DM SEMINAR 18 th January 2012 Swastik Aggarwal

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1 DM SEMINAR 18 th January 2012 Swastik Aggarwal

2 Undifferentiated cells capable of proliferation, self-maintenance, and differentiation into functional progeny

3 Embryonic stem cells Fetal stem cells Adult stem cells Mesenchymal stem cells (MSC) Endothelial progenitor cells (EPC) Hematopoietic stem cells (HSC)

4 Bone marrow (BMSC) -Hematopoietic stem cells -Mesenchymal stem cells Brain -ventricular & subventricular zone -hippocampus Peripheral blood Epithelia of skin & G.I.T. Endothelial cells Pancreatic duct &bile duct Islets of pancreas, Liver (oval cells, canals of Herring) Skeletal muscle

5 Cell Source Ethical Problems Acquisition Concerns Rejection Oncogenecity Embryonic Stem Cells Yes Yes Yes Yes Fetal stem cells Yes Yes Yes No Bone Marrow Stem Cells No No No No Adult Liver stem cells No Yes No Yes Skeletal Myoblasts No Yes No No

6 Direct contribution to the functional hepatocyte population Promotion of endogenous regenerative processes Decrease transaminases and bilirubin, increase in albumin Pai M et al. Am J Gastroeterol 2008;103: Increase in proliferation indices like AFP and proliferating cell nuclear antigen am Esch JS et al. Stem Cells 2005;23:463 70

7 Stem cell transplant less invasive, metabolically less demanding than OLT Native liver retained Fewer consequences of graft failure Can be performed multiple times Cryopreserved cells can be used urgently One donor can benefit multiple recipients No immunosupression in autologous cells

8 CD 34+ CD 133+ cells Derived from bone marrow, peripheral blood, umbilical cord blood Best studied and understood stem cell Act mainly by promoting regeneration am Esch JS et al. Stem Cells 2005;23: Also proven to trans-differentiate into hepatocytes- limited functional role (<5%) Gilchrist ES et al. Liver Transpl 2010;16: Yamazaki S et al. J Hepatol 2003;39:17 23.

9 Daily s.c. G-CSF at 300 µg for 5 days BM aspirate on day 6 Immuno-magnetic purification and selection for CD34+ and CD133+ stem cells Washed with phosphate buffered saline (ph 7.4), 0.5% albumin and 5mmol/L EDTA added Centrifuged at 1500 r/min for 10 min at cells suspended in 100mL NS Infused into PV under USG guidance

10 Usually BM derived. Found in most tissues Form albumin-producing hepatocyte like cells Schwartz RE. J Clin Invest 2002;109: Porada CD. Curr Stem Cell Res Ther 2006;1:365 9 Differentiate to hepatocytes, stimulate regeneration of endogenous parenchyma and enhance fibrous matrix degradation

11 3 vs 3 controls: CD133+ BM cells- 2.5 fold higher proliferation on CT am Esch JS. Stem Cells 2005;23: vs 7 controls: PV embolization ± CD133+ BM cells- higher proliferation on CT Fürst G. Radiology 2007;243: vs 10 controls: cirrhotic pt with HCC. Better LFT, less complication post-op Ismail A. J Gastrointest Cancer 2010;41:17 23.

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15 Oval cells- bipotent, derived from intrahepatic biliary tree EPCAM and NCAM positive Constitute % of liver cells Greatly increased in stress, liver injury via TNF-α, IL-6, IL-15, IFN-γ, TGF-α, HGF Human HPCs transplanted into mice yield mature liver tissue with human proteins Schmelzer E et al. J Exp Med 2007;204:

16 Hepatic progenitor cells can also be derived from cord blood (OV6 + cells) Differentiate in mice to hepatocytes expressing human proteins Crema A et al. Stem Cells Dev 2011;20: No oncogenic risk so far Most promising cells for future research Human studies lacking

17 Adult somatic cells genetically reprogrammed to an embryonic stem cell like state Can differentiate into cells of all 3 embryonic germ layers including hepatocytes Chun YS et al. Int J Biol Sci 2010;6: Major challenge- directing differentiation into specific adult cell lineage No in vivo studies yet Advantage- unlimited autologous stem cells, no need for immunosupression Disadvantage: teratoma formation

