Hematopoietic stem cell transplantation (HSCT) is the last and only hope for a cure for many patients with leukemia, lymphoma or severe immunodeficiencies. Following aggressive chemotherapy or radiotherapy - which destroys the patient's own bone marrow and therefore their immune system - healthy stem cells are transplanted to build up a new, functioning immune system.
These stem cells can come from the patient themselves (autologous) or from a donor (allogeneic). In both cases, they often have to be cryopreserved: The time between collection and transplantation can be days, weeks or months. And during this entire period, the quality of the cryopreservation determines whether the stem cells can develop their full regenerative power after thawing - or whether the patient receives a transplant with suboptimal cell quality.
In this article, we outline the path of the stem cells and show which cryotechnology makes the critical difference at each stage.
In most cases today, stem cells are obtained from peripheral blood by apheresis. The donor receives the growth factor G-CSF in advance, which mobilizes the stem cells from the bone marrow into the blood. They are then filtered out of the blood using an apheresis device.
In certain cases, stem cells are taken directly from the bone marrow - a surgical procedure under anesthesia in which the marrow is aspirated from the iliac crest.
After collection, the stem cells are processed in the laboratory: unwanted cells are removed, the CD34+ cells (the actual stem cells) are quantified, and a cryoprotectant (typically DMSO at a concentration of 10%) is added.
The freezing process in the controlled rate freezer is the most critical moment. The standard cooling rate is -1°C/min up to a final temperature of -80°C to -120°C before the samples are transferred to the nitrogen tank. The TC-Active function of the BIOFREEZE® is particularly valuable here: it automatically compensates for the crystallization heat and prevents the dreaded temperature rise that would reduce cell viability.
Autologous stem cells are often collected prior to aplasive chemotherapy and cryopreserved for the duration of treatment - typically a few weeks. In the case of allogeneic transplants, the storage period can be significantly longer, especially if the patient requires further conditioning prior to transplantation.
If collection and transplantation take place at different locations, the cryopreserved stem cells must be transported safely. Dry Shippers from the Consarctic® ASR+ series are optimized for this purpose: they maintain temperatures below -150°C for several days and are approved for air transport as non-hazardous goods.
On the day of transplantation, the stem cell bags are quickly thawed in a 37°C water bath and infused intravenously into the patient. The speed of thawing is critical: the faster, the less recrystallization, the higher the cell viability.
Before infusion, a sample of the thawed product is tested for cell count, viability and sterility. The results of this quality control are directly dependent on the quality of the entire previous process - from freezing to storage and transportation.
Consarctic® supplies transplant centers and stem cell banks across Europe with cryotechnology that meets the highest regulatory and clinical requirements. Our portfolio includes all elements of the stem cell cold chain: freezers, storage tanks, transport containers and monitoring systems.
Are you running a stem cell transplant program or planning to establish one? Contact our experts for a comprehensive consultation on the cryogenic infrastructure of your program.