13 Jun Matching Immunological Stem Cells Might Reduce Rejection in a Patient
One of the biggest challenges in medicine is when something is transplanted from a somewhat compatible donor to the patient, only for the patient’s body to reject them. Stem Cell transplantation is one of them.
For instance, people who lack bone marrow stem cells would require allogeneic stem cell transplants which are stem cells that are derived from a compatible donor.
The patient would undergo a series of chemotherapy sessions and sometimes radiation therapy to not only kill of the cancer cells, but to also suppress the person’s immune system as well.
But, for some reason, there are cases where the stem cells would be rejected by the patient’s body- probably because the immune system is not as “dead” as it may seem to be given the right chemotherapy medications.
In a study published in Stem Cell Reports, donor stem cells that were derived from retinal epithelial cells- those that have matching immune proteins to those of the recipient monkey- would tolerate the incoming cells and assimilate it as if it came from the body of the recipient itself.
In a follow-up experiment, the researchers used human lymphocytes as a means to mimic the immune system of a normal person and they also used retinal cells that closely match the immune cells of that lymphocyte. Guess what? The lymphocytes didn’t attack the donated cells!
Donor cell rejection is actually one of the biggest challenges that are present in regenerative medicine. You could say that our body’s mechanism is quite strong, given that it will fend off something that doesn’t come naturally in our bodies.
The Human Leukocyte Antigen or HLA is a group of proteins that have different surfaces that the body’s immune system can identify. If the immune system finds that there are cells that do not match the usual code, then it is sure to attack it.
If the stem cells are derived from the patient itself (a process that is commonly referred to as analogous), then that would provide the best chances of assimilation and it will dramatically reduce the chances of cell rejection.
Masayo Takashi at the Riken Center for Developmental Biology uses induced pluripotent stem cells in order to create retinal pigment epithelial cells.
She does this because she wants to treat people who suffer from macular degeneration which is a common condition of vision loss in old people. Although the process of using such cells could help treat people with this condition, making sure that the cells won’t be rejected by the patient’s body is both challenging and time-consuming at the same time.
To help determine whether matched donor iPSCs might perhaps reduce the risk of rejection, Takashi and her colleagues created RPE cells from monkeys that have a nearly matched cells and they’ve transplanted it to the eyes of monkeys with damaged eyes.
They found that if the cells do not have a matched code, the bodies of the monkeys would reject them without a second thought.
This means that whether you will use stem cell transplantation in the future, that you have to make sure that the cells match when transplanted into the patient.