Dynamics of RBCs with altered mechanicalproperties in shear flow. Towards a clinical
marker for sickle cell disease
Emmanuèle Helfer
Aix Marseille Univ, CNRS, CINaM, Marseille, France
Sickle cell disease: 1st genetic disease in the world
Hemoglobin polymerizationCell stiffening
- Dehydration- Deoxygenation
Mutation in Hemoglobin: HbSS
Partially reversible
Malaria atlas project
4.5 million people, 300 000 births/year
Life expectancy in developed countriesof the order of 40 years
Palliative care
Efforts only on systematic prevention
Decrease in RBC deformability
Clogging of small blood vessels
Vital prognosis: acute chest syndrome
Sequelae: stroke, bone necrosis
Unpredictable, very painful
Vaso-occlusive crisis
RBC mechanical marker sensitive to the imminence of a crisis?
Vaso-occlusive crises
Top view
8
µm
Sectional view
2
µm
Lipidmembrane
2Dcytoskeleton Elastic
shear modulus
Cytoplasmicviscosity
Hb solution
Aspectratio
Red blood cell deformability
Volume loss
Swelling
Need for a marker sensitive to these parameters
The mechanics of RBCs controls their motion under shear flow
γ.
.γ
Tank-Treading
Rolling
Tumbling
g.
gc
.
Bottom views
Y
Z
X
Flow chamber
Goldsmith and Marlow, 1972Fischer et al., Science 1978Abkarian et al., PRL, 2007Dupire et al., PNAS, 2012
The mechanics of RBCs controls their motion under shear flow
Y
Z
X
Flow chamber
γ.
.γ
Tank-Treading
Rolling
Tumbling
g.
gc
.
« broad spectrum » markerrelated to RBC deformability
Another marker?
Detection of RBC type of motion under shear flow
HbAA Healthy
HbSS Sickle
population of at least 250 cells
Shear rate (s-1)
fTT
Fraction of TT RBCs as function of shear rate
Shear rate: 10 s -1
Healthy Sickle Thalassemia
fTT
Fraction of TT RBCs SCD and thalassemia
Healthy
Sickle
Sickle
Healthy
d = 1,085
d = 1,092
d = 1,101
d = 1,122
d = 1,107
SickleHealthy
Volume reduction0.51 0.60.75
The fraction of TT RBCs is related to cell hydration and density
TT fraction during the course of a vaso-occlusive crisis
day after hospitalization
f TT
Sequence of two crises
crisis 11crisis
10Pre-crisis
decrease
European patent applicationEP 18305914.6
Clinical trial from sept. 2018
fTT trend evolution during vaso-occlusive crises
The fraction of tanktreading RBCs is
sensitive to genetic diseases that affect RBC deformability a perfect candidate for predicting vaso-occlusive crises in
SCD
Low cost device that can be installed at the patient’s bedside
Other applications: in-vitro test for drug evaluation…
Conclusion
Acknowledgments
• Scott ATWELL
• Alexander HORNUNG
• Maxime SAHUN
• Anne CHARRIER
• Annie VIALLAT
Marseille Medical Genetics
Aix-Marseille Université, INSERM
CINaM
Aix-Marseille Université, CNRS
• Catherine BADENS
THANK YOU FOR YOUR ATTENTION!
A*MIDEX project (n° ANR-11-IDEX-00001-02)
CNRS Pre-maturation