June 22, 2024
Cell Processing

Cell Processing: The Journey of Cells from Collection to Application

Collection of Source Cells

The first step in cell processing begins with collecting the source cells from donors. For certain applications like regenerative therapies, adult stem cells are collected from bone marrow or fat tissue. Bone marrow collection is typically done from the back of the hip bone using a specialized needle. Fat tissue containing stem cells is collected via liposuction. For other applications, cells may be taken from umbilical cord blood or peripheral blood. Stringent health screening and testing of donors is carried out to ensure the harvested cells are safe and free of infectious agents and genetic diseases.

Isolation and Enrichment of Target Cell Population

Once collected, the heterogeneous Cell Processing population obtained from the source tissues requires further processing to isolate and enrich the target cell type. For isolating mesenchymal stem cells from bone marrow or fat, the collected tissue is broken down into a single cell suspension and cultured. The stem cells stick to the surface of the culture flask due to their adhesive properties, while other cells such as red blood cells are removed with medium changes. This allows selective expansion of the stem cell population over multiple passages.

Similarly, CD34 positive hematopoietic stem cells are isolated from umbilical cord blood or peripheral blood through immunomagnetic separation techniques. In this method, antibodies targeting the CD34 cell surface marker are used to magnetically label and separate out the stem cells from other cells lacking this marker. The isolated population can then be cryopreserved for future therapeutic use.

Cell Expansion and Amplification

The isolated target cell population often needs to be expanded extensively ex vivo to obtain sufficient cell numbers required for clinical applications. This involves culturing the cells under optimal conditions in bioreactors to induce proliferation. Key factors like growth factors, scaffold materials and physiochemical parameters of oxygen, temperature, pH and nutrition are carefully controlled. Stem cells have the unique ability to self-renew while also differentiating into other cell types. By maintaining them under undifferentiated conditions, their expansion can be amplified over many population doublings.

Characterization and Quality Control Testing

Stringent quality testing and release criteria need to be fulfilled before cells can be approved for clinical use. Multiple assays are performed at various stages to characterize cell identity, purity, potency and viability. Molecular assays employing techniques like flow cytometry, PCR and microscopy help identify cell surface and intracellular markers confirming the purified cell population. Sterility testing rules out bacterial, fungal or mycoplasma contamination acquired during processing. Mycoplasma is of special concern as it can persist intracellularly undetected. Purity levels, long-term proliferation and differentiation potential into multiple cell lineages assessed in vitro and in vivo characterize the stemness and therapeutic potency of expanded cells. Only cell batches fulfilling pre-defined release specifications are cleared for clinical administration.

Formulation and Delivery

The final stage of cell processing involves formulation of purified, expanded and well-characterized cells into an appropriate delivery vehicle suitable for the intended application route – intravenous, intra-arterial, intrathecal etc. For certain applications, cells need to be encapsulated within biomaterial scaffolds or microcarriers to aid targeted delivery, engraftment and function at the site of injury or disease. Depending on the therapy, cells may be administered as a suspension, encapsulated within hydrogels or 3D printed scaffolds. Additional factors like dose, viability and sterility are controlled as per regulatory standards during formulation and packaging. Finally, quality assurance procedures ensure proper labelling, storage and distribution of the final cell therapy product under regulated environmental conditions till point of clinical administration.

cell processing encompasses a series of meticulous upstream and downstream stages from donor screening and source cell collection, to target cell isolation and amplification, thorough characterization and quality control testing before final formulation and delivery of cells as a therapeutic product. Advanced technologies and stringent quality systems have enabled translation of several cell therapies from lab to clinical setting. However, continuous innovation remains essential to address challenges in large-scale, GMP compliant manufacturing as the field of regenerative medicine evolves rapidly.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it