Instructions for Tumour Tissue Collection, Storage and Dissociation

Tumor tissue makes for highly valuable sample material. Samples are treated with utter care to prevent, for instance, sample degeneration or unwanted cell activation. Effective tumor tissue collection, storage, and dissociation are critical components in cancer research and clinical diagnostics. High-quality samples enable reliable data for understanding tumor biology, testing therapies, and developing personalized medicine.

Preparation for Tumor Tissue Collection

Before collection, meticulous preparation is vital. Establishing a sterile environment minimizes contamination risks and preserves sample viability. Comprehensive considerations should include the following:

• Sample selection. Researchers should select tumor specimens that are representative of the disease state to ensure the relevance of experimental results.
• Sterile equipment. Use sterile collection containers, forceps, and scalpels to minimize the risk of contamination.
• Preservation solutions. Prepare cold transport media or preservation solutions to maintain tissue viability during transport.

Tumor Tissue Collection Techniques

The choice of collection technique heavily influences the quality and applicability of the tissue samples. Surgical resection and biopsy techniques are utilized. In cases where tumors are surgically excised, the collection must occur promptly. Biopsies, either needle or excisional, provide valuable tissue with minimal invasiveness.

• Minimize the time between excision and stabilization in preservation media to limit ischemic changes.
• Use clean margins to ensure that the collected tissue is representative of the tumor's histology.
• Core needle biopsy allows for deeper penetration and larger samples, which can be especially beneficial for tumors that are not easily accessible.
• Fine needle aspiration (FNA) is less invasive, making it suitable for superficial tumors. While it yields smaller samples, proper technique can capture sufficient cellular material for diagnostic purposes.

Immediate Post-Collection Handling

Proper handling immediately after collection is crucial to maintaining sample integrity. Key considerations include:

• Transport conditions. Tumor tissues should be transported in an appropriate medium, such as saline or specialized preservation solutions, and kept at physiological temperatures to reduce metabolic activity.
• Time management. Aim to process or refrigerate the samples within 30 minutes of collection to minimize decomposition and enzymatic degradation.

Tumor Tissue Storage Techniques

Before freezing, divide tissue into 10-30 mg portions for most tissues (e.g. spleen, liver, kidney, brain), or 60 mg portions for tissues with low nuclei content relative to tissue mass. Tissues with higher nuclei content relative to tissue mass: spleen, brain, liver, lung, kidney, thyroid, colon, bladder, ovary, testes, colon, prostate, and most breast tissue. Tissues with lower nuclei content relative to tissue mass: some fatty tissues, including fatty breast tissue, and most skeletal muscle.

Short-term storage

For interim storage, maintaining the tissue at 4°C is advisable. This approach is suitable for samples that will be processed within a few hours. However, samples should not exceed 24 hours at these temperatures to prevent degradation.

Long-term storage

For extended preservation, cryopreservation is the preferred strategy. Important steps include:

• Flash freezing. This process rapidly lowers the tissue temperature to prevent ice crystal formation, which can damage cellular structures. Techniques involve immersing samples in liquid nitrogen or using specialized cryopreservation containers.
• Storage in liquid nitrogen. For optimal preservation, samples should be stored in liquid nitrogen tanks at temperatures below -150°C, effectively halting all biological activity.

Tumor Tissue Dissociation Techniques

Enzymatic dissociation

Utilizing enzymes such as collagenase or dispase can facilitate the breakdown of extracellular matrices, allowing for easier cell retrieval. This technique is preferred for its ability to maintain cell viability post-dissociation.

Mechanical dissociation

For larger fragments or more fibrous tissues, mechanical dissociation methods may be employed.

• Homogenization. This technique uses mechanical devices to shear tissue apart, suitable for obtaining large quantities of cells from solid tumors.
• Manually slicing. For certain applications, manually slicing and physically breaking up the tissue may yield adequate results without the risks associated with enzymatic treatments.

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