Hematopoietic Stem Cell Transplantation
Definition
Hematopoietic stem cell transplantation (HSCT) involves the intravenous infusion
of autologous or allogenic stem cells collected from bone marrow, peripheral
blood, or umbilical cord blood to re-establish hematopoietic function in patients
with damaged or defective bone marrow or immune systems. HSCT, as used
here, is a general term covering transplantation of progenitor/stem cells from any
source (eg, bone marrow, peripheral blood, cord blood).
The following conditions are also treated with HSCT:
• Scleroderma
• Aplastic anemia
• Thalassemia
• Sickle cell anemia
• Neuroblastoma
• Testicular carcinoma
• Malignant melanoma
• Soft tissue sarcoma
• Small cell lung cancer
• Colon cancer
• Ovarian cancer
• Uterine cancer
• Severe combined immunodeficiency disorders
Autologous transplantation
Generally, candidates for autologous transplantation have no demonstrable
malignancy in the blood or bone marrow. Whereas treatment-related morbidity
and mortality rates are lowest with autografts, the major problem is tumor
relapse. This finding relates to the absence of a graft versus tumor effect (ie,
immunologic attack on the tumor by immunocompetent T cells and natural killer
cells in the donor graft) and the reinfusion of occult tumor in the graft.
Peripheral blood
Hematopoietic stem cells circulate in blood and can be identified and quantified
using flow cytometry (cells express the CD34 antigen). Administration of
recombinant hematopoietic growth factors (ie, granulocyte colony-stimulating
factor, granulocyte-macrophage colony-stimulating factor) to patients or donors
releases marrow stem cells into the peripheral blood, which can be collected
from the veins of the patient or donor.
Apheresis instruments, similar to those used for collecting platelet concentrates
from volunteer donors for transplantation, are used in an ambulatory setting.
Using this technique, during a 3- to 4-hour period, approximately 1 log more
hematopoietic progenitors can be collected than in a bone marrow harvest.
Furthermore, the need for general anesthesia and a sterile operating room is
eliminated. This process, known as mobilization of stem cells, may be enhanced
in patients destined for autografts in whom exposure to cytotoxic drugs (eg,
cyclophosphamide) plus hematopoietic growth factor therapy causes the release
of 10 times as many (or more) primitive hematopoietic progenitors into the
circulation than the recombinant cytokines alone.
The use of peripheral blood rather than bone marrow as a source of
hematopoietic stem cells results in the collection of more CD34+ progenitor cells
and faster marrow recovery (ie, 2 wk vs 4 wk for neutrophil, platelet, and RBC
counts). In the autologous setting, most transplantation groups use PBPCs in the
majority of settings. In the allogeneic setting, the situation is considerably more
complex. The optimal product has yet to be determined with respect to the use of
bone marrow versus PBPCs. As previously mentioned, PBPCs engraft more
rapidly than bone marrow, but the increased T-cell load may result in higher rates
of (Graft Versus Host Disease) GVHD, particularly chronic GVHD.
Definition
Hematopoietic stem cell transplantation (HSCT) involves the intravenous infusion
of autologous or allogenic stem cells collected from bone marrow, peripheral
blood, or umbilical cord blood to re-establish hematopoietic function in patients
with damaged or defective bone marrow or immune systems. HSCT, as used
here, is a general term covering transplantation of progenitor/stem cells from any
source (eg, bone marrow, peripheral blood, cord blood).
The following conditions are also treated with HSCT:
• Scleroderma
• Aplastic anemia
• Thalassemia
• Sickle cell anemia
• Neuroblastoma
• Testicular carcinoma
• Malignant melanoma
• Soft tissue sarcoma
• Small cell lung cancer
• Colon cancer
• Ovarian cancer
• Uterine cancer
• Severe combined immunodeficiency disorders
Autologous transplantation
Generally, candidates for autologous transplantation have no demonstrable
malignancy in the blood or bone marrow. Whereas treatment-related morbidity
and mortality rates are lowest with autografts, the major problem is tumor
relapse. This finding relates to the absence of a graft versus tumor effect (ie,
immunologic attack on the tumor by immunocompetent T cells and natural killer
cells in the donor graft) and the reinfusion of occult tumor in the graft.
Peripheral blood
Hematopoietic stem cells circulate in blood and can be identified and quantified
using flow cytometry (cells express the CD34 antigen). Administration of
recombinant hematopoietic growth factors (ie, granulocyte colony-stimulating
factor, granulocyte-macrophage colony-stimulating factor) to patients or donors
releases marrow stem cells into the peripheral blood, which can be collected
from the veins of the patient or donor.
Apheresis instruments, similar to those used for collecting platelet concentrates
from volunteer donors for transplantation, are used in an ambulatory setting.
Using this technique, during a 3- to 4-hour period, approximately 1 log more
hematopoietic progenitors can be collected than in a bone marrow harvest.
Furthermore, the need for general anesthesia and a sterile operating room is
eliminated. This process, known as mobilization of stem cells, may be enhanced
in patients destined for autografts in whom exposure to cytotoxic drugs (eg,
cyclophosphamide) plus hematopoietic growth factor therapy causes the release
of 10 times as many (or more) primitive hematopoietic progenitors into the
circulation than the recombinant cytokines alone.
The use of peripheral blood rather than bone marrow as a source of
hematopoietic stem cells results in the collection of more CD34+ progenitor cells
and faster marrow recovery (ie, 2 wk vs 4 wk for neutrophil, platelet, and RBC
counts). In the autologous setting, most transplantation groups use PBPCs in the
majority of settings. In the allogeneic setting, the situation is considerably more
complex. The optimal product has yet to be determined with respect to the use of
bone marrow versus PBPCs. As previously mentioned, PBPCs engraft more
rapidly than bone marrow, but the increased T-cell load may result in higher rates
of (Graft Versus Host Disease) GVHD, particularly chronic GVHD.
| Hematopoietic Stem Cell Transplant Defined |
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| Contact brian@allyoumed.com |
| Great Video where Dr. Richard Burt, interviewed by JAMA, explains the process of immune-ablation. The disease treated is Type 1 Diabetes, but it is exactly the same procedure I underwent. It appears this procedure may be indicated for many auto-immune diseases. |
