This document summarizes the current status of stem cell research and therapy for cardiac repair. It discusses the types of stem cells used, including embryonic, bone marrow-derived, and resident cardiac stem cells. Methods of stem cell delivery like intravenous, intracoronary, and direct injection are presented. The mechanisms by which stem cells home to the heart and differentiate are described. Clinical trials using mesenchymal stem cells for acute myocardial infarction and heart failure are mentioned. While benefits are seen, long-term effects and several unresolved issues are still being investigated.

1. Where do we stand today?
Dr. B. K. Iyer

2. Today’s discussion?
 The background
 The procedure
 The current status
 The Limitations
 The Potential

4. Stem cell science: achievement
todate?
 Much biological
information from the
first study in 2001.
 Little clinical
knowledge:
in the heart – something
in other organs - very
little.
 Can stem cell therapy
correct / regenerate
blood vessels and / or
myocardium?
Orlic D, et al. Nature 2001Orlic D, et al. Nature 2001

5. Contrast stem cell research with
beta blocker research
Beta blockers:
 Slow evolution over 90
years
 Specific understanding of
defined molecular
species and a receptor
 Strong industrial –
academic collaboration
 Basic science and
clinical science linked
and reciprocal
Stem cells:
 Sudden discovery
 Little understanding
 Little industrial support
 Evidence of disjoint
between basic and
clinical science

6. The Hype

7. The Hype

8. The Basis
 Cell transplantation for cardiac repair and/or
inadequate blood supply: Rationale
Chronic heart diseases are characterized by
irreversible loss of myocytes
Although some mitotic activity can be identified, proliferative
capacity is inadequate
Permanent deficits in number of viable, functioning myocytes
promotes development and progression of HF

9. Damaged myocardium repair
Grounds MD et al. J Histochem Cytochem. 2002;50:589-610.

10. The types of stem cells
Embryonic
stem cells
Bone marrow
stem cells
Resident
stem cells
The whole body
Specialised tissue
(e.g. heart, blood vessels)
Repair of the organ
(e.g. in heart, repairs heart)

11. Embryonic stem cells
 Embryonic stem cells =
derived from embryonic
and fetal tissue while
adult stem cells are
undifferentiated cells
harvested from adults.
 Totipotent: capable of developing
into any cell of an organism eg.
zygote
 Pluripotent: capable of developing
into most tissues except the
placenta, eg. embryonic stem cells
 Multipotent: capable of developing
into a limited number of tissues,
eg. adult stem cells.

12. Adult stem cells
 Different type of adult
stem cells =
Hematopoietic stem cells
Mesenchymal stem cells
(MSCs)
Skeletal myoblasts
Resident cardiac stem cells

13. Why use Adult stem cells?
 Readily available
 Easy to isolate
 Autologous
 May be altered to increase gene
expression
 No ethical concerns

14. Role of the stem cells in cardiac
regeneration therapy
 As a cell, As a factory, As a courier
Werner N, Nickenig G.
Arterioscler Thromb Vasc Biol. 2006;26(2):257-66.

16. Steps in Stem Cell Therapy
1. Extraction of MSCs:
 They are extracted from the bone marrow of the
donor.
2. Expansion of MSCs in culture medium:
 This is done using off the shelf products like
enrichment cocktails and growth mediums.
2. Delivery of the MSCs to the site of the infarct.
3. Homing and differentiation of MSCs:
 Once in the system the MSCs migrate to the site of
the infarct and differentiate into myocytes under the
influence of cytokines and paracrine agents.

17. Routes of Delivery in Stem Cell
Therapy
 2 main routes of delivery:
1. Transvascular:
 Includes IV infusion and intracoronary infusion.
 Intracoronary infusion is done using percutaneous
coronary intervention (PCI).
2. Direct injection into the myocardium.
• In this approach, the MSCs are directly injected into
the myocardium at the borders of the site of the
infarct (endocardial) using a needle catheter during
a PCI or (intramyocardial) as an adjunct to a
coronary bypass graft (CABG).

