1) Podocytes are important cells that line the kidneys' blood filters and prevent protein leakage; their loss contributes to kidney damage. 2) Studies show podocyte injury and loss progress with age in Fabry disease and correlate with protein in the urine. 3) Measuring podocytes shed in urine, known as podocyturia, may serve as a non-invasive biomarker of kidney involvement in Fabry disease. However, more research is needed.

1. Urinary Podocyte Loss in
Fabry Disease
FSIG Expert Fabry Conference
San Diego, Feb 2014
Behzad Najafian, M.D.
Department of Pathology
University of Washington

2. KIDNEYS
• The average adult has 1 – 1.5 gallon of blood in
the body.
• Kidneys filter the entire blood in our body 400
times a day.

3. HOW DOES KIDNEY WORK?
• Each kidney has more than 1,000,000 blood filters
(nephrons).
• These blood filters are not replaceable.
Blood filter (nephron)

5. WHAT ARE PODOCYTES?
Podocyte
Blood filter (nephron)
Podocytes
Podocytes are spider-
shaped cells that
prevent passage of
proteins through blood
filter

6. #34
#35
#36
#37
#38#39
#40
Each glomerulus has 500-600 podocytes.
Podocytes do not efficiently proliferate.
Podocyte loss is cumulative in time
Each Podocyte Counts!
Once a glomerulus loses more than ~20% of its
podocytes, it scars down. This injury is irreversible.

7. Kidney International (1998) 54, 687–697
Podocyte Injury and Loss Leads to Segmental and Global
Glomerulosclerosis
Segmental Sclerosis
Global Sclerosis

8. Podocytse are Especially Vulnerable to Injury in Fabry
Disease
podocytes

9. Normal Fabry
Glomerulus

10. Podocyte injury progreses with age
Podocyte injury correlates with
proteinuria
Podocyte inclusion density correlates
with proteinuria
Mesangial cell inclusion density
correlates with proteinuria

11. 2 4 6 8 10 12 14 16 18 20
Age (year)
0.34
0.36
0.38
0.40
0.42
0.44
0.46
0.48
0.50
0.52
0.54
0.56
0.58
Vv(PC/G)
r=-0.65
p=0.02
Podocyte Mass Density Reduces with Age in Fabry Patients
Vv(PC/G) + Vv(Cap/G) + Vv(Mes/G) + Vv(US/G) = 1
Reduced podocyte mass density was
not associated with significant
change in other glomerular
compartments

12. CAN WE DIAGNOSE KIDNEY INJURY BY
STUDYING CELLS IN THE URINE?
Blood filter (nephron)
Number of podocytes in the urine correlates with
urine protein

13. We can recognize podocytes in the urine by
special stains for molecules that are
abundantly present in these cells in the kidney
PCX
CL1
dapi
Parietal cells
Distal tubules
Podocytes
Endothelium
Peritubular
capillaries
PCX+
CL1+
CL1+
PCX+
Normal Human Kidney

14. Preparation of Urine Samples for Counting Podocytes
50 ml Fresh urine
(up to 2-3 hrs) Centrifuge at
500 xg for 6 min
at 5C
local
Cytospin
preparation
outside
Resuspend in
preservative
and ship within
3 days
Virtual slide scanning
Podocyte
staining
podocyte

15. Podocytes in urine from a Fabry patient
Urinary Podocytes in Fabry Patients Resemble Those inside the Kidney
A glomerulus from a Fabry patient
PCX
CL1
dapi
synaptopodin GL3 merge
Podocytes
GL3

16. PCX+
CL1-
Small/apoptotic nu
PCX+
CL1+
Small/apoptotic nu
PCX+
CL1-
Normal size nu
~1/4 of Urine Podocytes in Fabry Patients were Apoptotic

17. Summary and Conclusion
• Podocytes play an important role in preservation of kidney
function.
• Biopsy studies suggest that podocyte injury and loss are
progressive with age in Fabry disease.
• Urinary podocytes (podocyte loss) increases with age in
(male) Fabry patients.
• Urinary podocytes (podocyte loss) correlates with
proteinuria in (male) Fabry patients.
• Podocyturia may become a useful non-invasive biomarker of
Fabry nephropathy.

18. Next Steps
• Fabry disease is very heterogeneous. We need to study
larger cohorts.
• Longitudinal studies are needed to understand podocyturia
changes in time and correlation of changes with renal
function.
• Parallel biopsy and podocyturia studies are needed to
confirm if increased podocyturia correlates with less
podocytes in the glomeruli.
• Laboratory methods to measure podocyturia easier and
faster are needed.

19. Acknowledgments
• University of Washington
Najafian Lab:
Brent Fall
Cindy Tower
Cecilia Ponchiardi
Alex Sokolovsky
Marzieh Panahi
Ronald Scot, M.D.
Stefanie Uhrich
• University of Minnesota
Michael Mauer, M.D
Chester Whitley, M.D, Ph.D.
• University of Alabama
David Warnock, M.D.
• Gnzyme
Daniel Gruskin
Miriam Gannon
Sincere thanks to all patients who volunteered in these studies!