Autologous Bone Marrow Transplantation - Blog Science Connections

Peripheral Stem Cell Transplantation 623
platelets, respectively. Follow-up has been too short to assess long-term
engraftment.
Patient 7 had about 600 leukocytes on day 26 and still needed regular
platelet support.
DISCUSSION
To be successful, blood stem cell transplantation to restore hematopoietic
function after myeloablative treatment has to fulfill two major
requirements: first, hematopoietic reconstitution (including the lymphopoietic
system) must be complete; and second, the reconstituted hematopoietic
function must be permanent. In our two patients who received
transplanted hematopoietic precursor cells in excess of 2 x 10 4
CFCI-GM/kg
b.w., hematopoietic recovery occurred very rapidly and resulted in complete
and permanent trilineage reconstitution. Peripheral blood counts reached
normal values within less than 2 weeks. Both patients were in a condition to
be discharged from the hospital 3 weeks posttransplantation. Although the
total number of CFCI-GM transfused per kilogram of body weight differed by a
factor of 3.5, there was no significant difference in the kinetics of cellular
reconstitution (Figs 2 and 3). Follow-up at 21 + and 10+ months after ABSCT
showed normal peripheral blood counts and normal bone marrow cellularity
in both patients. This demonstrates that blood-derived stem cells autotransfused
after myeloablative treatment are capable of sustaining long-term
hematopoiesis.
In five patients transplanted with 0.4 x 10 4 to 1.6 x 10 4 CFCI-GM/kg b.w.,
hematopoietic recovery after myeloablative therapy and ABSCT was variably
delayed except in patient 6. Patients 3 and 4 stayed thrombocytopenic for 4
and 2 months after ABSCT and at last follow-up, still needed platelet support
once a week. Both had about 1600-2300 leukocytes. Patients 5 and 6 who
received only 0.67 and 0.75 x 10 4 CFCI-GM/kg b.w. but high numbers of 7.5
and 5.8 x 10 8
mononuclear cells per kilogram of body weight had good early
reconstitution, despite receiving such low numbers of CFG-GM. Long-term
reconstitution remains to be evaluated.
Thus the minimal number of CFCI-GM needed for safe engraftment
seems to be in the range of 1 x 10 4 /kg b.w., a stem cell dose that is confirmed
by data in the canine blood stem cell transplantation model (28).
To the best of our knowledge, another 25 cases of ABSCT have been
reported from seven other centers (10-19; see also the aforementioned
Reiff ers et al. chapter in this volume) (Table 2). Patients who survived ABSCT
for more than 4 months showed complete hematopoietic engraftment; stable
engraftment has also been noted by Reiffers and Broustet (11), Bell et al. (10),
Juttner et al. (13), Castaigne et al. (15,16), and by Tilly et al. (17) with a
follow-up of 4+to 12+ months (median, 8+months). The CFCI-GM transfused
per kilogram of body weight in those studies ranged from 2.3 x 10 4
to 23 x
10 4 .