BONE MARROW TRANSPLANT LABORATORY,
DEPARTMENT OF ANATOMICAL
& CELLULAR PATHOLOGY
Bone marrow transplantation (BMT) has its role in the treatment of a significant number of
malignancies and hereditary disorders. It is basically the transplantation of haematopoietic stem cells
(HPSC) which inherit both the proliferative (self-renewing) mechanism and the differentiative
(maturing) ability. Besides bone marrow, HPSC can be harvested in peripheral blood after cytokine
mobilization. More recently umbilical cord blood emerges as another good source of HPSC.
The first paediatric BMT in Hong Kong was performed at Prince of Wales Hospital on 6th February,
1991. Thereafter, there has been a substantial increase in the clinical application of BMT both
quantitatively and qualitatively, and the modality was recently extended to adult patients as an adjuvant
high-dose chemotherapy on 6th June, 1994.
BMT Laboratory which is just adjacent to the BMT Unit is situated at Room 225 on the second floor
of Cancer Centre, Prince of Wales Hospital. The modern and well-equipped laboratory is partitioned
into the Apheresis Room, the Cryopreservation Room and the Culture Room. It is under the auspices
of the Department of Anatomical & Cellular Pathology, The Chinese University of Hong Kong, and is
presently staffed by 1 scientific officer, 1 medical technologist, 2 medical laboratory technicians and 1
laboratory attendant.
The scope of laboratory services is very extensive and depends much on the sources (bone marrow, peripheral blood and umbilical cord blood) and the genetic nature (autologous, allogeneic and syngeneic) of the HPSC. Apart from significant commitment in the research and development of new technologies in the manipulation and processing of HPSC, the services of BMT Laboratory can be categorically tabulated as follows:
The normal working hours are 08:45 am to 5:15 pm on Mondays to Fridays, and 08:45 am to 1:00 pm
on Saturdays. For odd, yet foreseeable, laboratory services outside normal working hours on
Saturday afternoons, Sundays and public holidays, arrangements should be made with the Scientific
Officer (BMT) well in advance. Limited laboratory staff on duty roster are available for urgent
services outside normal working hours.
INQUIRIES
Scientific Officer Phone : 2632 2571
Pager : 7110 9338 #1511
Fax : 2649 7267
Medical Technologist Pager : 7110 9338 #1512
Apheresis Room Phone : 2632 1164
Cryopreservation Room Phone : 2632 1157
Culture Room Phone : 2632 1165
Buffy Coat Preparation
This is often the first step in the marrow processing. HPSC are recovered and concentrated from
the harvested marrow with simultaneously removal of significant number of red cells and reduction of
harvested bone marrow volume.
CD34+ Cell Enumeration
The total number of HPSC in allo-/auto-grafts is crucial to achieve successful marrow engraftment
and haematopoietic reconstitution. CD34 is a cellular glycoprotein found in early HPSC and
progenitors, but not in mature functional cells. Flow cytometry is currently used to assess the
percentage of CD34+ cells in marrow grafts, cytokine-mobilized peripheral blood and peripheral
blood stem cell collections.
Chimerism Study
Fluorescent in-situ hybridization of X and Y chromosomes with specific a -satellite
centromeric probes are used to monitor the chimerism of haematopoietic interphase cells after
sex-mismatched BMT. Post-BMT mixed chimerism of leukaemic patients may predict the
regeneration of autologous marrow and hence disease relapse.
Cryopreservation and Storage
Metabolism is virtually put to an halt if cells are stored properly at very low temperature. With the
use of a cryoprotectant such as 10% dimethyl sulphoxide, a controlled-rate freezer and liquid
nitrogen, bone marrow, peripheral blood stem cell collection and umbilical cord blood can be
cryopreserved and kept in liquid nitrogen at -196oC for long term storage until required for use
.
|  |
Cytogenetic Studies
Karyotyping is the traditional way to study human genetics. There are totally 46 chromosomes in
normal subjects: 22 pairs of autosomes and 1 pair of sex chromosome. Numeric and structural
abnormalities are often encountered in human malignancies. Metaphases obtained from either direct
preparation, synchronization culture, non-synchronization culture or stimulated culture of bone
marrow samples of post-BMT patients are analyzed for any chromosomal abnormalities or
aberrations.
Haematopoietic Progenitor Cell Culture
HPSC and progenitors are proliferative and can be in-vitro cultured. Haematopoietic progenitor
cell culture is a biological assay to assess the number of cells with self-renewing ability by culture in
an in-vitro environment similar to the microenvironment of marrow for 2 weeks. Colonies of more
than 40 cells are scored. Colonies derived from HPSC and progenitors can be categorized according
to the various lines of maturation and differentiation. Granulocyte-macrophage colony forming units
(CFU-GM), macrophage colony forming units (CFU-M), burst forming units of erythroid series
(BFU-E), erythroid colony forming units (CFU-E) are commonly seen.
Granulocyte-erythroid-monocyte-megakaryocyte colony forming units (CFU-GEMM) can also be
encountered.