18 Derived mainly from fetal blood/amnion Contain HSC, MSC, progenitor cells Better homing and engraftment, greater multipotentiality and lower immunogenicity than adult stem cells Less ethically contentious than ESC O Donoghue K et al. Best Pract Res Clin Obstet Gynaecol 2004;18: In vitro show development in functional hepatocytes Riehle KJ et al. J Gastroenterol Hepatol 2011

19 Derived from inner cell mass of blastocyst Most potent differentiation potential, capacity for indefinite self renewal In vitro differentiation into functional hepatocytes documented Agarwal S et al. Stem Cells 2008;26: In vivo rodent studies: less efficient than adult hepatocyte transplantation Haridass D et al. Am J Pathol 2009;175: Ethics and oncogenecity major hurdles

20 Remarkable proliferative capacity of hepatocytes Respond to cell loss: enter cell cycle and undergo rapid self-renewal Hepatocytes Tx in liver or ectopic sites survive, function help regeneration

21 Autologous/ allogenic liver Only clinically used source Shortage of donors Ex-vivo cell lines, conditionally immortalized by thermolabile simian virus T antigen gene Risk of oncogenesis Xenogenic (porcine) hepatocytes Immunological hurdles Transmission of porcine viruses Fox IJ et al. Hepatology 1995;21:837. Rhim JA et al. Proc Natl Acad Sci U S A 1995; 92:4942.

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23 Dimethyl sulfoxide- cryoprotectant Slow freezing and rapid thawing when required to avoid osmotic shock -136 to -196 C Advantages Emergency/ planned retreatment Reduces infection risk Disadvantages Decreased viability and metabolic function Decreased cell engraftment

24 Splenic pulp/ Splenic artery Partial retention in spleen Can replace up to 40% of splenic mass With time bile canaliculi, sinusoids and endothelial cells develop in spleen Important extra-hepatic site for engraftment Useful in cirrhotics/ ongoing massive necrosisliver not hospitable for transplanted cells Ponder KP et al. Proc Natl Acad Sci U S A 1991; 88:1217

25 Portal vein Integrate into liver cord and functional in 24hours Syngenic hepatocytes can function life long No increase in portal pressure in non-cirrhotic livers even with transplant up to 5% of liver mass PHTN and increase RA pressure in cirrhotics Gupta S et al. Hum Gene Ther 1993; 4:249. Renal sub capsular space, subcutaneous tissue, and peritoneal cavity Hepatocytes are encapsulated, attached to collagen-coated microcarriers, or encased in Hydrogel-based hollow fibers Under investigation Dixit V et al. Artif Organs 1992; 16:336. Demetriou AA et al. Hepatology 1988; 8:1006. Honiger J et al. Biomaterials 1995; 16:753.

26 Blood group ABO compatible, Cell viability of 60% Negative viral screening like OLT Micro-organism free on Gram stain Dose: cells/kg B.W. (~10% liver mass) Upto cells/infusion (~1% liver mass) Infusion rate: 5 10 ml/kg per hour Concentration of hepatocytes/ml

27 Transplanted cells induced to proliferate preferentially over the host hepatocytes combination of proliferative stimuli to the Tx hepatocytes and impairment of host hepatocytes Occurs naturally in urokinase plasminogen activator (upa) transgenic, MDR3 gene knockout mice Non genetic approaches tried DNA-modifying agent (retrorsine) followed by partial hepatectomy and hepatocyte transplantation Preparative resection and irradiation of the host liver Guha C et al. Cancer Res 1999; 59:5871 Laconi E, et al. Am J Pathol 1998; 153:319

28 Inherited metabolic disorders Allogeneic Autologous with ex-vivo gene transfer. Acute liver failure As a "bridge" while awaiting liver transplantation. As definitive therapy in selected cases. Chronic liver failure For improving metabolic function and encephalopathy. To buy time while awaiting liver transplantation.

29 Patients requiring high doses of hepatic irradiation As a part of treatment. Generating animal models For human hepatocyte-specific infections by transplanting human hepatocytes into immunodeficient animals.

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34 Shortage of donor livers Only poor quality livers available Maximum upto 10% liver weight transplanted Only 30% cells engraft, last for around 1 year Cryopreservation techniques not infallible Repeated transfusions from multiple donors increases risk of rejection Immunosuppression hazards as in OLT Bench to bedside issues remain No controlled trials to prove efficacy

35 Proof of principle established Limited duration of efficacy Engraftment into liver biggest limitation Limited by technology Many bench to bed side issues remain Limited data on efficacy in clinical setting Progenitor cells attractive option for human trials