Sorting of hematopoietic progenitors for use in transplant is very
intriguing. A growing body of evidence has shown that tumor cells can
contaminate the cell collections and contribute to disease relapse
post-transplant. Purifying CD34+ cells could help improve disease-free
survival in breast cancer, lymphomas, and various solid tumors. Probably
not useful for most leukemias since the tumor cells may express the CD34
antigen.
I know of no published papers on the subject of flow sorting of CD34+ cel=
ls
for transplant. Problem is cell numbers. An average peripheral blood
apheresis has 4x10e10 nucleated cells. CD34% of the product is around
1-5%. Sorting of the apheresis collection at 10,000 cells/sec will take
over 3 weeks to complete. I've heard some claims that some special sorte=
rs
can operate efficiently at 100,000 cells/sec. Still 3 days. Bone marrow
harvests have 1 log less cells but many centers are getting away from usi=
ng
the cells since the collection procedure is more difficult on the patient
and clinical staff.
A number of biotech companies have developed immunological separation
methods such as immunoabsorption (Cellpro) and immunomagnetic (Baxter).=20
These procedures take about 3-4 hours, can achieve 90-99% purities and
around 50-60% yields.=20
I've heard of plans from some biotech companies interested in gene therap=
y
to enrich the CD34+ cells from PB or BM using one of these
immunomethodologies. Then use a cell sorter on the selected product to
sort out the pluripotent hematopoietic stem cells (CD34+,CD38-,CD90+).=20
Whole process can probably be done in a day. To get the flourescent
antibodies off of the cell surface, culture overnight at 37=B0C.
Tim Farley
Hematopoietic Stem Cell Lab
NY Blood Center
tfarley@computer.net
----------
> From: Lucia Mariano da Rocha Silla <silla@conex.com.br>
> To: Cytometry Mailing List <cytometry@flowcyt.cyto.purdue.edu>
> Subject: CD34 cells separation
> Date: Monday, July 28, 1997 6:26 PM
>=20
>=20
> Dear all!
> Is there anyone with informations about CD34s separation by flow for
> transplantation? I am very much interested in learn how to do that. Tha=
k
you
> very much.
>=20
> Lucia Silla
> Laborat=F3rio de Hematologia Celular
> Faculdade de Medicina
> Pontificia Universidade Catolica
> Porto Alegre - RS. BRAZIL
>=20