StemCell Therapy

Peripheral blood stem cell transplantation (PBSCT), also called "Peripheral stem cell support",[1] is a method of replacing blood-forming stem cells destroyed, for example, by cancer treatment. PBSCT is now a much more common procedure than its bone marrow harvest equivalent, this is in-part due to the ease and less invasive nature of the procedure.[2][3] Studies suggest that PBSCT has a better outcome in terms of the number of hematopoietic stem cell (CD34+ cells) yield.[4]

Immature hematopoietic stem cells in the circulating blood that are similar to those in the bone marrow are collected by apheresis from a potential donor (PBSC collection). The product is then administered intravenously to the patient after treatment. The administered hematopoietic stem cells then migrate to the recipient's bone marrow, a process known as stem cell homing, where the transplanted cells override the previous bone marrow. This allows the bone marrow to recover, proliferate and continue producing healthy blood cells.

The transplantation may be autologous (an individual's own blood cells saved earlier), allogeneic (blood cells donated by someone else with matching HLA), or syngeneic (blood cells donated by an identical twin). The apheresis procedure typically lasts for 46 hours, depending on the donor's total blood volume.[5]

Granulocyte colony stimulating factor (GCSF) are naturally occurring glycoproteins that stimulate white blood cell proliferation. Filgrastim is a synthetic form of GCSF produced in E.coli.[6] PBSC donors are given a course of GCSF prior to PBSC collection, this ensures a better outcome, as stem cell proliferation increases, thus increasing the number of peripheral stem cells in circulation.The course is usually given over a 4-day period prior to PBSC collection.[7] Mild bone pain usually results due to the excessive stem cell crowding within the bone marrow.

Since allogeneic PBSCT involves transformation of blood between different individuals, this naturally carries more complications than autologous PBSCT.[8]For example, calculations must be made to ensure consistency in the amount of total blood volume between the donor and recipient. If the total blood volume of the donor is less than that of the recipient (such as when a child is donating to an adult), multiple PBSCT sessions may be required for adequate collection. Performing such a collection in a single setting could result in risks such as hypovolemia, which could lead to cardiac arrest, thus health care providers must exercise careful precaution when considering donor-recipient matching in allogeneic PBSCT[9]

An early example of a successful peripheral stem cell transplant was carried out in the wake of the 1999 Tokaimura nuclear accident. One of the two technicians who received the highest dose of radiation was treated with PBSCT in an attempt to restore his destroyed immune system. Cells from the patient's sister's bone marrow were administered, and in the following weeks successfully began dividing and differentiating into leukocytes, but several weeks later, the cells were found to have been mutated by the radiation still present within the patient's body, and were observed carrying out autoimmune responses.[10] Later studies on the incident and subsequent use of PBSCT found that the transplant had also induced neoendothelialization of the aortic endothelium.[11]

This article incorporatespublic domain material from the U.S. National Cancer Institute document "Dictionary of Cancer Terms".

Originally posted here:
Peripheral stem cell transplantation - Wikipedia

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