18. Routes of Delivery in Stem Cell
Therapy
1. Intravenous:.
 Least invasive
 More effective in acute settings
 More systemic exposure.
2. Intracoronary:
 Intermediate
 More effective in acute settings
 Less systemic exposure
 High rate of engraftment at the site of infarct
2. Direct Myocardial injection:
• Most invasive
• Can be used later as compared to intravascular approaches
• Least systemic exposure
• High rate of engraftment at the site of infarct

19. Routes of Delivery in Stem Cell
Therapy
Strauer BE, Kornowski R. Circulation 2003;107:929-34.

20. Homing and Differentiation
 Myocardial necrosis causes release of
inflammatory signals which induce mobilization
and homing of MSCs to the site of the infarct.
 Some of these include:
Stem cell factor (SCF) and c-kit
CXCR4 and stromal cell derived factor-1(SDF-1)
Vascular endothelial growth factor (VEGF) and
VEGF receptor-2.

21. Homing – in of Graft
Ischemia=Hypoxia
Cytokines Increased vascular permeability V CAM
I CAM
VEGF – 2
GCSF
SDF – Increased
MMP 9

22. Stem Cell Homing –
Chemoattractive hypothesis
Rosenthal N. N Engl J Med. 2003;349:267-74.

23. Therapeutic implications

24. Allogenic vs. Autologous
 MSCs are considered to
be immune privileged
since they evade
allorejection.
 This is the result of 3
mechanisms:
1. Hypoimmunogenicity
2. Affect dendritic cells and
natural killer cells
3. Suppress T cell
proliferation and generate
a local
immunosuppressive
milieu

25. Allogenic vs. Autologous
 The 3 mechanisms:
1. Hypoimmunogenicity
○ MSCs lack MHC-II protein and thus evade recognition by T cells and they also
lack co stimulatory factors CD40, CD40L,CD80 and CD86 required for T cell
activation
1. Affect dendritic cells and natural killer cells
○ MSCs prevent maturation and migration to the lymph nodes of dendritic cells
and natural killer cells. They also decrease secretion of TNF-α by dendritic
cells and IFN-γ by natural killer cells and increase secretion of IL-10 by
dendritic cells.
1. Suppress T cell proliferation & generate local immuno-
suppressive milieu
○ MSCs produce NO which inhibits stat5 phosphorylation = essential for T cell
proliferation. MSCs also produce hepatocyte growth factor (HGF), PGE2 and
transforming growth factor-β1(TGF-β1) for a local immunosuppressive
environment.

26. Allogenic vs. Autologous
 The 3 mechanisms:
1. Hypoimmunogenicity
○ MSCs lack MHC-II protein and thus evade recognition by T cells and they also
lack co stimulatory factors CD40, CD40L,CD80 and CD86 required for T cell
activation
1. Affect dendritic cells and natural killer cells
○ MSCs prevent maturation and migration to the lymph nodes of dendritic cells
and natural killer cells. They also decrease secretion of TNF-α by dendritic
cells and IFN-γ by natural killer cells and increase secretion of IL-10 by
dendritic cells.
1. Suppress T cell proliferation & generate local immuno-
suppressive milieu
○ MSCs produce NO which inhibits stat5 phosphorylation = essential for T cell
proliferation. MSCs also produce hepatocyte growth factor (HGF), PGE2 and
transforming growth factor-β1(TGF-β1) for a local immunosuppressive
environment.

27. Conduction
 After the MSCs undergo differentiation it is
essential that they also acquire the electrical
properties of cardiac myocytes.
Electrical conduction through the differentiated MSCs is
attributed to the development of gap junctions, which are
seen at the interfaces between the MSCs themselves
and between the MSCs and cardiac myocytes.

28. Conduction
 MSCs have a resting potential of -30 to -40mV.
They express a small fraction of L-type Ca
channels and they are considered inexcitable
which results in slower conduction velocity in-vitro,
in a co-culture of MSCs and myocytes as
compared to only myocytes. But the conduction
velocity in a co-culture of MSCs and myocytes is
still faster than that observed in a co-culture of
fibroblasts and myocytes, which would be seen in
MI.
Resynchronization of two separately beating fields has
been seen within 24 to 48 hours of transplantation.

