Tues, June 7, 2016
New stem cell technology allows procedure to be carries out between non-relatives, writes Olivia Miwil
When previously stem cells transplant can only be done between siblings, it is now possible to do it with non-blood relatives.
Kuala Lumpur Allergic and Immunology Research Centre head and pathologist Dr Masita Arip says previously stem cells are harvested from bone marrow or umbilical cord, but now it can be obtained from peripheral blood. The process is similar to donating blood in which stem cells are obtained from a patient's blood and used in bone marrow transplantation.
Dr Masita says a match between donor and recipient lies on the number of similarity of both Human Leukocytes Antigens (HLA) markers.
She says the higher both of them share similarity of the markers, the better the recipient’s body could accept the stem cells. Due to this, it is possible to have stem cells transplant between unrelated persons.
“However, the probability to have matching stem cells between two unrelated persons will be higher if more people pledge and provide their saliva samples to be typed. As such, a wider gene pool is required to find a match,” she says during a recent inaugural forum on Hematopoietic stem cell transplant awareness at Universiti Malaysia Sabah.
Those who are eligible to donate include people aged between 18 and 50, as well as free of infectious diseases or blood disorders. Potential donors will be screened further by medical doctors and will be given counselling prior to making any stem cell donation.
As of March, Malaysian Stem Cell Registry has over 26,000 databases of gene pools among stem cell donors in the country.
HLA is inherited from both parents. Therefore, a patient is more likely to have a HLA match donor among his or her siblings. If there is no HLA match siblings then a HLA match unrelated donor is sourced from the Malaysia Stem Cell Registry (MSCR).
However the probability of getting a HLA match unrelated donor from MSCR is determined by the ethnicity of the patient. The chances of getting a HLA match unrelated donor from MSCR is higher if there is a large pool of unrelated donors from similar ethnicity.
With its diverse ethnic minority and mixed marriage ethnicity compounded by the fact that only one per cent of unrelated stem cell donors in the MSCR is from Sabah, the chances of a Sabahan who requires an unrelated stem cell donor from MSCR is slim.
It is imperative for Sabahans to pledge as unrelated stem cell donor in order to expand the unrelated donor pool from Sabah in the MSCR.
Dr Masita says Malaysian Stem Cell Registry could help patients to look for other match stem cell at other countries, but the search even without being able to find the right match will cost patients a lot of money.
Thalassaemia major, severe aplastic anaemia and leukaemia are treated with stem cell transplant.
Currently, there are seven haemopoietic stem cell transplant centres in the country. They are located at Universiti Malaya Medical Centre, Universiti Kebangsaan Malaysia Medical Centre, Hospital Kuala Lumpur, Hospital Ampang, Sabah Women’s and Children’s Hospital (SWACH) and Sime Darby Medical Centre.
SWACH’s paediatric haemato-oncologist and transplant specialist Dr Asohan Thevarajah says there must be a strong indication for stem cell transplant to be carried out on a patient.
“This is because stem cell transplant is not without any complications. Both the patient and stem cell donor will undergo a pre-stem cell transplant assessment which includes clinical examination and blood investigations to ensure the safety of both.”
Other than that, the socioeconomic background of the patient and family will be evaluated especially for those who are from poor socioeconomic background and rural areas.
“They have to understand they need to stay in the stem cell ward for longer period, which can be up to two months.
“Patients and their family need to comply with the post-transplant follow-up regularly,” says Dr Asohan.
Complications that occur in stem cell transplant are due to the side effects of the drugs given during the conditioning phase before transplant. The aim of the conditioning phase is to eradicate the patient’s diseased marrow and to prevent rejection of donor’s marrow.
Some of the more common complications that may occur are alopecia, nausea, vomiting, loss of appetite, liver, kidney or cardiac dysfunction, mouth ulcers and infection especially blood infection.
Another complication that can occur is graft versus host disease (GvHD), a condition whereby donor’s white cells attack patient’s normal tissue. Acute GvHD occurs in the first 100 days post-transplant involves mostly the skin, liver or gut while for chronic condition happens after 100 days post-transplant affecting almost all organs or tissues.
“That is why patients are put on immunosuppressive drug such as ciclosporin just before transplant and up to three months to a year depending on the disease to combat GvHD,” he says.
Comments
Post a Comment