CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 1, January/February 2013
AFRICA
289
3
Department of Pathology, Ewha Womans University, Seoul, Korea
4
Biomedical Research Institute, Medipost Co, Seoul, Korea
Background
: Pulmonary arterial hypertension (PAH) causes right
ventricular failure and possibly even death due to progressive
increase in pulmonary vascular resistance. Human umbilical cord
blood-derived mesenchymal stem cells (hUCB-MSCs) are regarded
as an alternative source of bone marrow-derived mesenchymal stem
cells because collection of cord blood is less invasive than that of
bone marrow. hUCB-MSCs have recently been studied for evaluation
of their potential as a source of cell therapy. However, it is rare to
investigate use of hUCB-MSCs in PAH. The purposes of this study
were to investigate changes in haemodynamics, pulmonary pathology
and gene expressions of endothelin (ET)-1, ET receptor A (ERA),
endothelial nitric oxide synthase (NOS) 3, matrix metalloproteinase
(MMP) 2, tissue inhibitor of matrix metalloproteinase (TIMP), inter-
leukin (IL) 6, and tumour necrosis factor (TNF)-
α
in monocrotaline
(MCT)-induced PAH rat models after hUCB-MSC transfusion.
Methods
: The rats were grouped as follows: control (C) group,
subcutaneous (sc) injection of saline (0.1 ml/kg); M group, sc injec-
tion of monocrotalline (MCT); hUCB-MSC transfusion (U group).
hUCB-MSCs (3 × 10
6
/ml/cm
2
) were transfused by intraperitoneal
injection one week after MCT injection.
Results
: The mean right ventricular pressure (RVP) significantly
decreased in the U group compared with the M group in weeks
two and four. Right ventricle (RV) weight and the ratio of RV/left
ventricle (LV) + septum significantly decreased in the U group
compared to the M group in weeks two and four. Gene expressions
of ET-1, ERA, NOS 3, MMP 2, TIMP, IL-6 and TNF-
α
significantly
decreased from week two in the U group compared with the M group.
Conclusion
: After hUCB-MSC transfusion, there was an improve-
ment in RVH and mean RVP. Decreases in several gene expressions
were observed. Additional research on the dose and frequency of
hUCB-MSC infusions is needed to better determine the optimal
parameters for PAH treatment
.
1459: REGULATORY B CELLS IN HUMANS: IDENTIFYING
THE REGULATORY CAPACITY AND INTERLEUKIN-10
PRODUCTION OF REGULATORY B CELL PHENOTYPES
Ying Ling
1,3,4
, Esmé Dijke
1,4
, Bruce Motyka
1,4
, Lori West
1,2,3,4
, Simon
Urschel
1,3,4
1
Department of Paediatrics, University of Alberta, Canada
2
Department of Surgery, University of Alberta, Canada
3
Department of Medical Microbiology and Immunology, University
of Alberta, Canada
4
Alberta Institute for Transplant Sciences, University of Alberta,
Canada
Background:
In mice, CD1d
+
CD5
+
B cells have regulatory proper-
ties associated with interleukin-10 (IL-10) production. In humans,
this phenotype is up to 10 times more frequent in infants than
in adults. Infants show better heart transplant outcomes than
older recipients, including acceptance of ABO-incompatible grafts.
However, they also show increased severity of infection with poly-
saccharide-encapsulated bacteria. We hypothesised that CD1d
+
CD5
+
B cells contribute to the altered immune response during infancy,
particularly towards polysaccharides, including ABO-antigens and
bacteria capsules.
Methods:
CD1d
+
CD5
+
B cells were FACS-sorted from paediatric
splenocytes and cultured parallel to non-CD1d
+
CD5
+
B cells using
T-dependent (TD;
α
-IgM
+
CD40L) and T-independent (TI; CpG or
α
-IgM
+
crosslinker) B cell stimuli to measure IL-10 in supernatants
by ELISA. The regulatory impact of CD1d
+
CD5
+
B cells on other
cells was assessed through proliferation of CFSE-stained (1) periph-
eral blood mononuclear cells (PBMC
original
), (2) PBMC to which
CD1d
+
CD5
+
B cells were added to double the original proportion
(PBMC
double
), and (3) PBMC from which CD1d
+
CD5
+
B cells were
depleted (PBMC
depleted
) after stimulation with B-cell stimuli or T-cell
stimuli (
α
-CD3
+
CD28).
