Answer:

Collecting biological samples or manipulating them inherently carries a risk of microbial contamination. Microorganisms are ubiquitous: in the air, on equipment surfaces, instruments, technicians, and patients.

To reduce the risk of infection, strict environmental control and thorough training of medical staff in aseptic techniques are essential. For liquid samples like cord blood, if microbial contamination occurs, the sample must be discarded. For solid samples such as tissues, they undergo a cell culture and isolation process. Cells harvested from these tissues are tested for sterility before cryopreservation; contaminated samples are also discarded.

Immediately after birth, cord blood or umbilical cord tissue samples are collected using sterile, single-use instruments, following strict infection control protocols. The samples are then placed in a specialized, sealed identification system and transported to the laboratory under controlled conditions.

At the lab, samples are received and inspected for packaging integrity, identification information, and transport conditions before processing.

After collection, stem cell samples are transported quickly to the lab and processed within a maximum of 24 h. This is a crucial factor, as a shorter time from collection to processing results in a higher cell viability rate. While some stem cell banks globally allow this period to extend to 48 h, the priority is to process samples as early as possible to optimize their quality.

For hematopoietic stem cells from cord blood, samples are processed using an automated system, supplemented with cryoprotectant solution, then transferred to a standardized programmed cooling system. The cooling protocol is specifically researched for each cell type to ensure optimal viability after thawing.

Mesenchymal stem cells from umbilical cord tissue, after collection, are cultured using a tissue fragment culture method, then harvested and stored similarly. Crucially, cells are stored at an early passage (typically P1) to ensure optimal quality.

Medical staff check the quality of the stem cell population at the Stem Cell Center. Illustration: Tam Anh General Hospital

At Tam Anh Hospital, all supplies and reagents used during processing comply with U.S. Food and Drug Administration (FDA) guidelines to ensure cells are suitable for clinical use. Before storage, samples undergo quality control checks based on criteria such as cell count, cell identification, viability, and sterility.

For cultured cells, the quality assurance process also includes mycoplasma testing and karyotype analysis. Sterility testing is performed according to European Pharmacopoeia standards, with a culture period of up to 14 days (longer than the usual three to 5 days) to detect even slow-growing or very low-density microorganisms.

Doctor Tham Thi Thu Nga

Head of Lab - Stem Cell Center

Tam Anh General Hospital System