30. Cell Therapy in Failing Heart
 GOAL
Transfer of functional myocytes to heart – Improve its
function
The DEALS “ Homing of grafted cells”
Engraft into non functional scar
Electromechanical coupling and synchronisation
Neo angiogenesis and myogenesis
Good craft survival
Low immunogenecity
Ethical acceptance
Low oncogenicity
Case of application

31. Cell Therapy studies in experimental
MI models

32.  Use of autologous cells in large randomised
control trials in patients with:
 Acute myocardial infarction
 Late presentation myocardial infarction
 Heart failure (both ischaemic and dilated)
 Use of autologous cells in small clinical
mechanistic studies
 Studies to test use of cytokines

33. Stem Cell Research Plan currently on
3 protocols approved by ethics committee
Ischaemic
Heart Failure
Dilated
Cardiomyopathy
Acute myocardial
infarction
(Total recruitment of 700 patients)

34. CV disease targets in cell therapy
trials in the US
 Refractory angina
Baxter: CD 34+
cells post G-CSF: (Phase 1 & 2)
 Acute myocardial infarction
Osiris IV mesenchymal cells (Phase 1)
Neuronyx: IM mesenchymal cells
NHLBI-CCTRN: IC BM mononuclear cells (TIME and
late TIME)
 Heart failure
Bioheart: skeletal myoblasts (MARVEL)
NHLBI-CCTRN: BM mononuclear cells (FOCUS)
 Peripheral arterial disease
Baxter: CD34+
cells post G-CSF for claudication

35. Risks vs. benefits
Risks:
 Highly invasive procedures
except for IV infusion
 Susceptible to re-entrant
arrhythmias
 Risk of propagating genetic
defects
 Tumors
Benefits:
 Clinical trials have shown
improvement of both systolic and
diastolic function after transplant
of MSC
 Increase in left ventricular ejection
fraction (LVEF)
 Decrease in the area of functional
defect
 Increase in the wall movement
velocity of the infarcted area
 No significant changes in the left
ventricular dystolic diameter
(LVDd)
 No significant changes in E/A ratio
 Small increase in isovolumic
relaxation time (IVRT)

36. Risks vs. benefits

37. Provacel
Current status:
 FDA has approved Phase I clinical
trial for Provacel an interventional
therapy using MSCs to prevent
heart failure resulting from an acute
myocardial infarction, sponsored by
Osiris Therauptics Inc.
 53 patients are admitted in this
double-blind, placebo-controlled,
dose escalating, multicenter,
randomized trial and were treated
using allogenic MSCs which were
delivered through a standard IV line
within 7 days of suffering from a
first MI.
 These patients are going to be
followed for a period of 2 years to
demonstrate the safety of the
product and to evaluate preliminary
efficacy data.
Control groupControl group
Experimental group treated using ProvacelExperimental group treated using Provacel

38. Conclusion
 Preclinical and human trials have showed short term benefits of
using MSCs post MI that include
1. improvement in LVEF,
2. reduction of scar tissue,
3. absence of hypertrophy and
4. improvement in in contractility and conduction
 But it is also essential to study long term effects. Further studies
are warranted to help design treatments that are best suited to
individual needs depending on the location of the infarct, time
elapsed since the MI and hemodynamic stability of the patient.
 Thus although MSC transplants have a long way to go from the
laboratory to the patient’s bedside, they do show promise, that
their use will help improve the quality of life of the patients and
reduce progression to heart failure.

40. Some Unresolved Issues
 Which Cells(s) type ?
 Which mode of delivery
 Tailored administration in clinical scenarios
 What dose ?
 Adjunctive therapy

41. Some Unresolved Issues
 Immunogenecity
 How effective / How risky
 Optimal timing of therapy
 Ethical timing of therapy
 Durability of therapy

42. You see things; and you say “Why”
But I dream things that never were;
And I say “Why not”
G.B. Shaw

43. In youth we learn
In age we understand
Mary Von Ebner Eschenbach

44. References
 Cardiovascular gene therapy by Ylä-Herttuala,
Martin, Lancet 2000;355:213-22, Understanding
of biological mechanisms necessary for
translation
 Stem cells and repair of the heart by Mathur,
Martin, Lancet 2004;364:183-92, Understanding
of biological mechanisms not necessary for
translation

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 Osiris Therapeutics Inc. Provacel clinical trial: http://www.osiristx.com/clinical_trials_provacel.php.

46. References
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