Results:
IL-10 levels were higher with TI than with TD stimulation,
however, little difference was observed between CD1d
+
CD5
+
B
cells and non-CD1d
+
CD5
+
B cells. The mean percentage of divid-
ing B cells stimulated with CpG was 21.9 lower in PBMC
double
than
in PBMC
original
(
p
=
0.018). When stimulated with
α
-IgM
+
CD40L, it
was 31.9 higher in PBMC
depleted
than in PBMC
original
(
p
=
0.042). The
percentage of dividing T cells was 26.2 lower in PBMC
double
than in
PBMC
original
(
p
=
0.088).
Conclusions:
These results indicate that CD1d
+
CD5
+
B cells in
humans inhibit the proliferation of B and T cells. Since IL-10 produc-
tion was also found in non-CD1d
+
CD5
+
B cells, these markers do
not uniquely identify regulatory B cells in humans. Further analyses
to determine the phenotype of IL-10-producing B cells are underway.
1546: EFFECTS OF MELATONIN TREATMENT ON CARDI-
AC FUNCTION IN A MODEL OF PULMONARY ARTERIAL
HYPERTENSION
Gerald Maarman
1
, Lori Blauwet
2
, Sandrine Lecour
1
, Karen Sliwa
1
1
Hatter Institute for Cardiovascular Research in Africa (HICRA),
Medicine, Faculty of Health Sciences, University of Cape Town,
South Africa
2
Mayo Clinic, Rochester, MN, USA
Background:
Pulmonary arterial hypertension (PAH) is a disorder
characterised by elevated pulmonary arterial pressure, which leads to
cardiac hypertrophy and ventricular dysfunction. Current treatments
are only marginally effective and additional therapies are required.
Melatonin is a natural product that has been shown to be cardiopro-
tective against hypertension and myocardial infarction. We therefore
propose that a chronic melatonin treatment may be cardioprotective
in a rat model of monocrotaline (MCT)-induced PAH.
Methods:
Male Long Evans rats (150–175g) received a single subcu-
taneous injection of MCT (80 mg/kg), which induced PAH after 28
days. Melatonin was given in the drinking water (4 mg/kg/day) for
the 28-day period. Cardiac hypertrophy was confirmed with a ratio
of the right ventricle weight over heart weight (RVW/HW). Cardiac
functional parameters were assessed at zero and 28 days using
isolated heart perfusion and/or echocardiography. These parameters
included right ventricular systolic (SP) and diastolic pressure (DP),
ejection fraction (EF) and fractional shortening (FS).
Results:
MCT increased RVW/HW, reduced EF (92.84
±
1.33% vs
60.53
±
4.23%,
p
<
0.0003), FS (28.23
±
2.68% vs 61.03
±
2.89%,
p
<
0.0002) and increased SP and DP. Chronic administration of mela-
tonin in MCT-treated rats improved EF (60.5
±
4.2% vs 84.1
±
1.7%,
p
<
0.0008), FS (28.2
±
2.7% vs 48.7
±
2.1%,
p
<
0.0005), SP and DP.
Conclusions:
Our data demonstrate that chronic melatonin improved
cardiac function in MCT-induced PAH and suggest a cardioprotective
role of melatonin in PAH.
1561: THE ROLE OF NOVEL PROTEIN–PROTEIN INTER-
ACTIONS IN THE FUNCTION AND MECHANISM OF THE
SARCOMERIC PROTEIN, MYOSIN-BINDING PROTEIN H
(MYBPH)
Jomien Mouton, Hanlie Moolman-Smook, Craig Kinnear
US/MRC Centre for Molecular and Cellular Biology, University of
Stellenbosch, South Africa
Introduction:
Left ventricular hypertrophy is a major risk factor for
cardiovascular morbidity and mortality and is a feature of common
diseases, such as hypertension and diabetes. It is therefore, important
to understand the underlying mechanisms influencing its develop-
ment. Hypertrophic cardiomyopathy (HCM) has been viewed as a
model disease in which to study the causal molecular factors under-
lying isolated cardiac hypertrophy. HCM is described as a disease
of the sarcomere, and one of the regions of the sarcomere that has
been identified as playing a key role in the regulation of contractil-
ity is the C-zone. Identifying binding partners of one of the C-zone
proteins, myosin-binding protein C (MyBPC), has led to insights
