ventricular biopsies during cardiac surgery Trypsin digestion, culture of tissue fragments for 1-3 weeks Adherent fibroblast-like cells migrating small, phase-bright cells c-kit + Cardiac Markers Collection of phase-bright cells (4x within 6-10 days) Passage of CSs every 2-3 days Immunofluorescence: ctni, ANP, MHC (external layers), CD34, C-kit, Sca1 and others (c-kit = BrdU incorporation) Messina et al., Circ Res 2004

9 Cardiosphere-derived cells from percutaneous endomyocardial biopsis RV endomyocardial biopsis from transplant and nontransplant patients 70 pts. 1.7± 0.4 x 10 6 CDCs per patient (in 69/70) C-kit, CD105, Ki67 (center), connexin43, α sarcomeric actin different from bone marrow derived C-kit + cells CDCs contain subpopulations with mesenchymal cells, fibroblasts No spontaneous contractions Co-culture to obtain beating cells Smith et al., Circulation 2007

10 Injection of CDCs in mouse heart Immunofluorescence after 20 days Improvement of function in infarcted hearts Smith et al., Circulation 2007

11 Autologous CDCs in Porcine ICM Endomyocardial biopsies from pigs Intracoronary infusion 4 weeks after MI CDCs versus placebo 94 % biopsy success (52.6 ± 6.7 mg) 91 % success of CDCs generation 24.5 ± 2.9 x 10 6 cells in 2.7 ± 0.1 passages and 26.9 ± 1.3 days Johnston et al., Circulation 2009

12 Infarct size after 8 weeks Johnston et al., Circulation 2009

13 Contractile function after 8 weeks Johnston et al., Circulation 2009

14 Cardiospheres open Questions Diffentiation into cardiomyocytes? Clinical studies are being performed Messina et al., Circ Res 2004

15 Human Cardiomyocyte progenitor cells (CMPCs) (Sca-1 based) LA Collagenase Smits et al., Nat Prot 2009

16 Cardiomyocyte progenitor cells (CMPCs) (Sca-1 based) Magnetic cell sorting: iron-labeled mouse Sca-1 AB [Sca-1 not expressed from human cells, however population of human cells is isolated, cross-reaction of AB with unknown protein] Rapid cell devision with 1 / day for 75 passages Differentiation into cardiomyocytes only with 5 Azacytidine (5 aza induces genome-wide demethylation) Smits et al., Nat Prot 2009

17 C-kit + human cardiac stem cells (hcscs) 1% c-kit + cadiac niches Myocardial biopsies Enzymatic digestion cell sorting with immunobeads based on c-kit-ab cell culture outgrow of c-kit + cells immunocytochemistry (3 weeks) sucess in 8 / 12 and 46 / 70 cases 1 % c-kit + cells Expression of myocyte markers no beating cardiomyocytes Injection of cells into mouse hearts with MI regeneration with new human myocytes and capillaries Bearzi et al., PNAS 2007

18 Myocardium control heart within 24h after death c-kit MDR1 Sca-1 Urbanek et al., PNAS 2003

19 Myocardium from outflow tract during valve replacement Urbanek et al., PNAS 2003

20 C-kit-positive cells Pouly et al., J Thor and CV Surgery 2007

21 C-kit-positive cells Pouly et al., J Thor and CV Surgery 2007

22 Cardiac stem cells in the real world 32 endomyocardial biopsies from heart transplant recipients 18 RA appendages 2.7 c-kit-positive cells / mm 2 in EM biopsies 1 c-kit-positive cell / mm 2 in RA tissue all c-kit-positive cells co-stained for CD45 and expressed tryptase as a specific mast cell marker no expression of stemness markers Pouly et al., J Thor and CV Surgery 2008

23 Summary No proof of cardiomyocyte differentiation of resident cardiac stem cells from human heart (without being brutal!) No convincing data against hypothesis that c-kit-positive cells are mast cells and that cardiospheres contain cardiomyocytes as carry over. Wait for clinical studies with cardiospheres